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The main purpose of this TCS was to introduce the students to the IGRP routed protocol. Students had to implement the protocol on a router and discuss how it differs from other routed protocols. There were also unrelated learning objectives.

The main learning objectives of the TCS were the following:

1. Describe the three major portions of an IP address.

This is known as the network part. It identifies your network number which is registered with InterNIC. This number is the same for all devices on your network depending on what type of license you have and how many devices you address.

This is known as the host part. This part, along with the network portion completes the IP address. The host part gives each device on your network an individual address. Every station on your network should have its own different host address.

The third part is a totally separate address. It's known as the subnet mask. This allows for flexibility in addressing your network. It also provides extra security for the network. The subnet mask tells your network devices how many bits were borrowed which indicates the subnet that the destination device is located on.

2. Describe the function of the TCP/IP network-layer protocols and how they are used for path determination.

1. IP - IP is a connectionless, best effort delivery protocol. It's concerned with determining the best path to send a datagram that it receives.

2. ICMP - This protocol is mainly used for testing connections between two communicating devices. It sends error and control messages between the two end users.

3. ARP - This protocol is used to map a physical address (MAC) to a known IP address.

4. RARP - This protocol is used to map a known MAC address to an IP address.

3. Describe what a routing metric is and what the various components mean.

A routing metric is the method by which a routing algorithm determines that one route is better than another. Each algorithm generates a number for each path through the network. Usually the smaller the number the better the path. These metrics can be calculated based on a single characteristic of a path, but it is also possible to calculate more complex metrics by combining several characteristics.

There are seven (7) different routing metrics used most often:

1. Bandwidth - Data capacity of a link.
2. Delay - Length of time required to move a packet from source to destination.
3. Load - Amount of activity on a network resource such as a router or link.
4. Reliability - The error rate of each network link.
5. Hop Count - Number of routers a packet must pass through.
6. Ticks - Delay on a data link using IBM PC clock ticks.
7. Cost - Arbitrary value based on any number of measurements that is assigned by a network administrator.

4. Describe the difference between distance vector and link state routing protocols.

Distance vector routing algorithm - Class of routing algorithms that iterate on the number of hops in a route to find a shortest-path spanning tree. Distance vector routing algorithms call for each router to send its entire routing table in each update, but only to its neighbors. Distance vector routing algorithms can be prone to routing loops, but are computationally simpler than link state routing algorithms. Also called Bellman-Ford routing algorithm.

Link state routing algorithm - Routing algorithm in which each router broadcasts or multicasts information regarding the cost of reaching each of its neighbors to all nodes in the internetwork. Link state algorithms create a consistent view of the network and are therefore not prone to routing loops, but they achieve this at the cost of relatively greater computational difficulty and more widespread traffic compared with distance vector routing algorithms.

5. How to implement IGRP on a router.

1. On a computer with some form of terminal or hyper-terminal program, open up that program and wait for the program to finish loading.

2. Once the program opens, hold down the "Alt" key and press "S" and then "C." A window will come up that has a title bar that says "Communications."

3. Configure all of the settings according to the following:

Baud Rate: 9600
Data Bits: 8
Stop Bits: 2
Parity: None
Flow Control: None
Connector: COM1

*Be sure to leave the "Parity Check" and "Carrier Detect" boxes unchecked.

4. Once this is all set press the "OK" button.

5. The program will then show you a blank screen. Hit enter a few times until a message comes up that says "Press return to get started"

6. Press enter and you should see a prompt that looks like this:

router-d>

*The letter after the word router may be a different letter, but for the purpose of writing these instructions, we will use the letter "d"

7. From here on you should see and type exactly as you see in the following instructions.

8. Prompt	Command
   router-d>	enable
   Password:	cisco
   router-d#	config t
   router-d(config)#	router rip
   router-d(config-router)#	network xxx.xxx.xxx.xxx	(xxx.xxx.xxx.xxx is the network address of any routers listed as directly connected on the information sheet. If you have more than than one network directly connected to your router you must type the network command with each individual address until you have entered all of the addresses.)
   router-d(config-router)#	exit
   router-d(config)#	exit
   router-d#	copy run start
   router-d#	config t
   router-d(config)#	router igrp 200
   router-d(config-router)#	network xxx.xxx.xxx.xxx	(xxx.xxx.xxx.xxx is the network address of any routers listed as directly connected on the information sheet. If you have more than than one network directly connected to your router you must type the network command with each individual address until you have entered all of the addresses.)
   router-d(config-router)#	exit
   router-d(config)#	exit
   router-d#	copy run start

9. If you wish to run both the RIP and IGRP protocols, you are finished. If you wish to run IGRP only, you must do the following.

Prompt	Command
router-d#	config t
router-d(config)#	no router rip
router-d(config)#	exit
router-d#	copy run start
router-d#	exit

10. You will be returned to the screen which says "Press return to get started" and you are now finished. All you have to do is exit the terminal program.

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