Wireless, how to improve....

Hi guys, I am a new user here so hello to you all . I have a number of questions, I was not sure whether to put them all in "General" or spread the love around
Situation is we have just got BT infinity (Woohoo!) I use a linux (openSuse) PC upstairs (3 bed semi, not big, so distance travelled by the WiFi is only say 15m) the FTTC comes in downstairs, my familiy's Win XP PC is there. I connect via a USB wireless adapter, a hawking dish http://www.amazon.co.uk/Hawking-Hi-Gain-Wireless-G-S... (wireless g)
Also connected to wireless is an all-in-one printer/scanner.
The family PC downstairs gets good DL speeds, with the BT tester often near the max configured speed of 37Mb (cabinet is AFAIK at the top of the Street, < 100m away)
Query is: If I boot my PC upstairs to my usual OS opensuse I get around 10-11 Mb download.
If I boot it to Windows XP I get 16-20Mb Can anyone explain why this might be?
If I upgrade to a wireless n adapter, would I get better speeds upstairs? Would the BTHomeHub default back to wireless g by the presence of the printer scanner on the network?
Is there a tool to measure throughput over the WiFi end alone?
When the engineer came to install he found that the HomeHub 3 sent was faulty, so he installed a HomeHub2. Am I missing any benefit? Should I contact BT to ask for a new HomeHub?
More dumb questions coming your way soon, I am sure.. Until then Ta for reading...

The difference will most likely be the configuation of the TCP stack in Linux, i.e. RWIN and MTU
It may be the drivers in linux for that card are not very good.

Given G is never going to provide 37Mbps, then the best bet is to get everything onto N i.e. connect the printer scanner via a cable

Wow! Thanks for the quick reply... You think wifi n would improve things? Could you point me to some info re. the TCP stacks RWIN/MTU settings or should I ask in a Linux forum?

Presume Family XP PC is Ethernet wired to router?

Try Linux forums for advice on IP parameters.

Ok, so I have delved in to the mysteries of MTU.... I am not much the wiser
I have discovered that if I ping at 1464(1492) it's OK, and at 1465(1493) it frags. I have accordingly set my MTU to 1492. No difference in speeds so far but a little knowledge gained... (a dangerous thing?)
Of now to the find out what RWIN is; does; and how I tweak it.....

Here's a program for viewing and tweaking your TCP paras in XP : SG TCP Optimizer

Perhaps it will help decide values for Linux?

TY Xray....
I have so many variables ATM that I am just tinkering about... I will shutdown and boot to XP and have a look around there.
And yes the family PC is wired to the router. I must check if any neighbours etc are using the same channel as well, which might give some wireless probs. (Dunno how in linux )
Deffo a diff in performance <> win and linux with my wireless set up. Unf I have no kit laying about to compare. My other USB dongle is "loaned" to ex-gf along with laptop, (never see them again) and the other one (Netgear WPN111) REFUSES to work with linux, despite carrying the the same chipset.

Dang and blast forgot that forum login and passwords are different..... so can't login here from XP (pen and paper still useful hmph)
But speeds are deffo better from windows ...... off to try XRAY's suggestion.

Hi,

If your OpenSuse is reasonably up to date I was under the impression that linux kernel TCP/IP stack was self-tuning. Certainly we've never needed to do any tuning at work (100M internet).

MTU is normally discovered and monitored automatically, both in Windows and Linux so I'd be surprised if it were that. (PMTUD)

I'd be wary about hard-coding any values for MTU / RWIN if this prevents any self-tuning for network adapters, especially on wireless which needs to adapt to different networks it connects to (less important in your case as it's not a laptop).

If you could get hold of a long ethernet cable it would be better to test OpenSuse's speed on a wired connection.

It may be down to the the wireless driver (and the USB driver if it's a USB adapter). For example before 'n'Wi-Fi came along, some manufactures had different (proprietary) enhancements for 'g' (Super G etc) which might only be present in the XP driver.

Other factors might be the version of Flash or Java in OpenSuse. If you have the Adobe Flash plugin try TBB's Flash-based tester too.

But as other posters mention, 'g' Wi-Fi may struggle to get much above 24M (even in the same room).

Finally are you certain nothing else was downloading (e.g. updates) when you were running the tests?

If you are happy with the internet connection generally it might be better to test your wi-fi by transferring files back and forth between two machines over the local network. TBB's test files are also suitable to this.

In reply to a post by wakou222:

Ok, so I have delved in to the mysteries of MTU.... I am not much the wiser
I have discovered that if I ping at 1464(1492) it's OK, and at 1465(1493) it frags. I have accordingly set my MTU to 1492. No difference in speeds so far but a little knowledge gained... (a dangerous thing?)
Of now to the find out what RWIN is; does; and how I tweak it.....

