Operation Manual – IPv6 Routing
H3C S5500-EI Series Ethernet Switches
Chapter 2 IPv6 RIPng Configuration
2-3
Figure 2-3
shows the format of the IPv6 prefix RTE.
IPv6 prefix (16 octets)
Route tag
Prefix length
Metric
0
7
15
31
Figure 2-3
IPv6 prefix RTE format
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IPv6 prefix: Destination IPv6 address prefix.
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Route tag: Route tag.
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Prefix len: Length of the IPv6 address prefix.
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Metric: Cost of a route.
2.1.3 RIPng Packet Processing Procedure
I. Request packet
When a RIPng router first starts or needs to update some entries in its routing table,
generally a multicast request packet is sent to ask for needed routes from neighbors.
The receiving RIPng router processes RTEs in the request. If there is only one RTE
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 there are multiple RTEs 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.
II. Response packet
The response packet containing the local routing table information is generated as:
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A response to a request
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An update periodically
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A trigged update caused by route change
After receiving a response, a router 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, whether the port number is correct. The response packet failed the check will
be discarded.
2.1.4 Protocols and Standards
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RFC2080: RIPng for IPv6
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RFC2081: RIPng Protocol Applicability Statement
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RFC2453: RIP Version 2