White Papers

ip community-list community-list-name
2. Configure a community list by denying or permitting specific community numbers or types of community.
CONFIG-COMMUNITYLIST mode
{deny | permit} {community-number | local-AS | no-advertise | no-export | quote-regexp
regular-expression-list | regexp regular-expression}
● community-number: use AA:NN format where AA is the AS number (2 Bytes or 4 Bytes) and NN is a value specific to
that autonomous system.
● local-AS: routes with the COMMUNITY attribute of NO_EXPORT_SUBCONFED.
● no-advertise: routes with the COMMUNITY attribute of NO_ADVERTISE.
● no-export: routes with the COMMUNITY attribute of NO_EXPORT.
● quote-regexp: then any number of regular expressions. The software applies all regular expressions in the list.
● regexp: then a regular expression.
To view the configuration, use the show config command in CONFIGURATION COMMUNITY-LIST or CONFIGURATION
EXTCOMMUNITY LIST mode or the show ip {community-lists | extcommunity-list} command in EXEC Privilege
mode.
Dell#show ip community-lists
ip community-list standard 1
deny 701:20
deny 702:20
deny 703:20
deny 704:20
deny 705:20
deny 14551:20
deny 701:112
deny 702:112
deny 703:112
deny 704:112
deny 705:112
deny 14551:112
deny 701:667
deny 702:667
deny 703:667
deny 704:666
deny 705:666
deny 14551:666
Dell#
Filtering Routes with Community Lists
To use an IP community list or IP extended community list to filter routes, apply a match community filter to a route map and
then apply that route map to a BGP neighbor or peer group.
1. Enter the ROUTE-MAP mode and assign a name to a route map.
CONFIGURATION mode
route-map map-name [permit | deny] [sequence-number]
2. Configure a match filter for all routes meeting the criteria in the IP community or IP extended community list.
CONFIG-ROUTE-MAP mode
match {community community-list-name [exact] | extcommunity extcommunity-list-name
[exact]}
3. Return to CONFIGURATION mode.
CONFIG-ROUTE-MAP mode
exit
4. Enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
AS-number: from 0 to 65535 (2 Byte) or from 1 to 4294967295 (4 Byte) or 0.1 to 65535.65535 (Dotted format)
Border Gateway Protocol IPv4 (BGPv4)
185