Dell S6000–ON - Page 194

IETF RFC 1997 defines the COMMUNITY attribute and the predefined communities of INTERNET,
NO_EXPORT_SUBCONFED, NO_ADVERTISE, and NO_EXPORT. All BGP routes belong to the INTERNET
community. In the RFC, the other communities are defined as follows:
• All routes with the NO_EXPORT_SUBCONFED (0xFFFFFF03) community attribute are not sent to
CONFED-EBGP or EBGP peers, but are sent to IBGP peers within CONFED-SUB-AS.
• All routes with the NO_ADVERTISE (0xFFFFFF02) community attribute must not be advertised.
• All routes with the NO_EXPORT (0xFFFFFF01) community attribute must not be advertised outside a
BGP confederation boundary, but are sent to CONFED-EBGP and IBGP peers.
Dell Networking OS 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.
Example of the show ip community-lists Command
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
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Border Gateway Protocol IPv4 (BGPv4)