ADTRAN AOS Version R10.1.0 Command Reference Manual page 1223

Command Reference Guide Global Configuration Mode Command Set
Functional Notes
This command specifies a prefix to be matched when filtering routes. Prefix lists can be useful in
configurations of Border Gateway Protocol (BGP) to define the routes that an AOS device can advertise to
or receive from a BGP address family (AF) neighbor. Common uses for prefix lists include: preventing a
network from becoming a transit for external traffic when multihoming, receiving only routes from remote
virtual private network (VPN) sites, prohibiting the advertisement of a network, and load balancing
outbound traffic. When using this command, if the network address is entered without specifying a range
for prefix lengths, the router assumes that the route must be an exact match.
Optionally, this command may specify a range of prefix lengths. The following rule must be followed: len <
ge-value < le-value. A filter that exactly matches a prefix length can be created by entering the length for
both the ge and le values. A prefix list with no entries allows all routes. A route that does not match any
entries in a prefix list is dropped. As soon as a route is permitted or denied, there is no further processing
of the rule in the prefix list. A route that is denied with the initial entry of a prefix list will not be allowed, even
if it matches a permitting entry further down the list.
Usage Examples
The following example creates a prefix list entry in the IPv6 prefix list TEST that allows all routes to prefixes
in the 2001:DB8:0:3F3B::/64 network:
(config)#ipv6 prefix-list TEST seq 5 permit 2001:DB8:0:3F3B::/64 le 24
60000CRG0-35E Copyright © 2012 ADTRAN, Inc. 1223