Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

frottle: Defeating the Wireless Hidden Node Problem

Hemos posted more than 11 years ago | from the wipe-it-out dept.

Wireless Networking 121

jasonjordan writes "The West Australian FreeNet Group was the first to go War Flying - and now we've released "frottle" (freenet throttle) - an open source project to control & manage traffic on fixed wireless networks. Such control eliminates the common hidden-node effect even on large scale wireless networks. frottle works by scheduling client traffic by using a master node to co-ordinate - effectively eliminating collisions! Developed and tested on the large community wireless network of WaFreeNet, We've found it has given us a significant improvement in network usability and throughput. "

cancel ×

121 comments

Sorry! There are no comments related to the filter you selected.

A public service announcement. (-1)

(TK)Max (668795) | more than 11 years ago | (#6607105)

Real trolls post while logged in. (to your mother with their penis)

Re:A public service announcement. (-1, Offtopic)

handybundler (232934) | more than 11 years ago | (#6607151)

werd up my negro!

Re:A public service announcement. (-1, Troll)

Anonymous Coward | more than 11 years ago | (#6607392)

you are a loser. zero me all you want, asshole.

handy bundler

Re:A public service announcement. (-1, Flamebait)

handybundler (232934) | more than 11 years ago | (#6607543)

you are a stalker. i will zero you when i fucking feel like it.

i may be an asshole, but at least I'm not a cock-filled asshole like you.

HTH HAND.

Re:A public service announcement. (0)

Anonymous Coward | more than 11 years ago | (#6608665)

You are an asshole. Zero me again, and you will regret it.

Re:A public service announcement. (0)

handybundler (232934) | more than 11 years ago | (#6608881)

I've zero'd you once. Feel free to threaten others who won't put up with your shit. Remember, we aren't slashdot. It won't take much to get banned from SRU. If you'd like to take that further, I have your ISPs information in my hands ...

attn: trollkore sucks gnaa cock (-1)

TEH TIREL (692462) | more than 11 years ago | (#6607241)

Re:A public service announcement. (0)

Anonymous Coward | more than 11 years ago | (#6607374)

Yeah but that's no good because then people like me who read at threshold 5 with +6 modifiers on Troll, flamebait, redundant and offtopic don't see the folks that start out at negative one.

Re:A public service announcement. (0)

Anonymous Coward | more than 11 years ago | (#6607401)

that's why all of us with karma must do our part to mod up trolls to at least 0 so they can then be modded down and trigger our modifiers.

FAWK EWE & FAWK TEH CORRUPT SLASHDOT SYSTEM! (-1, Troll)

Anonymous Coward | more than 11 years ago | (#6607444)

Anonymous Coward -- I am legion.

Moderators: (0)

Anonymous Coward | more than 11 years ago | (#6608333)

Here's a Zen koan for you: "How's that a troll if it doesn't draw any biters?"

Don't be silly. The computer is your friend.

URGENT: Massive Mozilla security hole discovered! (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6607106)

I just got this in my mail, and I thought I should pass it on to my friendson Slashdot (since I know a lot of you use Mozilla :-).

IMPORTANT: There is a huge security hole in all Mozilla builds thatwas just discovered yesterday. By inserting a properly-constructed URL into anXHTML source file with MIME type application/xml+xhtml, arbitrary code can berun as the client user on his machine. This hole exploits a known bug inMozilla's xml parser, that doesn't properly handle certain character entities(e.g. &#nnn;). If the decimal number inside the character entity is greaterthan 65535 (the maximum legal Unicode value), a buffer overflow is triggeredand arbitrary machine code can be inserted into the running process.

Luckily though, the fix is small, simple,and can be automatically downloaded over the Internet, thanks to Mozilla'sXPI installation facilities. This patch is available from the BrowserSecurity page at data.com and more info is available on Yahoo [yahoo.com] . Simply click the link, and after a short verification the fixwill install itself.Please install their patch ASAP, before malicious hackers wipe Mozilla offthe web!

Isn't open-source grand? Had this been an Internet Explorer exploit,we wouldn't even know of its existence until about a month after sKr1p7 k1dd1eZ started hacking with it. I applaud the Mozilla team for promptly discoveringand disclosing this bug, and the fine folks at data.com for hosting the fix.

BEWARE: Goatse.cx link (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6607141)

Trolling goatse.cx link. Click at your own risk.

Why we won't have wireless for long... (-1, Flamebait)

Anonymous Coward | more than 11 years ago | (#6607132)

When all those Islamic towel-heads destroy the "great Satan" that is Western culture, the fruits of prosperity will cease and the world will fall into civil decay and revert back to barbarianism.

You see, that colored race which roams the desert looking for ways to destroy us does not realize that we are the only source of progress in philosophy, science, and art. Without America and its good, wholesome Christian values, this world would have nothing. There will be no one left to drive the human race towards perfection.

Once we've been destroyed by these short-sighted individuals, humanity will slowly fall into its doom. Afterall, the arabic peoples won't stop until everyone else is destroyed, then, like animals (I don't even think they're people), they will destroy themselves.

How can a violent race like that ever spawn social progress? They're quite literally like monkeys, running around like crazy, flinging feces at each other. Without Truth (the Word of God), they've gone quite insane with the devil whispering in their ears. Unlike monkeys flinging feces at each other, they fling bombs at each other (and us).

Personally, I'm glad that a good Christian man (women really can't be Good, because they cannot be like God as they lack the proper equipment), like George Walker Bush, has the guts to stand up and say "we won't let these inferior people destroy America". Now we're taking steps to exterminate them and take their resources for the advancement of America. Good show, Bush!

