3Com WX3000 operation manual Routing Protocol Overview, Static Routing and Dynamic Routing

Routing Protocol Overview

Static Routing and Dynamic Routing

Static routing is easy to configure and requires less system resources. It works well in small, stable networks with simple topologies. It cannot adapt itself to any network topology change automatically so that 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. It is complicated to configure, and it not only imposes higher requirements on the system than static routing, but also occupies a certain amount of network resources.

Classification of Dynamic Routing Protocols

Dynamic routing protocols can be classified based on the following standards:

Operational scope

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Interior Gateway Protocols (IGPs): Work within an autonomous system, typically including RIP, OSPF, and IS-IS.

Exterior Gateway Protocols (EGPs): Work between autonomous systems. The most popular one is BGP.

An autonomous system refers to a group of routers that share the same route policy and work under the same administration.

Routing algorithm

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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 the above two types of routing algorithms lie in the way routes are discovered and calculated.

Type of the destination address

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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, refer to the part discussing Multicast.

Routing Protocols and Routing Priority

Different routing protocols may find different routes (including static routes) to the same destination. However, not all of those routes are optimal. In fact, at a particular moment, only one protocol can uniquely determine the current optimal routing to the destination. For the purpose of route selection,

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