Chapter 4. IP Routing

Open Shortest Path First

Open Shortest Path First (OSPF) link-state routing protocol is designed to be more scalable and efficient than Routing Information Protocol (RIP). Some OSPF features you should be aware of are as follows:

  • Runs on IP and uses protocol 89.
  • Classless with variable-length subnet mask (VLSM) support.
  • Uses multicasts (224.0.0.5—all shortest path first [SPF] routers; 224.0.0.6—Designated Router [DR]/Backup Designated Router [BDR]) for hellos and updates.
  • Plain text and Message Digest Algorithm 5 (MD5) authentication available.
  • Dijkstra's algorithm is used to produce a shortest-path tree for each destination. Link-state advertisements are used to build a database of the topology.

OSPF packet types

  • Type ...

Get CCIE Routing and Switching Exam Quick Reference Sheets now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial