Routers and routing switches use routing protocols to exchange reachability information. Routers use a routing protocol to advertise available paths on which the router can forward data. The routers use the protocol to determine the most efficient path to use. Routers use dynamic routing protocols to avoid sending data to inoperable links, and to send data to links that generally result in the fastest transmission times.
The switch routes frames using one of the following dynamic unicast IP routing protocols for path selection:
Routing Information Protocol version 1 (RIPv1) (RFC 1058)
RIPv2 (RFC 2453)
Open Shortest Path First version 2 (OSPFv2) (RFC 2328)
OSPFv3 (RFC 2740)
Border Gateway Protocol version 4 (BGPv4) (RFC 1771)
Unlike static IP routing, where you must create a manual entry in the routing table to specify a routing path, dynamic IP routing uses a learning approach to determine the paths and routes to other routers. Dynamic routing uses two basic types of routing: distance vector and link-state. Routing Information Protocol (RIP) is a distance vector protocol and Open Shortest Path First (OSPF) is a link-state protocol.
The switch uses routing protocols like OSPF and RIP to populate routing tables. Routers use a routing protocol to exchange network topology information. A router uses the IP address of an incoming data packet to send the packet according to the routing tables.
The most commonly used unicast routing protocols include OSPF, RIP, and BGP. For more information about BGP, see BGP. For information about multicast routing protocols, see IP Multicast. For information about OSPFv3 routing protocols, see OSPF.