Chapter Four

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Deciphering RIP, IGRP & EIGRP

This chapter will walk you through the commands and information that are concerned with the optional and mandatory commands for the configuration of the Routing Information Protocol (RIP). I will also explain the commands that are linked to the configuration of RIP Version 2 (RIP-2).

First of all, I will explain how you can turn and off the ip classless.

• The command Georgia(config)#ip classless will direct IOS to process the packets that are destined for the unknown subnet toward the top supernet route. Usually, you do not have to enable this command in cisco as it is enabled by default in interfaces.
• The command Georgia(config)#no ip classless will undo what you have done with the help of the previous command.

RIP Routing

• The command Georgia(config)#router rip will help you to enable RIP.
• The command Georgia(config-router)#network w.x.y.z is usually a network number of a directly connected network that you are looking forward to advertise.

If you happen to advertise a subnet, there will be no error message, because the router will convert that subnet into a classful address.

The above mentioned commands are mandatory. What you will see next will be the optional commands.

• The command Georgia(config)#no router rip will let you switch off the RIP routing process.
• The command Georgia(config-router)#no network w.w.w.w will let you remove the network mentioned in the command from the RIP process. This is easy and fun. You can simply name the network in the command and do away with it in no time.
• The command Georgia(config-router)#passive-interface s0/0 will let you lock the RIP updates so that they cannot be sent out of your interface.
• The command Georgia(config-router)#ip split-horizon will let you enable the split.
• The command Georgia(config-router)#no ip split-horizon will let you turn off your split horizon. The split horizon is usually on by default settings.
• The command Georgia(config-router)#neighbor x.x.x.x will let you define a neighbor to share your information.
• The command Georgia(config-router#timera basic 30 90 180 270 360 will let you change the timers of your RIP. You can update the timer at 30 seconds. The timer will turn invalid in 90 seconds and the hold-down timer is at 180. The flush timer is at 270 and the sleep timer is at 360 seconds.
• The command Georgia(config-router)#default-information originate will let you generate some default routes in the RIP.

RIP Version 2 Commands

• The command Georgia(config-router)#version 2 will let you tune the system as such that the RIP will only send and receive the RIP-2 packets in a global setting.
• The command Georgia(config-if)#ip rip send version 1 will let you send only the RIP-1 packets.
• The command Georgia(config-if)#ip rip send version 2 will let you send only the RIP-2 packets.
• The command Georgia(config-if)#ip rip send version 1 2 will let you send only the RIP-1 packets and RIP-2 packets.
• The command Georgia(config-if)#ip rip receive version 1 will let you receive only the RIP-1 packets.
• The command Georgia(config-if)#ip rip receive version 2 will let you receive only the RIP-2 packets.
• The command Georgia(config-if)#ip rip receive version 1 2 will let you receive only the RIP-1 packets and RIP-2 packets.

Troubleshooting Problems

The commands that you can use to troubleshoot problems are as under:

• The command Georgia#debug ip rip will let you see the entire RIP activity. The results will be displayed in real time.
• The command Georgia#show ip rip database will let you see the contents of the database of RIP.

Mandatory Commands for RIP Version 2

• The command Georgia(config)#router rip will let you switch on the RIP routing process. You can use the same command for RIP Version as well.
• The command Georgia(config-router)#version 2 will let you switch on Version 2 of your routing process. Version 1 is default.
• The command Georgia(config-router)#network y.y.y.y will let you advertise the network that has been mentioned.

Optional Commands for RIP Version 2

• The command Georgia(config-router)#no version 2 will let you change the version back to the previous one that is RIP-1
• The command Georgia(config-router)#version 1 will let you change the RIP routing back to RIP-1.
• The command Georgia(config-router)#no auto-summary will let you summarize different networks. The RIP-2 summarizes different networks at the boundary namely classful. The command tends to turn off the autosummarization process.
• The command Georgia(config-router)#auto-summary will let you enable the autosummarization process again at the boundary namely classful.

IGRP

In the following section, I will give the details of different mandatory and optional commands that are related to Interior Gateway Routing Protocol (IGRP).