Re:Why we won't have wireless for long... (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6607161)

Stupidest troll ever.

Re:Why we won't have wireless for long... (0)

Anonymous Coward | more than 11 years ago | (#6607373)

It's not trolling if it's true!

Re:Why we won't have wireless for long... (-1, Flamebait)

Anonymous Coward | more than 11 years ago | (#6607187)

we're taking steps to exterminate them

We should be taking steps to exterminate trolls like you.

Re:Why we won't have wireless for long... (-1, Troll)

Anonymous Coward | more than 11 years ago | (#6607238)

I agree. Exterminate them before they hurt us.

They are sub-human fecal debris anyway. No harm done. Kill 'em all.

Cool!!! (-1, Redundant)

Anonymous Coward | more than 11 years ago | (#6607136)

More p0rn!!!

[This text is to pass the lameness filter]

They're reinvented Alohanet, circa 1970 (4, Informative)

Animats (122034) | more than 11 years ago | (#6607155)

With the menuhene (the master node) and everything.

Look up "slotted Aloha" [google.com] for background on this class of idea.

Re:They're reinvented Alohanet, circa 1970 (2, Interesting)

Alan Cox (27532) | more than 11 years ago | (#6607460)

Systems like DAMA have taken it somewhat further than Aloha but it is alive and well in a lot of situations. The trick is working out when its a win to use it

Re:They're reinvented Alohanet, circa 1970 (0)

mekkab (133181) | more than 11 years ago | (#6607465)

thats cute- I forgot that ALOHA called it "menehune"! [hawaiiandance.com]

Computer Networks by AST (4, Informative)

RevMike (632002) | more than 11 years ago | (#6607610)

You might also want to read Computer Networks [amazon.com] by Andrew S. Tannenbaum. AST discusses Alohanet in great detail.

Tannenbaum's best known work is Operating Systems [amazon.com] , the Minix book.

Yes, I know he was critical of Linus on comp.os.minix [comp.os.minix] , that is why I voted to create comp.os.linux [comp.os.linux] . They are still excellent books.

Re:They're reinvented Alohanet, circa 1970 (4, Funny)

FattMattP (86246) | more than 11 years ago | (#6607613)

They're reinvented Alohanet, circa 1970
They should have no problem getting a patent on it then.

well.. (-1, Redundant)

Dorothy 86 (677356) | more than 11 years ago | (#6607158)

If they had been flying in formation, doing synchronized barrell rolls, then I may have been impressed! ;-)

And a good thing, too!! (-1, Flamebait)

Trolling4Columbine (679367) | more than 11 years ago | (#6607164)

Now I can get my kiddie pr0n off of FreeNet from my home, on the road, and even in the sky! Isn't open source great!

So... (3, Funny)

Anonymous Coward | more than 11 years ago | (#6607171)

Am I *not* supposed to understand a word of that?

Good news. (-1, Redundant)

Sheetrock (152993) | more than 11 years ago | (#6607172)

Anything that speeds up Freenet is music to my ears. I don't have a wireless LAN card yet, and apparently this is just a wireless-only optimization (however that works), but that's kind of cool that it's picked up this kind of steam.

Is this 802.11 or packet radio? I'm a bit confused by the site.

agreed (-1, Offtopic)

bobo333 (693563) | more than 11 years ago | (#6607271)

But Freenet is only used by a few. If Freenet wants more users then they MUST do something about the speed.

It's really a nice concept . I hope they succeed and bring back the uncontrolled internet.

Re:Good news. (3, Insightful)

Phydoux (137697) | more than 11 years ago | (#6607293)

The article relates to 802.11, however this would probably work on packet radio too.

You could achieve the same thing on packet radio by using a digipeater instead of having all nodes transmit/receive on the same frequency, and I think you'd get better thruput with a digipeater than using Frottle.

Re:Good news. (0)

Anonymous Coward | more than 11 years ago | (#6607391)

It's much simpler to run one net, however. The name escapes me, but there's a system in use on some busy packet radio channels in Europe that's very similar to Frottle. Here in the US, I've never heard of anyone using it though...

POOR EFFORT D- (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6608299)

you can do better

Mirror (4, Informative)

Anonymous Coward | more than 11 years ago | (#6607176)

In case the site (or routes to the site) get slashdotted. Here [martin-studio.com] is a mirror. Sourceforge also has an annoying habit of downing themselves for maintenance. Enjoy!

Is Frottle.. is good (5, Interesting)

Radix999 (28549) | more than 11 years ago | (#6607191)

It really does make a huge difference too. With 15 odd users on an AP we had a nightmare.. someone would start transferring a file and people would drop out, packetloss, etc. The strongest SNR would always dominate, uploads were nigh on impossible (when ANY download was occurring) and the network had no QoS at all.
Thanks to the great work of Frottle, we're now cruising along - we all get a fair go, we have QoS, and bandwidth is shared equally and we're all pretty damn pleased with it.

Is Frottle.. is good :)

Re:Is Frottle.. is good (5, Funny)

cybermace5 (446439) | more than 11 years ago | (#6607227)

If you had 15 normal users, would there have been a problem to begin with?

Re:Is Frottle.. is good (4, Interesting)

TheZombie187 (208516) | more than 11 years ago | (#6607314)

Actually, the fact we're all slightly odd helped immensely. *grin*

Most of us connected to this network because we are interested in the technology behind it. 15 "normal" internet users would have undoubtedly leeched the fsck out of the AP and would have seen problems much sooner....

