Chapter 15 Network Management
Network Management, here are some questions that may help improve Network Management Skills.
Documentation, are you doing it and is it up to date?
Baseline Measurements, what are you using for this now and how can you improve it?
Policies, Procedures, and Regulations, do you have one in place and when was the last time you reviewed it with users?
Fault and Performance Management what is your down time? How are you going to improve it?
Are you assessing and documenting the network’s status on an ongoing basis? What are the any daily routines? When was the last time you checked the event logs?
Performance management, how are you testing this?
Asset Management, can you identify and track hardware and software on your network?
Change Management, do you have the support of management, if so are you letting all users know of the changes and why?
Upgrade considerations, do you need to do it what is the compelling reason to do it? How much is it going to cost (labor, down time, etc.)?
NOS (Network Operating System) upgrades being the most critical upgrade type why are you changing?
Reversing a software upgrade, do you know how to do it prior to the upgrade?
Hardware and Physical Plant Changes, what is the compelling reason? How much is it going to cost (labor, down time, etc.)?
With network management if you are going to be a professional you need to continue to ask the obvious, WHY?
Thursday, December 3, 2009
Chapter 14 Ensuring Integrity and Availability
Chapter 14 Ensuring Integrity and Availability
CIA Triangle Confidentiality, Integrity and Availability: Three simple words with multiple meanings. Yet, one common thread unites them in the information environment to create a practical, organized approach to lowering the risks associated with managing data and systems.
Simply installing virus software is not enough you need to keep it up to date and educate your users. Watch and train users to notice and welcome them report the following symptoms:
•Unexplained file size increases
•Significant, unexplained system performance decline
•Unusual error messages
•Significant, unexpected system memory loss
•Periodic, unexpected rebooting
•Display quality fluctuations
When a user reports one of the symptoms or has heard of a virus ensure you don’t make them feel stupid for reporting otherwise they will not report it next time. As noted in security chapter 12 fifty perfect of your issues are human beings, I want the human factor on my side. Although you would like to tell them their latest issue was an “ID10T Error” hold your tongue and keyboard lashings. Mom always said, “If you don’t have something good about someone keep it to yourself”. Virus and Hoaxes users report use resources like SNOPES http://www.snopes.com/ or the knowledge database of the virus software you are running to verify legitimate viruses or Trojan viruses. A good rule of thumb/good practice is to check more than one resource to verify the information you are getting is correct. Once you have verified make sure to follow up with the user that has reported weather false or not and site your finds to them.
Fault-tolerant system goal is to prevent faults (malfunction) from progressing to failures (down) the following are items to insure you can reach your goal.
Physical environment, power techniques power backups (UPS's, Backup Generator, second power grid).
Topology and connectivity techniques dual internet/phone connections with failover techniques used in a router or firewall.
Server and storage techniques
Server mirroring is where you have an identical server in which one server continually duplicates the activities (data and transactions) of the main server.
Clustering servers is a technique that links multiple servers together to act as one server.
Storage RAID (Redundant Array of Independent [or Inexpensive] Disks) there are two differnet types hardware and software. Of the two hardware is faster and more reliable.
Different Raid Levels:
• RAIDZero means there is no redundancy the data is written across three drives. Fast however it is not fault tolerant.
• RAID level one disk mirroring the other automatically copying it to the second drive. SATA drives can write to both at the same time
• RAID Level one Disk duplexing two separate drives and two separate controllers.
• RAID Level 3 Disk Striping needs at least three drives data drive, data drive and a parity drive.
• RAID Level 5 -Disk Striping with Distributed Parity.
NAS (Network Attached Storage) is a specialized storage device group which provides centralized fault-tolerant data storage.
SANs (Storage Area Networks) Distinct networks of storage devices/servers that communicate directly with each other and other networks. Advantages are it is fast and fault tolerant. It uses special transmission methods using fiber-optic media and proprietary protocols.
Data backup Strategies:
Normal/Full: Backs up every file selected turns off A bit
Incremental: Backs up a bit files and turns off the A bit
Differential: Backs up a bit files - leaves A bit on
Copy: Backs up every file and leaves A bit on
Disaster Recovery Planning is a plan to ensure your organization is ready for a worst-case scenario disaster. Identifying and making people aware of who is on the disaster recovery team and the team members’ responsibilities. You will want contingency plans to restore and replace: Computer systems, Power, Telephony systems etc. To ensure your plan is solid stage an all systems to test (emergency outage) all systems to make sure they are working properly scheduled once a month, quarter, etc. Also when there are changes to hardware (Servers, Phones, Electrical, etc.) review your plan to ensure is has taken into account the changes.
CIA Triangle Confidentiality, Integrity and Availability: Three simple words with multiple meanings. Yet, one common thread unites them in the information environment to create a practical, organized approach to lowering the risks associated with managing data and systems.
Simply installing virus software is not enough you need to keep it up to date and educate your users. Watch and train users to notice and welcome them report the following symptoms:
•Unexplained file size increases
•Significant, unexplained system performance decline
•Unusual error messages
•Significant, unexpected system memory loss
•Periodic, unexpected rebooting
•Display quality fluctuations
When a user reports one of the symptoms or has heard of a virus ensure you don’t make them feel stupid for reporting otherwise they will not report it next time. As noted in security chapter 12 fifty perfect of your issues are human beings, I want the human factor on my side. Although you would like to tell them their latest issue was an “ID10T Error” hold your tongue and keyboard lashings. Mom always said, “If you don’t have something good about someone keep it to yourself”. Virus and Hoaxes users report use resources like SNOPES http://www.snopes.com/ or the knowledge database of the virus software you are running to verify legitimate viruses or Trojan viruses. A good rule of thumb/good practice is to check more than one resource to verify the information you are getting is correct. Once you have verified make sure to follow up with the user that has reported weather false or not and site your finds to them.
Fault-tolerant system goal is to prevent faults (malfunction) from progressing to failures (down) the following are items to insure you can reach your goal.
Physical environment, power techniques power backups (UPS's, Backup Generator, second power grid).
Topology and connectivity techniques dual internet/phone connections with failover techniques used in a router or firewall.
Server and storage techniques
Server mirroring is where you have an identical server in which one server continually duplicates the activities (data and transactions) of the main server.
Clustering servers is a technique that links multiple servers together to act as one server.
Storage RAID (Redundant Array of Independent [or Inexpensive] Disks) there are two differnet types hardware and software. Of the two hardware is faster and more reliable.
Different Raid Levels:
• RAIDZero means there is no redundancy the data is written across three drives. Fast however it is not fault tolerant.
• RAID level one disk mirroring the other automatically copying it to the second drive. SATA drives can write to both at the same time
• RAID Level one Disk duplexing two separate drives and two separate controllers.
• RAID Level 3 Disk Striping needs at least three drives data drive, data drive and a parity drive.
• RAID Level 5 -Disk Striping with Distributed Parity.
NAS (Network Attached Storage) is a specialized storage device group which provides centralized fault-tolerant data storage.
SANs (Storage Area Networks) Distinct networks of storage devices/servers that communicate directly with each other and other networks. Advantages are it is fast and fault tolerant. It uses special transmission methods using fiber-optic media and proprietary protocols.
Data backup Strategies:
Normal/Full: Backs up every file selected turns off A bit
Incremental: Backs up a bit files and turns off the A bit
Differential: Backs up a bit files - leaves A bit on
Copy: Backs up every file and leaves A bit on
Disaster Recovery Planning is a plan to ensure your organization is ready for a worst-case scenario disaster. Identifying and making people aware of who is on the disaster recovery team and the team members’ responsibilities. You will want contingency plans to restore and replace: Computer systems, Power, Telephony systems etc. To ensure your plan is solid stage an all systems to test (emergency outage) all systems to make sure they are working properly scheduled once a month, quarter, etc. Also when there are changes to hardware (Servers, Phones, Electrical, etc.) review your plan to ensure is has taken into account the changes.
Chapter 13 Troubleshooting Network Problems
Chapter 13 Troubleshooting Network Problems
If you see a bumper sticker that says, “User are losers” and you aren’t thinking about someone using drugs most likely you are a Network Administrator. Users come in many forms from button pushers, knob twisters or the indecisive user who doesn’t want to do anything that may screw up. With this in mind we need to look at every user issue as an opportunity to further the security policies, and the users’ basic understanding of the data …
Troubleshooting Methodology the following troubleshooting steps:
1. –Identify symptoms, problems
2. –Identify affected area
3. –Determine what has changed
4. –Establish most probable cause
5. –Determine if escalation necessary
6. –Create action plan, solution
7. –Implement solution, test result
8. –Identify results, effects
9. –Document solution, process
Troubleshooting Tools
Tone Generator and Tone Locator are used to located wiring from where begins to in telecommunications closet to where wire pair terminates.
Multimeters are used to tests cables for faults and measuring electric circuit characteristics (Resistance and voltage).
Cable Continuity Testers are used to tests whether cable carrying signal to destination. There are also Fiber optic continuity testers that issues light pulses onto the fiber cable to test.
Cable Performance Testers can do the same functions of a Cable Continuity tester however it is also do the following:
• Measure the distance to a connectivity device.
• Measure attenuation along a cable.
• Measure near-end cross talk between wires.
• Measure terminations resistance and impedance.
• Issue pass/fail ratings for Cat3, Cat 5, Cat 5e, Cat 6 or Cat 7 Standards.
• Store and print cable testing results or directly save data to a computer database.
• Graphically depict a cable’s attenuation and cross talk characteristics over the length of the cable.
Copper wire tester uses TDR(time domain reflectometers) where Fiber-optic connections testers use OTDRs (optical time domain reflectometers)
Voltage Event Recorders record voltage events any condition where voltage exceeds or drops below predefined levels and collects data about power quality.
Butt Set is a lineman’s handset, telephone test set giving the line man to butt into telephone conversations.
Network Monitors Software-based tools continually monitoring network traffic from server, workstation attached to network. It interprets up to Layer 3 can determine protocols passed by each frame however it cannot interpret frame data. To run it on the full network all Network adapters must support promiscuous mode. Common terms for abnormal data patterns, packets are local collisions, late collisions, runts, giants, jabber, negative frame sequence checks and ghosts.
Protocol Analyzers (network analyzer) captures traffic, analyzes frames typically to Layer 7. They have the same features as network monitor but it also generates traffic. Before using network monitor or protocol analyzer learn what network traffic normally looks like capturing data for time period on regular basis
Wireless Network Testers are tools containing wireless NICs, running wireless protocols.
If you see a bumper sticker that says, “User are losers” and you aren’t thinking about someone using drugs most likely you are a Network Administrator. Users come in many forms from button pushers, knob twisters or the indecisive user who doesn’t want to do anything that may screw up. With this in mind we need to look at every user issue as an opportunity to further the security policies, and the users’ basic understanding of the data …
Troubleshooting Methodology the following troubleshooting steps:
1. –Identify symptoms, problems
2. –Identify affected area
3. –Determine what has changed
4. –Establish most probable cause
5. –Determine if escalation necessary
6. –Create action plan, solution
7. –Implement solution, test result
8. –Identify results, effects
9. –Document solution, process
Troubleshooting Tools
Tone Generator and Tone Locator are used to located wiring from where begins to in telecommunications closet to where wire pair terminates.
Multimeters are used to tests cables for faults and measuring electric circuit characteristics (Resistance and voltage).
Cable Continuity Testers are used to tests whether cable carrying signal to destination. There are also Fiber optic continuity testers that issues light pulses onto the fiber cable to test.
Cable Performance Testers can do the same functions of a Cable Continuity tester however it is also do the following:
• Measure the distance to a connectivity device.
• Measure attenuation along a cable.
• Measure near-end cross talk between wires.
• Measure terminations resistance and impedance.
• Issue pass/fail ratings for Cat3, Cat 5, Cat 5e, Cat 6 or Cat 7 Standards.
• Store and print cable testing results or directly save data to a computer database.
• Graphically depict a cable’s attenuation and cross talk characteristics over the length of the cable.
Copper wire tester uses TDR(time domain reflectometers) where Fiber-optic connections testers use OTDRs (optical time domain reflectometers)
Voltage Event Recorders record voltage events any condition where voltage exceeds or drops below predefined levels and collects data about power quality.
Butt Set is a lineman’s handset, telephone test set giving the line man to butt into telephone conversations.
Network Monitors Software-based tools continually monitoring network traffic from server, workstation attached to network. It interprets up to Layer 3 can determine protocols passed by each frame however it cannot interpret frame data. To run it on the full network all Network adapters must support promiscuous mode. Common terms for abnormal data patterns, packets are local collisions, late collisions, runts, giants, jabber, negative frame sequence checks and ghosts.
Protocol Analyzers (network analyzer) captures traffic, analyzes frames typically to Layer 7. They have the same features as network monitor but it also generates traffic. Before using network monitor or protocol analyzer learn what network traffic normally looks like capturing data for time period on regular basis
Wireless Network Testers are tools containing wireless NICs, running wireless protocols.
Wednesday, December 2, 2009
Chapter 12 Network Security
Chapter 12 Network Security
As network technicians we all need to make sure we are aware of the threats out there and how to protect our systems from them. I find it amazing that half of the security breaches are human error, ignorance, omissions making the human factor the number one threat. Therefore the number one way to prevent it is the have a good security policy in place. Then educate our user populations on it making them aware of the threats/risks that come along with computers on a network attached to the internet. A good security policy should identify security goals, risks, authority levels, with a designated security coordinator, and team members. These need be reviewed and updated as security hardware and software change on our networks. Along with the security policy ensure strong password policies are in place and the frequency of having users changing their passwords on a regular 3 to 6 month basis.
The other fifty percent of threats and risks are associated with transmission and hardware the physical, data Link and network layers which require more technical sophistication.
Some of these risks are inherent in network hardware and design the following are examples: Network hubs broadcasting traffic over entire segment. Unused hub, switch, router, server ports not secured making private address availability to outside. Routers not properly configured to mask internal subnets or drop suspicious packets. Modems accept incoming calls access servers not secured or monitored.
