Users Guide

Layer 3 Routing Commands 1519
The prefix list identifies the prefixes that may be redistributed.
Route maps are ordered from lowest to greatest sequence number, with lower
sequence numbers being considered first. If no sequence number is specified,
the system assigns a value ten greater than the last statement in the route
map. The range is 0 to 65,535.
One use of a route map is to limit the redistribution of routes to a specified
range of route prefixes. The redistribution command specifies a route map
which refers to a prefix list. The prefix list identifies the prefixes that may be
redistributed.
Examples
The following example creates (or edits) the route map equal-access as the
first route map in the system for allowing matching packets into the system.
Route-map mode is also entered.
console(config)#route-map equal-access permit 0
In the following example, BGP is configured to redistribute all prefixes within
172.20.0.0 and reject all others.
console(config)# ip prefix-list redist-pl permit 172.20.0.0/16 le 32
console(config)# route-map redist-rm permit
console(config-route-map)# match ip address prefix-list redist-pl
console(config-route-map)# exit
console(config) router bgp 1
console(Config-router) redistribute ospf route-map redist-rm
set interface null0
Use this command to drop a packet instead of reverting to normal routing for
packets that do not match the route map criteria. This command should be
configured as the last entry in the route-map as no further set clauses will
operate on a dropped packet. Use the no form of this command to remove the
set clause from a route map.
Syntax
set interface null0
no set interface null0
• null0 — Specifies the null0 interface used to drop packets.