View Full Version : Many Simultaenous IP connections = Choked DNS?
bLack0ut
10-01-07, 12:20 PM
I'm running to a significant slowdown with http browsing while having uTorrent open in the background. My computer is connected through a whr-g125 router running DD-WRT to a Roadrunner 5mb/400kb connection. Even when uTorrent isn't downloading/uploading enough to saturate (for example, 100 kbps/5kbps) my http browsing slows to a crawl.
I've tried pinging various servers, and the pings come back at very nice speeds, so I'm thinking this is a DNS resolution issue. Right now, the router is forwarding the DNS servers from the cable modem to the computer.
Can anyone help?
BTW, before anyone asks, I love fansubbed, unlicensed anime :beer: .
gangaskan
10-01-07, 01:59 PM
try rebooting your router ... does this help?, also what you might want to look into is using OpenDNS or some other external dns system so you put some strain off the router.
It's most likely that bittorrent is creating too many TCP connections, making it so that when you try to browse websites, it can't create anymore connections. In dd-wrt, under the administration tab, at the bottom, there should be IP Filter settings. Where it says Maximum ports, the default should be 512, this can easily be saturated by using bittorrent. Try upping the value to at least 1000 or just max it out at 4096.
nd4spdbh2
10-01-07, 02:22 PM
It's most likely that bittorrent is creating too many TCP connections, making it so that when you try to browse websites, it can't create anymore connections. In dd-wrt, under the administration tab, at the bottom, there should be IP Filter settings. Where it says Maximum ports, the default should be 512, this can easily be saturated by using bittorrent. Try upping the value to at least 1000 or just max it out at 4096.
this is most likely the problem... i had just about the same problem when using azerus bit torrent client... it would work fine but then everything would lock up... i figured out that it was due to a glitch that azerus kept the ip connected even after it was done, or something of the sort... so i switched to utorrent, and limited my max number of connections to 200, havnt had a problem since.
this is on my wrt54GL with stock firmware btw.
bLack0ut
10-01-07, 04:39 PM
I tried restarting the router, but it didn't do anything.
For maximum tcp connections, even after setting it to 4096, it was difficult to connect. The number of connections hovers around 800.
Memory might be an issue, since it says 96% memory is being used.
Maybe I diagnosed this problem wrong: even when trying to connect my router (192.168.1.1), it hangs on "Connecting" for a few seconds if bittorrent is running. Is that a DNS problem or just a router choking problem?
The weird thing is, if I visit a site, say ocforums, and click on a link right after it loads, the next page loads almost instantaneously (like it should). However, if I wait 3-4 seconds, then click a link, it has trouble connecting again.
I have the wrt54g v5 router flashed to dd-wrt and there are a few things that makes my router slow down. When my router was at stock settings, right after the flash, bittorrent slowed my internet down to a crawl (just like what you're describing). This was because of my TCP connections being set at 512, which was the default. Once i upped this to like, 2000 everything became speedy.
The second thing that slows down my router is when I max out it's WAN bandwidth. My router's maximum wan bandwidth is about 30mbps and whenever it's maxed out, I don't really notice a slow down in my internet as much as the TCP connections setting affected but trying to access the router is virtually impossible.
I think with dd-wrt, you can also set your router to be a local dns server or not. At least there's an option in the setup tab, and the Services subtab under the Administration tab. I have Local DNS unchecked on my router.
bLack0ut
10-01-07, 07:09 PM
I have the wrt54g v5 router flashed to dd-wrt and there are a few things that makes my router slow down. When my router was at stock settings, right after the flash, bittorrent slowed my internet down to a crawl (just like what you're describing). This was because of my TCP connections being set at 512, which was the default. Once i upped this to like, 2000 everything became speedy.
The second thing that slows down my router is when I max out it's WAN bandwidth. My router's maximum wan bandwidth is about 30mbps and whenever it's maxed out, I don't really notice a slow down in my internet as much as the TCP connections setting affected but trying to access the router is virtually impossible.
I think with dd-wrt, you can also set your router to be a local dns server or not. At least there's an option in the setup tab, and the Services subtab under the Administration tab. I have Local DNS unchecked on my router.
I've already set the maximum connections to 4096 and saw no change.
I've capped uTorrent from using more than 350 kbps/10 kbps. The WAN bandwidth isn't being maxed out.