• The command Georgia(config)#router igrp will enable the routing process related to IGRP. IGRP routing uses autonomous system. The process ought to match other routers that will share the routing updates to make sure that the communication takes place.
• The command Georgia(config-router)#network x.x.x.x will let you advertise the network. The x.x.x.x is the name of the network that is directly connected and that you are looking forward to advertise.

You only have to advertise the classful network. You are not required to advertise a subnet. If you advertise a subnet, you will see no error message, because the router is likely to automatically convert the subnet into the address of a classful network.

Mandatory Commands for IGRP

There are few mandatory commands for IGRP routing. They are listed as under:

• The command Georgia(config)#no router igrp (enter number here) will let you disable the entire process of IGRP routing.
• The command Georgia(config-router)#no network x.x.x.x will let you remove the named network from the process of IGRP routing.
• The command Georgia(config-router)#bandwidth a will set up the bandwidth of the interface to a kilobit so that IGRP is allowed to make an improved routing decision.
• The command Georgia(config-router)#variance a will let the IGRP take on the unequal-cost routes.

The bandwidth command is also used for metric calculations. It will not change the performance of the interface.

Troubleshooting

You can use two commands to troubleshoot if an issue pops up in the middle of the operations.

• The command Georgia#debug ip igrp events will let you see the IGRP events in the real time.
• The command Georgia#debug ip igrp transactions will let you see the IGRP updates that exist in between the routers.

EIGRP

This section will explain how to configure EIGRP, verify EIGRP, autosummarize EIGRP, and troubleshoot EIGRP.

Configuring EIGRP

• The command Georgia(config)#router eigrp 100 will turn on process 100 of EIGRP, an autonomous system (AS) number. This can be a number in between 1 and 65535. All the routers in AS ought to use a similar AS number.
• The command Georgia(config-router)#network 10.0.0.0 will specify which network must advertise in EIGRP.
• The command Georgia(config-router)#eigrp log-neighbor-changes will log any kind of changes that happen to one of the EGRIP neighbors.
• The command Georgia(config-router)#no network 10.0.0.0 will allow you to remove the same network from EIGRP process.
• The command Georgia(config-router)#bandwidth a will allow you to set up the bandwidth of your interface to a kilobit. This allows the EIGRP to make an improved and beneficial routing decision. You only can use the bandwidth command to perform the metric calculations. This usually does not change the performance of your interface.

Auto-summarization

• The command Georgia(config-router)#no auto-summary will allow you to switch off the feature of auto-summarization. You will be able to summarize the networks, by default, at the boundary of the classful. The command Georgia(config-router)#int fa 0/0 is also a part of the auto-summarization process.
• The command Georgia(config-if)#ip summary-address eigrp 100 10.10.0.0 255.255.0.0 will allow you to enable the manual summarization process on your interface. This will be for the given mask and address.

EIGRP offers the facility to summarize different networks automatically at the boundary namely classful. If a network is poorly designed and is packed up with discontinuous subnets, it could create connectivity problems, especially if you leave the summarization feature open. There may be two routers that advertise the same network. However, the original intention can be the advertising of two different networks. In this situation, you should switch off the feature of auto-summarization and use the ip summary-address in its place. You can manually summarize what you have to do.

Verifying EIGRP

• The command Georgia#show ip eigrp neighbors will allow you to see the neighbor table.
• The command Georgia#show ip eigrp neighbors detail will allow you to see the contents of the same table.
• The command Georgia#show ip eigrp topology will allow you to see the table for topology.
• The command Georgia#show ip eigrp int 100 will allow you to see the data regarding running process 100 of interfaces.
• The command Georgia#show ip eigrp s 0/0 will allow you to see the information for a particular interface.
• The command Georgia#show ip eigrp interfaces will allow you to see the data that pertains to each interface.
• The command Georgia#show ip eigrp traffic will allow you to see the type of packets sent or received and the numbers.

Troubleshooting

You can use the following commands to troubleshoot a problem that pops up along the way.

• The command Georgia#debug eigrp fam will allow you to see the actions/events that are related to the DUAL FSM.
• The command Georgia#debug eigrp neighbor will allow you to see the actions/events that are connected to EIGRP neighbors.
• The command Georgia#debug eigrp packet will allow you to see the actions/events that are connected to the packets of EIGRP.

