Balancing Loads Over Connections To Different Neighbors - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring BGP
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Load balancing inbound traffic is more difficult. In many ways, it is up to the
ISP to decide through which connection to route traffic.

Balancing Loads over Connections to Different Neighbors

You may connect to multiple ISP routers through two or more interfaces on
the same router or on different routers. These instructions contain general
guidelines for load balancing over both types of connections.
For example, Router A and B both connect to an ISP. (See Figure 13-17.) Your
organization does not want to pay for two Internet connections, only to have
one underused. You cannot directly configure load balancing, nor manually
force the routers to send certain traffic over one link and other traffic over the
other. BGP uses a set algorithm to select routes.
However, you can attempt to manipulate BGP so that each local and ISP router
selects best routes that balance traffic across both links.
Balancing Outbound Traffic. In this situation, the BGP route-selection
algorithm automatically balances outbound traffic.
Routers prefer routes discovered through eBGP over those discovered by an
internal routing protocol. For example, the organization in Figure 13-17 mul-
tihomes using Router A and Router B. Router A receives external routes from
the ISP; it receives the same external routes from Router B. Because the first
were discovered through eBGP, Router A uses these routes. It routes traffic it
receives from Networks 1 and 2 directly to the ISP. Router B does the same
for Networks 3 and 4.