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Cisco Nexus 3548 Switch NX-OS Unicast Routing Command Reference
OL-27852-01
Chapter Unicast Routing Commands
ip as-path access-list
ip as-path access-list
To configure an access-list filter for Border Gateway Protocol (BGP) autonomous system (AS) numbers,
use the ip as-path access-list command. To remove the filter, use the no form of this command.
ip as-path access-list name {deny | permit} regexp
no ip as-path access-list name {deny | permit} regexp
Syntax Description
Command Default None
Command Modes Global configuration mode
Command History
Usage Guidelines You can apply autonomous system path filters to both inbound and outbound BGP paths. Each filter is
defined by the regular expression. If the regular expression matches the representation of the
autonomous system path of the route as an ASCII string, then the permit or deny condition applies. The
autonomous system path should not contain the local autonomous system number.
This command requires the LAN Enterprise Services license.
Examples This example shows how to configure an AS path filter for BGP to permit AS numbers 55:33 and 20:01
and apply it to a BGP peer for inbound filtering:
switch# configure terminal
switch(config)# ip as-path access-list filter1 permit 55:33,20:01
switch(config) router bgp 65536:20
switch(config-router)# neighbor 192.0.2.1/16 remote-as 65536:20
switch(config-router-neighbor)# address-family ipv4 unicast
switch(config-router-neighbor-af)# filter-list filter1 in
switch(config-router-neighbor-af)#
name AS path access list name. The name can be any alphanumeric string up to 63
characters.
deny Rejects packets with AS numbers that match the regexp argument.
permit Allows packets with AS numbers that match the regexp argument.
regexp Regular expression to match BGP AS paths.
Release Modification
5.0(3)A1(1) This command was introduced.
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