RIPng packet processing procedure
Request packet
When a RIPng router first starts or needs to update entries in its routing table, usually a multicast request packet is sent to ask for needed routes from neighbors.
The receiving RIPng router processes RTEs in the request. If only one RTE exists with the IPv6 prefix and prefix length both being 0, and with a metric value of 16, the RIPng router will respond with the entire routing table information in response messages. If multiple RTEs exist in the request message, the RIPng router will examine each RTE, update its metric, and send the requested routing information to the requesting router in the response packet.
Response packet
The response packet containing the local routing table information is generated as follows:
A response to a request
An update periodically
A trigged update caused by route change
After a router receives a response, it checks the validity of the response before adding the route to its routing table, such as whether the source IPv6 address is the link-local address and whether the port number is correct. The response packet that failed the check is discarded.