IPhones Flooding Wireless LAN At Duke 441
coondoggie sends us to a Network World story, as is his wont, about network problems at Duke University in Durham, N.C. that seem to be related to the iPhone. "The Wi-Fi connection on Apple's recently released iPhone seems to be the source of a big headache for network administrators at Duke. The built-in 802.11b/g adapters on several iPhones periodically flood sections of the school's wireless LAN with MAC address requests, temporarily knocking out anywhere from a dozen to 30 wireless access points at a time. Campus network staff are talking with Cisco, the main WLAN provider, and have opened a help-desk ticket with Apple. But so far, the precise cause of the problem remains unknown. 'Because of the time of year for us, it's not a severe problem,' says Kevin Miller, assistant director, communications infrastructure, with Duke's Office of Information Technology. 'But from late August through May, our wireless net is critical. My concern is how many students will be coming back in August with iPhones? It's a pretty big annoyance, right now, with 20-30 access points signaling they're down, and then coming back up a few minutes later. But in late August, this would be devastating.'" So far, the communication with Apple has been "one-way."
sigh (Score:3, Insightful)
At least the editors admit that coondoggie is filling the queue up with network world stories. Maybe they'll do something about it at some point
Critical? (Score:4, Insightful)
Wireless? Critical? Dumb.
Re:Critical? (Score:5, Insightful)
Re:Critical? (Score:3, Insightful)
Ofcourse, if they are using it for everything even desktop computers in labs... It could very easily be that a few iPhones can bring down APs but that would be a colossally stupid idea to begin with and any network designer approving such a plan should be shot.
Bet you 10 to 1... (Score:5, Insightful)
MAC address REQUEST? (Score:5, Insightful)
Slashdot...sigh...
So you're telling me (Score:2, Insightful)
Judging by the statement that they can exhibit the behavior after being handed from one access point to another kind of nullifies the theory that they may be trying to re associate with the users home network. They're trying to get back to the old AP, which arping wont do because it's on a different VLAN.
Mystery solved, now what can cisco do about it. I don't really care that it's an iPhone bug. I just think its one more DoS vector to patch up. Maybe de-associate the phone and drop traffic until it acts right? Set a threshold or something? You might still have a source of noise, hopefully it would realize it was dropped though. No link layer, no arp right?
Well tested (Score:3, Insightful)
I'd lay odds there's something screwed with their network...
Re:Interesting problem (Score:5, Insightful)
I didn't know MAC addresses were assigned dynamically.
But I'm over 40- what do I know?
Re:Critical? (Score:2, Insightful)
I agree 100% Wireless is nowhere near as reliable as wired.
Re:Taking out Cisco Router with ARP Floods? (Score:5, Insightful)
What's the big deal? (Score:4, Insightful)
Re:Critical? (Score:5, Insightful)
Yeah. Unless you're a university, and your "mission critical things" (remember the definition of "mission"?) include things like ... ohhh, I dunno ... students with laptops and shit?
Re:Economic class and higher education (Score:3, Insightful)
You are a fountain of ignorance, at least concerning your diatribe against Duke. Instead of being wealthy and pay tuition, you can also simply be smart and hard working. My daughter just graduated from Duke, from which she had gotten a full scholarship. Without that, there would have been no way she could have afforded to study there. Many Colleges and Universities give scholarships to exceptional young people who do NOT come from wealthy homes. Most likely, someone like you wouldn't get such a scholarship, especially in view of your ignorant rant.
Re:Well tested (Score:2, Insightful)
jeffk
Re:Apple DHCP client (Score:3, Insightful)
Re:Most likely a Cisco bug - firmware upgrade need (Score:5, Insightful)
Say what? The last time I saw something equally screwy it was a Cisco LightStream 1010 (ATM switch) running LANE (LAN Emulation) that played no part in layer 3 at all, yet it was still building up an ARP table of every IP datagram that flowed through it (and wondered why it kept running out of memory).
If you send out an ARP for an "unknown address", you'll get no response - it's not up to the router to respond on behalf of "non-local packets", it's up to the client to determine that the destination is non-local (by using the network and mask together) then picking a suitable gateway (usually default) for sending the packet on its way.
Therefore, the client already knows it needs to send the non-local/unknown-addressed packet through the router so it explicitly ARPs for the router's MAC address (if not already cached) - nothing to do with trying to get the MAC of the remote destination.
Re:Well tested (Score:4, Insightful)
Re:The just in (Score:4, Insightful)
Re:Most likely a Cisco bug - firmware upgrade need (Score:1, Insightful)
ARP is broadcast (not unicast nor multicast, unlike say, EIGRP which does use multicast); "floods" tend to be caused by broadcast (if from a single source - unicast if from multiple sources).
Re:Wrong problem (Score:3, Insightful)
Re:Economic class and higher education (Score:2, Insightful)
>> First, it's entirely possible to go to a perfectly respectable in-state school for just a few grand a year.
Where have you been living? I have financed the education of two children who were good students and went to good state schools (U of Oklahoma, and University of Buffalo.) Both approach $15K per year with tuition, room, board, and books. That is more that "a few thousand."
Back in the dark ages before the flood when I went to Florida State (B.S. 1977) and UMass (Ph.D. 1982) I could attend a good state school for about $2.5K. I could earn about 1/3 to 1/2 of that in a summer. Today's students can't do that anymore. I would also point out that much financial aid these days is in the form of loans. It is easy for a student at a state university to finish an undergraduate education with $50K in debt. An education at a private U can leave a debt load at least 2X...
Sounds plausible but what about Laptops? (Score:3, Insightful)
Re:Critical? (Score:3, Insightful)
Re:Critical? (Score:2, Insightful)
Re:Sounds plausible but what about Laptops? (Score:3, Insightful)
Re:Well tested (Score:4, Insightful)
Re:So when you (Score:3, Insightful)
Cisco has it's moments, but IMHO they're not remotely worth the premium you pay. Go with HP; they sell the same level of hardware and offer the same level of support, but it costs a hell of a lot less, and since it costs so much less you can get the hardware you actually need rather than just what you have to settle for because your budget doesn't swing more than one 10,000 dollar PIX.
Add to that the byzantine configurations, and it's easy for a non-gifted engineer to make pretty big mistakes.
Re:Well tested (Score:1, Insightful)
Websites are developed for browser being used to most by their visitors. Unless theres been some change in the laws of common sense..
Re:Well tested (Score:3, Insightful)
Dom