Dynamic vs Static Routing

Static routing describes the manual configuration of static, i.e., non-changing routes through a network via routing tables. This method has difficulties handling node or link failures, taking new links into account, and it cannot compute the cost of a route more then once.

Larger networks therefore require mechanisms that adjust automagically to a its environment, which is achieved through dynamic routing. It enables:

• Computation of the best route through a network
• Dynamically add or remove links as they come available
• Distribute load across multiple links
• Reduce administration effort

Routing Information Protocol (RIP)

Open Shortest Path First (OSPF)

Routing protocol that uses the Dijkstra algorithm compute shortest path first tree (spf-tree) for every router on the basis of a shared data set. This shared data set is constructed using link-state advertisements messages, containing information about the connection status of each link.

Dijkstra's: O(|E| + |V| \log|v|)

Intermediate System to Intermediate System (IS-IS)

Enhance Interior Gateway Routing Protocol (EIGRP)

Border Gateway Protocol (BGP)

Autonomous Systems (AS)

A group of routers which are administered together, use the same routing policy, have a common metric, and use the BGP to reach other AS.