Rip Version; Rip Message Format - 3Com MSR 50 Series Configuration Manual

4 RIP ages out routes by adopting an aging mechanism to keep only valid routes.

RIP Version

n

RIP Message Format

RIP has two versions, RIP-1 and RIP-2.
RIP-1, a Classful Routing Protocol, supports message advertisement via broadcast
only. RIP-1 protocol messages do not carry mask information, which means it can
only recognize routing information of natural networks such as Class A, B, C. That
is why RIP-1 does not support discontiguous subnet.
RIP-2 is a Classless Routing Protocol. Compared with RIP-1, RIP-2 has the following
advantages.
Supporting route tags. The route tag is used in routing policies to flexibly
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control routes.
Supporting masks, route summarization and classless inter-domain routing
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(CIDR).
Supporting designated next hop to select the best next hop on broadcast
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networks.
Supporting multicast routing update to reduce resource consumption.
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Supporting Plain text authentication and MD5 authentication to enhance
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security.
RIP-2 has two types of message transmission: broadcast and multicast.
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Multicast is the default type using 224.0.0.9 as the multicast address. The
interface working in the RIP-2 broadcast mode can also receive RIP-1 messages.
On a ComwareV5 device, you can configure the RIP version in RIP view and in
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interface view. On a ComwareV3 device, you can only perform such
configuration in interface view.
To enable a ComwareV5 device in the RIP-1 mode to interoperate with a
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ComwareV3 device in the RIP-2 broadcast mode, you need to use the undo
version command in RIP view and the undo rip version in interface view to
remove related RIP version configuration from the ComwareV5 device.
For a ComwareV5 device, the case that no RIP version is configured is different
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from the case that RIP-1 is configured. The former one uses the default RIP-1
version that is compatible with RIP-2, but the latter one is not compatible with
RIP-2.
RIP-1 message format
A RIP message consists of the Header and up to 25 route entries.
Figure 295 shows the format of RIP-1 message.
RIP Overview 973