ECS4660-28F_Management Guide-R03

C HAPTER 51 | IP Routing Commands
Border Gateway Protocol (BGPv4)
– 1835 –
no-advertise – Routes with this community attribute are not
advertised to any internal or external peer.
no-export – Routes with this community attribute are advertised
only to peers in the same autonomous system or to other sub-
autonomous systems within a confederation. These routes are not
advertised to external peers.
100-500 – Expanded community list number that identifies one or
more groups of communities.
expanded community-list-name – Name of expanded access list.
(Maximum length: 32 characters, no spaces or other special
characters)
regular-expression – Regular expression indicating the community
list number or name
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COMMAND MODE
Global Configuration
DEFAULT SETTING
No community lists are defined.
COMMAND USAGE
◆ Standard community lists are used to configure well-known
communities or community numbers. Expanded community lists are
used to filter communities using a regular expression.
◆ When multiple values are entered in the same community list, they
form a logical AND condition. When multiple values are configured in
separate community lists, the form a logical OR condition, where the
first list that matches a condition is processed.
◆ If the criteria specified for a community list is matched, then the
deny/permit condition is applied to the routing message.
◆ If a permit value is applied to a community list, the filter will implicitly
deny other community values.
◆ By default, the internet community is set with a route if no other
communities are defined.
◆ Use this command in conjunction with the neighbor send-community to
filter route updates sent to or received from a neighbor, or with the
match community route map command to implement a more
comprehensive filter for policy-based routing.