Implementers Guide- pls review

Jim Toga jim.toga at INTEL.COM
Mon Feb 8 12:17:20 EST 1999


My comments below... (I'm cc' this sg16 list so that others will understand
'tweaks' from what had been posted previously)

Best Regards,

At 12:18 PM 2/8/99 -0000, you wrote:
>I've drawn up a list of proposals for the implementer's guide, which I was
>planning to put in as my own contribution.  It can remain as a separate
>contribution for the meeting, or some or all of it can be subsumed into
>yours, as you see fit.  I've attached it to this mail.  Specific comments:
>1. Your reworking of the UDP Port usage question appears to be
>self-inconsistent and talks round the fundamental problem rather than fixing
>it (it both sanctions and forbids the use of port 1718 for unicast LRQ).
>The essential problem is that the usage of port 1718 is NOT directly related
>to the discovery issue.  I believe my solution is clearer as well as
>requiring less in the way of changes in H.225.0.

I thought the fundamental problem was that a receiving GK had no reliable
way to detect whether a message had arrived via multicast or unicast.  My
thinking was that the multicastaddress:1718 VS the localaddress:1718, would
be enough of a differentiator.  In any case port 1719 was always relegated
to unicast.

I see your point, but I believe we cannot arbitrarily make unicast on port
1718 'illegal.'   It is tighter ( and therefor not backward compatible)
with current v1 and v2 specs.  I also do not know the the impact would be
on existing products.   I guess I would be more comfortable with a (strong)
_should_ with respect to multi-cast only on port 1718.  This by the way is
why there is _should_ statement in the new existing text that I sent out.
I will make these changes and see if they are acceptable by others.

>2. I've drawn something up on the multiple aliases question.  I think
>something ought to be agreed and put into the guide asap - and I think this
>will only happen by being presented to a meeting and argued over.  I'm happy
>for this, as something a bit controversial, to be kept as my separate
>contribution, but I'd like to think there was some chance of getting it into
>the guide at this cut in some form or other.

I am in favor of resloving this during the meeting.

>I'll put in my contribution, containing whatever you leave me, first thing
>in MY morning tomorrow (ie the middle of tonight your time).
>Dr Chris Purvis - Senior Development Engineer, WAVE CC Software
>Madge Networks Ltd, Wexham Springs, Framewood Road, Wexham, Berks.  ENGLAND
>Phone: +44 1753 661 359  email: cpurvis at

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