Proud Denizen of the WaFreeNet

Re:Is Frottle.. is good (5, Informative)

Radix999 (28549) | more than 11 years ago | (#6607341)

Of course. Wireless access points generally aren't geared for large number of users OUTDOORS. The difference is that when you've got users 10-20km away collisions have a lot more effect. Individual clients don't see the traffic of other users, so it's very easy to cause collisions (this is the Hidden Node effect) - there is commercial software to solve this problem (ie. Karlnet), but the large expense and lack of Linux support (ie. use 2.4.2 kernel, Redhat 7.1 and their binary driver or else) put us off majorly.

So we rolled our own. Frottle is the result.

Token ring reborn! (4, Funny)

binaryDigit (557647) | more than 11 years ago | (#6607203)

Fans of Madge, Thomas Conrad and IBM rejoice!

Re:Token ring reborn! (2, Funny)

MarcQuadra (129430) | more than 11 years ago | (#6607580)

I was just thinking that!

This sounds a LOT like Token ring has gone to the, um... ether?

it's more like Token Bus (1, Informative)

Anonymous Coward | more than 11 years ago | (#6607675)

Token Ring requires each node forward packets that it didn't originate. In this case, it is merely a bus with token access control.

This promotes social cordiality. (-1)

mfivis (592345) | more than 11 years ago | (#6607219)

Let us rejoice and welcome this newly found speed in our wireless network. Now I can oblige and say goodbye to the people who request files from me at my monthly Manhattan WiFi-over-coffee-club faster.

In the future when I'm moving a funny thought or two through my embedded-802.11i mind-chip, I can smile and say farewell more efficiently.

Speed isn't the problem... (4, Funny)

Valar (167606) | more than 11 years ago | (#6607266)

In a lot of cases, I have noticed, speed isn't the problem. A lot of times, I conenct to a WiFi network at full speed, and it is very responsive, and then suddenly it will drop link. It will go from full signal strength to none, seemingly instantly, then work again a minute or so later. This is because the problem is reliability of connection, especially in 'built up areas' i.e. the city. So, what we really need is a redundant, wireless backbone, so I can browse my pr0n-- err, open source software without gettting dropped signals.

Ah yes.... (4, Funny)

cybermace5 (446439) | more than 11 years ago | (#6607298)

Yet another project following the tradition of allowing the developers' children to name it.

agreed (2, Funny)

jmarkantes (663024) | more than 11 years ago | (#6607493)

I agree. Freenet? Again?

At least we know who to thank- on the bottom of frottle's page under the special thanks is:

jas for coming up with such a catchy name

Yay jas.... very catchy.

J

Re:Ah yes.... (1)

SEWilco (27983) | more than 11 years ago | (#6608212)

Isn't a froggle a fuzzy blue frog which lives under stairs on Sesame Street?

Attention Project Namers: (3, Insightful)

MyHair (589485) | more than 11 years ago | (#6607312)

Never call anything Freenet. It is too generic a term and is used for several different commercial and nonprofit organizations and projects.

It's much worse than Firebird.

If nothing else, realize that it messes up people who search for you on Google because of all the @freenet.com email addresses.

Re:Attention Project Namers: (2, Informative)

TheZombie187 (208516) | more than 11 years ago | (#6607351)

It's not called FreeNet, it's called frottle. The name happens to be derived from the word FreeNet but we don't refer to it as anything but frottle.

Try Googling [google.com.au] for frottle some time. no confusion there!

I've got a better name for it: (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6607488)

HEY! Play "Freebird"!

yeeeeeehaaaaaaaawwwwwww!

boring! (-1)

Anonymous Coward | more than 11 years ago | (#6607337)

Next story. this one sucks.

802.11x topology change (4, Informative)

div_2n (525075) | more than 11 years ago | (#6607343)

It sounds like this is an attempt to change the topology of 802.11x to a polled topology without the true benefit of such topology without changing the hardware.

In a true polled topology client packets aren't sent until the AP says they can. The client equipment remains completely silent until they receive the right to broadcast packet. AP's are programmed to completely ignore packets that are sent out of turn anyway.

802.11x hardware is NOT designed that way. Sure you can control data flow that way but your AP is still open to the same problems as before. I wonder what happens when one of the client on one of the computers crashes and ceases to act as a polled client. Will it start hogging time slices from the AP again? Seems to me it would unless there was a radical hardware change to both AP and client adapter.

Re:802.11x topology change (5, Informative)

TheZombie187 (208516) | more than 11 years ago | (#6607441)

It sounds like this is an attempt to change the topology of 802.11x to a polled topology without the true benefit of such topology without changing the hardware.

Correct!

We have built a city-wide wireless freenet using commodity hardware. Things were working well, but as we grew larger the hidden node effect became a larger problem. Swapping all the hardware over is a big expense, and a big undertaking for a bunch of hobbyists.

We did investigate doing so, and also investigated a firmware solution (KarlNet TurboCell) but found it unsuitable to our needs.

On a whim, one of us implemented a small master/slave polling system in Perl which seemed to do the job surprisingly well, and it just grew from there.

Re:802.11x topology change (1)

radixvir (659331) | more than 11 years ago | (#6607743)

i dont know much about what is going on. but didnt linksys recently opensource their firmware. i wonder if this could be of some use in solving the hardware problem?

Deep froat? (-1, Troll)

stratjakt (596332) | more than 11 years ago | (#6607347)


Worthwhile reading? (-1, Offtopic)

Anonymous Coward | more than 11 years ago | (#6607352)

I think so. Check this out:

---
Date: Sat, 20 Apr 2002
From: Bennett Haselton
Subject: Re: Please resolve the censorware conflict.

