Features and Characteristics of OSPF Protocol

Before you start

Objectives : You will be able to understand OSPF and its feature after reading this article.

Prerequisites: You have to know what is routing protocols and different types of routing protocols

Tags : Routing Protocols, Router, OSPF, link-state routing protocol, OSPF configuration .

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Definition

Open Shortest Path First (OSPF) is an open standard directing convention that has been actualized by a wide assortment of system sellers, including CISCO. Also, it's that open standard trademark that is the way to OSPF's adaptability and prevalence.

OSPF Features and Operations

The vast majority settle on OSPF, which works by utilizing the Dijkstra calculation to at first build a most brief way tree and takes after that by populating the directing table with the subsequent best ways. EIGRP's meeting time might be blindingly quick, however OSPF isn't that a long ways behind, and its snappy union is another reason it's a top pick. Another two incredible preferences OSPF offers are that it bolsters numerous, equivalent cost courses to a similar goal, and like EIGRP, it likewise underpins both IP and IPv6 steered conventions.

OSPF additionally has a Dead Interval, which demonstrates to what extent a switch will hold up without hearing any welcomes before declaring a neighbour as "down." Default for the Dead Interval is 40 seconds for communicate and indicate point interfaces, and 120 seconds for non-communicate and indicate multipoint interfaces. See that, as a matter of course, the dead interval clock is four times the Hello interval.

OSPF switches construct a Topology Database of all connections inside their area, and all switches inside an area will have an indistinguishable topology database. Directing refreshes between these switches will just contain data about connections nearby to their area. Restricting the topology database to incorporate just the neighborhood transfer speed and lessens CPU loads.

Area 0 is required for OSPF to work, and is viewed as the "Backbone" area. Generally speaking, every other area must have an association into Area 0, however this run can be circumvent utilizing virtual connections (clarified in the blink of an eye). Area 0 is regularly alluded to as the travel area to associate every other area.

OSPF switches can have a place with numerous areas, and will along these lines contain isolated Topology databases for every area. These switches are known as Area Border Switches (ABRs). Consider the above illustration. Three areas exist: Area 0, Area 1, and Area 2. Area 0, once more, is the spine area for this Autonomous System. Both Area 1 and Area 2 should straightforwardly interface with Area 0.

Terms used in OSPF

• Router ID: The router ID (RID) is an IP deliver used to recognize the router. Cisco picks the router ID by utilizing the most elevated IP address of all arranged loopback interfaces. On the off chance that no loopback interfaces are arranged with locations, OSPF will pick the most elevated IP address out of all dynamic physical interfaces. To OSPF, this is essentially the "name" of every router.




• Neighbor: Neighbors are at least two routers that have an interface on a typical system, for example, two routers associated on an indicate point serial connection. OSPF neighbors must have various regular arrangement alternatives to have the capacity to effectively build up a neighbor relationship, and these choices must be designed the very same way.




• Adjacency: An adjacency is a connection between two OSPF routers that allows the immediate trade of course updates. Dissimilar to EIGRP, which specifically shares courses with the majority of its neighbors, OSPF is truly demanding about sharing steering data and will straightforwardly share courses just with neighbors that have additionally settled adjacencies. What's more, not all neighbors will wind up noticeably adjoining—this relies on both the kind of system and the setup of the routers. In multi-get to systems, routers frame adjacencies with designated and backup designated routers. In indicate and point multipoint systems, routers shape adjacencies with the router on the inverse side of the association.




• Designated router:. A designated router (DR) is chosen at whatever point OSPF routers are associated with a similar communicate system to limit the quantity of adjacencies framed and to advertise got directing data to and from the rest of the routers on the communicate system or connection. Races are won in light of a router's need level, with the one having Open Shortest Path First (OSPF) the most noteworthy need turning into the champ. In the event that there's a tie, the router ID will be utilized to break it. All routers on the mutual system will build up adjacencies with the DR and the BDR, which guarantees that all routers' topology tables are synchronized.




• Backup designated router: Backup designated router A backup designated router (BDR) is a hot standby for the DR on communicate, or multi-get to, connections. The BDR gets all steering refreshes from OSPF contiguous routers however does not scatter LSA refreshes..




• Hello packets: The OSPF Hello convention gives dynamic neighbor revelation and primary tains neighbor connections. Hello bundles and Link State Advertisements (LSAs) manufacture and keep up the topological database. Hello bundles are routed to multicast address 224.0.0.5.




• Neighborship database: The neighborship database is a rundown of all OSPF routers for which Hello parcels have been seen. An assortment of subtle elements, including the router ID and state, are kept up on every router in the neighborship database.