Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 356)

338 Brocade ICX 6650 Layer 3 Routing Configuration Guide
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Filtering
BGP4 filtering communities
You can filter routes received from BGP4 neighbors based on community names. Use either of the
following methods to do so.
A community is an optional attribute that identifies the route as a member of a user-defined class
of routes. Community names are arbitrary values made of two five-digit integers joined by a colon.
You determine what the name means when you create the community name as one of a route
attributes. Each string in the community name can be a number from 0 through 65535.
This format allows you to easily classify community names. For example, a common convention
used in community naming is to configure the first string as the local AS and the second string as
the unique community within that AS. Using this convention, communities 1:10, 1:20, and 1:30
can be easily identified as member communities of AS 1.
The Layer 3 switch provides the following methods for filtering on community information:
• Community filters
• Community list ACLs
NOTE
The Layer 3 switch cannot actively support community filters and community list ACLs at the same
time. Use one method or the other but do not mix methods.
NOTE
Once you define a filter or ACL, the default action for communities that do not match a filter or ACL
is “deny”. To change the default action to “permit”, configure the last filter or ACL entry as “permit
any any”.
Community filters or ACLs can be referred to by match statements in a route map.
Defining a community filter
To define filter 3 to permit routes that have the NO_ADVERTISE community, enter the following
command.
Brocade(config-bgp-router)#community-filter 3 permit no-advertise
Syntax: community-filter num permit | deny num:num | internet | local-as | no-advertise |
no-export
The num parameter identifies the filter position in the community filter list and can be from 1
through 100. Thus, the community filter list can contain up to 100 filters. The router applies the
filters in numerical order, beginning with the lowest-numbered filter. When a filter match is true, the
router stops and does not continue applying filters from the list.
NOTE
If the filter is referred to by a route map match statement, the filter is applied in the order in which
the filter is listed in the match statement.
The permit | deny parameter indicates the action the router takes if the filter match is true.
• If you specify permit, the router permits the route into the BGP4 table if the filter match is true.
• If you specify deny, the router denies the route from entering the BGP4 table if the filter match
is true.