OSPF Overview and Features

OSPF (Open Shortest Path First) is a link-state routing protocol that uses Dijkstra's Shortest Path First algorithm to build and calculate the shortest path to all known destinations. OSPF is an open standard protocol that can be implemented by any vendor.

Key Features:

• Fast Convergence: Uses SPF algorithm for rapid network adaptation.
• Hierarchical Design: Uses areas for better scalability and reduced routing overhead.
• Equal-Cost Load Balancing: Supports ECMP routing across equal-cost paths.
• Authentication: Supports MD5 and SHA authentication for security.
• VLSM Support: Enables efficient IP address utilization with variable-length subnet masks.
• Link-State Database: Maintains a complete topology of the network.
• No Hop Limit: Unlike RIP, OSPF has no 15-hop limitation.

OSPF vs EIGRP

While EIGRP is a Cisco proprietary protocol, OSPF is an open standard. OSPF uses bandwidth and delay by default, while EIGRP has more flexible metric calculations. OSPF is better for multi-vendor environments.