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Routing protocol overview
Static routing and dynamic routing
Static routing is easy to configure and requires fewer system resources. It works well in small,
stable networks with simple topologies. Its major drawback is that it cannot adjust to network
changes without intervention, so you must perform routing configuration again whenever the
network topology changes.
Dynamic routing is based on dynamic routing protocols, which can detect network topology
changes and recalculate the routes accordingly. Therefore, dynamic routing is suitable for large
networks. Its disadvantages are that it is difficult to configure, imposes higher requirements on the
system, and consumes a certain amount of network resources.
Dynamic routing protocols classification
Dynamic routing protocols can be classified based on the following standards: operational
scope, routing algorithm, destination address type, and IP protocol version.
Operational scope
•
IGPs: Work within an autonomous system, including RIP, OSPF, and IS-IS.
•
EGPs: Work between autonomous systems. The most popular one is BGP.
An autonomous system refers to a group of routers that share the same routing policy and work under the
same administration.
Routing algorithm
•
Distance-vector protocols: RIP and BGP. BGP is also considered a path-vector protocol.
•
Link-state protocols: OSPF and IS-IS.
The main differences between these two types of routing algorithms is the way routes are
discovered and calculated.
Destination address type
•
Unicast routing protocols: RIP, OSPF, BGP, and IS-IS.
•
Multicast routing protocols: PIM-SM and PIM-DM.
This chapter focuses on unicast routing protocols. For information on multicast routing protocols,
see the
IP Multicast Configuration Guide
.