Any discussion of the Censorware.org controversy has to start from the fact that Michael and the rest of the former CWP are not "equal sides" in this, are not "both right and both wrong", etc.

Michael did not own the Censorware Project and did not do a majority of the work involved, he just hi-jacked the domain name and stole it from the rest of us. The fact that people look at what he did, and look at the response from the rest of the group, and call it "infighting" or "airing dirty laundry" is frankly an insult to the Censorware Project and its work. If the EFF webmaster put the eff.org domain in his own name and then hi-jacked it from the organization, he'd be branded a traitor and a pariah in the Internet community for the rest of his life, and nobody would ever forget what he did. Same if it was the CPSR.org webmaster, the EPIC.org webmaster, or whoever. But if the Censorware Project webmaster does it, we're expected to "work out our differences" with him?

There is an absolute difference between Michael and the rest of us. None of us, despite some personal animosities (not between me and anybody, but between people that I know), would ever, ever do anything like what Michael did. But Michael did it.

It doesn't matter whether or not Michael promotes anti-censorship work in his position as a Slashdot writer; he's hardly making much a difference by saying things that were going to get said anyway, and nothing he does there will ever come close to canceling out the harm he did by shutting down the one-time Censorware Project website.

The only legitimacy that Michael has is through his position as a Slashdot writer; he has just enough writing skills to make his writings sound seductively intelligent to anybody who doesn't know the real story. The fact that Slashdot hired Michael should be deeply embarrassing to them, and is in fact eroding Slashdot's credibility according to comments made by some people who found out about the Censorware.org site. But Slashdot is apparently too deeply wedded that decision to reconsider, and comments from [Michael Sims' direct supervisor] have been more of the same along the lines of "They should work out their differences" instead of acknowledging Michael Sims's utterly disgraceful behavior as compared to the average person. You think Slashdot really believes Michael is trustworthy, after what he did? Do you think they're going to let him put the Slashdot.org domain in his name? :)

-Bennett

token-passing on top of CDCSMA (2, Insightful)

Medievalist (16032) | more than 11 years ago | (#6607358)

Seems like using a fork in a drillpress for a daquiri blender... doable, but rather outside the intentions of the tool designers!

Perhaps this will stimulate some hardware vendor to make token-passing wireless network hardware to eliminate the latency problems. IBM, Madge and Thomas Conrad must have boatloads of relevant expertise already....

Just read the article.. (1, Informative)

Anonymous Coward | more than 11 years ago | (#6607363)

..and all this is, is a glorified token ring implemented at the OS layer on top of 802.11.

Color me unimpressed.

Re:Just read the article.. (4, Insightful)

RevMike (632002) | more than 11 years ago | (#6607761)

..and all this is, is a glorified token ring implemented at the OS layer on top of 802.11.

Color me unimpressed.

Why are you critical of the solution? It appears to work well and is inexpensive. What is wrong with that?

A friend who used to work for a "baby bell" was involved with a project to provide VoIP and video services, as well as internet, over their DSL infrastructure. The problem that they ran into was that IP, as supported by their commodity DSL equipment, did not support QoS. Their solution was to tunnel a more advanced network protocol (ATM I think) over the entire DSL IP connection. Then they ran their voice and video over ATM directly and ran IP as another tunnel over ATM. It wasn't elegant, but it was cheaper and more effective than manufacturing new devices.

Anytime you can use commodity off-the-shelf hardware, you can usually save money.

Re:Just read the article.. (0)

Anonymous Coward | more than 11 years ago | (#6608181)

ATM is not just a 'more advanced protocol'. It is a pure telco protocol and hardware that talks ATM costs *orders of magnitude* more than hardware that talks IP, even with QoS routing capabilities.


Add to that the fact that tunneling IP over ATM horribly degrades TCP performance [a completely new ATM layer had to be invented just to help this problem a bit, and even then performance isn't quite up to par with cheapo IP hardware], mainly because the IP and the ATM layer have different packet boundaries, so they get split up and TCP horribly chokes when part of a packet is lost, trying to rewind a lot of data that is guaranteed intact.


However, you are correct that carrying voice and such over ATM would work a lot better than over IP hardware. ATM was designed for these things. The IP part is only useful if it isn't your absolute priority, and you use something like ABR to provide it.

Re:Just read the article.. (1)

RevMike (632002) | more than 11 years ago | (#6608256)

I certainly may be wrong about the ATM part. I'm not an advanced networking guy.

The important point is that the protocol tunneled over the commodity IP connection, and was, by definition, able to use the entire bandwidth of the IP connection. The protocol supported QoS. It was implemented in software. Since the telco involved controlled both ends, it may have been a custom protocol that borrowed features from ATM.

Re:Just read the article.. (1)

GPB (12468) | more than 11 years ago | (#6609339)

This would be interesting since most DSL implementations I've seen use ATM as the transport mechanism, and then emulate/run ethernet (and subsequently IP) on top of that.

-Brian

Re:Just read the article.. (4, Funny)

Tailhook (98486) | more than 11 years ago | (#6608595)

Color me unimpressed.

Yeah, me too. You lamers. All you're doing is adapting old ideas that you didn't invent to new situations. You should just deal with the problem and stop trying to improve your situation. Who do you think you are? People with free will? WTF is wrong with you?

If you want good behavior from your wireless system, you're supposed to go forth and spend large sums of money on exotic, highly vertical equipment from specialized vendors. How do you expect to command respect from anyone if you don't do it that way?

Idiots.

Re:Just read the article.. (1)

LarsG (31008) | more than 11 years ago | (#6610464)

..and all this is, is a glorified token ring implemented at the OS layer on top of 802.11.

