RFC 1793: Extending OSPF to Support Demand Circuits
The author of this RFC did an excellent job in summarizing its contents. A direct quote of selected sections taken from the RFC provides you with an excellent overview of this RFC and its contents. The following section comes directly from RFC 1371.
RFC 1850: OSPF Version 2 Management Information Base
This RFC defines a portion of the Management Information Base (MIB) for managing the Open Shortest Path First routing protocol. It had been over four years and twelve additional RFCs detailing many features of OSPF to include a new version. This RFC was needed to handle the many new enhancements to the protocol and includes over 20 new features or changes. Some of these are rather minor like name changes or clarifications and the reader is referred to the RFC for specific details. A brief list is provided of the more important modifications.
RFC 2178: OSPF Version 2
At over 211 pages, it is a document that explains the smallest internal workings of the OSPF protocol. Armed with this document, you would be able to program the code necessary for OSPF to operate on any type of network equipment it supports. The RFC will also be able to take you through every step of its operation to include those that are not apparent to the user.
RFC 2328: OSPF Version 2
This RFC is almost a book itself and having been recently released, it is the most current RFC concerning OSPF. It surpasses the previous OSPF RFC by weighing in at 244 pages, all about OSPF. The differences between this RFC and the previous are detailed in Appendix G of the document.
Any Chief Information Officer (CIO) who is considering an OSPF network should have this document available for their design engineers. This RFC is definitely written for a very advanced and specific target audience within the networking arena.
The differences between RFC 2178 and RFC 1583 are explained in Appendix G of the RFC. All differences are backward-compatible in nature. Implementations following this RFC and of those following RFC 1583 will be able to interoperate.
This section discussed the specific evolution of the OSPF protocol by tracing its path through the RFCs. Each RFC was examined and briefly discussed to include whether or not it is still relevant in todays networks. RFC 238 is the most current OSPF RFC, however, not every vendors implementation supports it, so check to be sure.
Now that you have a complete picture concerning the technical resources and documentation surrounding OSPF, you should familiarize yourself with the functional environment and hierarchy used by OSPF, as discussed in the next sections.
OSPF Functional Environment
This section describes the basic characteristics and features of the OSPF functional environment. The environment in which OSPF operates is defined by the features and characteristics of its operation and design. Simply put, the functional environment of OSPF is defined as the network architecture in which the protocol will function correctly.
RFC 1793 provides an example that concerns adding to OSPF the capability to operate in demand-based circuits. Until this RFC was published and implemented, OSPF did not properly function when dealing with such circuits like ISDN. Now that the protocol has been adjusted to operate properly when dealing with demand-based circuits, you can say that the functional environment of the protocol has expanded.
With that example in mind, turn your attention to the three network types that OSPF recognizes.