RIP Next Generation

In this section, I will explain how you can implement RIPng on your routers.

• The command Georgia(config)#ipv6 unicast-routing will allow you to enable to spread the IPv6 unicast datagrams across the router globally.
• The command Georgia(config)#interface serial0/0/0 will allow you to shift to the interface's configuration mode.
• The command Georgia(config-if)#ipv6 tip tower enable will allow you to create the process named tower. It also enables the RIPng on your interface. The RIPng processes are shorter and smarter than the processes of RIPv1 and RIPv2. In RIPng, you do not have to create RIP routing processes with the help of the router rip command. Also, you do not have to use the network command for the specification of your interfaces on which you will run RIP. In RIPng, these processes are created and done away with automatically on your interface. All it takes is the ipv rip name enable command. The name of the process should not be misspelled. If you misspell it, you will create a second process that carries the misspelled name. The name of the routing process need not match between the neighboring routers.
• The command Georgia(config)#ipv6 router rip tower will allow you to create a process named tower. It also takes you to the configuration mode of the router.
• The command Georgia(config-router)#maximum-paths 2 will allow you to define how many equal-cost routes there will be that are supported by RIPng. The number of paths may range between 1 and 64. The default number here is 64.
• The command Georgia(config-if)#ipv6 rip tower default-information originate will reveal the default route and other RIPng routes.
• The command Georgia(config-if)#ipv6 rip tower default-information only will reveal the default route. One difference is that this command will hide the other RIPng routes.

Troubleshooting RIPng

When you are using the debug command for RIPng, it is likely to affect the router performance adversely. It may even trigger a reboot in the router. Therefore, you should always stay cautious when you are using this command. You must never leave the debugging process open. You may use it long enough to collect the information and once you have harvested the information, you must immediately disable it with the undebug command. I will continue to use the router name Georgia in the following example as well. Here is the rundown of the commands for troubleshooting in RIPng.

• The command Georgia#clear ipv6 rip will help you to delete the routes from the IPv6 RIP table. It will also delete the routes from the IPv6 table as well. 
• The command Georgia#clear ipv6 route * will let you delete all the routes that exist in the IPv6 routing table.
• The command Georgia#clear ipv6 route 2001:db8:c18:3: :/64 will let you clear a specific route from the IPv6 table.
• The command Georgia#clear ipv6 interface will let you see the status of all the interfaces that have been configured for IPv6.
• The command Georgia#clear ipv6 routing will let you see the debug messages related to the updates of the IPv6 routing table and the routing cache updates.
• The command Georgia#clear ipv6 traffic will let you reset the IPv6 traffic counters.
• The command Georgia#clear ipv6 packet will let you see the debug messages that are for the IPv6 packets.
• The command Georgia#clear ipv6 rip will let you see the debug messages for the transactions regarding IPv6 RIP routing.
• The command Georgia#show ipv6 route rip will let you see the present routes for RIPng in the IPv6 table.
• The command Georgia#show ipv6 route will let you see the present status of the IPv6 table.
• The command Georgia#show ipv6 rip next-hops will let you see the processes of RIPng. It also displays the next-hop processes that are running under each major process.
• The command Georgia#show ipv6 tip database will let you see the database of the RIPng processes. Even if more than two processes are running in the system, this command will show all the databases.
• The command Georgia#show ipv6 rip will let you see the information about the present process.
• The command Georgia#show ipv6 protocols will let you see the protocols and the present state of all the IPv6 protocol processes.
• The command Georgia#show ipv6 neighbors will let you see the IPv6 neighbor discovery information.
• The command Georgia#show ipv6 traffic will let you see the statistics that are related to IPv6 traffic.
• The command Georgia#show ipv6 route summary will let you see the short form of the IPv6 table.
• The command Georgia#show ipv6 routers will let you see the advertisement data for the IPv6 router.

IPv6 Ping

If you are looking forward to diagnosing the basic connectivity in a network with the help of IPv6, you may enter the Ping command that can be seen below.

Georgia#ping ipv6 2001:db8: :3/64

In the next section, I will shed light on the characters that you will see and their meaning and understand how to read the symbols.