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BGP and BGP4+ Introduction
Software Reference Supplement for SwitchBlade® x8112, x908, x900 and x610 Series Switches
C613-50032-01 REV D AlliedWare Plus
TM
Operating System - Software Version 5.4.3-2.6 1.13
BGP and BGP4+ Neighbor Route Filtering
You can filter BGP and BGP4+ advertisements in two ways with neighbors:
■ Use autonomous system path filters, as with the ip as-path access-list (BGP and
BGP4+) Global Configuration mode command and the neighbor filter-list (BGP and
BGP4+) Router Configuration mode command
■ Use access or prefix lists, as with the neighbor distribute-list (BGP and BGP4+)
Router Configuration mode command.
If you want to restrict routing information that is learned or advertised, you can filter BGP
routing updates to and from neighbors. You can define an access list or a prefix list and
apply it to the updates.
To filter BGP routing updates for IPv4 routes, use the command below in Router
Configuration mode:
To filter BGP4+ routing updates for IPv6 routes, use the command below in Address Family
Configuration mode:
BGP and BGP4+ Path Filtering by Neighbor
You can specify an access list filter on both incoming and outbound updates based on the
BGP autonomous system paths. Each filter is an access list based on regular expressions.
To specify the access list filter, define an autonomous system path access list and apply it
to updates to and from particular neighbors.
To configure BGP path filtering, use the following commands starting in Global
Configuration mode:
awplus(config-router)#
neighbor <neighborid>
distribute-list <access-list>
{in|out}
This command filters BGP routing updates to and from
neighbors as specified in an access list for IPv4 routers in
Router Configuration mode.
awplus(config-router-af)#
neighbor <neighborid>
distribute-list <access-list>
{in|out}
This command filters BGP routing updates to and from
neighbors as specified in an access list for IPv6 routes in
Address Family Configuration mode.
awplus(config)#
ip as-path access-list (BGP and
BGP4+)
This command defines a BGP-related access list.
awplus(config)#
router bgp <asn>
This command enters Router configuration mode
awplus(config-router)#
neighbor <neighborid>
filter-list <listname> {in|out}
This command establishes a BGP filter for an IPv4 path in the
Router Configuration mode.