RFC 1058 specified an open standard RIP. This RIP, like its proprietary ancestors, was designed as a simple distance-vector routing protocol. It was specifically designed for use as an Interior Gateway Protocol (IGP) in small, simple networks.
RIP uses a special packet to collect and share information about distances to known internetworked destinations. This packet contains the following structure:
A 1-octet command field
A 1-octet version number field
A 2-octet zero field
A 2-octet Address Family Identifier (AFI) field
Another 2-octet zero field
A 4-octet Internetworking Address (i.e., IP Address) field
A 4-octet zero field
Another 4-octet zero field
A 4-octet metric field
Figure 8-2 illustrates the RIP packet ...