Concept Guide

The system also supports BGP Extended Communities as described in RFC 4360 — BGP Extended Communities Attribute.
To configure an IP community list, use these commands.
1. Create a community list and enter COMMUNITY-LIST mode.
CONFIGURATION mode
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#
Configuring an IP Extended Community List
To configure an IP extended community list, use these commands.
1. Create a extended community list and enter the EXTCOMMUNITY-LIST mode.
CONFIGURATION mode
ip extcommunity-list extcommunity-list-name
2. Two types of extended communities are supported.
CONFIG-COMMUNITY-LIST mode
{permit | deny} {{rt | soo} {ASN:NN | IPADDR:N} | regex REGEX-LINE}
Filter routes based on the type of extended communities they carry using one of the following keywords:
● rt: route target.
● soo: route origin or site-of-origin. Support for matching extended communities against regular expression is also
supported. Match against a regular expression using the following keyword.
● regexp: regular expression.
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Border Gateway Protocol IPv4 (BGPv4)