Other are associated with protocols and software these include the Transport, Session, Presentation, and Application layers. Some of these risk are TCP/IP security flaws, NOS back doors, security flaws allowing server operators to exit to command prompt, leaving the administrators default security options (Factory defaults) on new hardware.
Others are associated with Internet access these can be the network security compromise more often “from the inside” web browsers permit scripts to access systems or users providing information to sites. Common Internet-related security issues are improperly configured firewalls; outsiders obtain internal IP addresses by IP spoofing, transmitting user IDs and passwords in plain text.
Another is associated with physical security locked doors restricting physical access network components at minimum. Only authorized personnel can access computer rooms, wiring closets switches, unattended logged in workstations, equipment rooms, entrance to the facility, and storage rooms.
Of course the more security conscience you need to be is determined the products or data your organization are producing or providing. If you are a manufacturer of automotive parts your security is going to be less robust compared to a banking institution or a credit card company. These are examples where you are going to use more secure encryption and authentication methods.
Encryption uses algorithms to scramble data then reads by algorithm reversal (decryption) these are a few types of encryption methods: Key Encryption weaves key into original data’s bits and generates a unique data block a key. AES (Advanced Encryption Standard) also a key encryption type that weaves 128, 160, 192, 256 bit keys through data multiple times and is a private key encryption so the sender must somehow share key with recipient. Public Key Encryption the data is encrypted using two keys a private key: user knows public key: anyone may request. PGP (Pretty Good Privacy) is a public key encryption which secures e-mail transmissions by verifying the sender authenticity, developed by Phil Zimmerman (1990s). SSL (Secure Sockets Layer) encrypts TCP/IP transmissions web pages, web form data entered into web forms. This is one you want to make sure your user population knows if they are going to be using the internet to procure over the internet via credit card. Here are a couple of more acronyms of encryption methods: SSH (Secure Shell), SCP (Secure CoPy), SFTP (Secure File Transfer Protocol), IPSec (Internet Protocol Security)
Authentication is the process of verifying a user’s credentials to grant user access to secured resources. The following are authentication protocols: PAP (Password Authentication Protocol),CHAP and MS-CHAP (Microsoft Challenge Authentication Protocol), EAP (Extensible Authentication Protocol), 802.1x (EAPoL), Kerberos.
As network technicians we all need to make sure we are aware of the threats out there and how to protect our systems from them. I find it amazing that half of the security breaches are human error, ignorance, omissions making the human factor the number one threat. Therefore the number one way to prevent it is the have a good security policy in place. Then educate our user populations on it making them aware of the threats/risks that come along with computers on a network attached to the internet. A good security policy should identify security goals, risks, authority levels, with a designated security coordinator, and team members. These need be reviewed and updated as security hardware and software change on our networks. Along with the security policy ensure strong password policies are in place and the frequency of having users changing their passwords on a regular 3 to 6 month basis.
The other fifty percent of threats and risks are associated with transmission and hardware the physical, data Link and network layers which require more technical sophistication.
Some of these risks are inherent in network hardware and design the following are examples: Network hubs broadcasting traffic over entire segment. Unused hub, switch, router, server ports not secured making private address availability to outside. Routers not properly configured to mask internal subnets or drop suspicious packets. Modems accept incoming calls access servers not secured or monitored.
Other are associated with protocols and software these include the Transport, Session, Presentation, and Application layers. Some of these risk are TCP/IP security flaws, NOS back doors, security flaws allowing server operators to exit to command prompt, leaving the administrators default security options (Factory defaults) on new hardware.
Others are associated with Internet access these can be the network security compromise more often “from the inside” web browsers permit scripts to access systems or users providing information to sites. Common Internet-related security issues are improperly configured firewalls; outsiders obtain internal IP addresses by IP spoofing, transmitting user IDs and passwords in plain text.
Another is associated with physical security locked doors restricting physical access network components at minimum. Only authorized personnel can access computer rooms, wiring closets switches, unattended logged in workstations, equipment rooms, entrance to the facility, and storage rooms.
Of course the more security conscience you need to be is determined the products or data your organization are producing or providing. If you are a manufacturer of automotive parts your security is going to be less robust compared to a banking institution or a credit card company. These are examples where you are going to use more secure encryption and authentication methods.
Encryption uses algorithms to scramble data then reads by algorithm reversal (decryption) these are a few types of encryption methods: Key Encryption weaves key into original data’s bits and generates a unique data block a key. AES (Advanced Encryption Standard) also a key encryption type that weaves 128, 160, 192, 256 bit keys through data multiple times and is a private key encryption so the sender must somehow share key with recipient. Public Key Encryption the data is encrypted using two keys a private key: user knows public key: anyone may request. PGP (Pretty Good Privacy) is a public key encryption which secures e-mail transmissions by verifying the sender authenticity, developed by Phil Zimmerman (1990s). SSL (Secure Sockets Layer) encrypts TCP/IP transmissions web pages, web form data entered into web forms. This is one you want to make sure your user population knows if they are going to be using the internet to procure over the internet via credit card. Here are a couple of more acronyms of encryption methods: SSH (Secure Shell), SCP (Secure CoPy), SFTP (Secure File Transfer Protocol), IPSec (Internet Protocol Security)
Authentication is the process of verifying a user’s credentials to grant user access to secured resources. The following are authentication protocols: PAP (Password Authentication Protocol),CHAP and MS-CHAP (Microsoft Challenge Authentication Protocol), EAP (Extensible Authentication Protocol), 802.1x (EAPoL), Kerberos.
Wednesday, November 11, 2009
Chapter 11 Voice and Video Over IP
Chapter 11 Voice and Video Over IP
IP telephony (VoIP) gives you the ability to communicate via voice and/or video using an internet connection. This is a fairly new/old technology. In reality it started with the inventors of the telephone giving us the ability to transmit voice over copper wire. In the mid 1990s companies started testing with it however due to slower internet connection and less sophisticated data compression technologies the quality of these transmissions was sub-quality. Voices were garbled and transmissions were unreliable. With current technologies the VoIP arena has taken off like a rocket and in the next few years with the current state of the world economy we will see this become more and more widely used.
My current experiences using the VoIP technologies have saved our organization time and money. Examples of this are: We have been using the Vontage service for the last 4 to 5 years to communicate with our sales people in Europe, Asia and the UK. We are currently using Webex for conference calling, web presentations along with technical support. Then for the last year we have made it a standard for managers, sales and frontline information workers to use Skype as a softphone to communicate via voice and web cam. They are using it’s instant messenger feature to ping an online colleague to see if they are available to take a Skype call. In a cost comparison we are currently moving from WebEx to MicroSoft’s Live Meeting to further cut costs and give us better capabilities with our new Polycom CX5000 video conferencing equipment. http://www.polycom.com/products/voice/conferencing_solutions/microsoft_optimized_conferencing/cx5000.html Our next project research and move our outdated Nortel phone system to a hosted solution such as Microsoft Unified communications. http://www.microsoft.com/uc/en/us/default.aspx.
IP telephony (VoIP) gives you the ability to communicate via voice and/or video using an internet connection. This is a fairly new/old technology. In reality it started with the inventors of the telephone giving us the ability to transmit voice over copper wire. In the mid 1990s companies started testing with it however due to slower internet connection and less sophisticated data compression technologies the quality of these transmissions was sub-quality. Voices were garbled and transmissions were unreliable. With current technologies the VoIP arena has taken off like a rocket and in the next few years with the current state of the world economy we will see this become more and more widely used.
My current experiences using the VoIP technologies have saved our organization time and money. Examples of this are: We have been using the Vontage service for the last 4 to 5 years to communicate with our sales people in Europe, Asia and the UK. We are currently using Webex for conference calling, web presentations along with technical support. Then for the last year we have made it a standard for managers, sales and frontline information workers to use Skype as a softphone to communicate via voice and web cam. They are using it’s instant messenger feature to ping an online colleague to see if they are available to take a Skype call. In a cost comparison we are currently moving from WebEx to MicroSoft’s Live Meeting to further cut costs and give us better capabilities with our new Polycom CX5000 video conferencing equipment. http://www.polycom.com/products/voice/conferencing_solutions/microsoft_optimized_conferencing/cx5000.html Our next project research and move our outdated Nortel phone system to a hosted solution such as Microsoft Unified communications. http://www.microsoft.com/uc/en/us/default.aspx.
Thursday, November 5, 2009
Chapter 10 In-Depth TCP/IP Networking
Chapter 10 In-Depth TCP/IP Networking
Designing TCP/IP-Based Networks
Most Modern networks rely on the TCP/IP suite for transmitting data over private connections along with internet/public connectivity.
Subnetting is used to separate networks that logically defined segments (subnets) geographically, departmentally, technologically. This enhances security, improves performance along with simplifying troubleshooting. The following will address the techniques to set up a TCP/IP based network.
Classful Addressing in IPv4 addresses are made up of four 8-bit octets binary or dotted decimal. It is the simplest, and adheres to network class distinctions (Class A, B, and C). The address consists of network and host information. The follow is an example of an address from each class how it is broken down into the bit level (1 = on, 0 =off) and then broken down in to the network and host information.
Class A 114.150.129.67 = 01110010. 10100000.1000001.010000011
Class B 150.129. 151.131 = 10100000.100000001. 10100001.100000011
Class C 192.128.65.115 = 11000000.1000000.010000001.0111oo11
•Network information (network ID)
–First 8 bits in Class A address 01110010 = 114
–First 16 bits in Class B address 10100000.100000001 =150.129
–First 24 bits in a Class C address 11000000.1000000.010000001 = 192.128.65
•Host information
–Last 24 bits in Class A address 10100000.1000001.010000011 = 150.129.67
–Last 16 bits in Class B address 10100001.100000011 =151.131
–Last 8 bits in Class C address 01110011 = 115
I finally have a pretty good idea of how the binary numbers work to make up the octets of IP addressing and the following helped me understand how it works. Maybe it will help you.
1 1 1 1 1 1 1 1
128 64 32 16 8 4 2 1
00000001 = 1
00000011 = 3
00000111 = 7
00001111 = 15
00011111 = 31
00111111 = 63
01111111 = 127
11111111= 255
11111110 = 254
111111100 = 252
111111000 = 248
11110000 = 240
11100000 = 224
11000000 = 192
10000000 = 128
IPv4 Subnet Masks identifies how network subdivided and indicates where network information located. Each network class (A, B, C) is associated with a default subnet mask of 255 or in binary 11111111. As noted early the network information in each class is represented in the first 8 bits for class A… therefore following represents the subnet masks for each class
Class A 255.0.0.0 = 11111111. 00000000.00000000.00000000
Class B 255.255.0.0 = 11111111. 1111111.00000000.00000000
Class C 255.255.255.0 = 11111111.11111111.11111111.00000000
To come up with the network ID we then need to combine the bits.
•Bit value of 1 plus another bit value of 1 results in 1
•Bit value of 0 plus any other bit results in 0
As an example let’s use the Class C IP address from above and combine it with the subnet mask to get it Network ID
Class C Address 192.128.65.115 = 11000000.1000000.010000001.0111oo11
Class C Subnet Mask 255.255.255.0 = 11111111.11111111.11111111.00000000
Network ID: =192.128.65.0 = 11000000.10000000.010000001.00000000
Reserved Addresses cannot be assigned to node network interface or be used as subnet masks. Network ID bits available for host information set to 0 therefore a host address cannot be set to zero 192.128.65.0 and also can’t be set to the broadcast address of 11111111 or 255. 0-255 equals 256 combinations however we need to subtract 2 address (0 & 255) equaling 254 addresses available for that Class C network. (Class C 2 to the 8 = 256-2 =254)
IPv4 Subnetting Techniques breaking the classful IPv4 addressing rules. IP address bits representing host information change to represent network information. As you increase the number of subnets you reduce usable host addresses per subnet.
Calculating IPv4 Subnets
Formula: 2n−2=Y (n) is number of subnet mask bits needed to switched from 0 to 1 and y represents the number subnets. We need to – 2 because of the reserved addresses noted above.
Example of a Class C with the Network ID: 199.34.89.0 divided into six subnets: 6=2 (power of) N- 2 or 8 = 2(power of) 3 there for the bits borrowed are 3 so the subnet mask is made up of the first 27 bits.
11111111.11111111.1111111.11000000 or 255.255.255.224
Using 27 of the 32 bits available you are left with the five last bits (00011111) adding them up you get 31 = (16 + 8 + 4 + 2 +1). However, you still have the two reserved for Network ID and Broadcast so you only end up with 30 hosts each of the 6 subnets.
Extended network Prefix Broadcast Address Usable hosts
199.34.89.32 199.34.89.63 199.34.89.33-62
199.34.89.64 199.34.89.95 199.34.89.65-94
199.34.89.96 199.34.89.127 199.34.89.97-126
199.34.89.128 199.34.89.159 199.34.89.129-159
199.34.89.160 199.34.89.191 199.34.89.33.161-190
199.34.89.192 199.34.89.223 199.34.89.193-222
CIDR (Classless Interdomain Routing) AKA SUPER Networking were as in Subnet you remove the bits to the right to create more subnets into CIDR you move them to the left to create more useable IP addresses on your net work.
Example of a class C with the Network ID: 199.34.89.0/22 is use the CIDR notation (or slash notation) Network ID followed by forward slash ( / ), followed by number of bits used for extended network prefix. This changes your subnet mask to 255.255.252.000 from 255.255.255.000increasing your host addresses from 254 to 1022.
Internet Gateway facilitates communication between different networks and subnets. A default gateway first interprets its outbound requests to other subnets, and then interprets its inbound requests from other subnets.
NAT (Network Address Translation) allows you to hide internal/private IP addresses from the outside internet. The gateway provides valid internet addresses when sending transmissions to the internet.
SNAT (Static Network Address Translation) establishes a one to one correlation between each IP address and internet IP address.
DNAT (Dynamic Network Address Translation) AKA IP masquerading allows one or more IP addressed to be shared with multiple clients.
TCP/IP Mail Services are the most frequently used internet service to deliver, store, and communicate with other mail servers.
SMTP (Simple Mail Transfer Protocol) is responsible for moving messages from one mail server to another over TCP/IP-based networks operating at Application layer and replies on TCP at Transport layer over port 25.