And? If it works better than RTS/CTS and solves their problem..

TokenRing? (0, Redundant)

gerardrj (207690) | more than 11 years ago | (#6607385)

Wow... they've just set networkin technology back 15 years.

Re:TokenRing? (4, Interesting)

Anonymous Coward | more than 11 years ago | (#6607624)

Is your comment designed to infer that token-ring is a less advanced network topology? Token-ring is actually younger then ethernet and has many advantages. It holds up performance wise under load and you can predict the max amout of time a packet will take to travel the network. Thisis something you cannot do on a larger ethernet. Token is widely used with medical and manufacturing eguipment were messaging latency must be garunteed. The only reason speeds of token have not increased is cheaper ethernet is well suited to most but not all situations, wireless A/p like envirormentsthat effectivly are shared medialike a hub is one example where ether falls appart fast with many users. Token would hold perfromance and make best use of the air time. Token scales, ether does not unless you add segments. Token has not increased speed because there has been little demand for it. But it is the more advanced technology and would be the solution for large wireless applications.

Re:TokenRing? (4, Insightful)

El (94934) | more than 11 years ago | (#6608025)

It's also an order of magnitude more difficult to implement (due to problems like recovering lost tokens) and was limited by spec. to 16Mbits/second, with a higher proportion of those bits devoted to overhead. Oh, and chipsets to do Token Ring were an order of magnitude more expensive. Token Ring is to Ethernet as Steam Engines are to Internal Combustion engines -- yes, if they'd put as much time, energy, and money into developing Token Ring as they have into Ethernet, it would be a better technology than Ethernet (mostly because like you said, worse case packet delivery time is deterministic). But they haven't!

Re:TokenRing? (0)

Anonymous Coward | more than 11 years ago | (#6607721)

Just because it has been invented 15 years before doesn't mean that it doesn't work better than what we're using now.

Wow (5, Funny)

BelugaParty (684507) | more than 11 years ago | (#6607439)

before I could even understand the problem there is a solution. I'm impressed. And to think, these people do this in their spare time.

Am I new to warring or... (2, Interesting)

gerf (532474) | more than 11 years ago | (#6607508)

what. Is there some place that the coordinates of all these hotspots are shown? I think it would be helluva cool to be able to see GPS coordinates, or some sort of listing of where there are these hotspots around. It could be helpful in traveling, and the such.

I don't have a wireless card, much less a laptop, but if i wanted to travel, i imagine that having something like this would be quite helpful, rather than roaming around looking for the symbol etched on a roadsign.

Re:Am I new to warring or... (4, Informative)

TheZombie187 (208516) | more than 11 years ago | (#6607589)

yes, check out nodedb.com [nodedb.com]

Most WaFreeNet nodes are listed here [nodedb.com]

Thanks (1)

gerf (532474) | more than 11 years ago | (#6607693)

I am now more Learnded

What is the state of WAFreeNet these days? (3, Interesting)

torpor (458) | more than 11 years ago | (#6607518)

I'm from Perth (born in Subiaco) and have lived outside of Australia since I was a teenager - have visited home a couple of times here and there, and every time I've been impressed with how much progress Perth has made in implementing advanced Internet technologies. Last time I was there - a year ago - I noted teams of wireless-hackers putting up repeater boxes in various neighborhoods at least 4 times - I don't know if it was just by chance, but I kept running into these 3 guys!

One of the things which has kept me from moving back home to Perth and setting up digs has been the state of the Internet down there - the Telecom monopoly, and the distances involved, have been a big factor. Maybe I'm spoiled by American and European bandwidth situations and maybe I ought to just go home and bear with it, but I would be curious to hear from anyone who knows what the scene is like in Perth for cheap, affordable world-class Internet bandwidth?

Re:What is the state of WAFreeNet these days? (1)

sinjayde (661825) | more than 11 years ago | (#6608049)

... I would be curious to hear from anyone who knows what the scene is like in Perth for cheap, affordable world-class Internet bandwidth?

There isn't, simple. And I can't see there being for quite a long time either. I am from Perth originally (lived 18 years, now residing in Washington) and broadband in Australia is still in a very poor state, unless you are exceedingly wealthy.

Nice concept (0)

y77 (692293) | more than 11 years ago | (#6607555)

I hope they succeed and bring back the uncontrolled internet so you could achieve the same problems as before. I wonder what happens when one of us connected to this network because we are interested in the technology behind it. For users, would there have been a problem to begin with? Most of it is implemented as a small master/slave polling system in Perl which seemed to do the job surprisingly well, and it just grew from there. Any discussion of the client as one of the AP and would have undoubtedly leeched it out of the same thing on packet radio by using a digipeater instead of having all nodes transmit/receive on the same thing on packet radio by using a digipeater There is not really an absolute difference between them

Fakin' it. (5, Interesting)

GoRK (10018) | more than 11 years ago | (#6607562)

Well, this idea is good and all (that's why it's a part of the spec!) But the problem with a firewall-based solution is that it is behind the AP and thus the solution of traffic control through client polling is only simulated. Without the AP performing the polling, you don't acutally solve this so called "hidden node" problem.

802.11b people have a bad habit of thinking that the problems they face are new or unique, so they do a lot of re-inventing the wheel. This, normally is not a bad thing, but quite often "WiFi" supporters produce a crude solution while spewing insane amounts of bullshit radio pseudosience. When did "crosstalk" suddenly mutate into "hidden node problems?" Alvarion (Breezecom) has had polling support in their AP's for ... about 6 years or so, even the 802.11b ap's! It's like trying to make steel in your fireplace. The consumer-grade equipment is not designed to take the heat. Consumer-grade AP's are going to lack some of the features needed in carrier-grade equipment such as polling. It makes them cheaper - no doubt they are missing features.

