Appendix B. OSPF Basics of Operation

Open Shortest Path First (OSPF) is a protocol that was originally standardized in RFC 1131. It was subsequently updated in RFC 1247 in 1991 and then went through several other updates and revisions. The current protocol standard is described in RFC 2328. To fully understand current implementations of OSPF, you need to read the following RFCs:

• RFC 2328, "OSPF Version 2"

• RFC 3101, "The OSPF NSSA Option"

• RFC 1793, "Extending OSPF to Support Demand Circuits"

• RFC 2370, "The OSPF Opaque LSA Option"

Several other useful extensions are available beyond the base OSPF protocol, as described in the following RFCs:

• RFC 3137, "OSPF Stub Router Advertisement"

• RFC 3630, "Traffic Engineering (TE) Extensions to OSPF Version 2"

• RFC 3623, "Graceful OSPF Restart"

OSPF is a link-state protocol that has many advantages, among which are low traffic levels during normal operation and rapid convergence.