Bgp Neighbors; Bgp Messages; Bgp Configuration Concerns - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring BGP
13-68
to different neighbors. BGP keeps one link from being overused while leaving
the other idle. This ensures that your organization actually receives the benefit
of the connections for which it has paid.

BGP Neighbors

BGP routers advertise routes to their neighbors. Unlike other routing proto-
cols, BGP does not automatically select a neighbor. You must manually
configure the neighbors with which your private router can communicate.
External neighbors are on the same subnet, but internal neighbors can be on
different subnets. In other words, the ISP router (an external neighbor) is
connected to your router on the same subnet, while a router that is part of
your organization (an internal neighbor) may be on a different subnet at the
local or remote site.
You can use BGP in a WAN to distribute routes to an ISP or to a remote site
through the Internet. The BGP router at each remote site is an internal BGP
neighbor. The local router advertises routes to these neighbors through an
external neighbor such as an ISP router. The external neighbor is the neighbor
you configure on the router.

BGP Messages

BGP sends relatively few messages compared to a routing protocol such as
OSPF. A BGP update can include one new route and several withdrawn routes.
AS Field. When a BGP interface advertises a route, it adds its AS to the BGP
packet. The route thus accumulates a list of autonomous systems through
which packets must travel. The AS field is important because the organiza-
tions that own various autonomous systems have set arrangements with each
other about which networks they allow each other to access. Routers can
select routes according to the autonomous systems through which packets
must pass.
For basic BGP configuration on the ProCurve Secure Router, you need know
only that your ISP will provide you with its AS (the remote AS) and the AS
number for your local site.

BGP Configuration Concerns

To configure BGP on the ProCurve Secure Router, you must:
enable BGP and specify the local AS
advertise local networks
set the router ID