So its OSPF , the most popular routing protocol Open Shortest Path First. As the name clearifies it uses shortest paths between two remote routers . OSPF uses Link State algorithm or Dijkstra’s Algorithm (in simple terms). In OSPF the neighbor routers share the information about their routes. OSPF configuration must be done in every router which are in the nodes between the routers.
OSPF consists of areas , where area 0 is dedicated as the backbone area . The backbone area means that the two different area can only share there communication from area 0 i,e.(backbone area). And if a network doesn’t have a backbone area than other areas in the network cannot communicate with each other , but can communicate inside their own area. OSPF routing protocol is an IGP (Interior Gateway Protocol) routing protocol . OSPF is an IEEE standard protocol .
In OSPF the Router perform DR(Designated Router) and BDR(Backup Designated Router) elections to advertise their routes to the neighbor routers. DR BDR elections prioritize who will advertise the routes of entire area. An area in OSPF configured network can have only one DR router and one BDR router, and other routers will be slave in terms of only sharing the routes to the DR and BDR router. In OSPF hello packet is initiated in every 10 secs. I mentioned hello packet because the hello packets are responsible for establishing and maintaining the neighbors relations. OSPF allows collection of contagious network & host must be grouped together and individual are called areas.
IMPORTANT :
reserved multicast address is 224.0.0.5
reserved broadcast address is 224.0.0.6