MIME (Multipurpose Internet Mail Extensions) delivers the SMPT drawback of 1000 ASCII character limit. It also encodes, interprets binary files, images, video, non-ASCII character sets within e-mail message. It does not replace SMTP and works in conjunction with it.
POP (Post Office Protocol) the user retrieves messages from mail server. It is like the postal worker it brings the mail to your house and leaves it there. With this is mind you should only retrieve form one computer one mailbox.
IMAP (Internet Message Access Protocol) IMAP4 is the current version where E-mail stays on server after retrieval. Users can retrieve all or portion of mail message create delete when offline and update with the server when an internet connection is established.
TCP/IP Tools/Utilities to help track down most TCP/IP related problems discovering information about node, network
Ipconfig (Windows) and Ifconfig (UNIX)
Command-line utility to identify and change network adapter information (IP address, subnet mask, default gateway)
Netstat Displays TCP/IP statistics, component details, host connections and active TCP/IP connections on node
Nbtstat utility provides information about NetBIOS statistics along with resolving NetBIOS names to IP addresses. It is useful on Windows-based operating systems and NetBIOS
Hostname is a utility provides client’s host name.
Host utility to learn the IP address from host name.
Nslookup is used to query DNS database from any network computer and can find the device host name by specifying its IP address.
Dig (Domain information groper) similar to nslookup where it queries a DNS database and to find a specific IP address host name. Useful for diagnosing DNS problems and provides more detailed information than nslookup
Whois Query DNS registration database to obtain domain information
Troubleshoot network problems. Syntax: whois xxx.yy
Traceroute give you the ability to trace the path from one networked node to another identifying all intermediate hops between the two nodes using either IP address or host name.
Windows-based systems: tracert
Linux systems: tracepath
Designing TCP/IP-Based Networks
Most Modern networks rely on the TCP/IP suite for transmitting data over private connections along with internet/public connectivity.
Subnetting is used to separate networks that logically defined segments (subnets) geographically, departmentally, technologically. This enhances security, improves performance along with simplifying troubleshooting. The following will address the techniques to set up a TCP/IP based network.
Classful Addressing in IPv4 addresses are made up of four 8-bit octets binary or dotted decimal. It is the simplest, and adheres to network class distinctions (Class A, B, and C). The address consists of network and host information. The follow is an example of an address from each class how it is broken down into the bit level (1 = on, 0 =off) and then broken down in to the network and host information.
Class A 114.150.129.67 = 01110010. 10100000.1000001.010000011
Class B 150.129. 151.131 = 10100000.100000001. 10100001.100000011
Class C 192.128.65.115 = 11000000.1000000.010000001.0111oo11
•Network information (network ID)
–First 8 bits in Class A address 01110010 = 114
–First 16 bits in Class B address 10100000.100000001 =150.129
–First 24 bits in a Class C address 11000000.1000000.010000001 = 192.128.65
•Host information
–Last 24 bits in Class A address 10100000.1000001.010000011 = 150.129.67
–Last 16 bits in Class B address 10100001.100000011 =151.131
–Last 8 bits in Class C address 01110011 = 115
I finally have a pretty good idea of how the binary numbers work to make up the octets of IP addressing and the following helped me understand how it works. Maybe it will help you.
1 1 1 1 1 1 1 1
128 64 32 16 8 4 2 1
00000001 = 1
00000011 = 3
00000111 = 7
00001111 = 15
00011111 = 31
00111111 = 63
01111111 = 127
11111111= 255
11111110 = 254
111111100 = 252
111111000 = 248
11110000 = 240
11100000 = 224
11000000 = 192
10000000 = 128
IPv4 Subnet Masks identifies how network subdivided and indicates where network information located. Each network class (A, B, C) is associated with a default subnet mask of 255 or in binary 11111111. As noted early the network information in each class is represented in the first 8 bits for class A… therefore following represents the subnet masks for each class
Class A 255.0.0.0 = 11111111. 00000000.00000000.00000000
Class B 255.255.0.0 = 11111111. 1111111.00000000.00000000
Class C 255.255.255.0 = 11111111.11111111.11111111.00000000
To come up with the network ID we then need to combine the bits.
•Bit value of 1 plus another bit value of 1 results in 1
•Bit value of 0 plus any other bit results in 0
As an example let’s use the Class C IP address from above and combine it with the subnet mask to get it Network ID
Class C Address 192.128.65.115 = 11000000.1000000.010000001.0111oo11
Class C Subnet Mask 255.255.255.0 = 11111111.11111111.11111111.00000000
Network ID: =192.128.65.0 = 11000000.10000000.010000001.00000000
Reserved Addresses cannot be assigned to node network interface or be used as subnet masks. Network ID bits available for host information set to 0 therefore a host address cannot be set to zero 192.128.65.0 and also can’t be set to the broadcast address of 11111111 or 255. 0-255 equals 256 combinations however we need to subtract 2 address (0 & 255) equaling 254 addresses available for that Class C network. (Class C 2 to the 8 = 256-2 =254)
IPv4 Subnetting Techniques breaking the classful IPv4 addressing rules. IP address bits representing host information change to represent network information. As you increase the number of subnets you reduce usable host addresses per subnet.
Calculating IPv4 Subnets
Formula: 2n−2=Y (n) is number of subnet mask bits needed to switched from 0 to 1 and y represents the number subnets. We need to – 2 because of the reserved addresses noted above.
Example of a Class C with the Network ID: 199.34.89.0 divided into six subnets: 6=2 (power of) N- 2 or 8 = 2(power of) 3 there for the bits borrowed are 3 so the subnet mask is made up of the first 27 bits.
11111111.11111111.1111111.11000000 or 255.255.255.224
Using 27 of the 32 bits available you are left with the five last bits (00011111) adding them up you get 31 = (16 + 8 + 4 + 2 +1). However, you still have the two reserved for Network ID and Broadcast so you only end up with 30 hosts each of the 6 subnets.
Extended network Prefix Broadcast Address Usable hosts
199.34.89.32 199.34.89.63 199.34.89.33-62
199.34.89.64 199.34.89.95 199.34.89.65-94
199.34.89.96 199.34.89.127 199.34.89.97-126
199.34.89.128 199.34.89.159 199.34.89.129-159
199.34.89.160 199.34.89.191 199.34.89.33.161-190
199.34.89.192 199.34.89.223 199.34.89.193-222
CIDR (Classless Interdomain Routing) AKA SUPER Networking were as in Subnet you remove the bits to the right to create more subnets into CIDR you move them to the left to create more useable IP addresses on your net work.
Example of a class C with the Network ID: 199.34.89.0/22 is use the CIDR notation (or slash notation) Network ID followed by forward slash ( / ), followed by number of bits used for extended network prefix. This changes your subnet mask to 255.255.252.000 from 255.255.255.000increasing your host addresses from 254 to 1022.
Internet Gateway facilitates communication between different networks and subnets. A default gateway first interprets its outbound requests to other subnets, and then interprets its inbound requests from other subnets.
NAT (Network Address Translation) allows you to hide internal/private IP addresses from the outside internet. The gateway provides valid internet addresses when sending transmissions to the internet.
SNAT (Static Network Address Translation) establishes a one to one correlation between each IP address and internet IP address.
DNAT (Dynamic Network Address Translation) AKA IP masquerading allows one or more IP addressed to be shared with multiple clients.
TCP/IP Mail Services are the most frequently used internet service to deliver, store, and communicate with other mail servers.
SMTP (Simple Mail Transfer Protocol) is responsible for moving messages from one mail server to another over TCP/IP-based networks operating at Application layer and replies on TCP at Transport layer over port 25.
MIME (Multipurpose Internet Mail Extensions) delivers the SMPT drawback of 1000 ASCII character limit. It also encodes, interprets binary files, images, video, non-ASCII character sets within e-mail message. It does not replace SMTP and works in conjunction with it.
POP (Post Office Protocol) the user retrieves messages from mail server. It is like the postal worker it brings the mail to your house and leaves it there. With this is mind you should only retrieve form one computer one mailbox.
IMAP (Internet Message Access Protocol) IMAP4 is the current version where E-mail stays on server after retrieval. Users can retrieve all or portion of mail message create delete when offline and update with the server when an internet connection is established.
TCP/IP Tools/Utilities to help track down most TCP/IP related problems discovering information about node, network
Ipconfig (Windows) and Ifconfig (UNIX)
Command-line utility to identify and change network adapter information (IP address, subnet mask, default gateway)
Netstat Displays TCP/IP statistics, component details, host connections and active TCP/IP connections on node
Nbtstat utility provides information about NetBIOS statistics along with resolving NetBIOS names to IP addresses. It is useful on Windows-based operating systems and NetBIOS
Hostname is a utility provides client’s host name.
Host utility to learn the IP address from host name.
Nslookup is used to query DNS database from any network computer and can find the device host name by specifying its IP address.
Dig (Domain information groper) similar to nslookup where it queries a DNS database and to find a specific IP address host name. Useful for diagnosing DNS problems and provides more detailed information than nslookup
Whois Query DNS registration database to obtain domain information
Troubleshoot network problems. Syntax: whois xxx.yy
Traceroute give you the ability to trace the path from one networked node to another identifying all intermediate hops between the two nodes using either IP address or host name.
Windows-based systems: tracert
Linux systems: tracepath
Thursday, October 29, 2009
Chapter 9 Network Operating Systems
Chapter 9 Network Operating Systems
The three Network Operating Systems I have had experience with are Mac/Appletalk, Novell, and Windows, which all were based on client/server architecture to share resources. With the Mac and Windows the NO (Network Operating) software was already installed though it may require some more configuration changes to the network settings. With Novell the client needs to be installed on the Windows workstations and with Mac the server would have Mac NLM (Netware Loadable Modules) installed/enabled.
Client/Server Communication consists of a Logon process redirector belonging to the presentation layer of the OSI model. The Client server environment then uses 3-teir architecture to establish communication. The Client, Middleware and Server, examples are Web Bowser, Terminal Server, Citrix… connections.
Users and Groups are set up to gain access to resources basing the user permissions on a group basis to simplify account management and documentation. As a rule, users should only be given permissions on a user basis for personal/private file locations otherwise they should belong to groups for permissions.
One standard protocol to give objects (users, computers, files) access permissions is LDAP (Lightweight Directory Access Protocol). LDAP uses two types of object definitions: Classes (object classes): identifies object type specified in directories and Attributes (object attributes): stores information about object. LDAP standard directories and contents form trees. As you know a tree starts with a root/trunk/foundation then has branches and leaves. Hmm, were some of these programmers smoking some of the leaves when coming up with these definitions? As you know from basic biology, branches and leaves however separated from each other get all their main resources from the roots and trunks of the plant. To care for the LDPA system there is what we refer to as the administrator/arborist which can prune the tree or even cut down a tree/system. FYI: The administrator account for a UNIX system is the ROOT. Yep they definitely were smoking something out there in San Jose! Then came along Mr. Bill (SNL fame of course) with domains wanting to control the universe and stealing NDS (Novell Directory of Services) and naming it AD (Active/Attractive Directory)? Hmm, wonder if they both were not very secure and only AD (Attractive Directory) looked easier to organize, manage resources and security?
OK, Enough Mr. Bill bashing, UNIX develop in 1969 preceded to lead TCP/IP protocol suite development and runs most internets serves because it is efficient and flexible. UNIX comes in two flavors, proprietary, the sinful Apple/Mac OS XServer, Sun Microsystems /Solarus and IBM/ AIX systems an open non-proprietary/open source Linux.
All in all NO (Network Operating Systems) all do pretty much the same process of permitting access for users to share centrally located and managed resources.
The three Network Operating Systems I have had experience with are Mac/Appletalk, Novell, and Windows, which all were based on client/server architecture to share resources. With the Mac and Windows the NO (Network Operating) software was already installed though it may require some more configuration changes to the network settings. With Novell the client needs to be installed on the Windows workstations and with Mac the server would have Mac NLM (Netware Loadable Modules) installed/enabled.
Client/Server Communication consists of a Logon process redirector belonging to the presentation layer of the OSI model. The Client server environment then uses 3-teir architecture to establish communication. The Client, Middleware and Server, examples are Web Bowser, Terminal Server, Citrix… connections.
Users and Groups are set up to gain access to resources basing the user permissions on a group basis to simplify account management and documentation. As a rule, users should only be given permissions on a user basis for personal/private file locations otherwise they should belong to groups for permissions.
One standard protocol to give objects (users, computers, files) access permissions is LDAP (Lightweight Directory Access Protocol). LDAP uses two types of object definitions: Classes (object classes): identifies object type specified in directories and Attributes (object attributes): stores information about object. LDAP standard directories and contents form trees. As you know a tree starts with a root/trunk/foundation then has branches and leaves. Hmm, were some of these programmers smoking some of the leaves when coming up with these definitions? As you know from basic biology, branches and leaves however separated from each other get all their main resources from the roots and trunks of the plant. To care for the LDPA system there is what we refer to as the administrator/arborist which can prune the tree or even cut down a tree/system. FYI: The administrator account for a UNIX system is the ROOT. Yep they definitely were smoking something out there in San Jose! Then came along Mr. Bill (SNL fame of course) with domains wanting to control the universe and stealing NDS (Novell Directory of Services) and naming it AD (Active/Attractive Directory)? Hmm, wonder if they both were not very secure and only AD (Attractive Directory) looked easier to organize, manage resources and security?
OK, Enough Mr. Bill bashing, UNIX develop in 1969 preceded to lead TCP/IP protocol suite development and runs most internets serves because it is efficient and flexible. UNIX comes in two flavors, proprietary, the sinful Apple/Mac OS XServer, Sun Microsystems /Solarus and IBM/ AIX systems an open non-proprietary/open source Linux.
All in all NO (Network Operating Systems) all do pretty much the same process of permitting access for users to share centrally located and managed resources.
