Subject: Re: Revised BCM selection process

From: Peter Johansson <[email-masked]>
Date: Sat, 8 May 1999 17:19:58 EDT

In a message dated 99-05-08 15:40:59 EDT, [email-masked] writes:

<<So, is it your belief that, from a specification point of view, we can
catch people before they end up choosing channel 31 (hint, your answer had
better be "yes").>>

It's my belief that, Tom's concerns to the contrary, that it is exceedingly
unlikely that there is ANY equipment in the world that is LIKELY to elect
channel 31, of all the channels available.

31 is smack dab in the middle of the range; programmers are usually
unimaginative when it comes to selecting an algorithm to choose something
like a channel number:

a) start at zero and go up until a free channel is found;
b) start at 63 and go down until a free channel is found;
c) start at 31 and alternate going up and down until a free channel is found;
or
d) ???

Realistically, I doubt that anything other than a) or b) has been implemented
SO FAR!

Yes, I think we can make the world safe for a default broadcast channel if we
act quickly...

Regards,

Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

[email-masked]

---

From: Tom Suters <[email-masked]>
Date: Mon, 17 May 1999 14:13:48 +0200

> Realistically, I doubt that anything other than a) or b) has been

I agree with you Peter. Maybe I did not make myself clear. The situation
that I think will be common in a home network for the next couple of
years is the case where at times there is no BCM (no bridges and the PC
and all other IP/1394 capable nodes in the IHDN are switched off). It is
this situation that could cause the problem I described to occur. I did
not intend to say that the use of channel 31 by (current) equipment is a
likely thing.

Reserving channel 31 for the BCM in the standarsd simply prevents this
problem and is fine by me. Philips has no CE products in the pipeline
that would have a problem with this. Hopefully there is no product
around or being designed right now that has a problem with this. We
should check this (just as we did when async streams were invented).

However I feel not so comfortable if the BCM were to become mandatory
for every IRM. It prefer it to be optional so that only applications
that use the broadcast channel are forced to implement it.

Kind regards,

Tom

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