Subject: RE: IETF Wireless LAN history

From: RJ Atkinson <[email-masked]>
Date: Thu, 29 Jun 2000 13:22:32 -0400

At 09:54 29/06/00 , Dan Kohn wrote:
>I will bite regarding one issue near and dear to IETF hearts -- which is the
>seeming need to buy yet another 802.11 card for each IETF meeting.  And yes,
>I am actually suggesting an approach that would require one more purchase:

         Actually, IETF has made IEEE 802.11-DSSS the convention for wireless
LANs at all IETF meetings for some time now.  This has been supported 
at least at Oslo, DC, Adelaide, (and will be at Pittsburgh).  It probably 
has been  supported for some significant time before Oslo, though I 
don't have first-hand remembrance of that.  In DC, Nortel was pushing 
their 802.11-FH system, but a full 802.11-DS system was up and running 
in parallel.

         Probably due to overlap in organisational membership and the 
broad International acceptance of IEEE 802 standards, IEEE 802.11-DSSS 
has also become the de facto standard for use at several other 
networking meetings (e.g. NANOG, RIPE).

Ran
[email-masked]

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From: "Theodore Y. Ts'o" <[email-masked]>
Date: Thu, 29 Jun 2000 14:36:15 -0400

Date: Thu, 29 Jun 2000 13:22:32 -0400
   From: RJ Atkinson <[email-masked]>

I'm not sure that it's been officially decided as the convention, but
it's certainly been the practice most of the time (although the Nortel
use of frequency hoppers was a certainly an exception to this rule).  

I think there was one other time that frequency hoppers were used in the
past; I seem to recall dispairing that we would *ever* settle on a
standard 802.11 type when I broke down and purchased a 802.11-FH PCMCIA
card.  That way, I'd be ready no matter what a particular IETF meeting
site decided to use.

It would be good if we could standardize on one particular type, but as
I recall the last time the issue was raised, it was explained to me that
different systems worked better in different RF environments, so we
should get used to switching back and forth between DS and FH cards.  
If we we could depend on it always being 802.11-DS, that might make a
number of people's lives easier.

For what it's worth, 802.11-DS (both 2 and 11 mbits support) appears to
be the de facto standard at the main Usenix technical conference as
well.

						- Ted

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From: Joe Touch <[email-masked]>
Date: Thu, 29 Jun 2000 13:15:17 -0700

> number of people's lives easier.

DS appears to be better for large, flat spaces (largely 2-dimensional,
under 3 stories tall, since transcievers on the middle floor largely
cover the upper and lower).

FH is better for more spherical spaces (largely 3-dimensional).

And DS and FH do not play well together, i.e., it's much better to stay
away from concurrent overlapping installations. I had earlier measured a
BW penalty of between 1/2 to 3/4 (transferring data over only one of the
two technologies at a time, in a concurrent deployment).

The decision of what to use may depend on the local environment.

Joe

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From: RJ Atkinson <[email-masked]>
Date: Thu, 29 Jun 2000 18:18:46 -0400

>FH is better for more spherical spaces (largely 3-dimensional).

These optimisations do not appear to matter significantly in practice
in the locations that IETFs have been held or in other places where
I have experience with DS/FH being overlaid (a work campus environment).

>two technologies at a time, in a concurrent deployment).

IETF/DC is a fine counter-example of why the above might theoretically
be true, but is not really true in deployed networks.  IETF/DC had both
overlaid on the same 3D spaces and both worked OK.  Obviously one
must be thoughtful about the channel/frequency plan and such like
(which is true regardless of overlaid networks).

Ran
[email-masked]

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From: Joe Touch <[email-masked]>
Date: Thu, 29 Jun 2000 15:31:43 -0700

> I have experience with DS/FH being overlaid (a work campus environment).

That is interesting - it was the deciding factor in the deployment here.
DS was not capable of covering the 3-D space sufficiently, due the the
number of overlapping cells required, and the number of "channels"
available.

> be true, 

See "measured" above. Theory was not involved. :-)

but is not really true in deployed networks.  IETF/DC had both
> (which is true regardless of overlaid networks).

Agreed.

Joe