Speed - optimal settings: RWIN, MTU etc...

[ic]

I've been messing with RWIN and MTU on my PCs, running online tests etc.

So far all I've managed to do is sort out ICS by decreasing MTU size on all PCs to 1492 (max PPPoE).

RWIN on ICS gateway PC to 32767
(<i>not happy with that figure, but it is based on calculations with MSS of 1452</i>).

I know there are lots of factors that make these settings fairly unique to each of our setups, but what does evryone else find works best[?]

Apart from using RegEdt32 or RegEdit or DrTCP.exe, are there any other utils out there that allow you to change everything all at once[?]

[regardtv]

I'd recommend clamping a tad lower ... I've had some fragmentation problems above 1430 ...

[alchamy]

I got best result at 1370, anything higher fragmented, then again i'm quite far from the tower.

[sihen]

We have found that people using a router and having connection problems to some websites and mail should change there MTU to 1399. it seemed to fix my problem.

Dylan

[ic]

UUNET-SA: "We will be changing the Maximum Transmission Unit (MTU) on the router which may cause the router to stop responding." (http://www.uunet.co.za/_sanetwork/networknotices/networknotices.asp?txtAction=D&id=1361)

Just in case you thought you had optimised your own MTU settings to work with what's upstream, think again...

[BCO]

Guys, please help me... I wanna change my MTU. Apparently I have to go here:

System Key: [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic es\Tcpip\Parameters\
Interfaces\[Adapter ID]]

The thing is, when I open Interfaces there are 7 different folders with names like {712DB115-1270-44C7-A102-B0237F454F4A}

How do I ascertain what the correct adapter ID is?

[ic]

Related thread(s): Internet Connection Sharing (ICS)Yep, ok, I simply edit the registry with RegEdit or RegEdt32, but I'm using Win2KP and I don't know whether the settings are in the same place under WinXP-H/P +SP2.

You can try using http://www.dslreports.com/drtcp to change your MTU, I don't recommend using it to change any of the other settings it allows- note your user account will need Administrative privelleges to run DrTCP as it writes to the registry.

Alternatively, if you are ok with editing the registry, try finding something similar in XP to this (2KP):
HKEY_LOCAL_MACHINE\
SYSTEM\
CurrentControlSet\
Services\
Tcpip\
Parameters\
Interfaces\
{526421A4-C42F-47DA-969A-507AD0A797CD}

Now look for a DWORD value with the name MTU, set that to 570 hex or 1392 decimal. You can then reconnect, or to be sure do a restart.

PS: While you are about, please join the testing programme, click the testing link in my siggy.

[BCO]

Thanks ic, tried DrTCP. Hope it works. Also posted my link on the other thread.

[ic]

Totally by accident, I discovered something new today:

The iBurst software that you install on Windows 2000 Professional creates the iBurst_Terminal Connect UTL which we already know, what I for one did not know is that it has a trick that allows you to set MTU & monitor MTU for a particular IP address.

How2 set MTU in W2KP using iBurst_Terminal Connect UTL:
Establish your iBurst connection by using iBurst_Terminal Connect UTL to connect.
Once you have a connection, simply run iBurst_Terminal Connect UTL a second time (your iBurst connection must already be established).
You will be presented with a new mystery dialog box that has buttons: MTU Setting; Property; Disconnect; Cancel.
Click MTU Setting, now set MTU to 1392.
You will be asked/told to reboot.

Note that you must start the iBurst_Terminal Connect UTL with administrative priveleges, use RunAs (shift+rightclick on shortcut, then Run as) if you don't login with an administrators account.

[kuberkoos]

lowered my MTU again. started off with MTU 1390. got good speed in the iburst good ol' days - dec 2004.

lowered it to 1370 some time in jan 2005.

last week some sites (most notably slashdot and mybroadband.coza) stopped working. i could still ping them - classic MTU problem

i'm on 1350 at the moment and things look better. still not great, but at least most sites are working again.

chz,
kk

[michael]

Hi All,

Hope you can help. How do I change the MTU if my UTD is connected to a router? I'm running a Mac and want to try to optimise the connection.

Regards,

Michael

[ic]

Out of my depth here, but I assume your router is establishing the connection on its own, correct? There must be a router config option somewhere to "clamp" your MTU.

