Can routers get 'overloaded'

hp01jpc

hp01jpc

hp01jpc

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Just wondering, I'm using an old D Link wireless ADSL Modem/Router (DSL-G604T) and it sometimes 'gives up the ghost'. Internet access kinda 'dies' and it needs to be powered off and on again to get it back up to speed. I think the problem is to do with the number of connections it is making, as the router serves a network and some people on the network use p2p software.

If this is the problem I am experiencing, I want to purchase a new ADSL router which can make as many connections as the network requires (within reason). Can anyone recommend a router which is known to be fine in this respect? I have my eye on this one:

http://www.overclockers.co.uk/showproduct.php?prodid=NW-044-LS

Mainly because it is cheap, and I have heard the Linksys name mentioned in a good light before on these forums.

Thanks :)
 
Well I was informed a long time back that the router could handle around 256 connections without having problems, so I have advised my network people of this and that it should all be configured with this figure in mind. Whether they stick to these limits I don't know. It's almost competitive, in terms of bandwidth and connections hogging in this house!

We just thought that if we could solve this problem with an outlay of just £40 it would be worth it, but obviously I want to make sure it will rectify the problem. It's not too bad for me as the router is sited in my room, so if it fails I can simply reset it. But if I'm asleep or whatever, and my housemate wants to use the internet and can't, he's kind of stuck.

Cheers :)
 
The 256 figure sounds more like the number of devices you can connect at once, i.e. it can assign IPs 192.168.0.0-192.168.0.255, rather than the number of similtaneous connections you can make through the router.
 
Yes good point, I might have got mixed up somewhere along the line. But I still think that it's the number of connections that are being opened up by the router which is causing it to 'crash' so to speak. I looked into this a while back and someone told me (on these forums probably) that it was due to the chip in the router being a bit shoddy and that Linksys used a better controller chip. I just wondered if anyone could confirm this, before I fork out for the new router.
 
hp01jpc said:
But I still think that it's the number of connections that are being opened up by the router which is causing it to 'crash' so to speak.
Click to expand...

Sounds like it if it dies after running some kind of P2P app, but it could be something else.

that it was due to the chip in the router being a bit shoddy and that Linksys used a better controller chip.
Click to expand...

Wrong. If it is due to connections, it'll be the router running out of RAM, and some routers have more RAM. It's extremely unlikely to have anything to do with a "controller chip".
Google suggests the WAG354G has exactly the same amount of RAM (16MB) as the DSL-G604T (16MB), so the only difference you might see if there is an option to timeout connections quicker (or if the Linksys by default does it quicker), which might help.
 
Hi

I had this type of problem on a Dlink 504T where after a while the router would still be connected but I could not get online. The problem was the router was not closing the connection properly and had to be rebooted. The problem only happened if I was running P2P software and would happen at random as in sometimes I would need to reboot ever few hours and other times every few days. never got the issue resolved but it was a known issue on the 504T and may have been fixed in a firmware update. Check you have the latest firmware as Dlink were meant to be fixing the issue.
 
PhilthyPhil said:
The 256 figure sounds more like the number of devices you can connect at once, i.e. it can assign IPs 192.168.0.0-192.168.0.255
Click to expand...

[Pendat]No it can't, 192.168.0.0 will be reserved for the network address. 192.168.0.255 is reserved for the broadcast address. These are unassignable addresses. There will be a total of 255 assignable, but the router will also take one of these leaving a total of 254 assignable addresses for the hosts to use [/pedantic] :)
 
256 is a common limit on the number of network translation (NAT) entries. So every TCP and UDP connection started in the outbound direction will require one slot in this table. Note that even though UDP is connectionless, it still needs a state record stored in the NAT table.

Most BitTorrent programs come with stupidly high default settings - usually something like 500 connections. So on a well seeded torrent it's easy to make a cheap router crash. Obviously if you've got quite a few P2P users in the house, or just several torrents open concurrently, then the limit will be reached far more easily and frequently.

Although the router may not actually crash, it simply rejects any further connections because the NAT table is full up. Some routers just treat it as a buffer overflow and do crash/reboot.

If the router allows you to adjust the connection timeout values, try setting them to 1 minute. Most routers default to a 15 minute timeout which is stupidly high for most users. A lower value will ensure that zombie connections in the NAT table are flushed out quicker. This can be a workaround to the problem in some cases.
 
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Number of connections and NATs are different from THROUGHPUT.

Cheap routers are cheap because they use cheap ( ie slow ) processors and little memory. VoIP is a heavy processor overhead as prioritising packet latency puts heavy load on the processor.

Sounds like you're needing to size according to USAGE and not connections.
That's what "network engineers" and designers will do for you.
If it's for work, pay for the expertise.
You don't try to make your own motors to put in the company cars do you ?

Sorry, no easy answer. It needs planned :(
 
And packet prioritisation on a small home LAN isn't going to generate any noticable additional CPU load. Although that task does need more memory as in order to do it you have to store a small backlog of packets.
 
