Route Summaries

You can summarize routes reported by RIP to reduce the size of the routing table and the amount of traffic resulting from RIP updates. Configuring a RIP summary will cause that prefix to be advertised with the associated metric regardless of the presence of more-specific prefixes. Any more-specific prefixes will not be advertised when they are covered by the summary. You can choose the degree of summarization by using a prefix tree to specify the number of bits to report for routes matching a route map. Alternatively, you can explicitly specify routes for RIP to summarize.

Prefix Tree Example

The following example shows how to configure a 16-bit route summary:

1. Specify a route map for RIP in Router Configuration mode.

   host1#configure t

   Enter configuration commands, one per line. End with CNTL/Z.

   host1(config)#router rip

   host1(config-router)#route-map 1

   host1(config-router)#exit

2. Define a route map associated with a prefix tree.

   host1(config)#

   host1(config)#route-map 1

   host1(config-route-map)#match-set

   host1(config-route-map)#match-set summary prefix-tree boston

   host1(config-route-map)#exit

   host1(config)#

3. Set the conditions for summarization in the prefix tree, including which routes are summarized and how many bits of the network addresses are preserved as the network prefix.

   host1(config)#ip prefix-tree boston permit 2.1.0.0/16

This example summarizes routes for networks addressed by 2.1.x.x. The first 16 bits of the network address are preserved in the summary. For example, routes 2.1.3.0, 2.1.2.0, and 2.1.1.0 would all be summarized as 2.1.0.0.

Static Summary Example

You can use the ip summary-address command to specify routes that RIP will summarize.

Copyright © 2008, Juniper Networks, Inc. All rights reserved. Trademark Notice.