Hi, I learnt how to configure the MTU and RWIN settings from Broadband Reports website.
I use the RWIN that DrTCP gives.

http://www.dslreports.com/faq/5793

http://www.dslreports.com/faq/8159

http://www.dslreports.com/faq/9739

Edited by deleted (Fri 04-Mar-11 13:24:18)

Thank you prlzx, and everyone for your replies, I believe you are correct re the self-tuning aspect, but it is still fun learning about it...(fun? maybe I should get a life?)...

In reply to a post by prlzx:

If you could get hold of a long ethernet cable it would be better to test OpenSuse's speed on a wired connection

.

I might lug my box downstairs and try it wired and wireless from there and compare, or maybe boot the family PC to a liveCD and try that.

In reply to a post by prlzx:

For example before 'n'Wi-Fi came along, some manufactures had different (proprietary) enhancements for 'g' (Super G etc) which might only be present in the XP driver.

In reply to a post by wakou222:

and the other one (Netgear WPN111) REFUSES to work with linux, despite carrying the the same chipset

.

I think you have hit the nail squarely on the head, and this is why this particular adapter refuses to work at all with openSuse, or indeed any flavour of Linux according to Google (one guy reported he had got it working with Ubuntu, maybe he was lying )

In reply to a post by prlzx:

Other factors might be the version of Flash or Java in OpenSuse. If you have the Adobe Flash plugin try TBB's Flash-based tester too.

I had problems with this (java) but I think I have them cracked. I have tried both, results with both vary wildly, but both seem to average out at about 10Mb. I sometimes get above this (15-20) but rarely and not consistently, ie occasional spikes.

In reply to a post by prlzx:

If you are happy with the internet connection generally it might be better to test your wi-fi by transferring files back and forth between two machines over the local network. TBB's test files are also suitable to this.

I have a couple of other small problems, I shall post them in the BT forum area.....

In reply to a post by prlzx:

MTU is normally discovered and monitored automatically, both in Windows and Linux

In Vista & Win7 yes, but not in XP, where it just take default value (of 1500 I think). Hence popularity of tweaking programs, like TCP Optimizer, and variable pinging.

wakou222,

Both a friend and myself have been trying out Ubuntu 10.10 for the past few weeks and we both found that connecting to the net can often be a problem. He was trying to connect to a Homehub wirelessly from a Vista laptop both with the onboard card and a usb adaptor and couldn't hold the connection for more than a minute or two. I had a few problems from start-up, wired to a router, and had to uncheck and recheck, sometimes several times, the network settings box to get a connection - however once connected it would hold and speeds would be the same as under Windows XP.

His wireless connection problem was solved by installing Ubuntu as the single OS on a desktop computer and my problem was solved by using a TG585 v7 router upgraded with generic 8.2.6.5 firmware. Incidentally the dslreports.com "Tweaking for speed" test shows the Ubuntu auto internet setup is now fully optimised.

This info may not help you, but at least you know others have managed to resolve similar issues

4M2.

In reply to a post by XRaySpeX:

In reply to a post by prlzx:

MTU is normally discovered and monitored automatically, both in Windows and Linux

In Vista & Win7 yes, but not in XP, where it just take default value (of 1500 I think). Hence popularity of tweaking programs, like TCP Optimizer, and variable pinging.

Link

XP might not auto-adjust RWIN but MTU is set via PMTU Discovery, (on by default) unless you turn it off by tweaking.

XP has an additional setting EnablePMTUBHDetect (off by default) to spot when a network is behind a router that blocks ICMP but also needs a lower MTU to reach it. (Edit) you can turn that on if you have problems with a few websites when the rest are ok.

One reason for the popularity of tweaking programs is that people have previously tweaked their settings for dial-up connections, so subsequently on progressing to DSL the settings were not optimal.

A second reason is that some people just like to tweak things (me too)

A third is that some internet servers and firewalls were misconfigured such that they send full size packets with DF flag set, but then block all ICMP (including ping) so not get the replies back telling them they needed to fragment or send smaller packets. People then try to workaround that by setting their own MTU lower (even if there was nothing much wrong with the client settings).

In general the best place to set the correct MTU is on the router or device acting as DHCP server then you are only changing settings in one place rather than manually setting each device. Similarly people who like to set static IP for everything might not realise DHCP is giving out more info than just IP addresses and can inform the client about other settings.

If BT Infinity uses PPPoE then yes 1492 may well work better, but modern OSes with their default settings are able to use 1500 on the (link-local) LAN and a detect a lower value for internet-bound traffic.

Edited by prlzx (Fri 04-Mar-11 17:47:38)