Thanks for all these replies. I think what you're getting at Nathan is the issue I have with the router. It's filling up the table and after searching in the web admin panel I cannot see a way to reduce the timeout limit.

I have updated the firmware and that may fix it.

HomerJ you said you had this problem with another similar DLink router, did you just end up getting a different make/model?

Thanks
 
You could do what I did a week ago.. I was having trouble with my Netgear router crashing all the time due to torrents in my house so I built a Freesco router. This uses a Linux based OS which has all the features of your standard routers plus many more, its very easy to set up and can be done very cheaply.

I used some old parts that were lieing around and put myself together a cheap PC. Mine is a P3 750 with 128MB RAM, but this is way over spec for it and something much less would do the trick just as well. Also you don't need a harddrive in the machine as it all runs from a floppy disk.

The OS is freely available here Freesco for download. I've been testing mine the last week and it hasn't dropped the connection once, compared to my old Netgear router which would need rebooting several times a day usually.
 
Sorry to hijack this thread! My student house has the same problem, with everyone using BT, the router crashes constantly. Even with major settings tweaking, the thing runs soooo slowly.

For those that have tried their own PC based hardware solutions, can you recommend what you have tried and what type of machine its running on?

How do you deal with the network connections in this case. i.e. say you have the need for 4 ethernet connections - do you need to buy a switch before the PC or am I overlooking something here?
 
You could put network cards in the PC and turn it into a switch as well, but performance would almost certainly be crap - you're better with a switch, though if the router has a 4 port switch built in you could always just switch off DHCP and use that.
 
Hi

Yes I did get rid of the 504T router as I changed from ADSL to Blueyonder and decided to get a wireless router for that and got the Dlink Gaming Router and thing works like a dream.
 
I've had this problem with three routers. The first was a Linksys WRT54G version 1.1. I didn't realise it wasn't a fault with it as such at the time so just bought another WRT54G - version 2.2. I had exactly the same problem. I then turned to this forum for advice and was strongly recommended a ZyXEL - so I got a ZyXEL 652H. This worked fine for a bit, until I moved to 5 WAN IPs and needed to use its firewall. Enabling the firewall made it crash about once daily, presumably due to it running out of memory. By this point I was fed up with consumer routers so decided to build my own solution...

squawkBOX said:
Sorry to hijack this thread! My student house has the same problem, with everyone using BT, the router crashes constantly. Even with major settings tweaking, the thing runs soooo slowly.

For those that have tried their own PC based hardware solutions, can you recommend what you have tried and what type of machine its running on?

How do you deal with the network connections in this case. i.e. say you have the need for 4 ethernet connections - do you need to buy a switch before the PC or am I overlooking something here?
Click to expand...
I put together a PIII box (800MHz), with 256mB SDRAM - quite a bit more than necessary. It has an old 2gB Fujitsu hard drive, a nice, quiet power supply, and lives in a midi case (was beige but I hated it so sprayed it all black :p). There's one onboard LAN port and I added a PCI Realtek LAN card. I have ADSL so it needs a modem - I use the Linksys ADSL2MUE I used with the WRT54Gs.

The onboard LAN port is connected to the modem, and the PCI one goes to a Netgear FS108 switch where everything else is connected.

Software wise, I use m0n0wall: http://m0n0.ch/wall/. Really is brilliant, does everything I need in a router/firewall and more (and I'm quite demanding :p). The WebGUI is really easy to use aswell which is nice. Definately worth trying if you are looking for an operating system for a custom build router. Memory wise, it normally hovers at around 15% usage of the 256mB it has, so it's no surprise it hasn't ever crashed - right now, it has an uptime of 124 days (and was only rebooted due to me moving hardware around).

Unless freesco has changed significantly since I last tried it, m0n0wall is easily ten times better imo, and afaik they aren't that different in hardware requirements are they (m0n0wall isn't exactly demanding).

If I sound like I'm trying to sell the whole 'build your own router' idea, and m0n0wall too, it's because I am! I think I made the switch about eight months ago or so and my network has been so much better since.

Pics of m0n0wall being built: http://www.piggott.me.uk/?page_id=31 (was formerly the beige beast)

Hope this helps, null :)
 
MetA said:
Number of connections and NATs are different from THROUGHPUT.

Cheap routers are cheap because they use cheap ( ie slow ) processors and little memory. VoIP is a heavy processor overhead as prioritising packet latency puts heavy load on the processor.

Sounds like you're needing to size according to USAGE and not connections.
That's what "network engineers" and designers will do for you.
If it's for work, pay for the expertise.
You don't try to make your own motors to put in the company cars do you ?

Sorry, no easy answer. It needs planned :(
Click to expand...

Haha. Sometimes I completely bull**** just for fun too! A valiant (albeit unsuccessful) blag my friend. The incoherent motors metaphor is a dead giveaway that you have no idea what you're on about. Next time try throwing in something about the "multipath propogation delay" and "dispersive Rayleigh fading channels". :cool:
 
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