Open Shortest Path First (OSPF) is a dynamic routing protocol for use in Internet Protocol (IP) networks. Specifically, it is a link-state routing protocol and falls into the group of interior gateway protocols, operating within an autonomous system (AS).

OSPF is perhaps the most widely-used interior gateway protocol (IGP) in large enterprise networks.

Answered by Sumeet , an ibibo Citizen, at 1:41 AM on December 05, 2008

OSPF (Open Shortest Path First) is a router protocol used within larger autonomous system networks in preference to the Routing Information Protocol (RIP), an older routing protocol that is installed in many of today's corporate networks. Like RIP, OSPF is designated by the Internet Engineering Task Force (IETF) as one of several Interior Gateway Protocols (IGPs).

Using OSPF, a host that obtains a change to a routing table or detects a change in the network immediately multicasts the information to all other hosts in the network so that all will have the same routing table information. Unlike the RIP in which the entire routing table is sent, the host using OSPF sends only the part that has changed. With RIP, the routing table is sent to a neighbor host every 30 seconds. OSPF multicasts the updated information only when a change has taken place.

Rather than simply counting the number of hops, OSPF bases its path descriptions on "link states" that take into account additional network information. OSPF also lets the user assign cost metrics to a given host router so that some paths are given preference. OSPF supports a variable network subnet mask so that a network can be subdivided. RIP is supported within OSPF for router-to-end station communication. Since many networks using RIP are already in use, router manufacturers tend to include RIP support within a router designed primarily for OSPF.
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Answered by Nishu%27s , an ibibo Master, at 9:33 PM on December 04, 2008

OSPF is an abbreviation for Open Shortest Path First. It is an interior gateway routing protocol developed for IP networks based on the shortest path first or link-state algorithm.

Answered by Kamlesh B , an ibibo Specialist, at 7:29 PM on December 04, 2008

Hi Friend

OSPF stands for "Open Shortest Path First ".

Open Shortest Path First (OSPF) is a routing protocol developed for Internet Protocol (IP) networks by the Interior Gateway Protocol (IGP) working group of the Internet Engineering Task Force (IETF). The working group was formed in 1988 to design an IGP based on the Shortest Path First (SPF) algorithm for use in the Internet. Similar to the Interior Gateway Routing Protocol (IGRP), OSPF was created because in the mid-1980s, the Routing Information Protocol (RIP) was increasingly incapable of serving large, heterogeneous internetworks. This chapter examines the OSPF routing environment, underlying routing algorithm, and general protocol components.

OSPF was derived from several research efforts, including Bolt, Beranek, and Newman's (BBN's) SPF algorithm developed in 1978 for the ARPANET (a landmark packet-switching network developed in the early 1970s by BBN), Dr. Radia Perlman's research on fault-tolerant broadcasting of routing information (1988), BBN's work on area routing (1986), and an early version of OSI's Intermediate System-to-Intermediate System (IS-IS) routing protocol.

OSPF has two primary characteristics. The first is that the protocol is open, which means that its specification is in the public domain. The OSPF specification is published as Request For Comments (RFC) 1247. The second principal characteristic is that OSPF is based on the SPF algorithm, which sometimes is referred to as the Dijkstra algorithm, named for the person credited with its creation.

OSPF is a link-state routing protocol that calls for the sending of link-state advertisements (LSAs) to all other routers within the same hierarchical area. Information on attached interfaces, metrics used, and other variables is included in OSPF LSAs. As OSPF routers accumulate link-state information, they use the SPF algorithm to calculate the shortest path to each node.

Answered by kokila vani , an ibibo Advisor, at 6:33 PM on December 04, 2008

OSPF stands for "Open Shortest Path First." OSPF is a method of finding the shortest path from one router to another in a local area network (LAN). As long as a network is IP-based, the OSPF algorithm will calculate the most efficient way for data to be transmitted.

If there are several routers on a network, OSPF builds a table (or topography) of the router connections. When data is sent from one location to another, the OSPF algorithm compares the available options and chooses the most efficient way for the data to be sent. This limits unnecessary delays in data transmission and prevents infinite loops.

Answered by Shishir , an ibibo Master, at 6:22 PM on December 04, 2008