INTERNET ROUTING PROTOCOLS

     There are various networks and computer system on the Internet. In order send data to a particular system, the address of that system...

     There are various networks and computer system on the Internet. In order send data to a particular system, the address of that system in the network has to be specified and using this address the data reaches its destination. In the addressing scheme IP addresses are used to route data ti its destination. In packet switching, the data is divided into small  equal- sized packets and these packets are re-assembled into original data. The path that data follows to reach its destination is called 'routers'. When a computer sends data packets to another computer on the network, all the packets are given the IP address of another computer and then these packets are sent to the nearest router on the network. The router then sends the packets to the destination computer through the Internet.
In the Internet, routers are organised in the form of  a tree structure. Routers that are used to transmit information within independent computer system are called interior routers. which use Interior Gateway Protocols for routing data. Routers that transmit information between independent computer system are called exterior routers, which use Exterior Gateway Protocols (EGP) for routing data.

Interior Gateway Protocol (IGP)
IGP are used to route data in a Local Area Network such as a network in an office building. Following are the two type of IGP:

• Routing Information Protocol (RIP)
• Open Shortest Path First(OSPF)

Routing Information Protocol 
A routing database is maintained by RIP for storing information about the fastest route from one computer to another. An update process can be used by each router to inform other routers about the fastest route from its view point. Each router uses an update algorithm to update its routing database as per the fastest routes told by the eighbouring routers.
Open Shortest Path First
OPE maintains a database containing information about all the connection in the Local Area Network. The following terms describe the operating  of OSPE algorithm:
Startup : On turning on a router, Hello packets are sent by it to all the neighbouring routers. In return, it also receives their Hello packets and creates that are agreeable to synchronisation. Hello packets are these that are used to tell neighbouring routers that the sending router is now online.
Shortest Path Tree: Each router calculates a mathematical data structure, referred to as the 'shortest path tree' describing the shortest path to reach each of the destination addresses. For each communication, this address  tells you which is the the closest router to which the data packets should be sent, that is, open shortest path frist.