HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual page 711

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 13-90 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 13-78 for more detailed instructions.
You can also select routes according to other attributes, such as AS path
or community:
Syntax: match [as-path <listname> | community <listname>]
For example, if your network groups routes into two communities, you
could advertise routes in one of these communities with an artificially
high AS hop count. See "Configuring an AS Path List" on page 13-89 and
"Configuring a Community List" on page 13-88 for instructions on creating
the necessary lists.
3. Next, prepend the hops to selected routes. You can configure the router
to either prepend one or more fictive AS hops to selected routes. Alterna-
tively, you can have the router simply repeat the last AS in a route up to
ten times.
Enter this command:
Syntax: set as-path prepend [last-as <1-10> | <1-65535>]
Use the last-as keyword to have the router re-add the last AS as a new
hop. Specify the number of times that the router should repeat this AS.
IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring BGP
13-97