Thursday, October 22, 2009
Chapter 8 Wireless Networking
Chapter 8 Wireless Networking
As a Network Technician wired technologies are already a high-wire act without a net, with expectations of having all systems fully available 99.999%. As though that is not tough enough now we add in the Wireless Spectrum. Now we don’t even have a high-wire to walk on and we need to be able to deliver it just about anywhere anytime. Yikes! With this in mind it is especial essential that standards are developed and followed so all the wireless devices are able to work just about anywhere around the globe.
Similar to wired the Wireless Spectrum needs to follow the Layer 3 and higher protocols, however it has no fixed path to guide the signals from one node to the next. Instead of a wire, Wireless uses an Antenna on the same frequency (Channel) to transmit and receive information. An Antennas service specifications determine the power, frequency and radiation pattern. The two types of antennas are directional which are used more for point to point wireless communications. Satellites use direction antennas for downlinks such as cable TV, where omnidirectional signals give equal strength in all directions and used in wireless networks or wireless phones.
Signal Propagation LOS (line-of-sight) or in straight line, directly from transmitter to receiver is going to give you the clearest signal possible. As you know obstacles are going to get in the way affecting the signal. The signal needs to pass through them, get absorbed by them, bounce off them… These phenomena are Reflection, which it bounces back to the source, Diffraction, which splits it into secondary waves or Scattering, which diffuses it into multiple different directions.
Because of the three phenomena Multipath signals are created which can both enhance or cause delays in the wireless connection. Remember this is an extreme high-wire act and we are working without a net and wire (no wireless conduit/shielding).
Frequency Ranges are the area we are able to do our high-wire act. The oldest range is 2.4–2.4835 GHz contains 11 communication channels which include wireless phones which can interfere with your wireless network devices. The newer 5.1 GHz, 5.3 GHz, 5.4 GHz, 5.8 GHz contains 24 communication channels and because these are also used by weather, military radar communications your wireless gear must be able to sense this and switch to a different cannel automatically.
Narrowband , Broadband, and Spread Spectrum Signals
In Narrowband the Transmitter concentrates signal energy at single frequency, very small(narrow) frequency range where Broadband uses a relatively wide(broad) wireless spectrum band giving it higher throughputs than narrowband. The last one is Spread-spectrum used in WWII, which uses multiple frequencies to split them and transmit signals. The split signals are only known by transmitters and receivers so it is difficult for unauthorized receivers to capture the information because they need to know both frequencies to capture and decode the signals. This offering more security when send transmissions. There are two types of Spread-spectrum FHSS (frequency hopping spread spectrum) which the signal jumps between several different frequencies within a band. The other is DSSS (direct-sequence spread spectrum) where signal’s bits distributed over entire frequency band at once. Each bit then coded and the receiver reassembles original signal upon receiving.
WLAN (Wireless LAN) Architecture can be as simple as an Ad hoc WLAN where wireless nodes transmit directly to each other (laptop to laptop) or complex to where you would have one or many Access point (AP) throughout your location or locations to have multiple nodes authenticate to them to use the network. The AP is strategically placed for easy access and wired to the network to retransmit signals to the network and network operating system. Depending upon number of nodes you may need multiple APs (maximum number of nodes varies: 10-100).
IEEE’s Wireless technology standard is 802.11(802.11b, 802.11a, 802.11g, 802.11n (draft)) work at the Physical and Data Link Layer of the OSI model and work in the Half-duplex, access method, frame format.
Access Method for 802.11 same physical addressing schemes as 802.3 however, wireless devices are not designed to simultaneously transmit and receive so they cannot quickly detect collisions. Therefore instead of using CSMA/CD (Carrier Sense Multiple Access with Collision Detection) they use a method called CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to minimize potential collisions. It uses ACK packets to verify every transmission which requires more overhead than 802.3 therefore is slower than 802.3. Another method is RTS/CTS (Request to Send/Clear to Send) protocol it ensures packets are not inhibited by other transmissions and is more used for large transmission packets however; it further decreases overall 802.11 efficiency.
Association is the process of scanning and gaining access to an AP. The wireless NIC surveys its surroundings for access point using two types: Active scanning which transmits a special frame known as a probe to the AP waiting for it to issue a probe response and Passive scanning where it is listens for special signal known as a Beacon fame issued by the AP. The Beacon frame contains the transmission rate and SSID (service set identifier) the name of the AP. The node must then enter an access code, if the security is setup, then once authenticated they can begin to communicate.
There multiple frames in 802.11 are divided into three groups: control, management and data. The management frames are those involved in association and reassociation probe, beacon frames. Control frames are those related to medium access, data delivery such as ACK and RTS/CTS frames. Where Data frames carry data sent between stations.
802.11b is the oldest standard and uses DSSS (direct-sequence spread spectrum) signaling. It operates on the 2.4-GHz band and separated into 22-MHz channels. Throughput in theory is 11-Mbps but actual throughput is at 5-Mbps and has a 100 meters node limit.
802.11a although the standards task group started before 802.1b it was released after 802.11b. It operates on the 5-GHz band which is not as congested (like 2.4-GHz band) and has lower interference from other devices (microwaves, cordless phones) however it requires more power to transmit and travel shorter distances than the lower-frequency signals. Throughput in theory is 54 Mbps but actual throughput is between 11 and 18 Mbps and has a 20 meter node limit. It is also more expensive hence least popular.
802.11g is just as affordable and compatible with 802.11b networks. It operates on the 2.4-GHz band. Throughput in theory is 54-Mbps but actual throughput is between 20 to 25 Mbps and has a 100 meters node limit.
802.11n appears to have been in September 2009 and will be backward compatible with 802.11a, b, g standards. Therefore it operates on both 2.4-GHz or 5-GHz frequency ranges. Throughput in theory is a maximum of 600 Mbps.
Bluetooth Networking is a wireless technology compatible with multiple devices requiring little power and short range coverage. It is designed for PANs (personal area networks) cellular telephones, phone headsets, computer peripherals, PDAs. The standard uses FHSS (frequency hopping spread spectrum) RF signaling in 2.4-GHz band. Version 1.1 has a throughput in theory is 1 Mbps but actual throughput is 723 –Kbps and is recommended nodes be no more than 10 meters apart. Version 2.2 has an actual throughput is 2.1 Mbps and is recommended nodes be no more than 30 meters apart. If you ever catch me walking in store talking with a blue tooth head set please shoot me!
In designing a wireless network you need to first determine the needs of your organization. Are you a coffee shop having hot spots for your users, a large warehouse needing access to databases to update information via handheld devices and/or an office that uses it for convenience for laptop users to easily logon to the network when they are in the office? In your design you will need to determine the placement of APs for best coverage along with using the latest technologies 802.11g or 802.11n if available. You will also what to use hardware all one standard and along with one manufacturer, this will ensure the ability to document your wireless network easier.
In 2001 IEEE standardized a new wireless technology 802.16 WiMAX (Worldwide Interoperability for Microwave Access). The current version is 802.16e (2005) which has improved mobility and QoS characteristics making it better suited for digital voice signals and mobile phones. It functions in 2 and 66 GHz range on either Licensed or nonlicensed frequencies giving it two distinct advantages over Wi-Fi of a much greater throughput (70 Mbps) and a of range (30 miles). It is an alternative to DSL or broadband cable, well suited to rural users, internet access to mobile computerized devices, residential homes… One of the drawbacks are that it is expensive.
Satellite Internet Access, from my experience, is not a good option if you have any mission critical applications because weather can be big factor in flakey connections. However, if this is all that is available other than dialup it may be your best option.
As a Network Technician wired technologies are already a high-wire act without a net, with expectations of having all systems fully available 99.999%. As though that is not tough enough now we add in the Wireless Spectrum. Now we don’t even have a high-wire to walk on and we need to be able to deliver it just about anywhere anytime. Yikes! With this in mind it is especial essential that standards are developed and followed so all the wireless devices are able to work just about anywhere around the globe.
Similar to wired the Wireless Spectrum needs to follow the Layer 3 and higher protocols, however it has no fixed path to guide the signals from one node to the next. Instead of a wire, Wireless uses an Antenna on the same frequency (Channel) to transmit and receive information. An Antennas service specifications determine the power, frequency and radiation pattern. The two types of antennas are directional which are used more for point to point wireless communications. Satellites use direction antennas for downlinks such as cable TV, where omnidirectional signals give equal strength in all directions and used in wireless networks or wireless phones.
Signal Propagation LOS (line-of-sight) or in straight line, directly from transmitter to receiver is going to give you the clearest signal possible. As you know obstacles are going to get in the way affecting the signal. The signal needs to pass through them, get absorbed by them, bounce off them… These phenomena are Reflection, which it bounces back to the source, Diffraction, which splits it into secondary waves or Scattering, which diffuses it into multiple different directions.
Because of the three phenomena Multipath signals are created which can both enhance or cause delays in the wireless connection. Remember this is an extreme high-wire act and we are working without a net and wire (no wireless conduit/shielding).
Frequency Ranges are the area we are able to do our high-wire act. The oldest range is 2.4–2.4835 GHz contains 11 communication channels which include wireless phones which can interfere with your wireless network devices. The newer 5.1 GHz, 5.3 GHz, 5.4 GHz, 5.8 GHz contains 24 communication channels and because these are also used by weather, military radar communications your wireless gear must be able to sense this and switch to a different cannel automatically.
Narrowband , Broadband, and Spread Spectrum Signals
In Narrowband the Transmitter concentrates signal energy at single frequency, very small(narrow) frequency range where Broadband uses a relatively wide(broad) wireless spectrum band giving it higher throughputs than narrowband. The last one is Spread-spectrum used in WWII, which uses multiple frequencies to split them and transmit signals. The split signals are only known by transmitters and receivers so it is difficult for unauthorized receivers to capture the information because they need to know both frequencies to capture and decode the signals. This offering more security when send transmissions. There are two types of Spread-spectrum FHSS (frequency hopping spread spectrum) which the signal jumps between several different frequencies within a band. The other is DSSS (direct-sequence spread spectrum) where signal’s bits distributed over entire frequency band at once. Each bit then coded and the receiver reassembles original signal upon receiving.
WLAN (Wireless LAN) Architecture can be as simple as an Ad hoc WLAN where wireless nodes transmit directly to each other (laptop to laptop) or complex to where you would have one or many Access point (AP) throughout your location or locations to have multiple nodes authenticate to them to use the network. The AP is strategically placed for easy access and wired to the network to retransmit signals to the network and network operating system. Depending upon number of nodes you may need multiple APs (maximum number of nodes varies: 10-100).
IEEE’s Wireless technology standard is 802.11(802.11b, 802.11a, 802.11g, 802.11n (draft)) work at the Physical and Data Link Layer of the OSI model and work in the Half-duplex, access method, frame format.
Access Method for 802.11 same physical addressing schemes as 802.3 however, wireless devices are not designed to simultaneously transmit and receive so they cannot quickly detect collisions. Therefore instead of using CSMA/CD (Carrier Sense Multiple Access with Collision Detection) they use a method called CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to minimize potential collisions. It uses ACK packets to verify every transmission which requires more overhead than 802.3 therefore is slower than 802.3. Another method is RTS/CTS (Request to Send/Clear to Send) protocol it ensures packets are not inhibited by other transmissions and is more used for large transmission packets however; it further decreases overall 802.11 efficiency.
Association is the process of scanning and gaining access to an AP. The wireless NIC surveys its surroundings for access point using two types: Active scanning which transmits a special frame known as a probe to the AP waiting for it to issue a probe response and Passive scanning where it is listens for special signal known as a Beacon fame issued by the AP. The Beacon frame contains the transmission rate and SSID (service set identifier) the name of the AP. The node must then enter an access code, if the security is setup, then once authenticated they can begin to communicate.
There multiple frames in 802.11 are divided into three groups: control, management and data. The management frames are those involved in association and reassociation probe, beacon frames. Control frames are those related to medium access, data delivery such as ACK and RTS/CTS frames. Where Data frames carry data sent between stations.
802.11b is the oldest standard and uses DSSS (direct-sequence spread spectrum) signaling. It operates on the 2.4-GHz band and separated into 22-MHz channels. Throughput in theory is 11-Mbps but actual throughput is at 5-Mbps and has a 100 meters node limit.
802.11a although the standards task group started before 802.1b it was released after 802.11b. It operates on the 5-GHz band which is not as congested (like 2.4-GHz band) and has lower interference from other devices (microwaves, cordless phones) however it requires more power to transmit and travel shorter distances than the lower-frequency signals. Throughput in theory is 54 Mbps but actual throughput is between 11 and 18 Mbps and has a 20 meter node limit. It is also more expensive hence least popular.
802.11g is just as affordable and compatible with 802.11b networks. It operates on the 2.4-GHz band. Throughput in theory is 54-Mbps but actual throughput is between 20 to 25 Mbps and has a 100 meters node limit.
802.11n appears to have been in September 2009 and will be backward compatible with 802.11a, b, g standards. Therefore it operates on both 2.4-GHz or 5-GHz frequency ranges. Throughput in theory is a maximum of 600 Mbps.
Bluetooth Networking is a wireless technology compatible with multiple devices requiring little power and short range coverage. It is designed for PANs (personal area networks) cellular telephones, phone headsets, computer peripherals, PDAs. The standard uses FHSS (frequency hopping spread spectrum) RF signaling in 2.4-GHz band. Version 1.1 has a throughput in theory is 1 Mbps but actual throughput is 723 –Kbps and is recommended nodes be no more than 10 meters apart. Version 2.2 has an actual throughput is 2.1 Mbps and is recommended nodes be no more than 30 meters apart. If you ever catch me walking in store talking with a blue tooth head set please shoot me!
In designing a wireless network you need to first determine the needs of your organization. Are you a coffee shop having hot spots for your users, a large warehouse needing access to databases to update information via handheld devices and/or an office that uses it for convenience for laptop users to easily logon to the network when they are in the office? In your design you will need to determine the placement of APs for best coverage along with using the latest technologies 802.11g or 802.11n if available. You will also what to use hardware all one standard and along with one manufacturer, this will ensure the ability to document your wireless network easier.
