HP 7102dl - ProCurve Secure Router Configuration Manual page 819

IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring BGP
The simplest way to configure a prefix list is to permit the exact routes that
the BGP interface should advertise.
For example, your network includes two networks. You want the router to
advertise network 10.1.0.0 /16 but not network 10.2.0.0 /16. Enter this com-
mand to configure the prefix list:
ProCurve(config)# ip prefix-list LAN1 seq 10 permit 10.1.0.0/16
Remember that the local router's routing table must include this exact route
in order for the router to advertise it. If your network uses subnetted networks,
you may need to add a null route to the range of subnets. For example:
ProCurve(config)# ip route 10.1.0.0 /16 null 0
If you want the router to advertise separate routes for the subnets, you must
permit the address for the complete network and then specify the bit length
prefix for the subnets. For example, to configure the router to advertise /20
networks subnetted from the 10.1.0.0 /16 network, enter:
ProCurve(config)# ip prefix-list LAN1 seq 10 permit 10.1.0.0/16 ge 20 le 20
You could also specify a range of prefix lengths for routes to variable length
subnets:
ProCurve(config)# ip prefix-list LAN1 seq 10 permit 10.2.0.0/16 ge 18 le 24
You can, of course, also use the command to deny routes. For example, to
configure a prefix list to prevent advertisement of any /24 subnet in the 10.2.0.0
/16 network, enter:
ProCurve(config)# ip prefix-list LAN1 seq 10 deny 10.2.0.0/16 ge 24 le 24
In this case, the router could still advertise routes to subnets with a different
prefix length—for example, to 10.2.0.0 /16 or to 10.2.16.0 /20.
For a more detailed explanation of the many options available for specifying
routes in a prefix list, see "Creating Prefix Lists: Configuring Filters for Route
Exchange" on page 15-81.
After configuring the prefix list, match it to the route map. Create a route map
entry and enter this command:
Syntax: match ip address prefix-list <listname>
When you have finished configuring the route map, apply the map to the BGP
neighbor as an outbound policy. (See "Applying a Route Map Entry to a BGP
Neighbor" on page 15-106.)
15-93