Prepending Private As Numbers For Load Balancing - HP 7102dl - ProCurve Secure Router Configuration Manual

You can use multiple set commands to place selected routes in multiple
communities.
In order for the router to advertise routes' community attributes to the
external neighbor, you must move to the BGP neighbor configuration mode
and enter:
Syntax: send-community standard
You must also apply the route map that establishes routes' communities to the
neighbor as outbound policy. For example:
ProCurve(config-bgp-neighbor)# route-map CommunityMap out

Prepending Private AS Numbers for Load Balancing

Your router will send identical routes to all neighbors unless you configure
policies to filter and add attributes to these routes. When ISP routers receive
multiple identical routes from your organization, it is up to the ISP or ISPs to
select the connection over which they send inbound traffic to your network.
You can attempt to load balance inbound traffic over multiple Internet con-
nections by influencing the ISP routers' selection process.
One way to do so is to prepend extra hops in the AS path of certain routes.
For example, a router connects to ISPs A and B, but inbound traffic always
arrives over the connection to ISP A. The router could prepend several fictive
AS hops to the routes that is sends to ISP A for half of the private networks.
ISP routers would then be more likely to route traffic destined to these
networks through the ISP B connection.
Complete these steps to prepend AS hops to a route:
1. Create a route map entry from the global configuration mode context:
Syntax: route-map <mapname> <sequence number>
2. Select the routes to which the router should prepend AS hops using a
match command.
Generally, you select routes according to their network address and prefix
length. Match the entry to an already-defined prefix list:
Syntax: match ip address prefix <listname>
You can see "Filtering Advertised Routes According to Network Address"
on page 15-92 for quick instructions on how to configure a prefix list for
a route map. See "Creating Prefix Lists: Configuring Filters for Route
Exchange" on page 15-81 for more detailed instructions.
IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring BGP
15-99