In 2001 IEEE standardized a new wireless technology 802.16 WiMAX (Worldwide Interoperability for Microwave Access). The current version is 802.16e (2005) which has improved mobility and QoS characteristics making it better suited for digital voice signals and mobile phones. It functions in 2 and 66 GHz range on either Licensed or nonlicensed frequencies giving it two distinct advantages over Wi-Fi of a much greater throughput (70 Mbps) and a of range (30 miles). It is an alternative to DSL or broadband cable, well suited to rural users, internet access to mobile computerized devices, residential homes… One of the drawbacks are that it is expensive.
Satellite Internet Access, from my experience, is not a good option if you have any mission critical applications because weather can be big factor in flakey connections. However, if this is all that is available other than dialup it may be your best option.
Thursday, October 8, 2009
Chapter 7: WANs and Remote Connectivity
Chapter 7 WANs and Remote Connectivity
Through my experience I have been able to use many of these WANs and Remote Connectivity Technologies. Basically it comes down to the needs of the Organization you are working for, how large they are and their geographic layout. Even a small organization still has many needs to remotely work on their Network, Servers and Services. Who wants to drive to the office to run end of month reports, do end of year closings, restart a server or services…?
In my past life on the MAC we used products such as Timbuktu to do some of these tasks. As my career moved into the PC side we were using products such as PC Anywhere or VNC to do similar tasks. Then as my current company grew from five US locations sending packing slips to the Regional Service Centers (One person Warehouses around the US) via fax machines to World Wide IBUs (Independent Business Units) having to enter data and communicate into a centralized ERP (Enterprise resource planning), Communication (e-mail) and Contact Management systems. We needed to make sure all users have access to all these systems 24 X 7 anywhere in the world (New Zealand, Singapore, Germany, United Kingdom, Canada…).
First we hosted all services in a centralized location HQ (Head Quarters) in Wauconda, IL, using GroupWise Novell’s answer to email by use caching mailboxes for external users. Updating their mailboxes via an external/public address mapped to the servers local/private class C address 192.168.1.XXX. Then using a terminal server so global users were able to enter data into the ERP and Contact Management systems. Being these systems needed to be readily available 24 X 7 we moved these to a hosted environment using Citrix clients for everyone to access via the web. This made users able to access data anytime, anywhere as long as they have a computer and internet connection.
Other remote tools we are currently using are WebEx for, training, meetings, tech support, along with using Skype to talk for free globally. These technologies/tools have made tech support, a much less frustrating and time consuming job.
To do all of these things we have worked on many of the transmission and connection methods. From taking a single T1 and splitting into voice for long distance and data for internet use along with using POTS lines for phone back up and ISDN line for internet back up. Currently we have two T1s coming into our HQ (Head Quarters) location then coming into two identical firewalls for further failover protection. Next steps are to have more unified communications so our phone system follows customers, vendors and users around the globe. Hmm, what other technologies will we need to have in place to make this feasible??
Through my experience I have been able to use many of these WANs and Remote Connectivity Technologies. Basically it comes down to the needs of the Organization you are working for, how large they are and their geographic layout. Even a small organization still has many needs to remotely work on their Network, Servers and Services. Who wants to drive to the office to run end of month reports, do end of year closings, restart a server or services…?
In my past life on the MAC we used products such as Timbuktu to do some of these tasks. As my career moved into the PC side we were using products such as PC Anywhere or VNC to do similar tasks. Then as my current company grew from five US locations sending packing slips to the Regional Service Centers (One person Warehouses around the US) via fax machines to World Wide IBUs (Independent Business Units) having to enter data and communicate into a centralized ERP (Enterprise resource planning), Communication (e-mail) and Contact Management systems. We needed to make sure all users have access to all these systems 24 X 7 anywhere in the world (New Zealand, Singapore, Germany, United Kingdom, Canada…).
First we hosted all services in a centralized location HQ (Head Quarters) in Wauconda, IL, using GroupWise Novell’s answer to email by use caching mailboxes for external users. Updating their mailboxes via an external/public address mapped to the servers local/private class C address 192.168.1.XXX. Then using a terminal server so global users were able to enter data into the ERP and Contact Management systems. Being these systems needed to be readily available 24 X 7 we moved these to a hosted environment using Citrix clients for everyone to access via the web. This made users able to access data anytime, anywhere as long as they have a computer and internet connection.
Other remote tools we are currently using are WebEx for, training, meetings, tech support, along with using Skype to talk for free globally. These technologies/tools have made tech support, a much less frustrating and time consuming job.
To do all of these things we have worked on many of the transmission and connection methods. From taking a single T1 and splitting into voice for long distance and data for internet use along with using POTS lines for phone back up and ISDN line for internet back up. Currently we have two T1s coming into our HQ (Head Quarters) location then coming into two identical firewalls for further failover protection. Next steps are to have more unified communications so our phone system follows customers, vendors and users around the globe. Hmm, what other technologies will we need to have in place to make this feasible??
Tuesday, September 29, 2009
Chapter 6 Network Hardware
Chapter 6 Network Hardware
As it stated in the book “To understand the process it’s helpful to compare data transmission to the means by which the Canadian Postal Service delivers mail: Mail trucks, airplanes, and delivery staff serve as the transmission system that moves information from place the place. ” Network hardware is the transmission system that moves our data around the world to the correct recipient.
NICs (Network Interface Cards) act as mailboxes (Transceiver on both Physical and Data Link Layer of the OSI model) on the servers and workstations where the data is transmitted and received. Advances in NIC technology have made it so many NICs can also perform prioritization, network management, buffering and traffic filtering. Most new computers come with Gigabit NICs installed however, if you purchase a NIC today purchase Gigabit NIC and verify it is backward compatible!
The following are the two internal bus NICs:
• PCI is the most popular using a PCI slot on the mother board for installation.
• PCIe is also popular using the PCI Express slot on the motherboard.
The following are the four external bus NICs:
• Personal Computer Memory Card International Association or PCMCIA used mainly with laptops.
• USB (universal serial bus) NIC port using two USB standards 1.1: transfer rate of 12 Mbps and 2.0: transfer rate of 480 Mbps In the future there will be USB 3.0: transfer rate of 4.8 Gbps.
• Fire wire is another connection type developed by Apple Computer (1980s)–IEEE 1394 standard (1995) Traditional Firewire connection: 400 Mbps (max)Newer version: 3 Gbps
• CompactFlash NIC Latest standard: 4.0 Data transfer rate: 133 Mbps, connects devices too small for PCMCIA slots.
Wireless NIC’s are supported and installed on all bus types.
Interpreting LED Indicators
ACT - Indicates that the NIC is either transmitting or receiving data.
LNK - Indicates the NIC is functional.
TX - Indicates the NIC is functional and transmitting frames to the Network.
RX - Indicates the NIC is functional and receiving frames to the Network.
IRQ (Interrupt Request) – is a message to the computer that instructs it to stop what it was doing and pay attention to something else. NICs are devices installed most likely on IRQ 9, 10, or 11.
Repeater & Hubs operate on the physical layer of the OSI model and therefore, have no means to interpret the data they transmit. They can’t detect and/or improve bad or erroneous data they merely just repeat it. They share one connection (collision domain) with all other devices. These are becoming rarer in modern day networks.
Bridges operate at the data link layer of the OSI model. A bridge connects two network segments adding length beyond the segments maximum limits. Hence the name a bridge determines if the node needs to cross the bridge to talk with and another node. If it recognizes the node is on its side/segment it doesn’t cross over the bridge keeping local traffic on its side/segment of the bridge however, if it recognizes the node is trying to communicate with a node on the other side/segment it crosses over expanding the reach of the node.
Switches operate traditionally at data link layer of the OSI model switches operate at layers 3(Network) and 4(Transport). So instead of having 2 hubs with a bridge between them you can use a switch (multi port bridge) to connect and separate collision domains (hubs). Each channel on the switch represents its own collision domain limiting the potential for collisions.
Switching methods although there are four methods, the two following basic methods are most popular. Cut-Through Mode: The switch reads frame’s header (the first 14 bytes contains destination MAC address) and forwards before receiving entire packet. Although it can detect runts (shortened packets) it can’t detect corrupt packets which may increase the number of errors found on a network. The other method is Store-and-Forward Mode: The switch reads entire data frame into memory taking more time, then checks for accuracy before transmitting accurate information. Used in larger LAN mixed environments transferring data between segments running different transmission speeds.
With Switches you can create VLANs (virtual local area networks) and Trunking to logically separate networks within networks, by grouping a number of ports into a broadcast domain. One potential problem is that by grouping together certain nodes, you are also excluding another group. Planning needs to be carefully thought out so that you aren’t creating an Administrative nightmare so, use caution if you think you need to set one up. Personally I think for security could use the NO (Network Operating System) and really only seeing this used maybe for some type of high speed line access?
To prevent looping Switches use STP (Spanning Tree Protocol) technology that operates in the Data Link layer calculating paths avoiding potential loops and artificially blocking links completing loop. It takes the following three steps to do this, it first selects a root bridge, examines the possible paths between them the disables paths/links that are not part of the shortest path avoiding a loop back.
Switches operate at the data link layer of the OSI model and routers operate in the network layer of the OSI model. Now manufactures are producing Content and Multilayer Switches that are similar to routers and able to also operate on the Network and Transport layer know as a Layer3 and 4 switches. They are also producing switches that interpret Layer 4 through Layer 7 data know as content/application switches. Giving these types of switches the ability to do advance filtering, statistic recording and security functions.
Routers as noted earlier operate at the Network layer of the OSI model. Multiport connectivity device used to integrate and direct data through LANs and WANs. They operate at different transmission speeds, protocols and are slower than switches and bridges. From my experience these mainly have been used to tie in T1 or other internet connections to the LAN. They determine shortest, fastest path between two nodes connecting dissimilar network types.
The following are the six common routing protocols under the three sections, Distance-Vector, Link-State and Hybrid to give the Best path most efficient route from one node to another. Routers do this by looking at current information, hops between nodes, network activity, transmission speed, link availability, topology… This is characterized as convergence time the time it takes for a router to recognize a best path.
Distance-Vector: Determine best route based on distance to destination (Hops, latency, network traffic conditions). The following three protocols are distance-vector protocols.
RIP (Routing Information Protocol) and RIPv2 Only factors in number of hops between nodes.
BGP (Border Gateway Protocol) is configurable to follow policies which makes them the most complex to use.
Link-State: Is a protocol that enables routers to share information. This information is then used by each router independently maps network to determine the best path. It relies on their neighbors’ data path information. The following two protocols are distance-vector protocols.
OSPF (Open Shortest Path First) It uses interior or border router for it information. Unlike RIP there is no hop limit and uses a more complex algorithm to determine best path.
IS-IS (Intermediate System to Intermediate System) was originally codified by ISO, which referred to routers and “intermediate systems”. IS-IS is designed only for use on interior routers.
Hybrid: EIGRP (Enhanced Interior Gateway Routing Protocol) is the most popular which uses Link-state and distance-vector characteristics. These are easy to setup and has a fast convergence time with low network overhead. It supports multiple protocols
and accommodates very large, networks.
Gateways and Other Multifunction Devices are combinations of networking hardware and software used to connect two dissimilar networks using different formatting, communications protocols, and architecture to repackaging information.
They reside on servers, microcomputers, connectivity devices, mainframes. Examples of these are E-mail gateways, Internet gateways, LAN gateways, Voice/data gateways, and Firewalls.
As it stated in the book “To understand the process it’s helpful to compare data transmission to the means by which the Canadian Postal Service delivers mail: Mail trucks, airplanes, and delivery staff serve as the transmission system that moves information from place the place. ” Network hardware is the transmission system that moves our data around the world to the correct recipient.
NICs (Network Interface Cards) act as mailboxes (Transceiver on both Physical and Data Link Layer of the OSI model) on the servers and workstations where the data is transmitted and received. Advances in NIC technology have made it so many NICs can also perform prioritization, network management, buffering and traffic filtering. Most new computers come with Gigabit NICs installed however, if you purchase a NIC today purchase Gigabit NIC and verify it is backward compatible!
The following are the two internal bus NICs:
• PCI is the most popular using a PCI slot on the mother board for installation.
• PCIe is also popular using the PCI Express slot on the motherboard.
The following are the four external bus NICs:
• Personal Computer Memory Card International Association or PCMCIA used mainly with laptops.
• USB (universal serial bus) NIC port using two USB standards 1.1: transfer rate of 12 Mbps and 2.0: transfer rate of 480 Mbps In the future there will be USB 3.0: transfer rate of 4.8 Gbps.
• Fire wire is another connection type developed by Apple Computer (1980s)–IEEE 1394 standard (1995) Traditional Firewire connection: 400 Mbps (max)Newer version: 3 Gbps
• CompactFlash NIC Latest standard: 4.0 Data transfer rate: 133 Mbps, connects devices too small for PCMCIA slots.
Wireless NIC’s are supported and installed on all bus types.
Interpreting LED Indicators
ACT - Indicates that the NIC is either transmitting or receiving data.
LNK - Indicates the NIC is functional.
TX - Indicates the NIC is functional and transmitting frames to the Network.
RX - Indicates the NIC is functional and receiving frames to the Network.
IRQ (Interrupt Request) – is a message to the computer that instructs it to stop what it was doing and pay attention to something else. NICs are devices installed most likely on IRQ 9, 10, or 11.
Repeater & Hubs operate on the physical layer of the OSI model and therefore, have no means to interpret the data they transmit. They can’t detect and/or improve bad or erroneous data they merely just repeat it. They share one connection (collision domain) with all other devices. These are becoming rarer in modern day networks.
Bridges operate at the data link layer of the OSI model. A bridge connects two network segments adding length beyond the segments maximum limits. Hence the name a bridge determines if the node needs to cross the bridge to talk with and another node. If it recognizes the node is on its side/segment it doesn’t cross over the bridge keeping local traffic on its side/segment of the bridge however, if it recognizes the node is trying to communicate with a node on the other side/segment it crosses over expanding the reach of the node.
Switches operate traditionally at data link layer of the OSI model switches operate at layers 3(Network) and 4(Transport). So instead of having 2 hubs with a bridge between them you can use a switch (multi port bridge) to connect and separate collision domains (hubs). Each channel on the switch represents its own collision domain limiting the potential for collisions.
