RIPng Packets

A RIPng packet header contains 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 or when a request message is received. Periodic response messages are called update messages. Update messages contain the command and version fields and a set of destinations and metrics.
Version number—Specifies the version of RIPng that the originating router is running. This is currently set to Version 1.

The rest of the RIPng packet contains a list of routing table entries that contain the following fields:

Destination prefix—128-bit IPv6 address prefix for the destination.
Prefix length—Number of significant bits in the prefix.
Metric—Value of the metric advertised for the address.
Route tag—A route attribute that must be advertised and redistributed with the route. Primarily, the route tag distinguishes external RIPng routes from internal RIPng routes in cases where routes must be redistributed across an exterior gateway protocol (EGP).