Win/98 - wireless lan connection

[GMD999]

First off... I am fairly new to LAN's and the tweaking business... let me describe what I have setup and what my issues are:

Setup:
- Nexland WaveBase unit, connected to the Internet via DSL (PPPoE);
- desktop PC on Win XP connected to the WaveBase via an ethernet cablecto LAN port #1;
- laptop (IBM) on Win/98, connected to the WaveBase via a wireless LAN card;
- laptop (IBM) on Win/2000, connected to the WaveBase via an ethernet cable to LAN port #2. This PC also runs on a VPN when mobile and plugs into a base when at work using an ethernet cable.

I decided to try to tweak the wireless PC running Win/98. When I ran the initial TCP/IP Analyzer I got:

**************
MTU = 1472
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.

MSS = 1432
Maximum useful data in each packet = 1432, which is equal to MSS.
MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

Default Receive Window (RWIN) = 65535
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 65535
Note: Under Windows 9x, if you have RWIN set to any other value, and the Analyzer reports 65535 you might need to install the MS Vtcp386 fix.
For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
504064 (MSS x 44 * scale factor of 8)
252032 (MSS x 44 * scale factor of 4)
126016 (MSS x 44 * scale factor of 2)
63008 (MSS x 44)

bandwidth * delay product:
Your RcvWindow limits you to: 2621.4kbps (327.675KBytes/s) @ 200ms
Your RcvWindow limits you to: 1048.56kbps (131.07KBytes/s) @ 500ms

MTU Discovery (RFC1191) = ON

Time to live left = 50 hops
TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349)= 00000000

**************

I then downloaded the program "ispeed" and tried to tweak the various parameters... interestingly that program calculates and tells me that the maximum MTU value I should use is 1468 (and therefore 1428 for the MSS) not the 1500 recommended by the Analyzer! Using that program I changed the values [as an aside where would I find these values to change without this program...] I also changed the RWIN value to 51408 (a multiple of the MSS value... I used a multiple of 36 whereas the example goes as high as a multiple of 352... how does one determine what in fact is optimal??).I set the TTL to 64 hops and I allowed for Window scaling but no timestamps (frankly this section is not very intuitive to me...). I also set a parameter called NDI Cache size to 32 (this is a Win 9x/ME specific param. and the help section of ispeed gives very little info except to say experiment...). The ispeed program allows you to test your throughput, with a particular config, by dowloading a file from an ftp site. I did not find this very helpful as the results were all over the map.
I then saved the config and rebooted. Then I reran the TCP/IP Analyzer and got the following results:

********************
MTU = 1472
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.

MSS = 1432
Maximum useful data in each packet = 1432, which is equal to MSS.
MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

Default Receive Window (RWIN) = 51408
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 51408
For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
504064 (MSS x 44 * scale factor of 8)
252032 (MSS x 44 * scale factor of 4)
126016 (MSS x 44 * scale factor of 2)
63008 (MSS x 44)

bandwidth * delay product:
Your RcvWindow limits you to: 2056.32 kbps (257.04 KBytes/s) @ 200ms
Your RcvWindow limits you to: 822.528 kbps (102.816 KBytes/s) @ 500ms

MTU Discovery (RFC1191) = ON

Time to live left = 50 hops
TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349)= 00000000
******************
As you can see the system did not accept the values I entered for MTU and MSS, but did for the RWIN... which of course in now longer a multiple of the MSS!! The TTL value of 50 hops is also different from the entered 64 hops.

Looking at these results... (I am assuming that) the "bandwidth * delay product" numbers are telling me that my throughput is now worse than before!!! help....


GMD999

[Bob Carrick]

Leave your MTU as is, as it's controlled by the router, set your Ethernet card to match the MTU of the router, if you run any MTU ping tests etc, the value will be lower then 1472 because a proper evaluation can only be done when the MTU is 1500 which you can not set on PPPoE anyway.

[GMD999]

I now understand that the router does control the MTU value and that it should stay at 1472 (I tried to raise this to 1492 and was told that I could not!!). Having said that does that mean that my abilities to tweak the DSL connection have to be done on the router? Or can I still make changes to the other parameters... i.e. RWIN, TTL (although this also did not change!!)...etc. If so, I am still puzzled as to how I optimize the RWIN and then measure the results... is the TCP/IP Analyzer not useful/effective when going through a router?