Switching methods although there are four methods, the two following basic methods are most popular. Cut-Through Mode: The switch reads frame’s header (the first 14 bytes contains destination MAC address) and forwards before receiving entire packet. Although it can detect runts (shortened packets) it can’t detect corrupt packets which may increase the number of errors found on a network. The other method is Store-and-Forward Mode: The switch reads entire data frame into memory taking more time, then checks for accuracy before transmitting accurate information. Used in larger LAN mixed environments transferring data between segments running different transmission speeds.
With Switches you can create VLANs (virtual local area networks) and Trunking to logically separate networks within networks, by grouping a number of ports into a broadcast domain. One potential problem is that by grouping together certain nodes, you are also excluding another group. Planning needs to be carefully thought out so that you aren’t creating an Administrative nightmare so, use caution if you think you need to set one up. Personally I think for security could use the NO (Network Operating System) and really only seeing this used maybe for some type of high speed line access?
To prevent looping Switches use STP (Spanning Tree Protocol) technology that operates in the Data Link layer calculating paths avoiding potential loops and artificially blocking links completing loop. It takes the following three steps to do this, it first selects a root bridge, examines the possible paths between them the disables paths/links that are not part of the shortest path avoiding a loop back.
Switches operate at the data link layer of the OSI model and routers operate in the network layer of the OSI model. Now manufactures are producing Content and Multilayer Switches that are similar to routers and able to also operate on the Network and Transport layer know as a Layer3 and 4 switches. They are also producing switches that interpret Layer 4 through Layer 7 data know as content/application switches. Giving these types of switches the ability to do advance filtering, statistic recording and security functions.
Routers as noted earlier operate at the Network layer of the OSI model. Multiport connectivity device used to integrate and direct data through LANs and WANs. They operate at different transmission speeds, protocols and are slower than switches and bridges. From my experience these mainly have been used to tie in T1 or other internet connections to the LAN. They determine shortest, fastest path between two nodes connecting dissimilar network types.
The following are the six common routing protocols under the three sections, Distance-Vector, Link-State and Hybrid to give the Best path most efficient route from one node to another. Routers do this by looking at current information, hops between nodes, network activity, transmission speed, link availability, topology… This is characterized as convergence time the time it takes for a router to recognize a best path.
Distance-Vector: Determine best route based on distance to destination (Hops, latency, network traffic conditions). The following three protocols are distance-vector protocols.
RIP (Routing Information Protocol) and RIPv2 Only factors in number of hops between nodes.
BGP (Border Gateway Protocol) is configurable to follow policies which makes them the most complex to use.
Link-State: Is a protocol that enables routers to share information. This information is then used by each router independently maps network to determine the best path. It relies on their neighbors’ data path information. The following two protocols are distance-vector protocols.
OSPF (Open Shortest Path First) It uses interior or border router for it information. Unlike RIP there is no hop limit and uses a more complex algorithm to determine best path.
IS-IS (Intermediate System to Intermediate System) was originally codified by ISO, which referred to routers and “intermediate systems”. IS-IS is designed only for use on interior routers.
Hybrid: EIGRP (Enhanced Interior Gateway Routing Protocol) is the most popular which uses Link-state and distance-vector characteristics. These are easy to setup and has a fast convergence time with low network overhead. It supports multiple protocols
and accommodates very large, networks.
Gateways and Other Multifunction Devices are combinations of networking hardware and software used to connect two dissimilar networks using different formatting, communications protocols, and architecture to repackaging information.
They reside on servers, microcomputers, connectivity devices, mainframes. Examples of these are E-mail gateways, Internet gateways, LAN gateways, Voice/data gateways, and Firewalls.
Thursday, September 24, 2009
Chapter 5 Topologies and Ethernet Standards
Topologies and Ethernet Standards
When building a Network, whether building a small LAN or a large Global Network, you need to keep the end/finished product in mind. With both small and larger networks, you will see phases of a network completion. However, just like learning, you will really never see a Network 100% finished/complete. As time moves, the Network will continue to evolve staying abreast of technology and meeting the needs of the organizations network professionals are working in. In just the past 10 years, these network professionals have rarely been using technologies such as Bus or Ring topologies, Hubs, Modems etc… This chapter examines old and new technologies. Here are some of the current and future technologies thought to be the most important for us, network professionals, to understand and master.
The physical topologies- the Network physical layout has three main categories: Bus, Ring and Star. Star topologies are the most widely used topologies today and are also the most fault tolerant. Looking at the Star topology, everything comes to the center to communicate with other devices and resources (Switches and Servers), making the connections directly to the central resources not relying on other systems to be live to make their connection to these resources.
Hybrid Physical Topologies- There are two types: Star-Wired Ring and Star-Wired Bus. Of the two the most commonly used technologies; Star-Wired Bus is the most popular. It connects the devices using a single bus between devices (Routers, Hubs, Switches etc…).
Backbone Networks- There are four types: Serial Backbone, Distributed Backbone, Collapsed Backbone, and Parallel Backbone. None of these are the main types of backbone that would be used across enterprise. All four types may be used depending on the needs (number of users, the fault tolerance, scalability, cost etc…) of the segment you are setting up within the enterprise.
Switching- There are four types: Circuit Switching, Message Switching, Packet Switching, and MPLS (Multiprotocol Label Switching). The most popular method is Packet Switching; it breaks data into packets before they are transported. The packets contain both destination and sequence information; each packet can travel its own route to the destination. Each packet does not have to arrive at the same time because they will be reassembled with their sequencing information.
Ethernet technology was developed by Xerox in the 1970s, and later improved by DEC (Digital Equipment Corporation), Intel and XEROX make up the acronym of DIX. It is by far the most popular technology used on LANs today. All types have one thing in common: they use an access method known as CSMA/CD (Carrier Sense Multiple Access with Collision Detection). Basically CSMA/CD is listening on the network for activity and if it detects no activity it transmits data. If it detects collision, it stops transmission and goes back to listening for no activity and trying again until it is successful.
Ethernet Standards for Copper Cable- (The T stand for Twisted Pair)”:
100Base-T (Fast Ethernet)- IEEE 802.3u standard with the max length 100 meters.
1000Base-T (Gigabit Ethernet)- IEEE 802.3ab standard with the max length 200 meters.
10GBase-T- IEEE 802.3an standard with the max length 100 meters.
Ethernet Standards for Fiber-Optic Cable:
100Base-FX- (Fast Ethernet) IEEE 802.3u standard with the max length 412 meters in half duplex and 2000 meters in full duplex.
1000Base-LX- (1-Gigabit Ethernet) IEEE 802.3z standard with the max length 412 meters using multimode and 000 meters in single mode. The LX stands for Long wave length 1300 nanometers.
1000Base-SX- (1-Gigabit Ethernet) IEEE 802.3ae
10-Gigabit Fiber-Optic Standards: (IEEE 802.3ae)
10GBase-SR and 10GBase-SW (S stands for short reach max 300 meters)
10GBase-LR and 10GBase-LW (L stands for long reach max 10,000 meters)
10GBase-ER and 10GBase-EW (E stands for extended reach 40,000 meters)
SR, LR, & ER the R stands for LAN connections, where SW, LR, & ER the W specifies that it is specially encoded for SONET WAN links.
Ethernet Frames: There are four types: Ethernet_802.2 (Raw), Ethernet_802.3 (Novell proprietary), Ethernet_II (DIX), and Ethernet_SNAP. Of the four Ethernet_II (DIX) is the most commonly used today. Where the first two do not contain a 2 byte Ether net type both Ethernet_II and Ethernet_SNAP, do, however, SNAP calls for additional field controls making less room for data therefore Ethernet II is used more often. (Below is a sample of a Ethernet II Frame).
When building a Network, whether building a small LAN or a large Global Network, you need to keep the end/finished product in mind. With both small and larger networks, you will see phases of a network completion. However, just like learning, you will really never see a Network 100% finished/complete. As time moves, the Network will continue to evolve staying abreast of technology and meeting the needs of the organizations network professionals are working in. In just the past 10 years, these network professionals have rarely been using technologies such as Bus or Ring topologies, Hubs, Modems etc… This chapter examines old and new technologies. Here are some of the current and future technologies thought to be the most important for us, network professionals, to understand and master.
The physical topologies- the Network physical layout has three main categories: Bus, Ring and Star. Star topologies are the most widely used topologies today and are also the most fault tolerant. Looking at the Star topology, everything comes to the center to communicate with other devices and resources (Switches and Servers), making the connections directly to the central resources not relying on other systems to be live to make their connection to these resources.
Hybrid Physical Topologies- There are two types: Star-Wired Ring and Star-Wired Bus. Of the two the most commonly used technologies; Star-Wired Bus is the most popular. It connects the devices using a single bus between devices (Routers, Hubs, Switches etc…).
Backbone Networks- There are four types: Serial Backbone, Distributed Backbone, Collapsed Backbone, and Parallel Backbone. None of these are the main types of backbone that would be used across enterprise. All four types may be used depending on the needs (number of users, the fault tolerance, scalability, cost etc…) of the segment you are setting up within the enterprise.
Switching- There are four types: Circuit Switching, Message Switching, Packet Switching, and MPLS (Multiprotocol Label Switching). The most popular method is Packet Switching; it breaks data into packets before they are transported. The packets contain both destination and sequence information; each packet can travel its own route to the destination. Each packet does not have to arrive at the same time because they will be reassembled with their sequencing information.
Ethernet technology was developed by Xerox in the 1970s, and later improved by DEC (Digital Equipment Corporation), Intel and XEROX make up the acronym of DIX. It is by far the most popular technology used on LANs today. All types have one thing in common: they use an access method known as CSMA/CD (Carrier Sense Multiple Access with Collision Detection). Basically CSMA/CD is listening on the network for activity and if it detects no activity it transmits data. If it detects collision, it stops transmission and goes back to listening for no activity and trying again until it is successful.
Ethernet Standards for Copper Cable- (The T stand for Twisted Pair)”:
100Base-T (Fast Ethernet)- IEEE 802.3u standard with the max length 100 meters.
1000Base-T (Gigabit Ethernet)- IEEE 802.3ab standard with the max length 200 meters.
10GBase-T- IEEE 802.3an standard with the max length 100 meters.
Ethernet Standards for Fiber-Optic Cable:
100Base-FX- (Fast Ethernet) IEEE 802.3u standard with the max length 412 meters in half duplex and 2000 meters in full duplex.
1000Base-LX- (1-Gigabit Ethernet) IEEE 802.3z standard with the max length 412 meters using multimode and 000 meters in single mode. The LX stands for Long wave length 1300 nanometers.
1000Base-SX- (1-Gigabit Ethernet) IEEE 802.3ae
10-Gigabit Fiber-Optic Standards: (IEEE 802.3ae)
10GBase-SR and 10GBase-SW (S stands for short reach max 300 meters)
10GBase-LR and 10GBase-LW (L stands for long reach max 10,000 meters)
10GBase-ER and 10GBase-EW (E stands for extended reach 40,000 meters)
SR, LR, & ER the R stands for LAN connections, where SW, LR, & ER the W specifies that it is specially encoded for SONET WAN links.
Ethernet Frames: There are four types: Ethernet_802.2 (Raw), Ethernet_802.3 (Novell proprietary), Ethernet_II (DIX), and Ethernet_SNAP. Of the four Ethernet_II (DIX) is the most commonly used today. Where the first two do not contain a 2 byte Ether net type both Ethernet_II and Ethernet_SNAP, do, however, SNAP calls for additional field controls making less room for data therefore Ethernet II is used more often. (Below is a sample of a Ethernet II Frame).
Thursday, September 17, 2009
Chapter 4 Introduction to TCP/IP Protocols
Introduction to TCP/IP Protocols
Protocol (as described by Webster): Code prescribing strict adherence to correct etiquette and precedence (as in diplomatic exchange and in the military services).
TCP/IP Protocols were developed by the Department of Defense–ARPANET (1960s). Its purpose is to share data/talk to other computes and only share/talk to computers that we trust and want to allow access.
TCP/IP (Transmission Control Protocol/ Internet Protocol) is not just one protocol but a collection of specialized protocols/subprotocols. TCP/IP has become the protocol of choice and recently Microsoft and NetWare/Novell use it as their default protocol.
Certain subprotocals of the TCP/IP collection are known as the core protocols and operate in the Network layers of the OSI model. TCP and IP being the most significant in the TCP/IP collection.
TCP (Transmission Control Protocol) operates in the Transport layer of the OSI model and is a reliable data delivery service. It is connection oriented; meaning it must establish communication nodes prior to transmitting data.
UDP (User Datagram Protocol) also operates in the Transport layer of the ISO model. However, it is lightweight and has little overhead. It is connectionless; meaning that packets have no assurance that they will be received in the correct sequence. UDP is used where data must be transferred quickly such as live audio or video.
IP (Internet Protocol) operates at the Network layer of the OSI, providing how and where the data should be delivered. It enables TCP/IP to internetwork more than one LAN segment and more than one type of network through a router. Like UDP, it is connectionless, although it does contain a reliability component, the Header checksum, which verifies the integrity of the routing information in its header.
ICMP (Internet Control Message Protocol) is a Network layer protocol that can detect when part of a network is congested and reports on data delivery success/failure announcing failure to the sender. These announcements provide critical information for troubleshooting it can’t correct errors and the data will be discarded when TTL (Time to Live) expires.
IGMP (Internet Group Management Protocol) operates at the Network layer and manages multicasting (allowing one node to send data to defined group of nodes) used for Internet teleconferencing, videoconferencing, routers, network nodes
ARP (Address Resolution Protocol) operates at the Network layer protocol and is a method for finding a host's (node) MAC address when only its Internet Layer (IP) or some other Network Layer address is known. It then creates a database ARP table (ARP cache) that maps the MAC address to the host’s IP (Logical address). RARP (Reverse Address Resolution Protocol) is used when you do not know the (IP) address. RARP was made obsolete by BOOTP, which has been superseded by the Dynamic Host Configuration Protocol (DHCP).
IPv4 Addressing Networks recognize two addresses: Logical (Network layer) IP address assigned dynamically or manually, and the Physical (MAC, hardware) address is static, assigned by the manufacture.
