Overview
Open Shortest Path First (OSPF) is an Interior Gateway Protocol (IGP) based on the Dijkstra algorithm. It is highly scalable, fast-converging, and supports complex network topologies.
Key Concepts
- Areas: OSPF uses a hierarchical structure with Area 0 (the backbone) and other areas connected to it to reduce routing overhead.
- Metric: Cost, which is typically calculated based on the bandwidth of the link.
- Hello Packets: Used to discover and maintain neighbor relationships.
- LSA (Link State Advertisement): Packets used to share topology information.
Advantages
- Fast convergence.
- Support for VLSM and CIDR.
- Efficient use of bandwidth (only sends updates when changes occur).