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Duke's WLAN pummeled by 'misbehaving' iPhones - report - Page 2

post #41 of 49
Quote:
Originally Posted by djdj View Post

It seems like you just skimmed the article. The iPhone is trying to find the MAC addresses of IPs that don't exist on a given segment of the Duke network (the ARP flooding). It happens when the phone loses WiFi connectivity in one location and tries to reconnect in another location. When it connects to the new segment it shouldn't be flooding it with ARP requests for addresses that don't exist on that segment. This is an IP stack flaw, pure and simple. What other possible explanation is there for it?

Yep - that was the "ridiculously fast rate" bit I mentioned. I'd say 30,000 per second is ridiculously fast.

As for ARP'ing when it reconnects, that probably is the right thing to do (or flushing the arp cache of addresses on that segment when that interface goes down) - when connecting to a whole new network, it probably best to check the MAC addresses again, as wrong-MAC address hangs take ages to fix themselves. So yes, it should be ARP'ing and no, it shouldn't be flooding - 1 or 2 seconds between packets is usual.

Thanks for posting the results of all that research - nice one.

Cheers,

Martin.
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15" PB, 15" MBP, MB, MBA, G5 iMac, C2D iMac, Mac Mini, UK iPhone 3G, SGI RealityEngine2, SGI/Division Virtual Reality Rig, NetApp F760C
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post #42 of 49
Quote:
Originally Posted by digitalclips View Post

The writer you chastise is correct you are wrong in this particular argument. Your logic is like saying ... if lying down on the sidewalk with your head in the road is a problem because cars keep hitting you then it might be an issue with the cars. The writer simply stated they should be sure what is the problem first. Moving your head would be worth a try first ...

Sure they have identified the iPhones are involved but if as the writer correctly says, IF this is because of a network screw up they might be wise to trouble shoot before publicly stating it is the FAULT of the iPhones and thus feeding trolls with fodder to repeat and exaggerate and attempt to damage Apple's reputation.

Your example is bad, and its backwards. The cars/road is the network, the person is the iPhone entering the network. The person gets hit by car, or just causes the cars to stop, thus causing bottlenecks in the network. Who do you blame? The cars? No, the person.

But beyond that, why should Duke keep quiet? Isn't public disclosure the important thing? Or is it that you're supposed to make sure you don't look bad? If you were on the Duke campus with an iPhone, would you rather know that they were having issues with their network, or just think that the problem is your phone, so you could spend hours on end trying to figure out why the network keeps fading out? Also by making it public, you can find out if others have the same problem, and whether or not someone's got a solution or workaround for the problem.

Are you thrilled when your broadband goes out at home, you call up the local cable company and they're "No, the service is fine, must be you" and then it turns out, guess what, it was them, but they didn't want to say anything because they didn't understand the problem? Or feared that you would cancel?

Maybe the reasoning behind 'no one else reporting it' is just they're all thinking like you "Hey, the problem might be our network, so I don't want to look bad because my job might be on the line, so I'm going to stay mum and see if I can work something out myself".
post #43 of 49
http://www.dukenews.duke.edu/2007/07/cisco_apple.html

So apparently the blame mostly lies with Cisco.


So everyone jumped to wrong conclusions.
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A good brain ain't diddly if you don't have the facts
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post #44 of 49
Quote:
Originally Posted by djdj View Post

I just spent the last hour researching this in the original forums where the problem is being discussed. Definitely an iPhone problem... Why?

1. It isn't just happening at Duke. Other networks are seeing it too; Duke is the only one that has gotten picked up by the media so far. (And, by the way, they didn't go to the media, Network World found the discussion of the problem in a blog, and came to them to ask to publish the story.) Most other locations are banning the range of iPhone MAC addresses to prevent them from bringing their networks down. (And just because you haven't heard about it doesn't mean it isn't happening elsewhere, BTW!)

2. It isn't happening with all iPhones. It is a strange set of circumstances that trigger the problem. A given phone has to have been at three locations with similar configurations but different IP subnets successively (first at location A, then B, then C, though the specific locations of A,B and C do vary). At location C the iPhone tries to find a router that existed at location A, and sends out 30 ARP requests to find that router EVERY MILLISECOND, so each iPhone is sending out roughly 30,000 ARP requests per second.

6. The problem ticket has been escalated at Apple to try to find a solution.

It's a bug in the iPhone, and Apple will fix it.

