Open Shortest Path First (OSPF)

Open Shortest Path First (OSPF)

It’s a standard protocol supported by every vendor .
Its ospf v2.
It uses Djikstra’s algorithm to calculate shortest distance.
Its metric is cost. (10^8/bw), its chooses the path where it gets the lowest cost.
It uses unlimited no. of hops.

AD IS 110.
IT’S a classless routing protocol.
It supports vlsm.
It’s a dynamic category’s protocol.
Ospf uses the concept of areas, because it supports larger network

There are so many areas but ther e must be area 0 which is called area 0 in whole OSPF.

TYPES OF ROUTER WHEN USES AREA’S CONCEPT.

i.Internal Router:- when all interface come under singel area.
ii.Backbone router :- when atleast one interface comes under backbone area (arae 0)
iii.Area Border Router (ABR):- when router connect any two areas.
iv.Autonomous System Border Router(ASBR):- router connects any tow different autonomous areas.

OSPF Configuration:-

To configure OSPF we need some following terms:-

i.Process ID:- it’s a unique no. assigned on each router to configure router. Its range is from 1 to 65535.

ii.Wild card mask:- its given on router when we assign network on router.

iii.WCM = broadcast ip - subnet mask.

iv.Example – let we calculate acm of 10.0.0.0

WCM of 10= 255.255.255.255 - 255.0.0.0

WCM = = 0.255.255.255.

ROUTER ID:- it’s a unique identity of each router. The highest ip on a router is called the router id
To change router id-
R(config)#router ospf 1

#router-id 1.2.3.4

#do wr
OSPF timer: -

Hello timer- 10 sec
Dead interval – 40 sec

•R(config)#router ospf 10
• R(config)#network 10.0.0.00 0.255.255.255 area 0
•Where 10 is process id, 10.0.0.0 is network , 0.255.255.255 is wcm and area 0 is router area id.

Virtual Areas:-

R(config)#router ospf 10
 R(config)#area 1 virtual-link 20.0.0.1