Rip Features; Poison Reverse; Triggered Updates; Multicast - Lenovo CN4093 Application Manual

RIP Features

Poison Reverse

Triggered Updates

Multicast

Default Route

Metric

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Lenovo N/OS provides the following features to support RIPv1 and RIPv2:
Simple split horizon in RIP omits routes learned from one neighbor in updates sent
to that neighbor. That is the most common configuration used in RIP, with the
Poison Reverse feature disabled. Split horizon with poisoned reverse enabled
includes such routes in updates, but sets their metrics to 16. The disadvantage of
using this feature is the increase of size in the routing updates.
Triggered updates are an attempt to speed up convergence. When Triggered
Updates is enabled, whenever a router changes the metric for a route, it sends
update messages almost immediately, without waiting for the regular update
interval. It is recommended to enable Triggered Updates.
RIPv2 messages use IPv4 multicast address (224.0.0.9) for periodic updates.
Multicast RIPv2 updates are not processed by RIPv1 routers. IGMP is not needed
since these are inter-router messages which are not forwarded.
To configure RIPv2 in RIPv1 compatibility mode, set multicast to disable, and set
version to both.
The RIP router can listen and supply a default route, usually represented as
IPv4 0.0.0.0 in the routing table. When a router does not have an explicit route to a
destination network in its routing table, it uses the default route to forward those
packets.
The metric field contains a configurable value between 1 and 15 (inclusive) which
specifies the current metric for the interface. The metric value typically indicates
the total number of hops to the destination. The metric value of 16 represents an
unreachable destination.
Chapter 26: Routing Information Protocol
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