If not, are you using the iBurst software for the MAC to establish a PPPoE connection with the UTD via the router?

[AcidRaZor]

huh

[twixt]

Has anybody ever tried the ping -f -l test to try and work out what your optimal mtu setting is? I did it on the recommendation of a post here.

Initially it calculated in beautifully at 1392 as per the recommendation, I tried it again earlier and it worked out at 1352.

I'd really like to know what's happening here - does the test actually work?

For a side note (off topic) the abominal plague of bad service seems to have swept down and hit Durban :(

[ic]

Has anybody ever tried the ping -f -l test to try and work out what your optimal mtu setting is? I did it on the recommendation of a post here.

Initially it calculated in beautifully at 1392 as per the recommendation, I tried it again earlier and it worked out at 1352.

I'd really like to know what's happening here - does the test actually work?

For a side note (off topic) the abominal plague of bad service seems to have swept down and hit Durban :(Dylan posted one of those morsels for us wild dogs / dingos to fight over, I quoted him in the sticky Comms thread as saying they are testing 1352 - whatever that means...

[MaD]

Before you bring your connection to a grinding halt like I did with CableNut, check this page out:

http://www.speedguide.net/downloads.php

[michael]

Out of my depth here, but I assume your router is establishing the connection on its own, correct? There must be a router config option somewhere to "clamp" your MTU.

If not, are you using the iBurst software for the MAC to establish a PPPoE connection with the UTD via the router?

Hi IC,

Thanks for your help. The router is establishing a connection on its own. I found the configuration option and set the MTU to 1352. Range is from 1000 to 1500.

I saw somwhere else in the thread that the correct value can be calculated - but could not see how. Can someone either repost or point me to the message?

Regards,

Michael

PS - My connectivity is extremely variable today.

[ic]

Hi IC,

Thanks for your help. The router is establishing a connection on its own. I found the configuration option and set the MTU to 1352. Range is from 1000 to 1500.

I saw somwhere else in the thread that the correct value can be calculated - but could not see how. Can someone either repost or point me to the message?

Regards,

Michael

PS - My connectivity is extremely variable today.No problemo, glad u found the setting.

Yes, MTU can definitely be calculated, it is very easy, and I know I need to put a proper how2 up here, but in the meantime forage here: http://dslnuts.com/ping.shtml

Basically open a cmd prompt, then do a ping as per above url with:
ping -f -l xxxx 196.30.31.100Start out with a value of 1410 for xxxx, you should see a msg saying packet needs to be fragmented but df flag set. Then you repeat but with xxxx-10 (i.e. 1400 next) until the df msg goes away, then you repeat with xxxx+1 until it says df flag msg again, and the last one that worked without the msg is what's called MSS, so the MSS==xxxx max that didn't need fragmentation, and MTU==MSS+28. If all works well then MTU of 1352 should mean that your xxxx value is 1352-28==1324==xxxx highest MSS that works without df msg.

[MaD]

On the link i posted above you can download TCPOptimiser - it finds the max mtu by pinging a specified address with different size packets until it fragments.
It's the first link.

[ic]

On the link i posted above you can download TCPOptimiser - it finds the max mtu by pinging a specified address with different size packets until it fragments.
It's the first link.Geez, some people just don't appreciate a command prompt :D I will bookmark that url for future foraging ;)

[michael]

On the link i posted above you can download TCPOptimiser - it finds the max mtu by pinging a specified address with different size packets until it fragments.
It's the first link.
Hi MaD,

Thanks for the info. Tried the link before my previous post and it points to a Windows executable. I'm running a Mac :)

Regards,

Michael

[Jerrek]

Windows default settings are more than fine. I get 1 MB/sec out of the box.

[ic]

Scroll through the following which I have just run, you will see that the highest possible MTU value for a PPPoE connection (UTD via ethernet) is still 1392, which is 1364+28:
Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.

