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Cell Relay Retreat>List Archive>month:1995-Oct> msg00025



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denser ar$pro space.

  • From: James Watt <james@newbridge.com>
  • Date: Thu, 12 Oct 1995 14:03:12 -0400 (EDT)
  • CC: james@ca.newbridge.com, gja@thumper.bellcore.com, ip-atm@matmos.hpl.hp.com

Grenville Armitage writes:
+--------
|My initial reaction was that the above table only encompasses
|NPLIDs that identify a protocol, rather than NLPIDs that really
|mean "there are more protocol bytes to follow".
+--------
Ok.  So we could add text to say so.
But...

+---------
|But I think you've inadvertently hit on an 'almost standard' way
|of including SNAP based protocol IDs. People may remember a few weeks
|ago I said that the existing MARS message format could carry SNAP
|fields as a TLV, with ar$pro = 0x400 being interpreted as the flag
|saying "go look in the TLV list". Of course, 0x400 was a rather arbitrary
|value.
+--------
Grenville:
 This works well  for the data plane (as I said in my original note).  

However I do not think it is acceptable for the control plane.  Recall that
the sequence number is protocol-specific.  Now I need to look at the ar$pro
and if it is 0x80 go look for a TLV and _then_ do sequence number processing ?

I think not.  Let us just burn the extra bytes and get it over with.  It is
only the control plane after all.  I like the way the data plane works
out but I don't think that saving the bytes in the control plane justifies
the increase in complexity.

Regards,
-james
____________________________________________________________________________
James W. Watt,     james@newbridge.com                   Ph: +1 613 591-3600
Newbridge Networks 600 March Rd Kanata ON Canada K2K 2E6 FAX:+1 613 591-3680