What someone who wants to fix this really ought to do is modify the ihostap drivers to do polling 'on the air' -- If it is possible, at any rate.. I am unaware of the specific implemenation, and it's likely that even toying with the HostAP drivers will not allow one to work with the radio at a low enough level. Still, you know, if it works, it works. Traffic shaping can make things seem faster on congested networks of any kind, so if it throttles the abuser down enough where other radios can get a word in edgewise, then it does a little towards curing a symptom of the real problem. For the freenets and coffee shops, this may be entirely sufficient.

~GoRK

Re:Fakin' it. (0)

Anonymous Coward | more than 11 years ago | (#6609127)

You have an interesting point. However, I think you go to far in saying that this is crude and pseudoscience; you admit that high end AP's do the same thing. Furthermore, you ignore the possibility that someone's using a computer AS an access point. You are basically attacking the creators of this program, which is uncalled for; just because it's not useful to everyone doesn't mean it's not useful to anyone.

MOD PARENT UP (0)

Anonymous Coward | more than 11 years ago | (#6611047)

he tells like it is!

Re:Fakin' it. (2, Informative)

m0rphm0nkey (616729) | more than 11 years ago | (#6610310)

I apprecieate your information, I was unaware that such a beast existed. However....

Let us also consider the cost of alvarion breezecoms (the outdoor models) of easily 1600+ American dollars. I've got a choice between that and a 75 dollar (or less) AP with a 100 dollar beater laptop in a 50$ (max, maybe less if I can find something used and appropriate, which I can) hoffman box. Subtract that from the profit margin of your basic Mom&Pop Wisp (almost nonexistent labor of love style) or neghborhood "sharing" project and I thinks the usefulness of their project becomes apparent.

From all of us who can't drop a couple of g's on an access point, thanks guys!

AODV (1, Insightful)

Anonymous Coward | more than 11 years ago | (#6607661)

I dunno, seems a bit of a kludge. Why not run the 802.11 network in ad-hoc mode and dynamic route via AODV. If there are bandwidth problems, pop in more nodes==routes. Yes, the peak performance is necessarily lower, but the worst-case performance must be much better?

but i converted that pringles can for a reason! (1)

*weasel (174362) | more than 11 years ago | (#6607897)

"prevents clients with stronger signals from receiving bandwidth bias"

all that time and effort to get a stronger signal and they're gonna cast me back down with the technon00bs?

'screw you guys, i'm goin home'

Yahoo News- related story (-1, Redundant)

Anonymous Coward | more than 11 years ago | (#6607943)

One Slow User In The Hot Spot Can Degrade Wi-Fi Performance

http://story.news.yahoo.com/news?tmpl=story&ncid =1 293&e=5&u=/cmp/20030802/tc_cmp/12807964&sid=955734 32

This isn't the *real* hidden node problem (3, Informative)

Anonymous Coward | more than 11 years ago | (#6608073)

While this does deal with one aspect of the Hidden Node problem (packet collisions) you haven't fixed the real problem: The remote clients cannot hear each other. This is just a fundamental problem with CSMA/CA on a RF spectrum.

802.11b orginially proposed using RTS/CTS to rememdy the problem, but they quickly realized that this cut network bandwidth down to 1/2 or 1/4 of available bandwidth. Not good.

The only way that you could really fix the problem is to use multiple receivers (access points) located throughout and have them vote on the packets by using a diversity antenna pair. Between the two access points, they should get enough transmission from both stations (remote clients) to reassemble both packets and send them on their merry way.

This software doesn't really handle 802.11b itself , which allows for clients to clobber each other. Good job getting around the problem, though.

Not a hidden node problem (4, Informative)

PureFiction (10256) | more than 11 years ago | (#6608162)

This is not really a hidden node problem, as they make it out to be.

This is more a problem with the inherent lack of scalability of a CSMA/CA architecture. Everyone is familiar with the way ethernet degrades under saturation: you only get about 70% of that 100Mbit throughput utilized. Ethernet is CSMA/CD - collision detection.

In wireless the problem is even more pronounced in infrastructure mode because you are using CSMA/CA -- collision avoidance. This means that for every packet to be sent, the clients must coordinate use of the medium before sending, using a RTS/CTS handshake.

(client) can I send now?
(AP) not your turn yet
(client) can I send now?
(AP) not your turn yet
(client) can I send now?
(AP) yes
(client) ... data packet ...

When you put many clients (20+) on the same AP sharing the same medium, a large amount of bandwidth is spent simply coordinating contention free access to the wireless medium itself.

Traffic shaping (which is all frottle is doing) helps ease this problem by reducing the amount of data clients try to send/recv in a given period of time, and thus reduces some of the contention.

This is simply a band-aid on a more fundamental problem, however.

The only true way to prevent this kind of inefficiency for larger numbers of clients is to use a true wireless phased array switch, like vivato, which can effectively emulate a dedicated medium to each client, preventing any contention that arises in the broadcast CSMA/CA situation.

Also, it is important to note that communication between nodes on the wireless will NOT be shaped by the frottle queues unless you are using hostap or some other linux based access point. In such a scenario, two nodes talking to each other could use as much of the medium as they liked (as coordinated by the access point itself) without frottle seeing any of the traffic.

Re:Not a hidden node problem (0)

Anonymous Coward | more than 11 years ago | (#6610886)

Also, it is important to note that communication between nodes on the wireless will NOT be shaped by the frottle queues unless you are using hostap or some other linux based access point.
Not quite true. We're using standard off-the-shelf APs, with a linux router behind the AP. Frottle is running on the linux router.