D:\Documents and Settings\...>ping -f -l 1400 196.30.31.100

Pinging 196.30.31.100 with 1400 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

D:\Documents and Settings\...>ping -f -l 1392 196.30.31.100

Pinging 196.30.31.100 with 1392 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

D:\Documents and Settings\...>ping -f -l 1390 196.30.31.100

Pinging 196.30.31.100 with 1390 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

D:\Documents and Settings\...>ping -f -l 1380 196.30.31.100

Pinging 196.30.31.100 with 1380 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

D:\Documents and Settings\...>ping -f -l 1370 196.30.31.100

Pinging 196.30.31.100 with 1370 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

D:\Documents and Settings\...>ping -f -l 1360 196.30.31.100

Pinging 196.30.31.100 with 1360 bytes of data:

Reply from 196.30.31.100: bytes=1360 time=430ms TTL=255
Reply from 196.30.31.100: bytes=1360 time=1072ms TTL=255
Reply from 196.30.31.100: bytes=1360 time=220ms TTL=255
Reply from 196.30.31.100: bytes=1360 time=1152ms TTL=255

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 220ms, Maximum = 1152ms, Average = 718ms

D:\Documents and Settings\...>ping -f -l 1361 196.30.31.100

Pinging 196.30.31.100 with 1361 bytes of data:

Reply from 196.30.31.100: bytes=1361 time=771ms TTL=255
Reply from 196.30.31.100: bytes=1361 time=821ms TTL=255
Reply from 196.30.31.100: bytes=1361 time=1101ms TTL=255
Reply from 196.30.31.100: bytes=1361 time=1202ms TTL=255

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 771ms, Maximum = 1202ms, Average = 973ms

D:\Documents and Settings\...>ping -f -l 1362 196.30.31.100

Pinging 196.30.31.100 with 1362 bytes of data:

Reply from 196.30.31.100: bytes=1362 time=521ms TTL=255
Reply from 196.30.31.100: bytes=1362 time=291ms TTL=255
Request timed out.
Reply from 196.30.31.100: bytes=1362 time=221ms TTL=255

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 221ms, Maximum = 521ms, Average = 258ms

D:\Documents and Settings\...>ping -f -l 1363 196.30.31.100

Pinging 196.30.31.100 with 1363 bytes of data:

Request timed out.
Reply from 196.30.31.100: bytes=1363 time=901ms TTL=255
Reply from 196.30.31.100: bytes=1363 time=942ms TTL=255
Reply from 196.30.31.100: bytes=1363 time=591ms TTL=255

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 591ms, Maximum = 942ms, Average = 608ms

D:\Documents and Settings\...>ping -f -l 1364 196.30.31.100

Pinging 196.30.31.100 with 1364 bytes of data:

Reply from 196.30.31.100: bytes=1364 time=291ms TTL=255
Reply from 196.30.31.100: bytes=1364 time=420ms TTL=255
Request timed out.
Request timed out.

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 2, Lost = 2 (50% loss),
Approximate round trip times in milli-seconds:
Minimum = 291ms, Maximum = 420ms, Average = 177ms

D:\Documents and Settings\...>ping -f -l 1365 196.30.31.100

Pinging 196.30.31.100 with 1365 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 196.30.31.100:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

D:\Documents and Settings\...>I suggest that you verify this for the base-station that you are connected to by running the following at a command prompt:
ping -f -l 1365 196.30.31.100
ping -f -l 1364 196.30.31.100If 1365 says it needs to be fragmented, and 1364 works then your MTU is in fact 1364+28==1392.

[Gatecrasher]

IC, that is very odd. When I first tried just now, it fragmented above 1324.

But since my MTU was set at 1352, I guessed that was why. So I reset my MTU to 1500 and re-tested. Here are the results:



>ping -f -l 1405 www.iburst.co.za

Pinging www.iburst.co.za [196.30.31.120] with 1405 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 196.30.31.120:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

>ping -f -l 1404 www.iburst.co.za

Pinging www.iburst.co.za [196.30.31.120] with 1404 bytes of data:

Reply from 196.30.31.120: bytes=1404 time=294ms TTL=126
Reply from 196.30.31.120: bytes=1404 time=359ms TTL=126
Reply from 196.30.31.120: bytes=1404 time=296ms TTL=126
Reply from 196.30.31.120: bytes=1404 time=312ms TTL=126

Ping statistics for 196.30.31.120:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 294ms, Maximum = 359ms, Average = 315ms


I got the same with 196.30.31.100 (what is that?)

