Quick Reference Guide

794 PowerConnect B-Series TI24X Configuration Guide
53-1002269-02
Filtering
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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 –
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”. The Layer 3
Switch advertises the route only within the sub-AS.
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.
The no-export keyword filters for routes with the well-known community “NO_EXPORT”. A route in
this community should not be advertised to any BGP4 neighbors outside the local AS. If the router
is a member of a confederation, the Layer 3 Switch advertises the route only within the
confederation.
Defining a community ACL
To configure community ACL 1, enter a command such as the following.
PowerConnect(config)# ip community-list 1 permit 123:2
This command configures a community ACL that permits routes that contain community 123:2.
NOTE
Refer to “Matching based on community ACL” on page 800 for information about how to use a
community list as a match condition in a route map.