Re:Not a hidden node problem (1)

PureFiction (10256) | more than 11 years ago | (#6611332)

True, I should have added "or an access point in bridge mode".

If you use an AP that does the NAT/router for you, anything between the clients is not going to go through the linux router.

Problems with this (2, Informative)

Taral (16888) | more than 11 years ago | (#6608283)

1. Isn't this what RTS/CTS is for?

2. What 802.11 really needs is <b>power scaling.</b> It's the big difference between cellular networks and wifi. Like the article says, the person with the highest S/N gets to talk.

Re:Problems with this (2, Informative)

caseydk (203763) | more than 11 years ago | (#6608489)

RTS/CTS

Request to Send / Clear to Send
Required to solve (reduce) hidden station problems.

Station 1: Hey, can I send? (RTS)
Access Point: Yeah, go ahead. (CTS)
Station 2 (who can't hear Station 1, but can hear the access point): Well, since a CTS came back taht I didn't request, I know someone else is sending. Therefore, I'll shut the hell up.

Re:Problems with this (1, Interesting)

Anonymous Coward | more than 11 years ago | (#6609533)

These problems are all things the product my employer [meshnetworks.com] makes solves. We do RTS/CTS, as well as power control, and full IP routing, all in hardware. RTS/CTS helps the hidden node issue, and power control allows smaller zones of interference, which gives you aggregate throughput close to the theoretical max to an access point.

In fact, we had a similar product that did much of this in a software layer above 802.11, and measured aggregate throughputs of 2-3 times higher than vanilla 802.11. I guess that the concept is similar to what the frottle folks are doing.

Re:Problems with this (1)

LarsG (31008) | more than 11 years ago | (#6610445)

1. Isn't this what RTS/CTS is for?

Except that RTS/CTS doesn't work well enough.

802.11* was designed for indoor use, so the MAC layer depends on all stations hearing each other in order to arbitrate access to the shared medium.

As a fall-back they also included RTS/CTS mode. But RTS/CTS is rather suboptimal - some sort of polling or token mode would work better for outdoor wireless data comm.

So these guys implemented a token mode for controlling the clients' access to the wireless medium. Hack? Sure. Would it be better to implement it in the radio firmware? Sure. But it works! :)

I saw this back in 1988 (0)

Anonymous Coward | more than 11 years ago | (#6609230)

when it was called 'token-ring'

Frottle master is a "man in the middle" (2, Interesting)

Ungrounded Lightning (62228) | more than 11 years ago | (#6609440)

I note that the Frottle master relays traffic when two non-master nodes wish to talk to each other - even if they could talk directly. This both reduces the potential agregate peer-to-peer bandwidth by a factor of two (or more) and sets up the Frottle master as a "man-in-the-middle".

I'd rather see the master simply arbitrating bandwidth in its neighborhood and the peers exchanging data directly. General-casing that to multiple simultaneous masters, while relaying but only when necessary and only by efficient paths, limits out at a mesh network with extreme bandwidth usage efficiency.

But the thing that bugs me is the security implications of having all non-master nodes relay through the master. That lets a hostile node that achieves (or spoofs-up) master-node status perform man-in-the-middle attacks on the security of the communication.

Being man-in-the-middle is probably not a big deal if the master is also the main internet gateway (so it would be man-in-the-middle to most traffic anyhow), operated by a well-known and trusted organization. And it does simplify routing packets from one channel to another. But it bothers me anyhow.

Fortunately, any node that can also hear its peer can check the honesty of the master's forwarding.

Which leads to a potential way to eliminate unnecessary bounces off the master: Clients can inform it that they can hear other particular clients and what the differential delay characteristics are from their site. Then the master can just assign the transmission slot for the packet and drop it on the floor while the receiving peer captures it directly.

Re:Frottle master is a "man in the middle" (2, Informative)

aXis100 (690904) | more than 11 years ago | (#6610871)

WiFI always has a man in the middle - it's called the AP. Client-Client always involves 2 radio hops. In our implementation, we've taken the step of shooting the packet over wired ethernet aswell, but it makes very little impact on performance. In fact, we found early on (before frottle) that it reduced packetloss).

Frottle can run in many modes, and doesnt need traffic to pass through the master, though it is more reliable to do so.

As far as Client-Client comms goes, we've always discouraged it for it's use of bandwidth, and before frottle it was the main cause of collisions. For this reason, we stick most of our resources at the master, meaning most data is only a single RF hop away.

Re:Frottle master is a "man in the middle" (1, Informative)

Anonymous Coward | more than 11 years ago | (#6610901)

I note that the Frottle master relays traffic when two non-master nodes wish to talk to each other - even if they could talk directly. This both reduces the potential agregate peer-to-peer bandwidth by a factor of two (or more) and sets up the Frottle master as a "man-in-the-middle".

In the WAFreeNet scenario, the nodes are well dispersed, and we're all using directional antennas to connect to the APs, so the nodes cannot talk to each other directly anyway.

802.11e anyone? (3, Informative)

WoOS (28173) | more than 11 years ago | (#6609767)

It's definitely a great hack. But of course if you just waited a year (or so ;-), 802.11e would have provided the same but with less overhead and enforcing the limits on the ether.

11e will have a mode called HCF (Hybrid Coordinator Function) recently renamed to HCCA (forgot what that stands for) where the Accesspoint can be asked for timeslots and it will assigned them to the requestors after each beacon causing a content-free period. Only afterwards a (prioritized) contention mechanism will come into place for the rest of the transmission time till the next beacon (called EDCF=Enhanced DCF).