Which would make for an MTU of 1432.

:confused:

I am certain I ran the same exercise 2 days ago and got to 1352.

Am I going nuts? Or are WBS continuing with their "experiments"?

[ic]

...
I got the same with 196.30.31.100 (what is that?)

Which would make for an MTU of 1432.

:confused:

I am certain I ran the same exercise 2 days ago and got to 1352.

Am I going nuts? Or are WBS continuing with their "experiments"?196.30.31.100 is our closest IP peer - maybe the 1st visible router or what I don't know, call it our iBurst gateway into the Internet.

Very odd results, but an indication that either WBS are playing games again, or each base-station its own router(s) with potentially different MTU settings.

[Gatecrasher]

196.30.31.100 is our closest IP peer - maybe the 1st visible router or what I don't know, call it our iBurst gateway into the Internet.

Very odd results, but an indication that either WBS are playing games again, or each base-station its own router(s) with potentially different MTU settings.

Do you get 1432? You have to set your MTU higher before you test, otherwise you will, of course, get back to your current MTU setting. I've kept mine at 1500, and I'm still getting 1432, confirmed by the broadbandreports tweak test.

[ic]

GC, the way I understand it, the MTU setting on your PC is the default to use when, however the MTU can be overriden by applications, in this case ping with the -f (don't fragment) and -l (small L MSS value for buffer size). What this means is that running these ping tests will tell you the highest MSS value that you can use, when you are using PPPoE MTU==MSS+28.

[Gatecrasher]

Yes, then how do you explain getting 1324 when I had MTU set at 1352, and 1404 when I had the MTU set at 1500? The -f command doesn't appear to overule the MTU setting.

Here's what I get using TCPOptimizer.



Pinging [63.217.30.70] with 40 bytes ->bytes=40 time=385ms TTL=48
Pinging [63.217.30.70] with 750 bytes ->bytes=750 time=514ms TTL=48
Pinging [63.217.30.70] with 1125 bytes ->bytes=1125 time=467ms TTL=48
Pinging [63.217.30.70] with 1312 bytes ->bytes=1312 time=482ms TTL=48
Pinging [63.217.30.70] with 1406 bytes -> ..fragmented
Pinging [63.217.30.70] with 1359 bytes ->bytes=1359 time=652ms TTL=48
Pinging [63.217.30.70] with 1382 bytes ->bytes=1382 time=529ms TTL=48
Pinging [63.217.30.70] with 1394 bytes ->bytes=1394 time=529ms TTL=48
Pinging [63.217.30.70] with 1400 bytes ->bytes=1400 time=591ms TTL=48
Pinging [63.217.30.70] with 1403 bytes ->bytes=1403 time=529ms TTL=48
Pinging [63.217.30.70] with 1404 bytes ->bytes=1404 time=513ms TTL=48
Pinging [63.217.30.70] with 1405 bytes -> ..fragmented
The largest possible non-fragmented packet is 1404 (1432 - 28 ICMP & IP headers).
You can set your MTU to 1432


I did the same test 2 days ago, setting my MTU to 1500 first, and then testing. I got 1324 and 1352.

Well, I'm going to use 1432 for a few days and see how it goes. Wish WBS would make their minds up.

[ic]

Yes, then how do you explain getting 1324 when I had MTU set at 1352, and 1404 when I had the MTU set at 1500? The -f command doesn't appear to overule the MTU setting.

Here's what I get using TCPOptimizer.



...
Pinging [63.217.30.70] with 1405 bytes -> ..fragmented
The largest possible non-fragmented packet is 1404 (1432 - 28 ICMP & IP headers).
You can set your MTU to 1432


I did the same test 2 days ago, setting my MTU to 1500 first, and then testing. I got 1324 and 1352.

Well, I'm going to use 1432 for a few days and see how it goes. Wish WBS would make their minds up.If we had more iBursters doing this test & posting the results along with the base-station(s) they are likely to be connected to, we would be able see a trend. What I want to find out is whether each base-station has it's own IP router with a potentially different MTU value to other base-stations. I was under the impression that base-stations transmitted IP packets using a non-IP based proprietary protocol using microwave links between base-stations. If more iBursters participate we should be able to make an educated guess, right now it's anyone's guess.

