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250 | Border Gateway Protocol IPv4 (BGPv4)
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Manipulate the COMMUNITY attribute
In addition to permitting or denying routes based on the values of the COMMUNITY attributes, you can
manipulate the COMMUNITY attribute value and send the COMMUNITY attribute with the route
information.
By default, FTOS does not send the COMMUNITY attribute.
Use the following command in the CONFIGURATION ROUTER BGP mode to send the COMMUNITY
attribute to BGP neighbors.
To view the BGP configuration, use the
show config command in the CONFIGURATION ROUTER BGP
mode.
If you want to remove or add a specific COMMUNITY number from a BGP path, you must create a route
map with one or both of the following statements in the route map. Then apply that route map to a BGP
neighbor or peer group. Use these commands in the following sequence, starting in the
CONFIGURATION mode:
Command Syntax Command Mode Purpose
neighbor {ip-address |
peer-group-name} send-community
CONFIG-ROUTER-
BGP
Enable the software to send the router’s
COMMUNITY attribute to the BGP neighbor or
peer group specified.
Step Command Syntax Command Mode Purpose
1
route-map map-name
[permit | deny]
[sequence-number]
CONFIGURATION Enter the ROUTE-MAP mode and assign a name
to a route map.
2
set comm-list
community-list-name delete
CONFIG-ROUTE-MAP Configure a set filter to delete all COMMUNITY
numbers in the IP Community list.
set community
{community-number |
local-as | no-advertise |
no-export | none}
CONFIG-ROUTE-MAP Configure a Community list by denying or
permitting specific community numbers or types
of community
• community-number: use AA:NN format
where AA is the AS number (2 or 4 Bytes)
and NN is a value specific to that autonomous
system.
• local-AS: routes with the COMMUNITY
attribute of NO_EXPORT_SUBCONFED
and are not sent to EBGP peers.
• no-advertise: routes with the
COMMUNITY attribute of
NO_ADVERTISE and are not advertised.
• no-export: routes with the COMMUNITY
attribute of NO_EXPORT.
• none: remove the COMMUNITY attribute.
• additive: add the communities to already
existing communities.