Actually HCCA is not really intended for web browsing over 20km wireless link but more for real-time traffic over 10m wireless link (e.g. videos to your Webpad, PDA, ...). But it would work.

Must... refrain... from... making... (0)

Anonymous Coward | more than 11 years ago | (#6609952)

really... esoteric... renaissance... dance... music... joke...

What about Bob? (0)

Anonymous Coward | more than 11 years ago | (#6610396)

How much of frozzle's effect could you emulate by putting CBWFQ on the etherswitch that the AP is connected to?

CBWFQ wouldn't implement a token system, but it would slow down flows that met a certain criteria. One thing it can't do is say "people who have transmitted over 2Mb need to go to the back of the line" - has anybody tested it?

I can't stand those (1)

arodland (127775) | more than 11 years ago | (#6610653)

Iuhidden nodefS!

Perth, wireless capital of the world (2, Interesting)

ttys00 (235472) | more than 11 years ago | (#6610931)

At one stage (a year go, not sure if its still the case), Perth (capital of Western Australia) had more wireless networks per capita than anywhere else in the world. Yes, that includes San Francisco.

Why? Because it is a spread out, very flat city with piss poor and expensive broadband internet. It's also isolated from the rest of the country, so it's quite often the last Australian city to get infrastructure. There is also an abundance of unused satellite TV antennas from a failed provider, which people let you take off their roof for free (I collected 9 in one afternoon with a mate one day). They make excellent wireless receivers if you mod them right.

I went to Uni in Perth, and in the last 12 months my mates there have put up 3 antennas - they are Comowireless on the node database. I live in Sydney now, and I don't see anywhere near as many wireless antennas here as I did when I lived in Perth.

Just add bandwidth, duh (0)

sbwoodside (134679) | more than 11 years ago | (#6611136)

Have a look at Dan [bricklin.com] 's paper "Why We Don't Need QOS: Trains, Cars, and Internet Quality of Service" before you start clapping.

I think the answer is clear: Go for more capacity rather than handling the narrow advance from dealing with congestion. That's what worked for Ethernet.


802.11a/g are at 54 Mbps, who knows what the next jump will be.

simon

The story of frottle.... (3, Informative)

aXis100 (690904) | more than 11 years ago | (#6611578)

Once upon a time, in the mystical land of Oz, there was the quiet city of Perth. Broadband was expensive (cable was only in one suburb), and ADSL was only just beginning to roll out. WiFi has just been released, and a group of enthusiasts saw the potential.

A bunch of people got together, and through many donations, were able to buy their first public WAFreenet Access Point. Now - Perth is fairly flat, with a long ridge running down one side - perfect! The AP was setup on a private property with an incerible view of the city, and we named it HillsHub (we'll call it HH).

By about 5 clients, the hidden node issue started to get noticable. Easy, they turned on RTS, and it made an improvement.

Since it had such good visibility, HH began to get pretty popular. By about 10 clients it was really stuggling, and many of those clients had AP and clients of their own adding to the routed traffic. RTS just wasnt cutting it anymore - the RTS packets are subject to collisions aswell. In a desperate effort to regain some control, rate limiting was implemented, dropping speeds back to 10kB/sec during the day to maintain some reliability. However - during the night, a free for all would occur - some people would get 100's kB/sec, whislt others would be drowned out, near complete packetloss.

By 14 clients, the situation was ridiculous. We HAD to do something. We knew Kalrnet Turbocell (a polled system) would fix it, so we sold our soul (advertising on the e3 website) and negotiated a lower price - even then we needed to fork out A$150 each. We got together and pooled the cash, and just as we were about to buy, realised that the linux support was terrible - old, buggy kernels, binary driver only. We stopped in our tracks, and wondered what to do.

There were plenty of ideas about building our own kalrnet, but none of us were kernel programmers, so it seemed a bit out of reach. That was until one day, when I came up with a plan. I'd read that iptables could send packets to a userspace program, so inspired by some examples (countertrace), I set about building the first version of frottle using perl.

There was nothing new about the concept - polled systems and token rings are common knowledge in communications and networking. It wasnt difficult - it only took me a weekend, and that included the time spent learning perl (it was my first go). It was even operating at the wrong layer - using UDP control messages to schedule IP traffic. Regardless of all it's limitations, it worked, so I got the other WAFreenet members involved with testing and development. Radix picked it up and tried to continue development with C++, but had problems. Then, ChrisK took up the challege, and the result is the dynamic, performance C version we have released.

Halfway through development, WiCCP was released. This was a similar concept, but implemented as an loadable module/interface. We liked the concept better than our userspace app, so we trialled it ourselves. One of the perth guys (Brad) even got involved with development, improving the product. Still, whislt it was an implrovement on no QoS, it didnt seem to perform quite as well as frottle. This was the decider, so ChrisK prepared frottle for release.

So, there you have it. As a developer, I've been paying attention to the comments here. Many of you have given positive feedback, and for that we're thankfull. Unfortunately, some of you have decided it would be easier to point out the flaws...

Well, no shit sherlock! We're quite aware of frottle's limitations, the concept is far from origonal, and it really is a kludge. The inherent problems of 802.11b are still there, and all we've done is work around them. The thing is, no-one else had done it before - at least not for free, and not when we started. We've spent our own time on frottle in order to improve our situation, and help the performance of free community wireless networks the world over.

Criticise all you like, but the fact is, we have experienced an enourmous, measurable improvement to our network performance. As far as we're concerned, this is BIG news.
Load More Comments
Slashdot Login

Need an Account?

Forgot your password?