Now, about TCPOptimizer, notice that it is pinging 63.217.30.70, and it will be measuring the MTU for the router(s) associated with 63.217.30.70. I haven't tried TCPOptimizer, but it would be better if it could test against 196.30.31.100 instead, is there a config option anywhere that allows you to use 196.30.31.100 instead of 63.217.30.70?

If you use an MTU higher than that allowed by 196.30.31.100 (or that of intermediary base-stations) then your packets will be fragmented along the way, which will affect throughput, and therefore also speed due to the increased number of ACKs.

Anyway I am not an IP expert, so don't take my word for it, I would rather Dorris or Kuberkoos commented as they are far more knowledgable than I am.

More info: http://dslnuts.com/pppoe.shtml

[ic]

Another setting that will affect your connection's throughput/speed is TcpWindowSize (on Windoze boxes, not sure how/where you set it on Unix/Linux boxes). TcpWindowSize is the same as RWIN (AFAIK, Receive Window). The default value for TcpWindowSize on Windoze is usually way too small, and not optimized for "broadband" connections. You can calculate the optimal value for TcpWindowSize, but it is tricky bcos you first need to know what your latency is, and latency differs from one IP host to the next, and also if different routes are used.

So, if your are an online gamer or you have other latency dependent applications, your best bet is to measure latency "under stress" to the IP hosts that you need to optimize for.

If you have an application A that you need optimized over & abover any other applications, then measure the latency for that IP host, and then use the RWIN calculator to get the optimal TcpWindowSize for that application.

If you have applications A, B, C, .. Z and you want to optimize for all of them, you will have to measure latency for all of them, and then use the highest latency value of all the IP hosts, feed that into the RWIN calculator, and then set TcpWindowSize.

More info:
http://dslnuts.com/ping.shtml
http://www.dslnuts.com/bitsbytes.shtml

[Gatecrasher]

Now, about TCPOptimizer, notice that it is pinging 63.217.30.70, and it will be measuring the MTU for the router(s) associated with 63.217.30.70. I haven't tried TCPOptimizer, but it would be better if it could test against 196.30.31.100 instead, is there a config option anywhere that allows you to use 196.30.31.100 instead of 63.217.30.70?


You can use any IP address...



Pinging [196.30.31.100] with 40 bytes ->bytes=40 time=80ms TTL=255
Pinging [196.30.31.100] with 750 bytes ->bytes=750 time=264ms TTL=255
Pinging [196.30.31.100] with 1125 bytes ->bytes=1125 time=280ms TTL=255
Pinging [196.30.31.100] with 1312 bytes ->bytes=1312 time=327ms TTL=255
Pinging [196.30.31.100] with 1406 bytes -> ..fragmented
Pinging [196.30.31.100] with 1359 bytes ->bytes=1359 time=247ms TTL=255
Pinging [196.30.31.100] with 1382 bytes ->bytes=1382 time=233ms TTL=255
Pinging [196.30.31.100] with 1394 bytes ->bytes=1394 time=217ms TTL=255
Pinging [196.30.31.100] with 1400 bytes ->bytes=1400 time=249ms TTL=255
Pinging [196.30.31.100] with 1403 bytes ->bytes=1403 time=279ms TTL=255
Pinging [196.30.31.100] with 1404 bytes ->bytes=1404 time=248ms TTL=255
Pinging [196.30.31.100] with 1405 bytes -> ..fragmented
The largest possible non-fragmented packet is 1404 (1432 - 28 ICMP & IP headers).
You can set your MTU to 1432


TCPOptimizer warns that you set MTU to 1500 before running the test. I guess because you will fragment above your current MTU setting. I still think that is why you are getting 1392, while I'm getting 1432, rather than there being differences from station to station.

But I do agree it would be great if other Ibursters tried this out, and posted their results.

[ic]

GC, dude, I am flumaxed :confused:, I think I will just wait for more test results from other iBursters & more clued up people than myself to comment...

[MaD]

The joys of technology.. ahhhhh... :)

[Gatecrasher]

A minor tweak, after some research:

I bumped up my RWIN size because I had misread how to determine the ideal setting. The mistake was using a normal 32 byte ping instead of a big ping to determine latency, ie latency in the calculation is determined by sending a full data packet. This works out about 300ms local, rising to 500ms for international. I figured on an average of 420ms. So the calculation is:

420ms x 1.5 x 128K/s = 80640.

