HP 7102dl - ProCurve Secure Router Configuration Manual page 843

3. Create two prefix lists for external traffic, each of which specifies routes
to half of all IP networks. You can configure the router to accept only
routes with longer prefixes so that the router does not learn too many
over-specific routes. (You should be sure that your ISP advertises routes
with the prefix lengths that you specify.)
ProCurve(config)# ip prefix-list External1 seq 10 permit 0.0.0.0/1 le 8
ProCurve(config)# ip prefix-list External2 seq 10 permit 128.0.0.0/1 le 16
4. Configure a list of communities that the router is permitted to advertise
to external neighbors. Deny communities that the router cannot advertise.
ProCurve(config)# ip community-list Advertise
ProCurve(config-comm-list)# deny no-advertise local-as no-export
5. Configure a list of community attributes that the router should delete from
inbound routes. In this example, the router deletes all well-known com-
munities so that it can apply its own policies to the routes it receives from
neighbors.
ProCurve(config)# ip community-list Clear
ProCurve(config-comm-list)# permit internet no-export local-as no-advertise
6. Configure the outbound policy for the first neighbor:
a. If necessary, and if your ISP allows this option, the local router can
request that the ISP router not export certain private routes to neigh-
bors in other autonomous systems.
ProCurve(config)# route-map ISP1Out 10
ProCurve(config-route-map)# match ip address prefix-list Private
ProCurve(config-route-map)# set community no-export
b. Permit the router to advertise half of the local routes to this neighbor
and specify a multi-exit discriminator metric for load balancing. You
should also filter out any routes that should not be advertised to
external neighbors.
ProCurve(config)# route-map ISP1Out 20
ProCurve(config-route-map)# match ip address prefix-list LAN1
ProCurve(config-route-map)# match community Advertise
ProCurve(config-route-map)# set metric 100
IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring BGP
15-117