IP protocol handles logical addressing. The IP address contains specific parameters (unique 32-bit number, divided into four octets, and separated by periods). Example: 192.168.1.99. The addresses are then further divided in classes. The first octet specifies the network class you are using on your network.
Classes
A 1-126 00000001 - 01111111 Subnet Mask 255.0.0.0
B 128-191 10000000 - 10111111 Subnet Mask 255.255.0.0
C 192-223 11000000- 11011111 Subnet Mask 255.255.255.0
D 224-230 11100000-11101111 Reserved for Multi Casting Video Conferencing
E 240-254 11110000-11110111 Testing and Research
IPv4 has 2 to the power of 32 with total number of 4,294,000,000 addresses.
IP Address Break down: 192.168.1.37
192.168 Network Part First two sets of number
1.37 Host Part second set of numbers
Reserved Addresses
127.0.0.1 local host HOME There is no place like home.
APIPA (Automatic Private IP Addressing) 169.254.0.1-169.254.255.254
Can’t use 169.254.0.0 & 169.254.255.255 it is part of a block reserved by IANA.
0.0.0.0 is network 00000000
255.0.0.0 Broadcast 11111111
I need an address.
For the node/workstation to have a unique IP address it can be statically setup or dynamically setup using the following methods:
BOOTP (Bootstrap Protocol) an Application layer protocol which sends a broadcast message asking to be assigned an address. The broadcast will include the MAC address. The BOOTP server then responds with a client IP address, Server IP address, server host name and the IP address of the default router. This has been surpassed by the following protocol. However, you may still encounter these most likely in diskless workstations.
DHCP (Dynamic Host Configuration Protocol) operates at the application layer protocol. It is widely used to assign the network device’s unique IP address automatically (BOOTP replacement). This saves time and reduces headaches due to not having to document and resolve address duplication on workstations/networks.
DHCP leasing is a process where the device borrows/leases IP addresses. Again like any lease car, house, building, it is for a limited time. Once the lease is over, another lease is negotiated or terminated.
APIPA (Automatic Private IP Addressing) if a client cannot communicate without a valid IP address, APIPA will assign it. ***** IANA (Internet Assigned Numbers Authority) reserved predefined pool of addresses 169.254.0.0 through 169.254.255.255
IPv6 Addressing is the next generation of IP addressing that is gradually replacing IPv4. Most new development of applications, servers, and network devices support it. Advantages are a more efficient header, better security, better prioritization provisions, automatic IP address configuration, and it also adds billions of additional IP addresses.
Note: IPv6 2 to the power of 128 with the total number of 340,282,366,920,938,000,000,000,000,000,000,000,000 addresses.
Sockets and Ports
Processes assigned unique port numbers ranging from 0- 65535. A port number is similar to a building number “80” and the IP address “192.168.1.34” may be the suite number within the building. Together the IP and port number make up a socket “192.168.1.34:80“
Example:
Telnet is port: 23
Host IP: 10.43.3.87
Socket: 10.43.3.87:23
Host Names and DNS (Domain Name System) TCP/IP addressing is made up of numbers which are not easily remembered by most humans. Therefore a naming system was established. Which takes the host/device or domain IP and gives it a common name such as Host Name “SERVER” or Domain Name “procomps.com”. The DNS (Domain Name System) relies on many computers across the globe. These computers are related in hierarchical and distributed manners, with 13 computers, known as root servers, so DNS will not fail if there are a handful of the servers experiencing errors. Thus, when changing your DNS for a mail server, it can take up to 24 hours for all DNS servers in the system to update.
Application Layer Protocols
Telnet: Terminal emulation protocol often used to connect two dissimilar systems.
FTP (File Transfer Protocol): sending and receiving files via TCP/IP with no special client software required.
TFTP (Trivial File Transfer Protocol) also enables file transfers between computers and is simpler (more trivial) than FTP. It is connectionless and useful in loading data and programs on diskless workstation
NTP (Network Time Protocol) Synchronizes network computer clocks.
PING (Packet Internet Groper) is a utility used to assist in verifying TCP/IP installed bound to NIC, configured correctly, and communicating with network.
Ping the IP address or host name
Ping loopback address: 127.0.0.1
Protocol (as described by Webster): Code prescribing strict adherence to correct etiquette and precedence (as in diplomatic exchange and in the military services).
TCP/IP Protocols were developed by the Department of Defense–ARPANET (1960s). Its purpose is to share data/talk to other computes and only share/talk to computers that we trust and want to allow access.
TCP/IP (Transmission Control Protocol/ Internet Protocol) is not just one protocol but a collection of specialized protocols/subprotocols. TCP/IP has become the protocol of choice and recently Microsoft and NetWare/Novell use it as their default protocol.
Certain subprotocals of the TCP/IP collection are known as the core protocols and operate in the Network layers of the OSI model. TCP and IP being the most significant in the TCP/IP collection.
TCP (Transmission Control Protocol) operates in the Transport layer of the OSI model and is a reliable data delivery service. It is connection oriented; meaning it must establish communication nodes prior to transmitting data.
UDP (User Datagram Protocol) also operates in the Transport layer of the ISO model. However, it is lightweight and has little overhead. It is connectionless; meaning that packets have no assurance that they will be received in the correct sequence. UDP is used where data must be transferred quickly such as live audio or video.
IP (Internet Protocol) operates at the Network layer of the OSI, providing how and where the data should be delivered. It enables TCP/IP to internetwork more than one LAN segment and more than one type of network through a router. Like UDP, it is connectionless, although it does contain a reliability component, the Header checksum, which verifies the integrity of the routing information in its header.
ICMP (Internet Control Message Protocol) is a Network layer protocol that can detect when part of a network is congested and reports on data delivery success/failure announcing failure to the sender. These announcements provide critical information for troubleshooting it can’t correct errors and the data will be discarded when TTL (Time to Live) expires.
IGMP (Internet Group Management Protocol) operates at the Network layer and manages multicasting (allowing one node to send data to defined group of nodes) used for Internet teleconferencing, videoconferencing, routers, network nodes
ARP (Address Resolution Protocol) operates at the Network layer protocol and is a method for finding a host's (node) MAC address when only its Internet Layer (IP) or some other Network Layer address is known. It then creates a database ARP table (ARP cache) that maps the MAC address to the host’s IP (Logical address). RARP (Reverse Address Resolution Protocol) is used when you do not know the (IP) address. RARP was made obsolete by BOOTP, which has been superseded by the Dynamic Host Configuration Protocol (DHCP).
IPv4 Addressing Networks recognize two addresses: Logical (Network layer) IP address assigned dynamically or manually, and the Physical (MAC, hardware) address is static, assigned by the manufacture.
IP protocol handles logical addressing. The IP address contains specific parameters (unique 32-bit number, divided into four octets, and separated by periods). Example: 192.168.1.99. The addresses are then further divided in classes. The first octet specifies the network class you are using on your network.
Classes
A 1-126 00000001 - 01111111 Subnet Mask 255.0.0.0
B 128-191 10000000 - 10111111 Subnet Mask 255.255.0.0
C 192-223 11000000- 11011111 Subnet Mask 255.255.255.0
D 224-230 11100000-11101111 Reserved for Multi Casting Video Conferencing
E 240-254 11110000-11110111 Testing and Research
IPv4 has 2 to the power of 32 with total number of 4,294,000,000 addresses.
IP Address Break down: 192.168.1.37
192.168 Network Part First two sets of number
1.37 Host Part second set of numbers
Reserved Addresses
127.0.0.1 local host HOME There is no place like home.
APIPA (Automatic Private IP Addressing) 169.254.0.1-169.254.255.254
Can’t use 169.254.0.0 & 169.254.255.255 it is part of a block reserved by IANA.
0.0.0.0 is network 00000000
255.0.0.0 Broadcast 11111111
I need an address.
For the node/workstation to have a unique IP address it can be statically setup or dynamically setup using the following methods:
BOOTP (Bootstrap Protocol) an Application layer protocol which sends a broadcast message asking to be assigned an address. The broadcast will include the MAC address. The BOOTP server then responds with a client IP address, Server IP address, server host name and the IP address of the default router. This has been surpassed by the following protocol. However, you may still encounter these most likely in diskless workstations.
DHCP (Dynamic Host Configuration Protocol) operates at the application layer protocol. It is widely used to assign the network device’s unique IP address automatically (BOOTP replacement). This saves time and reduces headaches due to not having to document and resolve address duplication on workstations/networks.
DHCP leasing is a process where the device borrows/leases IP addresses. Again like any lease car, house, building, it is for a limited time. Once the lease is over, another lease is negotiated or terminated.
APIPA (Automatic Private IP Addressing) if a client cannot communicate without a valid IP address, APIPA will assign it. ***** IANA (Internet Assigned Numbers Authority) reserved predefined pool of addresses 169.254.0.0 through 169.254.255.255
IPv6 Addressing is the next generation of IP addressing that is gradually replacing IPv4. Most new development of applications, servers, and network devices support it. Advantages are a more efficient header, better security, better prioritization provisions, automatic IP address configuration, and it also adds billions of additional IP addresses.
Note: IPv6 2 to the power of 128 with the total number of 340,282,366,920,938,000,000,000,000,000,000,000,000 addresses.
Sockets and Ports
Processes assigned unique port numbers ranging from 0- 65535. A port number is similar to a building number “80” and the IP address “192.168.1.34” may be the suite number within the building. Together the IP and port number make up a socket “192.168.1.34:80“
Example:
Telnet is port: 23
Host IP: 10.43.3.87
Socket: 10.43.3.87:23
Host Names and DNS (Domain Name System) TCP/IP addressing is made up of numbers which are not easily remembered by most humans. Therefore a naming system was established. Which takes the host/device or domain IP and gives it a common name such as Host Name “SERVER” or Domain Name “procomps.com”. The DNS (Domain Name System) relies on many computers across the globe. These computers are related in hierarchical and distributed manners, with 13 computers, known as root servers, so DNS will not fail if there are a handful of the servers experiencing errors. Thus, when changing your DNS for a mail server, it can take up to 24 hours for all DNS servers in the system to update.
Application Layer Protocols
Telnet: Terminal emulation protocol often used to connect two dissimilar systems.
FTP (File Transfer Protocol): sending and receiving files via TCP/IP with no special client software required.
TFTP (Trivial File Transfer Protocol) also enables file transfers between computers and is simpler (more trivial) than FTP. It is connectionless and useful in loading data and programs on diskless workstation
NTP (Network Time Protocol) Synchronizes network computer clocks.
PING (Packet Internet Groper) is a utility used to assist in verifying TCP/IP installed bound to NIC, configured correctly, and communicating with network.
Ping the IP address or host name
Ping loopback address: 127.0.0.1
Thursday, September 10, 2009
Chapter 3 Transmission Basics and Networking Media
Transmission Basics and Networking Media
In any type of communication we have a transmitter and a receiver. Mediums like the book we are using to understand the networking material for this class, is transmitting the information to the reader (receiver). After reading each chapter there are review questions and projects to ensure the message was delivered and understood. These questions acting as a transceiver, asking questions to get a response to acknowledge the user has received the message. Ultimately the class final or certification test will let us know if these mediums transferred the knowledge to the user/node.
Like hand signals the OK sign, the Peace sign or Flipping of the bird, networking has its own type of signaling.
Analog and Digital signal both use electronic current as their source to travel over the medium wire.
Analog is a waveform made up of the following four properties: amplitude, frequency, wavelength, and phase. One of the drawbacks to analog signals is their voltage is varied and imprecise. Analog signals also need to go through technology to modify the signals to make them suitable for carrying data over a communication path.
Digital signal is composed of pulses or precise positive voltages and zero voltages. The positive pulse represents a 1 (one) and a pulse of zero voltage represents a 0 (zero)
Data whether analog or digital is also characterized by the direction it travels over the media (Wire).
Simplex (one way/unidirectional) – Speaker giving a speech and you can’t ask any questions.
Half-duplex (both directions but only one way at a time) – The speaker gives his speech then you can ask a question and the speaker can respond. Still one at a time, people can’t over each other they need to wait.
Full-duplex (bidirectional transmission)–Speaker is giving a speech and hecklers can speak over him blocking his message. Another example would be an argument everyone is talking and not listening.
Now that we can travel in Full-duplex the next thing to do is hold more than one transmission over the same media (wire). This is a technology known as multiplexing which separates the media into smaller sub-channels. An example of this is Voice communications which uses a frequency band of 300-3400 Hz (This is the frequency of human hearing) so they are able to subdivide the band width above 3400 Hz because we are unable to hear the transmissions.
Transmitters and receivers what are their common relationships? Point-to-point transmission is when the sender only transmits data intended for a specific receiver. Point-to-multipoint transmission is still only one sender with multiple receivers. Point-to multipoint is split into two types: broadcast (TV station broadcasting its message) and non-broadcast (Cable TV/pay preview).
Throughput and bandwidth are how we measure the amount/capacity of data transmitted during given time period. Throughput and bandwidth are often interchangeable however the real definition for bandwidth is a measure of the difference between highest and lowest frequencies a medium can transmit.
What is the difference between baseband and broadband transmissions? Baseband transmissions are where digital signals are sent via direct current (DC) requiring exclusive use of one channel. Where broadband transmissions are modulated as radiofrequency analog waves that use different frequency ranges.
Both digital and analog signals have flaws that degrade the signal prior to the signal being received. Noise is any type of undesirable influence degrading or distorting signal. Listed are a few noises that will degrade or distort the signal.
EMI (electromagnetic interference)
RFI (radiofrequency interference)
Cross talk (one signal in a cable infringes on the signal traveling over an adjacent cable)
Environmental influences (Heat, water…)
Another transmission flaw is attenuation the loss of signal’s strength as it travels away from source. There is signal boasting equipment know as an amplifier however, if you have noise on a analog transmission the noise is just going to be amplified creating a bigger issue. With digital signals they use a repeater that regenerates the signal eliminating the noise and increasing the signals strength.