Then divide by 1392 (MSS) gives 57.93. Round up to the nearest even number = 58.

RWIN = 58 x 1392 = 80736.

Window scaling on.

It seems to have helped with browsing speed and single threaded downloads. I haven't done any other testing. I'll see how it goes.

Interestingly, With MTU at 1432 I'm only sending/requesting packets of size 1392 through the WBS server, even though the ping -f -l goes up to 1404. Hence the use of 1392, not 1404 in the RWIN calculation. However this seems to consitent with the following:

http://www.broadbandreports.com/faq/2053

[WickedWeasel]

Does you distance from the tower not affect the MTU ? size ? as I have seen this on normal 802.11 ?

[Gatecrasher]

Does you distance from the tower not affect the MTU ? size ? as I have seen this on normal 802.11 ?

It will directly affect the latency, and if your latency goes up, your "ideal" RWIN setting should rise proportionally. It has no effect on MTU.

Having the wrong MTU has the potential to cause web pages not to load and downloads to stall, but having the "wrong" RWIN will only reduce the efficiency of your connection, rather than being a cause of errors.

[ghostim]

hhhmm , IPCOP gave me MTU = 1432 on pppoe the last week or so , and just now after a disconnect its 1352.

[ic]

I have decided to leave my MTU @ 1352 until (if ever) the network "stabilises", then I will go optimizing again :rolleyes:

[Gatecrasher]

hhhmm , IPCOP gave me MTU = 1432 on pppoe the last week or so , and just now after a disconnect its 1352.

Yikes. We are iburst, resistance is futile...

I don't know whether to laugh or cry. I will check when I get home in an hour or so. But it may well be that MTU varies from station to station, day to day, hour to hour, minute to minute, second to second, milli.... nah. But I wish they'd make their minds up!

[Mayh3m]

hhhmm , IPCOP gave me MTU = 1432 on pppoe the last week or so , and just now after a disconnect its 1352.

My IpCOP has always set it to 1432. That is the highest you can use on a pppoe connection as far as I know. It has never changed, and I don't think they can set it to change on their side

[ic]

My IpCOP has always set it to 1432. That is the highest you can use on a pppoe connection as far as I know. It has never changed, and I don't think they can set it to change on their sideThe highest on PPPoE is actually 1492 == 1500 - 8.

[Gatecrasher]

back home. It's true. My cutoff is now 1324. MTU = 1352. Back to the drawing board. :mad:

[zepher]

My IPCOP has also been coming up with different MTU sizes.

It seems to negotiating it or getting it from the modem.

[NTC]

I found this site to be the most accurate on reporting how to find your optimum MTU setting (particularly because it tells you the exact size of the header - and there seems to be much opinion on that):
http://www.dslreports.com/faq/5793

And now my question(s):
1) What is the feeling RE using USB vs Ethernet? I prefer ethernet because you need no drivers...and I find USB connections less than robust in general
2) When adjusting the MTU on your ethernet PPPoE connection - do you need to set it only on the actual PPPoE connector (call it iBurst for arguments sake) OR on the physical LAN port (i.e. Local Area Connection X) OR on BOTH? I have opted for the "Both" option, but I'd like to hear some feedback from other users...

[ic]

My preference is ethernet instead of USB for much the same reasons you mentioned.

MTU: if you have an old spare PC, try a Linux distro (like SmoothWallExpress2 or IPCop) to manage your connection & deal with the ever changing MTU or to just clamp it for all your Windoze lan PCs, in theory this saves you the trouble of having to go changing MTU on every Windoze PC.

[Raithlin]

1) What is the feeling RE using USB vs Ethernet? I prefer ethernet because you need no drivers...and I find USB connections less than robust in generalEthernet - because the USB cable isn't long enough.

2) When adjusting the MTU on your ethernet PPPoE connection - do you need to set it only on the actual PPPoE connector (call it iBurst for arguments sake) OR on the physical LAN port (i.e. Local Area Connection X) OR on BOTH? I have opted for the "Both" option, but I'd like to hear some feedback from other users...Both - but mainly because I was unsure.

