Re: [manet-dlep-rg] 802.11 Adhoc scenario
Henning Rogge <hrogge@gmail.com> Fri, 07 March 2014 07:25 UTC
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References: <38A5475DE83986499AEACD2CFAFC3F98FA6C34C0@tss-server1.home.tropicalstormsoftware.com>
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Date: Fri, 7 Mar 2014 07:25:29 +0000
Message-ID: <CAGnRvup+MHevtq7YVPZZws7B4DyrKfK5uZCNTAvqsPJ6nfTcEg@mail.gmail.com>
From: Henning Rogge <hrogge@gmail.com>
To: Joseph Macker <jpmacker@gmail.com>
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Cc: "DLEP Research Group, \(manet-dlep-rg@ietf.org\)" <manet-dlep-rg@ietf.org>,
Rick Taylor <rick@tropicalstormsoftware.com>,
Stan Ratliff <sratliff@cisco.com>
Subject: Re: [manet-dlep-rg] 802.11 Adhoc scenario
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And "iwconfig" has been deprecated for a number of years and have been replaced by the much more powerful/versatile "iw" command. Henning On Mar 6, 2014 10:43 PM, "Joe Macker" <jpmacker@gmail.com> wrote: > We did the same in early experiments many moons ago by fixing BSSID. > As I was mentioning I think iwconfig supports that directly. > > -Joe > > On Mar 6, 2014, at 2:40 AM, Henning Rogge <hrogge@gmail.com> wrote: > > > Damned Stan... > > > > I read your long post and decided "I will formulate a great argument > > when I got a shower"... and I think I have found a good argument how > > to resolve the problem, unfortunately its self-defeating. > > > > I somehow managed to convince me that it might be better to change the > > mac address of the wifi card and not the mac address of the routers > > interface, because that is more along the line "the router > > controls/configures the radio". Consider the request for the "mac" TLV > > in the first peer discovery dropped. > > > > About the Adhoc stuff, I think you underestimate the amount of work > > the linux community did with their wifi-stack in the last 5 years. > > IBSS/Adhoc mode is normally working very well, I have not heard about > > huge "split net" problems for quite some time. > > > > Of course most community networks solved this problem even earlier by > > just setting a fixed BSSID on all nodes. > > > > Henning Rogge > > > > On Wed, Mar 5, 2014 at 10:57 PM, Joe Macker <jpmacker@gmail.com> wrote: > >> Cool (especially Waikiki), that;s old one but a goodie as they say! > >> I think non-spec workarounds exist (dependent on the hardward/software > driver). > >> > >> Early on in 802.11 spec there was this idea a coalesce algorithm (like > always move towards the highest BSSID you hear in your neighborhood) in > early 2000s I remember some systems worked this way (not saying the spec > ever said anything about it). Certainly even when manufacturers did > something like this there was a convergence time and this was reported in a > few older research papers. > >> > >> I don't think it was ever included because everyone in the committee > had different ideas of how to do it? (sound familiar). > >> > >> ---- not a solution to the adhoc formation problem but----- > >> I think I remember openWRT having both some form of convergence setting > (pick older BSSID you hear so allowing for eventual convergence) and some > way to override this manually when planning say a community network. Maybe > not. I assume Henning would know more given experience that hardware,etc. > >> > >> Even though it may not be well documented I thought there was an > "iwconfig command" for overriding the BSSID and also a convergence > algorithm that still works in that deployment hardware if chosen. > >> > >> I agree not being in the spec has caused people and systems to develop > work arounds and the very least makes for inconsistent features. > >> --------------------------- > >> > >> On Mar 5, 2014, at 5:12 PM, Stan Ratliff (sratliff) <sratliff@cisco.com> > wrote: > >> > >>> I was just downstairs, smoking a cigarette, when I remembered one of > the basic scenarios that stops people from using 802.11 adhoc for really > mobile deployments. Thought I'd offer it up as some rationale for my > earlier statement regarding 802.11 adhoc. I wish I had the lightening > recall and scathing keyboard abilities of some in the MANET working group, > but alas, the years, the beer, the medical conditions, and the prescription > drugs that go with the medical conditions have slowed the memory access > somewhat... ;-) > >>> > >>> I've heard this referred to as the "Split-BSSID Problem", but I don't > know if that's the official term, so let me lay out the scenario. While I > don't put interval times in my scenario, there on the order of a small > number of seconds. That being said, the scenario goes like this: > >>> > >>> 1) I configure up 4 802.11 adhoc radios and associated gear for a > demo. I configure the radios with 802.11 BSSID "Foo". The gear and the > software is works great; everyone can talk to everyone else, it looks > beautiful. Now, all I need to do is to get some people for the