MTU Size

**achtungbaby** · 03-14-01, 04:48 PM

Greetings all, I'm a newbie at this, so forgive me if you've heard this a thousand times before but: can the MTU be increased past 1500? I've heard conflicting things out there.

I just got a Road Runner, and based on the tests I've been running, I wonder if this thing is for real or what...

I ran the [ping -f -l 1500 www.isp.com] test
several times, increasing the bytes from 1500 to...30,000 eventually...and hadn't gotten any errors until I went up to about 35,000. Does this mean my MTU should be around 29,000...and if so, would it really do anything significant?

Thanks!

Lobo · 03-14-01, 04:53 PM

The highest you can go is 1500, you can set it above that but Windoes wil not reconize it

Lobo · 03-14-01, 04:55 PM

They say that Broadband Wizard sets theirs at 7500, but it's all a joke ,1500 that's it

**achtungbaby** · 03-14-01, 04:58 PM

Thanks anyway!

Lobo · 03-14-01, 04:58 PM

Take test at: http://forums.speedguide.net/optd.shtml

**achtungbaby** · 03-14-01, 05:00 PM

(I took the test previously at home...for some reason, my MTU was 1500 then...there were also some other changes...)

SpeedGuide.net TCP/IP Analyzer
TCP properties for IP = 208.12.125.239
Note: Read the FAQ if the above is not your IP address.

TCP options string = 02040564010101010101080a000000000000000001010402

MTU = 1420
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput.

MSS = 1380
Maximum useful data in each packet = 1368, which is less than MSS because of Timestamps, or other TCP/IP options used.
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:
507840 (MSS x 46 * scale factor of 8)
253920 (MSS x 46 * scale factor of 4)
126960 (MSS x 46 * scale factor of 2)
63480 (MSS x 46)

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

MTU Discovery (RFC1191) = ON

Time to live left = 121 hops
TTL value is ok.

Timestamps (RFC1323) = ON
Note: Timestamps add 12 bytes to the TCP header of each packet, reducing the space available for useful data.

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349)= 00000000

18126 connections tested since 03-10-2001, 14:30 ET
Analyzer version: Beta 0.94

Lobo · 03-14-01, 05:02 PM

That is not a good test and in future x out your IP address, what is your OS, CPU and do you have a speed patch in

**achtungbaby** · 03-14-01, 05:04 PM

The computer I'm using:
OS - Windows2K
CPU - Pentium III, x86 648mhz
RAM - 192
NIC - Xircom Cardbus Ethernet II 10/100
Hard Drive - 11Gigs

I use my computer at work...and everytime I log into my work server, it seems like my tweaking is changed, and the same when I log in at home. Anyway around this? I know that my cable modem at home is something like 1600kbps (according to Broadband wizard) and 600kbps at work...

**achtungbaby** · 03-14-01, 05:06 PM

I've installed/removed/installed/removed so many patches, I have no idea what's in there any more

Lobo · 03-14-01, 05:09 PM

Well your at home now right, and you just took test

**achtungbaby** · 03-14-01, 05:13 PM

No, sorry, am at work.

BTW...you guys rock! Why can't Road Runner's customer service hire guys like you?

Lobo · 03-14-01, 05:15 PM

Do you want a patch for your work pooter

**achtungbaby** · 03-14-01, 05:18 PM

Sure...but will it really solve anything at this point? I've even re-installed RR's activation software/medic a few times and noticed that they set their RWIN at 372300...

Lobo · 03-14-01, 05:25 PM

Listen closely as you may want to do this at home an I assure you it is better than Broadband wizaed: The only site with speed patch that will take your registry back to default before appling patch is Cablenuts, it's a good patch, after you install it, take the test above and post results, hers how:
First go to www.cablenut.com , click on software at top of page
Download 4.0
His patch will uninstall previous patchs
Install 4.0

Then on desktop click on cablenut 4.0
Click on ccs files
then click on cable
Select fast cable
this will enter settings
click on save to registry at bottom, reboot or it will not work.

If you decide to remove Cablenut's patch, use uninstaller in Cablenut 4.0 folder on desktop. This will take you back to Windows default. Come back here with tweak test results

Lobo · 03-14-01, 05:31 PM

You do NOT, want version as that just fixes flaw in 4.0 to allow it to work in WIN 95 & ME

Lobo · 03-14-01, 05:37 PM

You also need to download an instakk from patch page, this site the faster loading of web pages patch, reboot after you install, see directions foe installation, then you need to backup registry, might save you in future from having to do the "R" word, here's how: do it at home too:
This is a must unless you the future in want to format because you did not do it, please do this. First bring up REGEDIT, type REGEDIT in your run box and hit OK.
Under Registry at the top of the box, click on that, now click on Export Registry File, a box will come up asking where you want to export it to, just put it in your C drive, then name it at the bottem of box, Registry plus date. Click on ALL at the bottom so it copies all of your registry.
Click on save.
Now if you ever get in trouble or want the old regestry back, bring REGEDIT back up and click on Registry and click on import registry file, go to your C drive and click on registry and click open, reboot and your good to go.
Anytime you add a new program, backup again, any program, back it up to the same place as the last one, it will overwrite it. If you do not backup after each new program is instaled you will not have those setting's in regestry if you have to backup for some reason.

Do nothing else in this box as it is the heart of your computer, just what it says above and no more!!!!!!!!!!!!!

Lobo · 03-14-01, 05:39 PM

Gee, you do not want version 4.02

Lobo · 03-14-01, 06:02 PM

Here print some of this when you get home so you will know how:
How do do speed test
1. The best time is early in the morning (3 AM - 6 AM)
2. Make sure defrag has been run so no files are fragmented
3. Delete Temp internet files, not while testing, but after each test. IE browser, click tools, internet options, click on delete files and no this will not harm system, just get rid of temp files
4. Go to a fast server such as www.happypuppy.com and click on 10 demos, select a LARGE file to download (not all of it of download, just most of it, before you click cancel) this will show you how fast you are downloading, it's not going to be quick except except early in morning when not many people on net. I recommend you go to www.analogX.com and download Net State live, run this while downloading as it will give you avg of your download speed.
5. Probably the most important, nothing can be running during test, no firewalls, no virus stuff, no ICQ, no AIM (some of you may have to go into BIOS to disable virus scanner, nothing running except Net Stat live
Scheduled tasks will run disk defrag, 98 & SE in Taskbar, WIN ME in control panel

Or if you wish you may go to www.testmyspeed.com and do one of the online tests, these vary to much for me but you may like them. Another one is at www.dslreports.com/tools