![Cisco Nexus 3548 series Command Reference Manual Download Page 179](http://html.mh-extra.com/html/cisco/nexus-3548-series/nexus-3548-series_command-reference-manual_2609162179.webp)
159
Cisco Nexus 3548 Switch NX-OS Unicast Routing Command Reference
OL-27852-01
Chapter Unicast Routing Commands
ip community-list
Command History
Usage Guidelines
The
ip community-list
command is used to configure BGP community filtering. BGP community values
are configured as a 4-byte number. The first two bytes represent the autonomous system number, and the
last two bytes represent a user-defined network number. BGP community attribute exchange between
BGP peers is enabled when the
send-community
command is configured for the specified neighbor. The
BGP community attribute is defined in RFC 1997 and RFC 1998.
BGP community exchange is not enabled by default. Use the
send-community
command in BGP
neighbor fix-family configuration mode to enable a BGP community attribute exchange between BGP
peers.
The Internet community is applied to all routes or prefixes by default until any other community value
is configured with this command or the
set community
command.
Once you configure a permit value to match a given set of communities, the community list defaults to
an implicit deny for all other community values. Use the
internet
community to apply an implicit permit
to the community list.
Standard Community Lists
Standard community lists are used to configure well-known communities and specific community
numbers. You can pick more than one of the optional community keywords.A maximum of 16
communities can be configured in a standard community list. If you attempt to configure more than 16
communities, the communities that exceed the limit are not processed or saved to the running
configuration file.
You can configure up to 32 communities.
Expanded Community Lists
Expanded community lists are used to filter communities using a regular expression. Regular
expressions are used to configure patterns to match community attributes. The order for matching using
the * or + character is the longest construct is first. Nested constructs are matched from the outside in.
Concatenated constructs are matched beginning at the left side. If a regular expression can match two
different parts of an input string, it matches the earliest part first.
Community List Processing
When multiple values are configured in the same community list statement, a logical AND condition is
created. All community values must match to satisfy an AND condition. When multiple values are
configured in separate community list statements, a logical OR condition is created. The first list that
matches a condition is processed.
This command requires the LAN Enterprise Services license.
Examples
This example shows how to configure a standard community list where the routes with this community
are advertised to all peers (internal and external):
switch#
configure terminal
switch(config)#
ip community-list standard test1 permit internet
switch(config)#
Release
Modification
5.0(3)A1(1)
This command was introduced.