demo, which > uses the radios in a man-packable fashion. Oh, by the way, the demo is at > some remote location (let's say Honolulu, because I've always liked the > beach). So, I power down the gear, pack it up, and... > >>> > >>> 2) I get Henning, Teco, Rick, and Stan (after all, I'm going to > Honolulu) to do the demo. Once we're down around Waikiki Beach, I hand out > the gear (it's still powered off, BTW). > >>> > >>> 3) With the gear powered off, Henning and Teco walk to the right; Rick > and Stan walk to the left (non-smokers in one direction, smokers in the > other). They stroll along the beach, until they get quite a distance from > each other (out of 802.11 radio range). > >>> > >>> 4) Since it's still early, Henning and Teco, as well as Rick and Stan, > get a coffee at the Starbucks (there's one on every corner), and Rick and > Stan light up a cigarette (nasty habit). At the appointed time for the demo, > >>> > >>> 5) Stan turns his radio and gear on. So does Teco. Stan's radio > BEACONs with "Foo" as the BSSID. So does Teco's radio. They don't find > anyone. Both radios think "Well, I'm the first guy here". So Stan's radio > adds a "magic number", which is really a hash of its MAC address, to the > BEACON. Teco's radio computes a different magic number (since he has a > different MAC), and does the same thing. A second or two later, > >>> > >>> 6) Rick turns his radio on. So does Henning. Rick's radio BEACONs, but > sees Stan's radio BEACON as well. So Rick's radio basically says "Oh, cool. > There's someone here. I'll just take his magic number, and join the BSSID". > So Stan's radio and Rick's radio are chatting away. Henning's radio BEACONs > as well, and sees Teco's radio. Henning's radio also says "Cool! Someone's > already here", and adopts Teco's magic number. Henning's radio and Teco's > radio are also chatting away with each other. > >>> > >>> 7) Now, the "mobility scenario" starts. Rick and Stan start walking > back down the beach, toward the starting point. Henning and Teco do the > same. Before long, all 4 come into radio range with each other. But since > they've got different "magic numbers", they *WILL NOT* establish one big, > happy, 4-person BSSID. Stan's radio can't talk to either Henning or Teco; > neither can Rick's. The demo is starting to go spectacularly wrong... > >>> > >>> The only way out of this to power off two of the radios - well, the > *right* two radios (either Stan's and Rick's; OR Teco's and Henning's), and > power them back up. Then, they'll join the existing adhoc BSSID, and > everyone will be happy. The moral of the story? Every radio that > participates in an adhoc BSSID MUST be powered up whilst "in range". > Otherwise, said radio won't be able to ultimately join the BSSID, even > though they're configured correctly. IMO, it's a flaw (and a BIG one) in > the adhoc portion of the 802.11 spec. > >>> > >>> Thanks for reading and considering my little story... ;-) > >>> > >>> Regards, > >>> Stan > >>> _______________________________________________ > >>> manet-dlep-rg mailing list > >>> manet-dlep-rg@ietf.org > >>> https://www.ietf.org/mailman/listinfo/manet-dlep-rg > >> > >
- [manet-dlep-rg] London meet up? Rick Taylor
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] London meet up? Henning Rogge
- Re: [manet-dlep-rg] London meet up? Rick Taylor
- Re: [manet-dlep-rg] London meet up? Joseph Macker
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] London meet up? Rick Taylor
- Re: [manet-dlep-rg] London meet up? Henning Rogge
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] London meet up? Henning Rogge
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] London meet up? Henning Rogge
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] London meet up? Henning Rogge
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] London meet up? Henning Rogge
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- [manet-dlep-rg] 802.11 Adhoc scenario Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Joe Macker
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Joe Macker
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Henning Rogge
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] London meet up? Henning Rogge
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Teco Boot
- Re: [manet-dlep-rg] London meet up? Taylor, Rick
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] 802.11 Adhoc scenario John Dowdell
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Henning Rogge
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Joe Macker
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Teco Boot
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Henning Rogge
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)
- Re: [manet-dlep-rg] 802.11 Adhoc scenario Taylor, Rick
- Re: [manet-dlep-rg] London meet up? Taylor, Rick
- Re: [manet-dlep-rg] London meet up? Teco Boot
- Re: [manet-dlep-rg] London meet up? Stan Ratliff (sratliff)