When the router is multihomed, ingress filtering becomes more complex. There are perfectly reasonable operational scenarios in which a packet could arrive on one interface, but that specific interface might not have a route to the source address. For the routers near the edge of the Internet, packet filters can provide a simpler and more effective solution than methods that employ routing information lookup, though this approach can be challenging when managing routers which are reconfigured often. Ingress filtering for multihomed routers will accept the packet if there is a route back to its source address from "any" interface on the router. For this type of filtering, the router may also maintain an "adjacency table", also organized for fast lookup, that keeps track of the router interface addresses that are on all directly connected routers.