Static Routing and Distance Vector Routing Protocols - CCIE Routing and Switching Exam Certification Guide - page 323

show ip rip database Command (Continued) Example 7-1

172.16.3.0/24
[1] via 172.16.1.2, 00:00:02, Ethernet0
172.16.4.0/24 directly connected, Serial0

RIPv1 Message Format
As described in RFC 1058, the RIPv1 message format is shown in Figure 7-1. The RIP message
is appended to a User Datagram Protocol (UDP) header.

IPv1 Message Format

Figure 7-1

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

Command Version Unused (must be zero)

Address Family Identifier Unused (must be zero)

IP address (1 st route entry)
Unused (must be zero)
Unused (must be zero)
Metric

Address Family Identified Unused (must be zero)

IP address (2 nd route entry up to 25)

Unused

Unused

Metric

The following is a description of each field:
•

Command —Describes the purpose of the packet. Five commands are described in the
RFC, of which two are obsolete and one is reserved. The two commands that you use are
as follows:

— request —Sent to request all or part of the responding router's routing table.

— response —Contains all or part of the sender's routing table. This message can
be sent in response to a request, or it can be an update message generated by the
sender.

•

Version —Set to 1 for RIPv1.

•

Address Family Identifier (AFI) —Set to a value of 2 for IP.