The Open Shortest Path First (OSPF) protocol, defined in RFC 2328, is an Interior Gateway Protocol used to distribute routing information within a single Autonomous System. The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth. An OSPF network can be divided into sub-domains called areas. An area is a logical collection of OSPF networks, routers, and links that have the same [...]

The Border Gateway Protocol (BGP) is an interautonomous system routing protocol. An autonomous system is a network or group of networks under a common administration and with common routing policies. BGP is used to exchange routing information for the Internet and is the protocol used between Internet service providers (ISP). BGP is used between autonomous systems (AS), the protocol is referred to as External BGP (EBGP). If a service provider is using BGP to exchange routes within an AS, then the protocol is referred to as Interior BGP (IBGP). BGP is a very robust and scalable routing protocol, as evidenced [...]

Two categories of protocol exist at the network layer: routed and routing. A routed protocol is a Network Layer protocol that is used to move traffic between networks. Routed protocols allow a host on one network to communicate with a host on another, with routers forwarding traffic between the source and destination networks. IP, IPX, and AppleTalk are all examples of routed protocols. Routing protocols let routers route routed protocols after a path has been determined. RIP, IGRP, EIGRP, OSPF, IS-IS, BGP are all examples of routing protocols.