Unicast Routing Overview
Unicast Routing Overview |
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In a single-path routing infrastructure, only a single path exists between any two networks in the internetwork. While this may simplify the routing tables and the packet flow paths, single-path internetworks are not fault tolerant. A fault can be sensed with a dynamic router, but the networks across the failure are unreachable for the duration of the fault. A downed link or a downed router must be brought back up before packets can be delivered successfully across the downed link or router.
In a multipath routing infrastructure, multiple paths exist between networks in the internetwork. Multipath internetworks are fault tolerant when dynamic routing is used, and some routing protocols, such as OSPF, can balance the load of network traffic across multiple paths with the same metric value. Multipath internetworks, however, can be more complex to configure and can have a higher probability of routing loops during convergence when using distance vector–based routing protocols.