5-2
Each RIPng router maintains a routing database, including route entries of all reachable destinations.
A route entry contains the following information:
z Destination address: IPv6 address of a host or a network.
z Next hop address: IPv6 address of a neighbor along the path to the destination.
z Egress interface: Outbound interface that forwards IPv6 packets.
z Metric: Cost from the local router to the destination.
z Route time: Time that elapsed since a route entry is last changed. Each time a route entry is
modified, the routing time is set to 0.
z Route tag: Identifies the route, used in a routing policy to control routing information. For
information about routing policy, refer to Routing Policy Configuration in the IP Routing Volume.
RIPng Packet Format
Basic format
A RIPng packet consists of a header and multiple route table entries (RTEs). The maximum number of
RTEs in a packet depends on the IPv6 MTU of the sending interface.
Figure 5-1 shows the packet format of RIPng.
Figure 5-1 RIPng basic packet format
…
z Command: Type of message. 0x01 indicates Request, 0x02 indicates Response.
z Version: Version of RIPng. It can only be 0x01 currently.
z RTE: Route table entry, 20 bytes for each entry.
RTE format
There are two types of RTEs in RIPng.
z Next hop RTE: Defines the IPv6 address of a next hop
z IPv6 prefix RTE: Describes the destination IPv6 address, route tag, prefix length and metric in the
RIPng routing table.
Figure 5-2 shows the format of the next hop RTE:
Figure 5-2 Next hop RTE format
IPv6 next hop address is the IPv6 address of the next hop.
Figure 5-3 shows the format of the IPv6 prefix RTE.
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