I tried both local DNS enabled and disabled, no change. Do you have DNSMasq enabled?
Welcome to bit torrent.
It's always happened with me...but that's cause I try running it as fast as I can.
I only have DNSMasq enabled for dhcp. The Load Average on the status page isn't almost 100% is it?
Other than what I mentioned I can't really think of anything else in terms of the router settings unless the router just can't handle it. Do you have other computers that slow down when your main computer is using bittorrent? If it's only your computer that's being affected, then it could be something with your computer.
bLack0ut
10-02-07, 06:01 AM
Ok I've definitely pinpointed it to the router(I just plugged the computer straight into the modem and it handles bittorrent fine). I've played around with the DNSmasq settings, doesn't seem to do much. The load average is about 2%, so I'm not worried about that.
It's strange, but even if I have only one torrent running, and less than 15 connections, the slowdown still occurs. Basically, any torrent will bring the router down to its knees.
YoMatta
10-02-07, 11:24 AM
same thing happens to me, hoping to use a few of the suggestions here when i get home to see if they help out. as it stands i can't torrent at all if i want to be able to use my internet connection for -anything- else =(
Mr. Chambers
10-02-07, 12:43 PM
Simply lowering the maximum amount of simultaneous connections uTorrent allows and you should be able to both browse and download just fine.
Or upgrade to a better router, something like Smoothwall or Endian on an older PC.
bLack0ut
10-02-07, 12:54 PM
so is the whr-g125's hardware the problem?
there is a page in the ddwrt wiki that has a bunch of setting suggestions for getting around the torrent problem.
edit: here it is - http://www.dd-wrt.com/wiki/index.php/Torrent
Consumer grade routers are really bad at 100's of connections. You should build a smoothwall box and use it as a router. It will run on a PII fine and handle 1000+ connections and 30Mbit/s+ without a hiccup.
www.smoothwall.org
bLack0ut
10-02-07, 08:11 PM
@CJ
Yep, after reading through some of the smoothwall forum, I found that consumer routers can only handle up to 500 connections, which really sucks since I'm using 1200 atm :D.
I guess I'll throttle the ips until I can make myself a smoothwall.
EDIT: I guess 500 is the magic number, any more and it slows to a crawl. Weird, you'd think it'd be a gradual decrease in performance.
EDIT2: Wow, spoke way too soon. It's sitting at 300 connections, 200 kbp/s down and 8 kbp/s up, still slow. WTF?
If you want to reduce the number of TCP connections you can change the TCP Established Timeout. If I remeber correctly the default is 86400 seconds or 24 hours.
bLack0ut
10-04-07, 07:57 AM
Nah, I'm running dd-wrt, defaults are 90s for both udp and tcp, and I've already messed around with those. I'm just gonna chalk this up as a failure due to hardware reasons, as I've found several other sources reporting that consumer routers have trouble with a few hundred. I don't think the WHR-G125 is top of the line either, so looks like smoothwall is my only option right now, since I want to option to run 1000+ connections :)
under IP settings, is "Maximum Ports" the same, or analogous to "max number of connections"? if so, as the dd-wrt wiki suggests, upping the Max Ports to 4096 and dropping the timeout of UDP and TCP connections to 90s should take care of this problem. I know it did on my Linksys router. I had to up the timeout to 200-300 tho, because my AIM/Google talk kept timing out and disconnecting.
did you look at http://www.dd-wrt.com/wiki/index.php/Torrent and try all the solutions posted on that page?
@CJ
Yep, after reading through some of the smoothwall forum, I found that consumer routers can only handle up to 500 connections, which really sucks since I'm using 1200 atm :D.
I guess I'll throttle the ips until I can make myself a smoothwall.
EDIT: I guess 500 is the magic number, any more and it slows to a crawl. Weird, you'd think it'd be a gradual decrease in performance.
EDIT2: Wow, spoke way too soon. It's sitting at 300 connections, 200 kbp/s down and 8 kbp/s up, still slow. WTF?
It really just depends on the quality of the router. I had an old dlink that would be fine to 700 and at 701 would immediately crash.
Smoothy is a good choice. It is easy to configure and use. Right now I'm running the beta of the now released 3.0 since I do not want to reboot it. ;) 59 days of uptime with over 400GB of stuff put though it during that time.
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