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 :

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to remove the previously installed route i.e., to perform route poisoning which is a method of quickly forgetting outdated routing information from neighbor router’s routing table.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.