More network worries

[ffutures]

I'm beginning to think that the MiniNote wireless card is causing the network problems. I seem to be getting a modem and/or router crash every time it is switched on - this has now happened with two, possibly three routers (I think this may have happened when I tried it at work, though everyone thought at the time that it was just a crap WiFi point).

Is this even possible? If so, what the hell do I do about it?

Comments

[cdybedahl.livejournal.com]

If it is, I guess a bunch of network security people would be interested. Being able to knock out access points just by sending it packets from a client is kind of bad.

[ffutures.livejournal.com]

To say the least. The only possibility I can think of is that it's somehow overloading the access point, maybe trying to communicate too fast or something, and that it's shutting down in self defence.

The only thing I can find that could possibly have a bearing is this, in the WAN setup screen for the router:

MTU = 1500

The normal MTU (Maximum Transmit Unit) value for most Ethernet networks is 1500 Bytes, 1492 Bytes for PPPoE connections, or 1436 for PPTP connections. For some ISPs you may need to reduce the MTU. But this is rarely required, and should not be done unless you are sure it is necessary for your ISP connection.

AFAIK there are no special limits on the modem or ISP, but could reducing the MTU to 1400 or something help?

[cdybedahl.livejournal.com]

WLAN frame maximum size is 2336 bytes, with 2312 being payload, so a 1500 MTU should not be a problem.

[ffutures.livejournal.com]

OK, scratch that one then - I'm at a bit of a loss then...

[ffutures.livejournal.com]

I just came across this (not sure how relevant it is)

A single iPhone is enough to bring down a Wi-Fi network, according to staff at Duke University in North Carolina.

A problem with the university's wireless internet connection is being caused by iPhones making up to 18,000 MAC address requests to the network every second.

This in turn causes the specific section of the wireless network to freeze for a 10-minute period.

Could the MiniNote be doing something like that? If so, how the hell do I stop it?

[cdybedahl.livejournal.com]

I'm not sure what they mean by "MAC address request", but I can see how spamming an access point with packets with made-up MAC addresses could fill up some tables and DoS it. However, I can't really see how something could do that by accident and ever get a working net connection at all.

[ffutures.livejournal.com]

Fair enough.

I've just arranged to have it returned under warranty anyway - nobody else seems to be having this problem so I suspect it's a hardware fault, and I really can't spend the rest of my life messing around with it.