RE: iSCSI: keys/parameter dependence

["Robert D. Russell" <rdr@io.iol.unh.edu>]

Julian:

I have found the following dependencies between keys in draft 12-96,
and would ask other people on the mailing list to contribute others
they have found so we can all be aware of the complete set.

There seem to be very few dependencies, which I believe is a credit
to a clean, orthogonal design.

With a bit of work, we could probably get rid of all the dependencies
between the OFMarkInt (IFMarkInt) and OFMarker (IFMarker) keys, perhaps,
as suggested by Martins Krikis, by eliminating the OFMarker (IFMarker)
key and substituting a default (and response) value of 0 for the
OFMarkInt (IFMarkInt) to mean "no markers in that direction".

This would also eliminate the need for a "Reject" reply to an OFMarkInt
(IFMarkInt) offer.


"Meaningful" dependencies (i.e., those that cannot be ignored because
they effect operation):

1.  Between FirstBurstSize and MaxBurstSize
      Section 11.15: "FirstBurstSize MUST NOT exceed MaxBurstSize."

2.  Between OFMarkInt (IFMarkInt) and OFMarker (IFMarker)
      Section A.3.2: "When the interval (in an OFMarkInt (IFMarkInt)
      offer) is unacceptable the responder answers with "Reject".
      Reject is resetting the marker function (i.e., OFMarker
      (IFMarker)) in the specified direction (Output or Input) to No."

3.  Between SessionType and MaxConnections
      Section 11.22: "The discovery session implies MaxConnections = 1
      and overrides both the default and an explicit setting."


"Trivial" dependencies (i.e., those that only allow the option of
replying with "Irrelevant" instead of a normally selected value, and
therefore can be ignored).

1.  Between FirstBurstSize, InitialR2T, and ImmediateData
      The table in section 11.12 implies that the combination
      InitialR2T=Yes and ImmediateData=No allows the response
      FirstBurstSize=Irrelevant.

2.  Between OFMarker (IFMarker) and OFMarkInt (IFMarkInt).
      Sections A.3.1 and A.3.2 imply that OFMarker=No (IFMarker=No)
      allows the response OFMarkInt=Irrelevant (IFMarkInt=Irrelevant).



Bob Russell
InterOperability Lab
University of New Hampshire
rdr@iol.unh.edu
603-862-3774