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3.1 RIPng Overview
RIPng is a distance-vector routing protocol, which measures the distance to the destination host
by the hop count.
The Routing Information Protocol Next Generation (RIPng) protocol is an extension of RIPv2
that is applied to IPv4 networks. Most RIP-related concepts are applicable to RIPng.
Extension of RIP
For IPv6 applications, RIPng extends RIP as follows:
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UDP port number: In RIPng, UDP port number 521 is used to send and receive routing
information.
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Multicast group address: In RIPng, FF02::9 is used as the multicast group address of RIPng
routers.
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Prefix length: In RIPng, the prefix length of a destination address is 128 bits (the mask
length).
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Next-hop address: In RIPng, a next-hop address is a 128-bit IPv6 address.
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Source address: In RIPng, link-local address is used as the source address to send RIPng
Update packets.
Operation Principle of RIPng
RIPng is a distance-vector routing protocol. It exchanges routing information by using User
Datagram Protocol (UDP) packets through the port 521.
RIPng employs the hop count to measure the distance to the destination. The distance is called
the routing metric. In RIPng, the hop count from the switch to its directly connected network is
0, and the hop count from the switch to a network, which can be reached through another
switch, is 1. The hop count that is equal to or exceeds 16 is defined as infinity, indicating that
the destination network or host is unreachable.
By default, RIPng sends an Update packet every 30 seconds. If no Update packet is received
from a neighbor in 180 seconds, RIPng marks all the routes learned from the neighbor as
unreachable. If no Update packet is received from a neighbor in 300 seconds, RIPng deletes the
routes of the neighbor from the routing table.
To prevent routing loops, RIPng supports split horizon and poison reverse. In addition, RIPng
can import routes from other routing protocols.
Each switch running RIPng manages a routing database, which contains routing entries to all
accessible destinations on a network. These routing entries contain the following information:
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Destination address: indicates the IPv6 address of a host or network.
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Next-hop address: indicates the address of the next switch to the destination.
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Interface: indicates the interface through which an IP packet is forwarded.
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Cost: indicates the hop count to the destination. The value is an integer that ranges from 0
to 16. If the value is 16, it indicates that the destination host or network is unreachable.
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Timer: indicates the time since a routing entry is last updated. The timer is reset to 0 when
a routing entry is updated.
S6700 Series Ethernet Switches
Configuration Guide - IP Routing
3 RIPng Configuration
Issue 01 (2012-03-15)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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