RIP Packets

RIP packets contain the following fields:

Command—Indicates whether the packet is a request or response message. Request messages seek information for the router’s routing table. Response messages are sent periodically and also when a request message is received. Periodic response messages are called update messages. Update messages contain the command and version fields and 25 destinations (by default), each of which includes the destination IP address and the metric to reach that destination.
Version number—Version of RIP that the originating router is running.
Address family identifier—Address family used by the originating router. The family is always IP.
Address—IP address included in the packet.
Metric—Value of the metric advertised for the address.
Mask—Mask associated with the IP address (RIP version 2 only).
Next hop—IP address of the next-hop router (RIP version 2 only).