Still in need of help....

GMD999

[Bob Carrick]

The anylizer is fine and tweaks work through a router except for the MTU.

[Lobo]

Yes you can still tweak other settings, try RWIN's listed on analyzer, TTL if you set yours to 64 does not mean analyzer shows 64






Click on SG patches and download and install MS Vtcp 386th Fix patch for 98

Make sure you have newest firmware for your router from router's web site

[GMD999]

The more I dig into the more I learn... but it is a journey...

I now see that the IP address returned by the Analyzer is not mine! It appears to be that of a server of my high speed service provider... I did what was suggested on the Analyzer FAQ page and used winipcfg to find my IP address... I note that there are several IP addresses listed there... am I right to assume that the address of the LAN (wireless) card is the correct one that should ba analyzed? Then I checked my LAN settings and made sure that "Automatic settings" were unchecked.... yet I still am analyzing the wrong address?

Does this explain why I am still getting 65535 as a RWIN value despite having 504064 in the registry?

Any suggestions on how to test the right address... should I try the suggestion for the @Home Web Proxy and if so can I reverse the impact of that command easily?

I have also run the MS Vtcp386 fix (and verified that the right file is in Windows\system)...

GMD999

[Lobo]

Set Tcp1323Opts to 1 to allow scalling to fix RWIN, I don't know about other

[GMD999]

I checked and Tcp1323Opts is set to 1 in the registry...

Any other thoughts?


GMD999

[Lobo]

Yes now there are two things I run from, wireless and AOL, lol

[Lobo]

Check and see if it's set to 1 on main puter

[GMD999]

By the main puter... I assume that you mean the desktop connected to the router... (see my setup description in first post)... this puter is running Win Xp and shows a value of 3 for Tcp1323Opts!! I am not sure why this would have any impact given that my connection is going through the router!! Do you still suggest that I change that to 1?

GMD999

[Lobo]

Yes

[GMD999]

Okay... I changed the Tcp1323Opts value on the main puter to 1... at the same time I downloaded the SG Optimizer and ran it on both pc's... interestingly this program does something behind the scenes such that the Analyzer now shows an RWIN value equal to what is the registry!! (just uninstalled iSpeed...).

Now my results are as follows:

*******************
TCP options string = 020405980103030301010402
MTU = 1472
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.
MSS = 1432
Maximum useful data in each packet = 1432, which is equal to MSS.
MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.
Default Receive Window (RWIN) = 511104
RWIN Scaling (RFC1323) = 3 bits
Unscaled Receive Window = 63888
For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
504064 (MSS x 44 * scale factor of 8)
252032 (MSS x 44 * scale factor of 4)
126016 (MSS x 44 * scale factor of 2)
63008 (MSS x 44)
bandwidth * delay product:
Your RcvWindow limits you to: 20444.16 kbps (2555.52 KBytes/s) @ 200ms
Your RcvWindow limits you to: 8177.664 kbps (1022.208 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 50 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349)= 00000000
*************

Question 1: am I correct that the "bandwidth * delay product" results represent the throughput numbers I am trying to improve with this tweaking?

Question 2: do these values reflect the speed at which one can download files or does it also reflect the speed at which screens are refreshed?

Now... I still have a problem

The Analyzer is still analyzing the parameters of the connection between SpeedGuide.net and my high-speed ISP!! (at least there speed looks acceptable...) As I mentioned in an earlier post, I have made sure that my LAN settings reflect that "Automatic settings" are unchecked.... yet I still am analyzing the wrong address...

Question 3: How do I analyze my IP address?

Question 4: Why is it that once I changed the RWIN parameter on my pc (and using the Optimizer, got the Analyzer to see the same value as in the registry) the Analyzer returns a significantly higher speed for the high-speed ISP address than it did before? If the analyzer is looking at the wrong address, I would think that the RWIN value on my pc would be irrelevant...

GMD999

[GMD999]

I guess I asked too many questions!!

I would still appreciate some thoughts on those questions...

Another question... would it make sense to disconnect the router and try the Analyzer on the PC's connected to the net via the DSL modem??

GMD999