What do you need to know about OSPF?
- OSPF stands for open shortest path first. It also uses the SPF (shortest path first) algorithm to determine the best route to its neighbors.
- OSPF is a standard routing protocol, as defined byÂ RFC2328Â andÂ RFC1247. This means that OSPF can run on just about any company’s’ routers and OSPF routes from a non-Cisco router can be exchanged with Cisco routers.
- The administrative distance for OSPF is 110.
- The entire network that OSPF routes for is called an “Autonomous System”, or “AS”.
- All OSPF routing updates must traverse area 0. Because of this, you should carefully design your network before you begin deploying OSPF.
With OSPF, every router has its own unique “picture” (topology map) of the network. Routers use “HELLO” packets to periodically check with routers to ensure they are still there. Every router in OSPF is identified with a “router ID”. The router ID can be manually entered or OSPF will automatically choose the IP address with the highest number.