Possible bottleneck in T41 wifi? Can't use my full 10mb line

[aphex]

I am a little perplexed by this one.

I have two systems, Mac Mini (wifi, 20-30 feet from the router, running OSX and Vista) and an IBM T41 laptop.

Router is a Buffalo WHR-HP-G54 (tried a Netgear 54g in the past)

I have now tried two wifi cards in the T41 laptop, the original Intel 2200bg and the IBM a/b/g (that i currently use)

Roadrunner Connection is a 10/1 line.

On the Mac Mini (which uses an Atheros wifi chipset i believe), i can use the ENTIRE 10mb down connection, files usually download between 850-950k per sec in both OSX and Vista. However, on the laptop, the max i can get is 400-450k, same files, even when i am closer to the router than the Mini.

Also, when i run a speedtest on the mini (speakeasy.net/speedtest - Atlanta site), my connection shows basically a 10/1 line on the Mini, and a 4/1 line on the Laptop.

Is there some bottleneck i am encountering here?

[Dimitri_P]

Update drivers, and go to configuration of the wireless card. See if certain settings help.

D.

[aphex]

Update drivers, and go to configuration of the wireless card. See if certain settings help.

D.

Tried all the latest drivers, even tried some old ones. Tried 3rd party firmware on the latest router. Nothing seems to push it past that bottleneck.

[agarza]

Have you tried using a generic PCMCIA wireless adapter. Just to see if that same behaviour happens.

[NathanA]

I would head on over to www.broadbandreports.com to run their Tweak Tester II, which should in turn tell you the optimum values for your system to input into DrTCP.

-- Nathan

[Dimitri_P]

I would head on over to www.broadbandreports.com to run their Tweak Tester II, which should in turn tell you the optimum values for your system to input into DrTCP.

-- Nathan

Good program, but won't do much in his case

[Wiz]

You could try to set the Power Save Mode to Off and see if that help. If you use Access Connections it could change it back unless you turn it off there as well. In access connections under your profile change it to "Low (Best network performance)" which is the same as Off for power save mode in device manager.

[NathanA]

Good program, but won't do much in his case

Huh. I'm not sure how you came to that conclusion. (No sarcasm intended: I'm genuinely interested and wonder if there is something I missed in this discussion.)

The reason that I recommended that course of action had to do with my own experience...I have a 4Mbit up/down (symmetric) connection to my ISP, and was having problems with download speeds myself on my ThinkPad under Windows (Linux seemed to be fine). In fact, in speed tests, I would routinely see more upload throughput than download, and by a fairly large margin!

Increasing the TCP Receive Window value (RWIN) under Windows to a not-insanely-low default value fixed it completely for me.

What we know so far is:

1) It happens on one computer (Mac), but not on the other (IBM).
1a) It happens on one OS but not the other (still two different computers, so we can't necessarily pin it on the OS).
2) It happens with two different wireless cards with two different chipsets (Intel vs. Atheros) in the laptop.
3) It happens with two different routers on the one PC (Buffalo and Netgear), and the router change did not affect the other PC.
4) It happens with different versions of drivers for the different wireless cards.
5) It happens with this one ThinkPad T4x-series laptop, but not with others, even when using the same/similar wireless cards.

From point #1, there isn't a whole lot that we can infer (hard to say whether the difference is in the hardware or the software between the two machines) except that it is not his internet connection, since at least one machine can utilize the complete internet pipe in the downward direction. We don't know what another Windows machine would do, nor do we know what would happen if he ran a different OS on either his Mac or his PC.

From point #2, we can be nearly certain that it is not a physical defect in either wireless card, and it is most likely not a problem with the design of either card, either: hardware or software (drivers). Having two different cards by different manufacturers using two different chipsets by two different vendors showing nearly the exact same performance characteristics on the same machine makes it seem very unlikely that it is either card's fault.

From point #3 (combined with point #2), we can be nearly certain that it is not a problem with the router (which we already determined partially by the fact that the Mac has no problem with _either_ router). When you throw in the factor of the different wireless cards on the laptop into the mix, it seems even less likely that it is some strange interoperability problem between the laptop and the two routers since two different 802.11 client cards showed the same performance characteristics between two different routers! Unless both routers used in these tests are built on the same hardware/chipset platform or are OEM'd by Netgear and Buffalo from the same manufacturer, it seems unlikely that the problem lies with the router, and this fact makes it even _less_ likely that the problem is with the wireless cards in the laptop.

Point #4 only helps expand on point #2, but limits the discussion to the software side of things. For two different chipset manufacturers to make the exact same mistake in their driver or firmware reference code in turn causing the same performance penalty would, it seems to me, be very unlikely to happen.

Point #5 I threw in there because I have a T42 myself, and I'm using the old Atheros (5001X) card in my ThinkPad in WinXP and do not suffer from throughput problems. I can associate to either my 11a or 11g AP at 54Mbit/s modulation and move 20+Mbit/s real TCP throughput to another machine in my network easily. I can also take maximum advantage of my internet connection in both directions.

I also don't see how there could be anything inherent in any ThinkPad with built-in wireless that would cause a throughput issue...the built-in wireless rides the PCI bus, and there should be no lack of bandwidth _there_, for sure.

So, after ruling all of these things out, I'm left with nothing other than that it is a software issue of some kind. Because we've tried different wireless cards that use different driver sets, and because we've tried different driver revisions within these driver sets, I'm inclined to think that it is not a driver issue, but some issue with the OS's network stack itself. This is why I suggested running Tweak Tester and DrTCP: combined together, they're both really near-foolproof ways of finding and changing some really stupid Windows IP stack default settings.

It would be interesting to see the OP trying to use a different PC Card (preferably CardBus) wireless client. It would also be interesting to hear whether or not plugging in his ThinkPad to his network via ethernet showed the same symptoms, as well. And, of course, Wiz makes a great point about power saving options. That also brings to mind another question: does the problem occur equally as much when the PC is running off of AC as it does when it is running off of battery power?

Regards,

-- Nathan

[Dimitri_P]

Duh... sorry , don't know what I was thinking about...

He should try it.

D.

[aphex]

It worked, setting the RWIN value to 100000 sped everything up to full speed. Thanks!

[jim_0068]

Worked for me too!

Thanks