[jcifs] MaxMpxCount and the MID field.

Christopher R. Hertel crh at nts.umn.edu
Sun Jul 21 16:15:05 EST 2002

Has anyone had any practical experience with the MID field and the
MaxMpxCount returned in the Negotiate Protocol Response?

I am wondering if/how the server enforces the MaxMpxCount.  According to
what I have read, there can be no more than MaxMpxCount requests
outstanding between a client and a server.  So, if the server sets
MaxMpsCount to 1 (in the NegProt response), then whenever the client sends
a request it must wait for a reply before sending another request.  If
MaxMpsCount is greater than 1, (say, <n>) then the client may send
multiple requests (as many as <n>).

What error message does the server send back if the maximum number is 

Also, both the SNIA and the X/Open docs state that there may only be one
outstanding request per [client,PID,MID] tuple.  So, if MaxMpxCount is >1,
then multiple PIDs or multiple MIDs would need to be used in order to
multiplex the requests.  It makes sense that the client would want to do
this (use PIDs and/or MIDs as identifiers so that it can match the replies
to the requests), but I'm wondering if the server enforces that limit (and
if so how).  It seems to me that the server would need to maintain a lot
of state and do a lot of up-front work whenever it received a request in
order to enforce the one outstanding [PID,MID] per client limit.  I would
think that managing that limit would be handled better on the client side.

I'm trying to wrap my brain around this one...

Chris -)-----

Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org

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