Subject: Please help share your 802.11 multivendor interop experience

From: Lenny Foner <[email-masked]>
Date: Fri, 23 Jun 2000 14:38:24 -0400 (EDT)

[Please keep 802.11 CC'ed; see [1] at bottom for more.]

There's a huge amount of fuzz when it comes to figuring out whether any
given 802.11b (direct-sequence, 11MBit/sec, RF) card or base station will
actually work with each other, or when roaming, etc.  Fixing this could
help both IETF meeting hosts and members who want to use wireless
networking at meetings, not to mention the projects suggested below.

I've asked quite a number of people who -should- know, and nobody seems to
know the whole story, or know what entity -would- know.  The www.wi-fi.com
website (which claims to address such issues) is less than impressive, and
has little useful information on it.  So I'm trying to find actual
operational experience.  Please help!  You'll be helping several different
projects:
 (a) I'm working with some well-known-to-IETF folks to figure out what to
     specify for a fast-deployment, temporary net for the Oregon Country
     Fair in Eugene, which happens in early July.  This will serve as a
     beta-test for a later setup (in late August) on the playa at Black
     Rock City, Nevada, as part of Burning Man, for use by everyone there.
     Both installations are part of events that last only a few days and
     cover a few square kilometers at which up to 20,000 people may be
     present.
 (b) There may be a sufficient density of people in the Davis Square
     area of Somerville, MA (and maybe elsewhere) to make an ad-hoc bunch
     of cells---enough that it might be quite likely that any given laptop
     will be near enough someone's cell to see the greater Internet. [2]
     [I'm using Davis Square as an example because that's where I live,
     and that's where a lot of other Boston-area geeks live.]

The end results of this survey & discussion will hopefully be:
 (a) Archives for people to read later
 (b) A set of web pages describing what to buy and how to configure it
 (c) Whatever else we all want to generate

Here are the things we need to figure out.
 (a) Exactly how interoperable is any given 802.11 DS, 11MBit/sec card with
     any base station?  Any known losing combos?
 (b) Which cards roam properly with which base stations?  For any given
     card from vendor X and base station from vendor Y, which ones roam
     correctly, and which do not?  How does this answer change if both
     cards and base stations are from the same vendor?
 (c) Which cards and base stations are easiest or hardest to retrofit other
     antennas?  Are there unusually difficult-to-obtain connectors on
     particular cards or base stations?  [The installations in the middle
     of nowhere, surrounded by mountains, might use unusual techniques;
     installations in Somerville must of course stay under FCC limits.]
 (d) Do any particular cards have driver problems, for either *BSD, Linux,
     or Windows?  How does roaming affect this issue?  How available are
     drivers?
 (e) Do any base stations allow roaming -without- requiring bridging?
 (f) For operation at very low signal strengths (e.g., to extend range),
     can we step down to 2Mbps?  Does this have to be decided in advance,
     for all users of the net?  Is there a good source for such antennas?
     For an installation in the middle of the desert, should we consider
     linears?  From what source?  How do we cope with the power asymmetry
     between base stations and laptops?
 (g) A big, spread-out net, with either directional antennas or roaming,
     might mean that not all mobiles can hear each other to avoid
     collisions.  How big a problem might this be?
 (i) Crypto---how easy is it to use 128-bit keys?  Must everyone on the net
     have the same key, or can we key per-user somehow?  Has anyone
     evaluated the cryptographic strength of whatever PNRG is generating
     the keys?
 (h) What other problems might we expect?  What questions -should- I be
     asking?

[1] This message is being sent, separately, to several small lists and a
few individuals.  This keeps cross-discussion on each individual list.
If you'd like to see what everyone has said, add yourself to the new
802.11 interop mailing list by sending "help" in body or subject to
[email-masked].  I will announce any results, web pages, etc,
that come out of this to the [email-masked] list.  Also, -please-
keep 802.11 CC'ed on replies!  Doing so means that everyone's replies to
the various lists all wind up in a common archive that people can read.
See also http://lcs.www.media.mit.edu/projects/802.11/.

[2] There are a number of obvious issues here, which will be explored in a
separate mailing list; send "help" to [email-masked] or
see http://lcs.www.media.mit.edu/projects/Davis-Net/ for more details.