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Why Do We Have To Restart Routers?
jaypaulw writes "I've owned a WRT54G, some cheap D-Link home Wi-Fi/firewall/routers, and now an Apple Airport Extreme (100/10 ethernet ports). In the context of the discussion about the worst uses of Windows — installation in places where an embedded device is superior — I've gotten to wondering why it's necessary to reboot these devices so frequently, like every few days. It seems like routers, purpose-built with an embedded OS, should be the most stable devices on my network."
TCP connection timeouts on some routers default to 3600 seconds or one hour. So, when you use some Bittorrent or such, opening lots of connections, your router keeps these connections (even after disconnection) in its memory for up to an hour. It fills up and your router grinds to a halt, opening connections very slowly.
There's other timeouts too, but I'm not sure exactly what they do. Firmware like HyperWRT lets you change these timeouts to something much shorter, like 90 seconds, which typically prevents lock-ups like that.
(I'm actually not 100% sure that this is the sole cause for router lock-ups)
Not to be a dick, but I use a wrt54g with tomato firmware and it's about the most stable and powerful (QOS is great on it) router anywhere close to the consumer price range.
I never have to restart my DSL router or Vonage router either, and I've kept all this stuff up 24/7 often with heavy use for years at a time.
If you're restarting networking stuff all the time, perhaps you've misconfigured it...
So you are lucky. My Airport Express needs to be rebooted from time to time (nothing damning, the express sometime stands month without needing it). My previous UFO Apple Airport also needed to be rebooted (and much more frequently than the Express).
The symptom on the Express are that DNS queries stop working. I can ping it, ping my DSL modem, and ping website for which I have IP. I can nslookup into my provider DNS. I cannot lookup into the Express DNS.
Another issue is that sometimes, I start getting more and more lag. Rebooting the mac or the DSL model doesn't fix it. But I discovered, amazed, that rebooting the express fixed it.
Btw "Buy one that works" is an extremely arrogant comment. Those units work for you, it does not prove it works for anyone else.
I'm a network admin for an ISP, and we've been recommending UPSs for the frequent-reboot routers that our customers have. We've found that routers (especially Linksys) have a real problem with power fluctuations that most other systems and devices don't notice. A decent line-conditioning UPS might solve your problems, but a cheap one will suffice.
Also, could be the device is running out of memory, if your ISP is changing the properties of your connection a lot, or you might have a duplex issue causing a lot of retransmissions. . .
Just a couple of thoughts :)
"He may be mad, but there's method in his madness. [...] It's what drives men mad, being methodical." G.K.Chesterton
I think you're right. This seems to be especially common on D-Link routers. I used to run a DI-624 which was stable for years, until one day it just started rebooting itself. Did it infrequently at first, but progressed to the point where it rebooted continuously and was unuseable. Poking around, I discovered that the AC adapter (power brick) was not only VERY warm, the plastic shell was actually deformed a little on one side. I replaced the AC adapter, and the router worked good as new... until a few years later, when AGAIN it started rebooting, then stopped working entirely. And AGAIN, the AC adapter was at fault (totally dead this time). And again, replacing the AC adapter resurrected the DI-624.
It seems to me that the manufacturers of residential-class routers really skimp on the power supply, or at least D-Link does. The AC adapters they've bundled in recent years are smaller than a deck of cards, yet I'm supposed to believe that they can put out 3 amps of current at 5VDC indefinitely?
it's simple, most router keep tcpip connections alive for 3600 sec or more (especially d-link one), so each time you establish a connection on a bittorrent client your router open a new one. After a few hours, sometimes a day or a few ones, it can become a problem very quickly as you might imagine. Just install dd-wrt or tomato and drop the timeout to 360sec, it'll do the job.
In theory, none of those routers should need a UPS, just a better AC-DC converter perhaps with a bigger capacitor across the DC lines. I've never investigated the quality of the wall warts they supply with routers, but my guess is they are very cheap and simply don't handle voltage fluctuations as well as they should.
The problem I've had with dd-wrt and torrents is the max tcp connections is by default very low. Not something you would notice under normal traffic, but during swarms it can fill up fairly quickly.
It give the appearance the unit has locked up since it is difficult to establish a tcp connection. These will bleed away eventually and allow a connection to be established.
I just set the max number of tcp ports and it fairs fairly well using bit torrent now.
"You should always go to other people's funerals; otherwise, they won't come to yours." -- Yogi Berra
Most often, actually, I've found that the cause is, gasp, Bittorrent. Fills up the NAT tables and they're not purged fast enough, unable to open / map more ports, effectively, no more connectivity.
This MS KB may help.
http://support.microsoft.com/kb/932134
There is also an MS KB related to the broadcast flag which may be what is being referred to.
http://support.microsoft.com/kb/928233