OSPFv2 rfc 2328 reading instructions
The OSPF specification is much longer and more complex than the RIP
specification. But OSPF is a much more complicated protocol thus
requiring a more complex specification. Nevertheless it is still
readable, some sections are excellent, while many sections tend to be
too technical for this course.
In short, the first three sections are an overview, while the rest of
the sections specify the protocol in more detail.
In general, most text describing NBMA (non-broadcast multi-access)
and point-to-multipoint networks can be skipped.
The instructions are as follows:
- Section 1 is included, the definitions can be browsed through.
- Section 2 gives a very good understanding of OSPF issues. The
example is realistic (complex) and the section can be quite hard to
get through. But it is well worth the reading. In particular, the
figures can be difficult to get a grasp of since they are written in
ASCII. Section 2.1.1 can be skipped.
- Section 3 introduces areas to the previous example. Again, the
example is quite demanding, but a thorough reading of this section
will give you a good understanding of OSPF areas. Section 3.5, only
the last two paragraphs, the rest discusses CIDR: you should know
- Section 4 goes into more detail, but includes repetition or a lot
of too technical implementation-related issues. Read the intro (before
4.1), section 4.3 (which gives an overview of the protocol). Skip the
rest (ie skip 4.1, 4.2, 4.4, and 4.5)
- Section 5: skip
- Section 6: skip
- Section 7: Good section describing the Hello protocol and how two
neighboring OSPF routers communicate. Skip the NBMA and point-to-multipoint paragraphs in section 7.1
- Section 8: Detailed description on how to send and receive packets: skip.
- Sections 9 and 10: Detailed descriptions on how interfaces are
brought up, neighbors are detected and how designated routers are
elected. Figures 11, 12, and 13 can give an overview on how the
interfaces and neighbor adjencies are brought up and may be useful
when debugging in a lab situations. The sections are otherwise too
detailed and should only be used for reference. However, read section
10.10 since it has an illuminating example on how neighbors start
- Section 11: Describes the OSPF routing table structure. Sections
11.2 and 11.3 can be used as a detailed complement to the examples in
Section 2 and 3, respectively. In particular, study Tables 12 and 13.
- Section 12: Description of LSAs.
- Section 13: Description of the flooding protocol.
- Section 14: Aging the link state database.
- Section 15: Virtual links.
- Section 16: Calculation of the routing tables.