28-06-2012, 03:44 PM
ROUTERS
routers.ppt (Size: 364 KB / Downloads: 42)
DEFINITION
A router is a device that actually delivers information to its intended destination, using one of several different routing protocols.
Routers have access to network layer addresses and contain software that enable them to determine which of several possible paths between those addresses is the best for particular transmission.
Classification of Routers
Internal Routers - routers with all directly connected networks belonging to the same area.
Area Border Routers - routers that are attached to multiple areas.
AS Boundary routers - routers that exchange routing information with routers belonging to other AS.
Routing Algorithm’s
each network node (router) maintains a Distance Vector table containing the distance between Itself and ALL possible destination nodes.
Dijkstra’s Algorithm [Link State Algorithm]:-
Each router constructs a link state packet (LSP) . which is transmitted to ALL other routers. Each router stores the most recently generated LSP from each other router.
LINK STATE ROUTING
Each router is responsible for meeting its neighbors and learning their names.
Each router constructs a link state packet (LSP) which consists of a list of neighbors’ names and the cost to reach each neighbor.
Each router uses complete information on the network topology to compute the Shortest path route to each destination node.