[NTC]

Thanks for the suggestions. Problem is that for most configurations that I set up for clients, I use a router device or - more commonly - a server running Small Business Server. If I understand the science behind all this correctly, I will only need to adjust the MTU on the physical connection and/or PPPoE connector that hooks up to the iBurst modem. The rest of the network operates on a different set of NICs / ports on the router / switch / server altogether etc so I can't see them having to change their MTU's as well. But then again I am here to learn from those who have got the T-shirt so I am all ears...

[ic]

There is a definite problem with Windoze2000 machines - if you don't change the MTU on those (or use a Linux box to clamp MTU on all iBurst traffic) then you end up with problems.

[mlungu1]

Hi,

I have a speed problem (from the beginning). Spoke to Shaun Green who told me to test different MTU's by pinging : ping -f -l www.iburst.co.za 1322 where the last part is the mtu which I will then change to see what the best mtu would be.

The problem is: it doesn't matter what mtu I put there, it just times out, even with an mtu as low as in the 500's. That was very odd according to iburst and they asked me to test it on another computer which I did. Same thing. However, I run three other places with ADSL connections and the same thing happens there - that command always seems to time out no matter where and on which computer. The normal ping works fine.

Is this command actually supposed to work and if so why doesn't it work anywhere that I try?

Tks

[jmn]

ping -f -l www.iburst.co.za 1322
ping -f -l 1322 iburst.co.za

[mlungu1]

Thanks a lot, That works!!!!

I'll let Shaun know to get some sleep because that's the one he gave me!!!

[mlungu1]

following on my previous post: what should I be looking for as a good ping time?

[jmn]

My MTU is set to 1352. Ping adds 28 bytes of its own, so if I use 1325 bytes, fragmentation occurs:
C:\>ping -f -l 1325 iburst.co.za
Pinging iburst.co.za [196.30.31.120] with 1325 bytes of data:
Packet needs to be fragmented but DF set.

You want to use a value so that fragmentation doesn't occur:
C:\>ping -f -l 1324 iburst.co.za
Pinging iburst.co.za [196.30.31.120] with 1324 bytes of data:
Reply from 196.30.31.120: bytes=1324 time=239 ms TTL=119

In this example my MTU is set to 1324 + 28 (ping's contrib) = 1352

Watch out for values where fragmentation occurs.

Also other things that increase ping packet size. I think if you use PPPoE, then it adds another 8 bytes to packets, but not sure now...

Edit: You should find other threads here that deal with MTU, also notes in the FAQ.

Ping times would vary, I typically get from 60 - 120 ms, sometimes peaking at 200+ ms. You should watch out for fragmentation however.

[SupaMonkey]

Ok, I thought I would jump on the bandwagon here- I set my MTU to what the site says (I think its 1352?) - anyway, I did the above, and this is what it said:

Pinging iburst.co.za [196.30.31.120] with 1322 bytes of data:

Reply from 196.30.31.120: bytes=1322 time=263ms TTL=125
Reply from 196.30.31.120: bytes=1322 time=265ms TTL=125
Reply from 196.30.31.120: bytes=1322 time=286ms TTL=125
Reply from 196.30.31.120: bytes=1322 time=211ms TTL=125

Ping statistics for 196.30.31.120:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 211ms, Maximum = 286ms, Average = 256ms


So what should I be setting my MTU to ?

[Setup Config]
iBurst going through router on ethernet

[mlungu1]

Hi Jmn

the maximum mtu I see to be able to set is 1372. that gives me 236ms and ttl 122. I use pppoe so I would set the mtu to 1408 if the 8bytes for pppoe is correct. however, the 236ms sounds like a hell of a lot longer than yours.....would that explain my speed problem? The best I have ever gotten out of Iburst is a downspeed of 70kbit (yes bit not bytes) and upspeed of usually about 10kbit (again bits not bytes).

