The IP over ATM Mailing List Archive by date

[Grenville Armitage <gja@bellcore.com>]

Andrew,

I get the feeling this has lost track of something important
(like context):

>>Not true: we need to specify necessary and sufficient rules.
>>The problem in this 
>>case is that a MCS perfectly compliant with the current text *is allowed* to 
assume
>>that its ServerControlVC will be point-to-multipoint because the text says th
at
>>the MARS *must* use a point-to-multipoint VC. If we now *allow* the MARS to
>>use a pt-pt then we have a classic interoperability loophole. Hence, the
>>right "flexibility" fix is to *allow* the MARS to use a pt-pt but also *not
>>allow* the MCS to assume pt-pt.

This is ipmc-12 here. In ipmc-12 we actually _assume_ that there
are no current solutions to the load-sharing-multiple-MCS-per-group
problem. ipmc-12 hardly says all that much about MCSs anyway, punting
that to a separate document on "What an MCS should or should not expect"
(which is what I'd encouraged Rajesh to be developing).

That's where you tighten up (or explicitly allow) certain MCSs behaviours
(to fill in the gaps I _deliberately_ tried to leave in ipmc-12).

The reason I think this issue is losing context is that you're
discussing a MARS behaviour (having a single leaf ServerControlVC)
that is valueless under MARSv1 (since we're solving the distributed,
load sharing MARS in MARSv2, right?) So, there's _nothing_
wrong with leaving ipmc-12 as it is (MARS always builds ServerControlVC
as a pt-mpt VC), and clarifying in Rajesh's 'How to build MCSs'
document the concept of "accept pt-pt or pt-mpt calls". Then MCSs
built now will happily accept a pt-pt ServerControlVC from some
new advanced MARS you're playing with.

I'm sorry if I've not been clear on the strategy of follow-on
documents I'd envisaged when I left gaps in ipmc-12.

	[..]

>>> (b) I couldn't find anything in ipmc-12 that currently requires an
>>> MCS to verify that the SJOIN/SLEAVE arrived on the actual ServerControlVC. 
>>
>>Again, it does not *require* MCS to verify but it does *allow* MCS to 
>>assume it. The text probably should not allow this assumption.

The text in Rajesh's 'How To...' guide, not ipmc-12.

cheers,
gja