LAN Speed Limited by Router?

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ashtonaut

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#65293 2-Aug-2010 00:02

My home network is dead simple, consisting of a Belkin F1PI242EGau and Dell Vostro notebook which connects either via 802.11g or direct LAN connection.

I've recently purchased a WD My Book Word Edition NAS that I'm integrating into this setup.

I have a question about transfer speed. The Belkin box is 10/100 only, and both the notebook and the NAS are gigabit ethernet.

When the NAS is directly connected to the laptop via ethernet cable, I get transfer speeds of 12-15MB/s. This is what I expected to get, as the NAS has a weak processor and can't support full gigabit speeds. All good so far.

However, when I connect the NAS to the Belkin, and also plug my notebook into the Belkin, transfer speeds drop to 1.8-2.2MB/s. I get this speed consistently, regardless of whether the notebook is connected to the Belkin via wireless or wired connection.

Is this sort of performance drop when going through the router to be expected? I know the NAS is capable of faster, I know the laptop can go faster, and I would have thought that the 10/100 ethernet in the Belkin could go faster. I know I'll never get the theoretical maximum 100Mb/s throughput, but I expected to be able to get 5-8MB/s going through the router - am I being too optimistic?

If this sort of LAN speed is common, I'll just live with it, but if anyone has any suggestions as to why the router is slowing down the connection so much, I'd appreciate it. Could something be running on the router that's slowing things down?

webwat

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#361297 2-Aug-2010 04:24

I would suggest experimenting with jumbo frames on the NAS, or get a Gigabit switch that should do all configuration automatically without breaking the connection to the modem.

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smac

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#361352 2-Aug-2010 09:19

Are you talking about slow when connecting the laptop via wireless? 'g' might be 54Mbs but file transfers involve traffic going both ways (ie there are packets returned by the recipient) - as soon as you have two way traffic your speed will fall out cause g is only half duplex. I've never seen file transfers via G go any faster (consistently) than about 2.5

cyril7

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#361407 2-Aug-2010 10:36

Hi, I assume that when you connect the laptop to the Belkin you are infact connecting via one of the wired LAN ports not WiFi, its not totally clear from your post.

If WiFi then read Smac's comments above, if it is using a wired lan connection then it does not sound right, typically the LAN ports of a router have no soft function and are a hardware ethernet switch sitting down stream from the soft NAT in the CPU, so in essence between lan ports should be full 100Mb/s fastethernet speeds.

Does the PC's network connection state that its connected 100Mb/s or 10, and full duplex? Other things you can try are using a seperate switch, and also using a couple of PCs check the speed through the lan ports of the router using wsttcp or similar tool, I have rarely found router switchs to not do full fastethernet speeds.

Cyril

ashtonaut

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#361424 2-Aug-2010 11:01

Thanks for the suggestions. Just to clarify, I'm getting the higher speed when directly connected to the NAS via ethernet cable. I get the lower speed when connected via LAN cables through the router. I also get the same lower speed when the notebook - router connection is wireless. I understand that when connected via wireless, the speed I'm seeing is about right for a 'G' connection, but when plugged in I expected more. I'll do some more tests and report back - it's possible that I was still connected via wireless even though I'd plugged the notebook in (I have set up the network adapter priority correctly in Vista though). I'll look into jumbo frames - any suggestions as to what I need to change where for this?

cyril7

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#361428 2-Aug-2010 11:05

And just to clarify, the NAS and notebook are connected to two of the LAN ports, ie you are not passing them through the NAT router itself.

Cyril

ashtonaut

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#361531 2-Aug-2010 12:57

I'm not 100% sure what you mean, but what I did was simply plug both LAN cables into the LAN ports on the back of the router, so I assume there's nothing going through NAT or anything like that.

When I get home tonight I'll test again with wireless turned completely off, I'm suspicious that the wireless connection was still being used even when the notebook was plugged in, as the speed was 2MB/s, which is suspiciously similar to what I should be ablento get on 'G' wireless…

Ragnor

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#361648 2-Aug-2010 15:15

This sounds really odd, normally lan traffic between two devices is fairly direct and passes through the switch and doesn't go through the routers software.

Maybe there is some option for this in the routers admin ui.

smac

333 posts

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#361741 2-Aug-2010 17:19

My money is on the fact you were using the wireless.....depending on the OS it doesn't necessarily drop to ethernet just cause you plugged in, especially if you still had whatever software you were using open.

ashtonaut

614 posts

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#361997 2-Aug-2010 22:40

OK, I'm an idiot.

Physically turned off wireless, plugged the notebook in, and now I'm getting 8.5-9.5MB/s, just as I expected to.

So, In summary:

Wireless 'g': ~2MB/s
10/100 LAN: ~9MB/s
Direct gigabit: ~14MB/s

Looks like an upgrade to a 'n' router might be next on the list. I've heard that wireless 'n' gets about the same real world throughput as a wired 10/100 LAN, so a gigabit switch/router wouldn't add a lot unless I plug the notebook in (which I prefer not to).

As an aside, the WD My Book World Edition is a fantastic little product...

richms

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#363332 4-Aug-2010 22:46

300 meg N will do about the same as 100 base T when you are close, but there is a lot of " n" stuff out there withonly one antenna that gets a 150 air rate and only will do 40-50megabit of thruput.

Richard rich.ms