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PowerConnect B-Series FCX Configuration Guide 1039
53-1002266-01
Filtering
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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.
PowerConnect(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.
The <num>:<num> parameter indicates a specific community number to filter. Use this parameter
to filter for a private (administrator-defined) community. You can enter up to 20 community
numbers with the same command.
If you want to filter for the well-known communities “LOCAL_AS”, “NO_EXPORT” or
“NO_ADVERTISE”, use the corresponding keyword (described below).
The internet keyword checks for routes that do not have the community attribute. Routes without a
specific community are considered by default to be members of the largest community, the
Internet.
The local-as keyword checks for routes with the well-known community “LOCAL_AS”. This
community applies only to confederations. The Layer 3 Switch advertises the route only within the
sub-AS. For information about confederations, refer to “Configuration notes” on page 1021.
The no-advertise keyword filters for routes with the well-known community “NO_ADVERTISE”. A
route in this community should not be advertised to any BGP4 neighbors.