So how much of this did you actually research? What websites did you get your information from? From http://www.dukenews.duke.edu/2007/07/cisco_apple.html

Quote:
Cisco worked closely with Duke and Apple to identify the source of this problem, which was caused by a Cisco-based network issue. Cisco has provided a fix that has been applied to Duke's network and there have been no recurrences of the problem since. We are working diligently to fully characterize the issue and will have additional information as soon as possible. Earlier reports that this was a problem with the iPhone in particular have proved to be inaccurate.
post #45 of 49
Quote:
Originally Posted by Louzer View Post

Your example is bad, and its backwards. The cars/road is the network, the person is the iPhone entering the network. The person gets hit by car, or just causes the cars to stop, thus causing bottlenecks in the network. Who do you blame? The cars? No, the person.

But beyond that, why should Duke keep quiet? Isn't public disclosure the important thing? Or is it that you're supposed to make sure you don't look bad? If you were on the Duke campus with an iPhone, would you rather know that they were having issues with their network, or just think that the problem is your phone, so you could spend hours on end trying to figure out why the network keeps fading out? Also by making it public, you can find out if others have the same problem, and whether or not someone's got a solution or workaround for the problem.

Are you thrilled when your broadband goes out at home, you call up the local cable company and they're "No, the service is fine, must be you" and then it turns out, guess what, it was them, but they didn't want to say anything because they didn't understand the problem? Or feared that you would cancel?

Maybe the reasoning behind 'no one else reporting it' is just they're all thinking like you "Hey, the problem might be our network, so I don't want to look bad because my job might be on the line, so I'm going to stay mum and see if I can work something out myself".

See above, the problem was with Cisco's wireless network.

That's why Duke shouldn't have gone public with their speculation that the iPhone was to blame-- they didn't have all the info, and now they look like idiots.

And they're not the only ones.
They spoke of the sayings and doings of their commander, the grand duke, and told stories of his kindness and irascibility.
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They spoke of the sayings and doings of their commander, the grand duke, and told stories of his kindness and irascibility.
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post #46 of 49
My original posting on the 17th when this idiotic story first appeared:
\t
Not the iPhone

It's got to be the network. A Mac address request is very small. It would take an iPhone Flashmob of about 200,000 people to generate 10MB of Mac address requests.

Come on guys, it's the network, not the iPhones. Otherwise this result would be worldwide.

Just another fruitless attack on the iPhone. Oh, they can be soooo jealous, can't they?


PC BOY'S misguided attack on my posting:



Quote:
Originally Posted by djdj View Post

First, its 10 megaBIT, not megaBYTE. 10 mbit isn't that much. Especially if there is a flaw in the iPhone's IP stack. I have had single devices on my network broadcast way more traffic than that when misbehaving. This is entirely within the realm of possibility.

Its statements like yours that cause people to accuse us of being blind Apple zealot fanboys. Please, lets be open minded. Apple doesn't do everything quite perfectly.

If the explanation in the article is correct, which it seems to be, its the iPhone that is generating the traffic that is causing the problem. I'm an IT guy, and the explanation is perfectly plausible and credible. From their description, it truly looks like Apple made a mistake. And it should be fixable.

Duke's network probably could be configured better to handle misbehaving devices, but let's not place all of the blame on them. If I run over someone with my car, does that mean the person I hit is at fault?


Well, it turns out that this Apple zealot fanboy was right. IT WAS THE NETWORK (misconfigured Cisco switches) that caused the problem. As I said in my original post a mac address request is very small (a few bytes) and it would literally take hundreds of thousands to generate that much traffic.

So this humble Apple zealot fanboy accepts your apology. Don't be so anxious to blame the iPhone for all the pestilence an the planet. It's just an outstanding consumer product, probably the best designed in decades. "Don't hate it for it's looks" Oh, that's right you're probably too young to get that reference...Sorry


It's too bad the correction to this article will hardly be noticed.
post #47 of 49
Quote:
Originally Posted by ajhill View Post

Well, it turns out that this Apple zealot fanboy was right. IT WAS THE NETWORK (misconfigured Cisco switches) that caused the problem. As I said in my original post a mac address request is very small (a few bytes) and it would literally take hundreds of thousands to generate that much traffic.

So this humble Apple zealot fanboy accepts your apology. Don't be so anxious to blame the iPhone for all the pestilence an the planet. It's just an outstanding consumer product, probably the best designed in decades. "Don't hate it for it's looks" Oh, that's right you're probably too young to get that reference...Sorry

It's too bad the correction to this article will hardly be noticed.

I was right too. Do I get a cookie?

Where is your quote from?
Dick Applebaum on whether the iPad is a personal computer: "BTW, I am posting this from my iPad pc while sitting on the throne... personal enough for you?"
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Dick Applebaum on whether the iPad is a personal computer: "BTW, I am posting this from my iPad pc while sitting on the throne... personal enough for you?"
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post #48 of 49
here's a link to a brief Computer World article.
post #49 of 49
Stop blame iPhone in every WLAN crash, think with your head first.
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