[OSPF] AD Review of draft-ietf-ospf-cap

Bill Fenner <fenner@research.att.com> Thu, 19 October 2006 12:32 UTC

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From: Bill Fenner <fenner@research.att.com>
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Subject: [OSPF] AD Review of draft-ietf-ospf-cap
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I'm sorry for taking so long on this review.

My major comment is that I think that the bit order in
the RI TLV is confusing.  (Partly because the IETF-standard
packet picture is confusing!)

Check this combination:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Informational Capabilities                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Bit       Capabilities

      1         OSPF graceful restart capable [GRACE]
..

>From the picture, this could mean 0x40000000, while I think it intends
0x00000001.  This may be more confusing when (if) the 33rd bit is
assigned.  I'd recommend a description of the bit numbering, along
the lines of

Bits in the Informational Capabilities field are numbered beginning at
1, starting at the low-order bit of the first 32-bit word.  If further
32-bit words are used, the low-order bit of the second one is numbered
33, the next one is 65, etc.

(That's just off the top of my head and may not make complete sense).
Alternately, you could represent the bits as hex values, e.g.
0x1, 0x2, 0x4, 0x8, 0x10 instead of 1,2,3,4,5.

The other item is the IANA considerations.  Normally we don't say
that a WG is the expert, since the WG may not live forever; we say
that the IESG designates an expert, and the IESG designates the
current WG chairs while the WG exists.

  Bill

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