OSPF (Open Shortest Path First) is an Interior Gateway Protocol (IGP). It’s used to decision routing in the autonomous systems. It realizes the Link State Routing Protocol, belonging to IGP, so that it works in the internal system. As a common protocol, let’s know 7 benefits of it.
1. OSPF is a true LOOP- FREE (route-free loop) routing protocol. It is derived from the merits of the algorithm itself.
2. Fast convergence of OSPF: The route changes can be transmitted to the entire autonomous system in the shortest time.
3. The concept of area division is proposed. After the autonomous system is divided into different regions, the summary of routing information between the regions is adopted, which greatly reduces the quantity of routing information to be transmitted. It also makes routing information not expand rapidly as the network scale increases.
4. The protocol itself minimizes the overhead. See below:
(1) For the discovery and maintenance of neighbor relationships, the hello messages that do not contain routing information are sent regularly and are very short. The message containing the routing information is the mechanism that triggers the update. (Send when there is a route change). However, in order to enhance the robustness of the protocol, it is re-issued every 1800 seconds.
(2) In broadcast networks, multicast addresses are used instead of broadcast to reduce the interference to other network devices that do not operate OSPF.
(3) In various types of networks that can be accessed multiple times (broadcast, NBMA), by electing DR, the number of route exchanges (synchronizations) between routers on the same network segment is reduced from O (N*N) times to O (N) times.
(4) The concept of an NSSA area is proposed so that the introduced ASE route is no longer propagated within the NSSA area.
(5) Supports route aggregation on ABRs (Area Border Routers) to further reduce routing information transfer between regions.
(6) In the point-to-point interface type, OSPF over On Demand Circuits is configured so that it no longer sends hello packets periodically and updates routing information regularly. Updates are sent only when the network topology really changes.
5. Through the strict division of the level of routing (a total of four points), it provides more reliable routing.
6. Good security. OSPF supports interface-based plaintext and md5 authentication.
7. OSPF adapts to various scales of networks, up to thousands of units.