routing information is stored in a vector in most routers.
routing information is stored in a vector in most routers.
where is routing information stored in most routers?
a vector
the oldest routing protocol, and the oldest distance-vector protocol, is version 1 of the routing information protocol (ripv1). ripv1 was formally standardised in 1988. it establishes the shortest path across a network purely on the basis of the hops, that is numbers of routers that need to be passed to reach the destination network. rip is a interior gateway protocol, so it can be used in local area networks (lans) on interior or border routers. routers with ripv1 implementation exchange their routing tables with neighbouring routers by broadcasting a ripv1 packet every 30 second into all connected networks. ripv1 is not suitable for large networks as it limits the number of hops to 15. this hop limit was introduced to avoid routing loops, but also means that networks that are connected through more than 15 routers are unreachable.
distance-vector routing protocol
as a link state routing protocol, ospf establishes and maintains neighbor relationships for exchanging routing updates with other routers. the neighbor relationship table is called an "adjacency database". two ospf routers are neighbors if they are members of the same subnet and share the same area id, subnet mask, timers and authentication. in essence, ospf neighborship is a relationship between two routers that allow them to see and understand each other but nothing more. ospf neighbors do not exchange any routing information – the only packets they exchange are hello packets. ospf adjacencies are formed between selected neighbors and allow them to exchange routing information. two routers must first be neighbors and only then, can they become adjacent. two routers become adjacent if at least one of them is designated router or backup designated router (on multiaccess type networks), or they are interconnected by a point-to-point or point-to-multipoint network type. for forming a neighbor relationship between, the interfaces used to form the relationship must be in the same ospf area. while an interface may be configured to belong to multiple areas, this is generally not practiced. when configured in a second area, an interface must be configured as a secondary interface.
open shortest path first