Network cabling and getting it right the first time. Best practices in my experience with cabling along with network gear (switches, routers, firewalls…) and other peripherals is to purchase the latest approved technology following the TIA/EIA standards. Remind decision makers that once we have the infrastructure installed most likely it will not be changing it for ten to 15 years if the latest cabling technologies are used.
Other considerations:
If you are making long runs between two segments of the network, pull two cables at once instead of just one. Therefore if you have issues down the road or need to further expand the segment you have the second cable there without the labor to pull another cable.
When you make a purchase of peripherals (switches, routers, firewalls…) budget to purchase a spare of each therefore in the middle of a day where access to resources are high you are able to repair the issue and keep users working. Many dollars are lost when a network segment is down at 9:00 am in the morning.
In any type of communication we have a transmitter and a receiver. Mediums like the book we are using to understand the networking material for this class, is transmitting the information to the reader (receiver). After reading each chapter there are review questions and projects to ensure the message was delivered and understood. These questions acting as a transceiver, asking questions to get a response to acknowledge the user has received the message. Ultimately the class final or certification test will let us know if these mediums transferred the knowledge to the user/node.
Like hand signals the OK sign, the Peace sign or Flipping of the bird, networking has its own type of signaling.
Analog and Digital signal both use electronic current as their source to travel over the medium wire.
Analog is a waveform made up of the following four properties: amplitude, frequency, wavelength, and phase. One of the drawbacks to analog signals is their voltage is varied and imprecise. Analog signals also need to go through technology to modify the signals to make them suitable for carrying data over a communication path.
Digital signal is composed of pulses or precise positive voltages and zero voltages. The positive pulse represents a 1 (one) and a pulse of zero voltage represents a 0 (zero)
Data whether analog or digital is also characterized by the direction it travels over the media (Wire).
Simplex (one way/unidirectional) – Speaker giving a speech and you can’t ask any questions.
Half-duplex (both directions but only one way at a time) – The speaker gives his speech then you can ask a question and the speaker can respond. Still one at a time, people can’t over each other they need to wait.
Full-duplex (bidirectional transmission)–Speaker is giving a speech and hecklers can speak over him blocking his message. Another example would be an argument everyone is talking and not listening.
Now that we can travel in Full-duplex the next thing to do is hold more than one transmission over the same media (wire). This is a technology known as multiplexing which separates the media into smaller sub-channels. An example of this is Voice communications which uses a frequency band of 300-3400 Hz (This is the frequency of human hearing) so they are able to subdivide the band width above 3400 Hz because we are unable to hear the transmissions.
Transmitters and receivers what are their common relationships? Point-to-point transmission is when the sender only transmits data intended for a specific receiver. Point-to-multipoint transmission is still only one sender with multiple receivers. Point-to multipoint is split into two types: broadcast (TV station broadcasting its message) and non-broadcast (Cable TV/pay preview).
Throughput and bandwidth are how we measure the amount/capacity of data transmitted during given time period. Throughput and bandwidth are often interchangeable however the real definition for bandwidth is a measure of the difference between highest and lowest frequencies a medium can transmit.
What is the difference between baseband and broadband transmissions? Baseband transmissions are where digital signals are sent via direct current (DC) requiring exclusive use of one channel. Where broadband transmissions are modulated as radiofrequency analog waves that use different frequency ranges.
Both digital and analog signals have flaws that degrade the signal prior to the signal being received. Noise is any type of undesirable influence degrading or distorting signal. Listed are a few noises that will degrade or distort the signal.
EMI (electromagnetic interference)
RFI (radiofrequency interference)
Cross talk (one signal in a cable infringes on the signal traveling over an adjacent cable)
Environmental influences (Heat, water…)
Another transmission flaw is attenuation the loss of signal’s strength as it travels away from source. There is signal boasting equipment know as an amplifier however, if you have noise on a analog transmission the noise is just going to be amplified creating a bigger issue. With digital signals they use a repeater that regenerates the signal eliminating the noise and increasing the signals strength.
Network cabling and getting it right the first time. Best practices in my experience with cabling along with network gear (switches, routers, firewalls…) and other peripherals is to purchase the latest approved technology following the TIA/EIA standards. Remind decision makers that once we have the infrastructure installed most likely it will not be changing it for ten to 15 years if the latest cabling technologies are used.
Other considerations:
If you are making long runs between two segments of the network, pull two cables at once instead of just one. Therefore if you have issues down the road or need to further expand the segment you have the second cable there without the labor to pull another cable.
When you make a purchase of peripherals (switches, routers, firewalls…) budget to purchase a spare of each therefore in the middle of a day where access to resources are high you are able to repair the issue and keep users working. Many dollars are lost when a network segment is down at 9:00 am in the morning.
Thursday, September 3, 2009
Chapter 2 Networking Standards
Networking Standards and the OSI Model
Networking standards are established norms or requirements that are formally documented by professional organizations. It’s like having a standard/national language that everyone speaks, but let’s not go there. ISO International Organization for Standardization which goal is to establish international technological standards to facilitate global exchange of information and barrier free trade. ISO has more than 17,000 industrial standards and of these fewer than 3000 of them apply to the computer related products and functions.
The OSI (Open System Interconnection) Model was developed by ISO in the early 1980s. It is a theoretical model the divides network communications into Seven Layers to assist in understanding during the development process of network computer-to-computer communications.
Application (Top - Seventh Layer) - Facilitates communication (security, formatting, procedural, synchronization…) between software applications and lower-layer network services.
Presentation (Sixth Layer) - Formats data understandable to different applications and hosts.
Session (Fifth Layer ) – Builds, maintains and tears down the communication between network nodes.
Transport (Fourth Layer) –Manages reliable end-to-end delivery of data between network nodes.
Network (Third Layer) – Translates network addresses into their physical counterparts and decides how to deliver them between network nodes.
Data Link(Second Layer) -Divides data received into distinct frames for transmission in Physical layer. It is divided into two sub layers the LLC (Logical Link Control) which communicates with network layer and the MAC (Media Access Control) which manages access to the physical layer.
Physical (Bottom- First Layer) – Accepts frames from the data link layers and generates signals as changes in voltage at the NIC(Network Interface Card). Wireless the signals are sent via antennas as electromagnetic waves.
The following are other significant organizations helping ensure interoperability within the global computer technology industry.
ANSI (American National Standards Institute) http://www.ansi.org/
EIA (Electronic Industries Alliance) http://www.eia.org/
TIA (Telecommunications Industry Association) http://www.tai.org/
IEEE (Institute of Electrical and Electronics Engineers) http://www.ieee.org/
ITU (International Telecommunication Union) http://www.itu.int/
ISOC (Internet Society)http://www.isoc.org/
IAB (Internet Architecture Board) http://www.iab.org/
IETF (Internet Engineering Task Force) http://www.ietf.org/
IANA (Internet Assigned Numbers Authority) http://www.iana.org/
ARIN (American Registry for Internet) https://www.arin.net/
APNIC (Asia Pacific Network Information http://www.apnic.net/
RIPE (Réseaux IP Européens) http://www.ripe.org/
ICANN (Internet Corporation for Assigned Names and Numbers) http://www.icann.org/
Networking standards are established norms or requirements that are formally documented by professional organizations. It’s like having a standard/national language that everyone speaks, but let’s not go there. ISO International Organization for Standardization which goal is to establish international technological standards to facilitate global exchange of information and barrier free trade. ISO has more than 17,000 industrial standards and of these fewer than 3000 of them apply to the computer related products and functions.
The OSI (Open System Interconnection) Model was developed by ISO in the early 1980s. It is a theoretical model the divides network communications into Seven Layers to assist in understanding during the development process of network computer-to-computer communications.
Application (Top - Seventh Layer) - Facilitates communication (security, formatting, procedural, synchronization…) between software applications and lower-layer network services.
Presentation (Sixth Layer) - Formats data understandable to different applications and hosts.
Session (Fifth Layer ) – Builds, maintains and tears down the communication between network nodes.
Transport (Fourth Layer) –Manages reliable end-to-end delivery of data between network nodes.
Network (Third Layer) – Translates network addresses into their physical counterparts and decides how to deliver them between network nodes.
Data Link(Second Layer) -Divides data received into distinct frames for transmission in Physical layer. It is divided into two sub layers the LLC (Logical Link Control) which communicates with network layer and the MAC (Media Access Control) which manages access to the physical layer.
Physical (Bottom- First Layer) – Accepts frames from the data link layers and generates signals as changes in voltage at the NIC(Network Interface Card). Wireless the signals are sent via antennas as electromagnetic waves.
The following are other significant organizations helping ensure interoperability within the global computer technology industry.
ANSI (American National Standards Institute) http://www.ansi.org/
EIA (Electronic Industries Alliance) http://www.eia.org/
TIA (Telecommunications Industry Association) http://www.tai.org/
IEEE (Institute of Electrical and Electronics Engineers) http://www.ieee.org/
ITU (International Telecommunication Union) http://www.itu.int/
ISOC (Internet Society)http://www.isoc.org/
IAB (Internet Architecture Board) http://www.iab.org/
IETF (Internet Engineering Task Force) http://www.ietf.org/
IANA (Internet Assigned Numbers Authority) http://www.iana.org/
ARIN (American Registry for Internet) https://www.arin.net/
APNIC (Asia Pacific Network Information http://www.apnic.net/
RIPE (Réseaux IP Européens) http://www.ripe.org/
ICANN (Internet Corporation for Assigned Names and Numbers) http://www.icann.org/
Chapter 1 An Introduction to Networking.
Networking: In a social sense is a way of connecting and sharing with others who have similar interest, careers, religions, languages… This is similar with computer networking computers have to have a common language, users that have common interests/gaols. Whether it be business, social, religious… we are seeing more networking as the net(internet) grows.
This networking has grown from the simple Sneaker Net(One to One) sharing files via the floppy disk, USB drive ... To Peer to Peer hooking up small network sharing files between up to 10 computers. To Client Server Networks where data and resource are centrally stored/shared on a server. Users/clients then login into share the resources provided by the servers (Printing, File Sharing, e-mail,). Although it is more complex to set up it then the first two methods it creates central administrative feature making them easier to manage, more scalable and more secure if set up properly.
The Client Server Networks needs a NO (Network Operating System). These are some of the popular NOs are Novell, Linux, MS Windows Server, Unix, MAC. Each of these are purchased as a per user/client license so your cost based on the number of users.
The following are the types of networks that support Client Server Networks:
LAN (Local Area Network) – A network in one building. This could also be a Peer to Peer Network.
WLAN (Wireless Local Area Network) – A network that links two or more computers or devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area. This gives users the mobility to move around within a broad coverage area and still be connected to the network.
MAN (Metropolitan Area Network) - A network that is larger than a LAN, typically connecting clients and servers from multiple buildings, but within a limited geographic area.
WAN (Wide Area Network) - A network that spans a long distance and connects two or more LANs.
GAN (Global Area Network) –A network that is composed of different interconnected computer networks (WANs) and also covers an unlimited geographical area.
Another type of network:
PAN (Personal Area Network) - A computer network used for communication among computer devices (including telephones and personal digital assistants) close to one's person.
Certifications:
There are two types of Certifications, professional organizations and vendor specific. The CompTIA (Computer Technology Industry Association) is an example of a non-vendor specific certification. To see the certifications they support click on the following link.
http://www.comptia.org/certifications/listed.aspx
Vendor Specific would be certification by the vendor of their products (Microsoft, Cisco, Novell...).
Both types of certifications are recognized worldwide as a trusted indicator of qualified and competent professionals in the IT industry. Obtaining these certifications will help you obtain the career goals you have in the IT industry.
This networking has grown from the simple Sneaker Net(One to One) sharing files via the floppy disk, USB drive ... To Peer to Peer hooking up small network sharing files between up to 10 computers. To Client Server Networks where data and resource are centrally stored/shared on a server. Users/clients then login into share the resources provided by the servers (Printing, File Sharing, e-mail,). Although it is more complex to set up it then the first two methods it creates central administrative feature making them easier to manage, more scalable and more secure if set up properly.
The Client Server Networks needs a NO (Network Operating System). These are some of the popular NOs are Novell, Linux, MS Windows Server, Unix, MAC. Each of these are purchased as a per user/client license so your cost based on the number of users.
The following are the types of networks that support Client Server Networks:
LAN (Local Area Network) – A network in one building. This could also be a Peer to Peer Network.
WLAN (Wireless Local Area Network) – A network that links two or more computers or devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area. This gives users the mobility to move around within a broad coverage area and still be connected to the network.
MAN (Metropolitan Area Network) - A network that is larger than a LAN, typically connecting clients and servers from multiple buildings, but within a limited geographic area.
WAN (Wide Area Network) - A network that spans a long distance and connects two or more LANs.
GAN (Global Area Network) –A network that is composed of different interconnected computer networks (WANs) and also covers an unlimited geographical area.
Another type of network:
PAN (Personal Area Network) - A computer network used for communication among computer devices (including telephones and personal digital assistants) close to one's person.
Certifications:
There are two types of Certifications, professional organizations and vendor specific. The CompTIA (Computer Technology Industry Association) is an example of a non-vendor specific certification. To see the certifications they support click on the following link.
http://www.comptia.org/certifications/listed.aspx
Vendor Specific would be certification by the vendor of their products (Microsoft, Cisco, Novell...).
Both types of certifications are recognized worldwide as a trusted indicator of qualified and competent professionals in the IT industry. Obtaining these certifications will help you obtain the career goals you have in the IT industry.
Thursday, August 27, 2009
Introduction Post
I'm taking the class to acquire the Network+ Certification.
Currently the company Progressive Components I have been working for the past 11 years has moved from a Netware(GroupWise, iFolder, ) environment to a internal and hosted Microsoft environment. My company is now requiring me to get my Microsoft Certified Systems Administrator(MCSA) over the next year and I think this class will help me prep for the exams.
I look forward to learning more along with refining my networking skills.
Currently the company Progressive Components I have been working for the past 11 years has moved from a Netware(GroupWise, iFolder, ) environment to a internal and hosted Microsoft environment. My company is now requiring me to get my Microsoft Certified Systems Administrator(MCSA) over the next year and I think this class will help me prep for the exams.
I look forward to learning more along with refining my networking skills.
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