Filtering Inbound Routes - HP 7102dl - ProCurve Secure Router Configuration Manual

Filtering Inbound Routes

Just as you can control the routes that the local router advertises to a neighbor,
you can also control the routes that the router accepts from a neighbor. You
can filter inbound routes according to:
destination network address and prefix length
community
AS path
You can see "Creating Prefix Lists: Configuring Filters for Route Exchange"
on page 15-81 for a discussion of filtering inbound routes according to the
routes' destination addresses and prefix lengths.
You use a route map to apply such a filter in much the same way as you would
use a prefix list. First, you configure the prefix list. However, instead of
applying the list directly to the neighbor, you match a route map entry to the
list and apply the route map to the neighbor as inbound policy.
If you are only filtering routes, there is no reason to use a route map. However,
the advantage of a route map is that you can also apply attributes to the filtered
routes. (See "Applying Policies to Inbound Routes" on page 15-104.)
To use a route map to filter inbound routes according to network address and
prefix length, first create the prefix list and then enter these commands:
Syntax: route-map <mapname> <sequence number>
Syntax: match ip address prefix <listname>
Syntax: router bgp <local AS>
Syntax: neighbor <neighbor ID>
Syntax: route-map <mapname> in
Rather, or in addition to, filtering routes with a prefix list, you can filter routes
according to:
community
AS path
metric
To configure the router to accept only routes in a certain community or with
a certain AS path, you must configure a community or AS path list. (See
"Configuring a Community List" on page 15-90 or "Configuring an AS Path List"
on page 15-91.)
IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring BGP
15-103