Editing Border Gateway Protocol (section)

=== Load balancing ===
Another factor contributing to the growth of the routing table is the need for load balancing of [[multi-homed]] networks. It is not a trivial task to balance the inbound traffic to a multi-homed network across its multiple inbound paths, due to limitation of the BGP route selection process. For a multi-homed network, if it announces the same network blocks across all of its BGP peers, the result may be that one or several of its inbound links become congested while the other links remain under-utilized, because external networks all picked that set of congested paths as optimal. Like most other routing protocols, BGP does not detect congestion.

To work around this problem, BGP administrators of that multihomed network may divide a large contiguous IP address block into smaller blocks and tweak the route announcement to make different blocks look optimal on different paths, so that external networks will choose a different path to reach different blocks of that multi-homed network. Such cases will increase the number of routes as seen on the global BGP table.

One method to address the routing table issue associated with load balancing is to deploy [[Locator/Identifier Separation Protocol]] (BGP/LISP) gateways within an [[Internet exchange point]] to allow ingress traffic engineering across multiple links. This technique does not increase the number of routes seen on the global BGP table.