Configuring RIP Interface Options in Cisco

Pre-requisite: RIP, Configuring RIP Versions 1 and 2 in Cisco.

RIP is a classless, distance-vector routing protocol (DVRP). It is a timer-driver routing protocol. It uses User Datagram Protocol (UDP) as a transport protocol and port 520. It uses hop count as the metric ranging from 1 to 16 where 15 is considered to be the maximum metric and 16 as the infinite (inaccessible) to remove the previously installed route i.e., to perform route poisoning which is a method of quickly forgetting outdated routing information from neighbor router's routing table. RIPv2 supports both plain text MD5 authentication.

When RIP is enabled on a router, there are some Per-Interface Actions/ interface options in RIP, and also disable them when these actions are enabled. There are 2 actions under interface configuration mode which allows setting the RIP version(s) in which the router will send and/or receive RIP advertisements and process them. Also, there is an option to enable RIPv2 to send broadcast updates on a per-interface basis in interface configuration mode. 

RIP Interface Options Command:

Configuring RIP Interface Options:

Step 1: Create the 3 router topology in GNS3 as shown in the image below:

Step 2: Configure IPv4 address on the physical interface of the routers :

R1(config)#int f0/0
R1(config-if)#ip address 12.1.1.1 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#int f1/0
R1(config-if)#ip address 13.1.1.1 255.255.255.0
R1(config-if)#no shutdown

R2(config)#int f0/0
R2(config-if)#ip address 12.1.1.2 255.255.255.0
R2(config-if)#no shutdown
R2(config-if)#int s2/0
R2(config-if)#ip address 23.1.1.1 255.255.255.0
R2(config-if)#no shutdown

R3(config)#int f0/0    
R3(config-if)#ip address 13.1.1.2 255.255.255.0
R3(config-if)#no shutdown
R3(config-if)#int s2/0
R3(config-if)#ip add 23.1.1.2 255.255.255.0
R3(config-if)#no shutdown

Step 3: Enabling RIP on all routers using the router rip global configuration command :

R1(config)#router rip
R1(config-router)#network 12.0.0.0 

R1(config-router)#network 13.0.0.0

R2(config)#router rip 
R2(config-router)#network 12.0.0.0
R2(config-router)#network 23.0.0.0

R3(config)#router rip
R3(config-router)#network 13.0.0.0
R3(config-router)#network 23.0.0.0

Step 4: Checking the IPv4 routing table on the routers for RIP route entry :

R1#show ip route

R2#show ip route

R3#show ip route

Step 5: Configure R2 to send and receive RIP Version 1 and 2 updates on the point-to-point link towards R3:

R2(config-if)#int serial2/0           
R2(config-if)#ip rip send version 1 2 
R2(config-if)#ip rip receive version 1 2
R2(config-if)#end

Step 6: Verifying the RIP interface option configuration on R2's serial interface:

R2#show ip protocols

Step 7: Configure R1’s fastethernet interface towards R2 to send RIPv2 updates as broadcast and not multicast:

R1(config)#interface fa0/0
R1(config-subif)#ip rip v2-broadcast
R1(config-subif)#end

Step 8: Verifying the RIP interface option configuration on R1 by debugging RIP events packets and verifying destination address of the packets as layer 3 broadcast address:

R1#debug ip rip events

To turn off debugging : 

R1#undebug all

Step 9: Verifying RIP configuration on all 3 routers;

R1#show ip protocols

R2#show ip protocols

R3#show ip protocols

Capturing Interface using Wireshark :

To capture the interface in GNS3 :

1. Make sure that the Wireshark is installed on your PC.
2. Hover over the interface you want to capture and right-click on the interface  
3. A drop-down menu will appear with some options.
4. Select the option that says “Start capture”.

RIP Advertisements:

Packets highlighted in red are RIPv1 advertisements:

RIPv1 advertisement (request message) packet format :

jt9999709701

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Article Tags :

• Computer Networks
• Technical Scripter 2022