Consistent Use of Routers that Support Route Aggregation

Route aggregation into an NLSP area is possible only if all routers in that area support address summaries. Routers that do not support route aggregation do not recognize destination addresses for aggregated routes; they forward packets to the default route or drop packets if no default route is configured. Because routers that support route aggregation route packets differently from routers that do not support route aggregation, routing loops can occur. Therefore, if a router that supports route aggregation detects that the next-hop router on the path to an aggregated destination is a router that does not support route aggregation, it will drop the packet.