Lecture 9: Network Routing Protocols

Planning for Information Networks
Lecture 9: Network Routing Protocols

There are many ways to characterize routing protocols, including the following:

? Static versus dynamic routing
? Interior versus exterior routing protocols
? Distance vector versus link-state versus hybrid protocols
? Routing protocol metrics
? Routing protocol convergence
? Flat versus hierarchical routing protocols

Static Routing:
The term static routing denotes the use of manually configured or injected static routes for traffic forwarding purposes. Using a static route might be appropriate in the following circumstances:

? When it is undesirable to have dynamic routing updates forwarded across slow bandwidth links, such as a dialup link.

? When the administrator needs total control over the routes used by the router.

? When it is necessary to reach a network that is accessible by only one path (a stub network)

A stub network is a computer network, or part of an internetwork, with no knowledge of other networks, that will typically send much or all of its non-local traffic out via a single path, with the network aware only of a default route to non-local destinations.

* Configuring and maintaining static routes is time-consuming.
* Properly implementing static routes requires complete knowledge of the entire network.

Static routes are unidirectional. A static route configured in one direction via one router must have a corresponding static route configured on the adjacent router, in the opposite direction, for the return path.

Static routes are appropriate in situations such as with stub networks, hub-and-spoke connections (Star connections), and dialup environments.