[jmn]

Sorry, made a typo, those are the times for normal 64 byte pings, average at the moment about 239 ms, minimum 190 ms on 1352 bytes

[nocilah]

if you guys needmore help with mtu's and all kinds of other network settings check out www.speedguide.net and try the tcp/ip analyser : http://www.speedguide.net/analyzer.php

[ic]

..., But I suppose their 'software' should set all that including your connection for you (can be done).
BIG SUGGESTION WBS - Make the software & save all that time on MTU related calls!
...The iBurst s/w for Windoze2000 has this feature of being able to set MTU, however MTU Path Discovery in Windoze is better IMO - not that it works 100%...again the info is linked via the FAQ thread, look for MTU...

[seburn]

All the optimal settings ie mtu rwin path discovery should be set(but isn't) in s/w developed by wbs. This can be done and will eliminate need for this thread to exist, That is what I meant.

[slimothy]

it shouldnt be done because it will take the control out of your hands, oh and the software was not developed by WBS rather it was developed by the company who invented the technology, Kyocera

[seburn]

err.. um ...not ganna reply

[slimothy]

well that in itself was a reply

[seburn]

Ok then
1. You still have control after installation to change the settings from default after any point.

2. It is irrelevant that Kerio made/didn't make the s/w I was Asking WBS to make NEW s/w for both USB & Ethernet that sets the optimal settings after install

[patrick123]

Seburn, I see your specs are ipcop & mtu of 1352 :confused: did you force mtu settings?

[slimothy]

WBS are in the business of providing internet access, what about linux users? should they make RPM's for them too? why reinvent the wheel, drtcp is there, the helpdesk know about it, we know about it, I just dont see a point. And there might be licencing issues with the software or maybe they don't have access to the API because Kyocera kept it closed

[Kei]

Yes Kyocera kept the API closed. Slim, I am working on opening it up. Sorry man, just been very busy with work and family

[seburn]

More importantly mtu path finding is on Those are mainly for windows ppl. I set it to 1352 on boot doesn't stay there tho.

[slimothy]

ts cool, once you hack that puppy open we should be able to have some fun :)

[seburn]

1. I don't see every tom **** and harry being able to use drtcp on there own accord
2. This means a waste in call center resources explaining to each new customer how to do this.
3. Mweb is the same as wbs an ISP but they have all these one click packages to do anything (not that i like them)

They don't need access to the API they can make a standalone program and make it run the Kerocera part before or afterwards

[slimothy]

ok well its Kyocera and why don't you write it

[seburn]

when i have time I will think about it

[slimothy]

tell me whats involved and i'll write it tonight, is it just a registry key?

[regardtv]

The whole issue is that this should be integrated into the initial install...

So even having this app does NOTHING truly productive unless it's included in iBurst's cds

[slimothy]

yeah, but i'll make the source public and they can use it, or myadsl could, or I'll just use it :p

so does anyone know whats involved or should I google?

[ic]

yeah, but i'll make the source public and they can use it, or myadsl could, or I'll just use it :p

so does anyone know whats involved or should I google?Oddly enough the info is in this very same thread...:p

[slimothy]

so i will google then.. google this thread

[seburn]

You will need the reg keys for each different windows version I haven't looked into this fully so I cannot give them all some are mentioned in this thread tho(like i said when i have time)
ie win95/98/98me/2000/xp

replace the autorun on the cd with your prog detect os ask for ethernet/usb if ethernet then just run your prog if usb run theirs then yours after. send new image of cd to wbs.

you could also make a linux version that sets the appropriate boot setting ... they somewhere in this forum and on my office pc

Also there is an autoconfig file that can be made for dial up in windows so you could just ask for user and password and set up the user connection for them

[rustic]

Hi guys,

I managed to get hold of a little program available at www.speedguide.net, amoung other features it's got an option to work out the largest MTU setting. You just input any url and off it goes. Work out my optimal setting at 1432

Hope it helps
Ciao :p

[needhelp]

I need help setting/changing my MTU to at least 1365 for the xbox 360 live connection to detect my computer to have at least a 1365. I did the command test and it said it had 1364 plus 28 which makes 1392. So why is the xbox 360 still not picking up the required mtu settings to be confirmed?

[Ekhaatvensters]

I need help setting/changing my MTU to at least 1365 for the xbox 360 live connection to detect my computer to have at least a 1365. I did the command test and it said it had 1364 plus 28 which makes 1392. So why is the xbox 360 still not picking up the required mtu settings to be confirmed?

What do you mean by the command test? Because what I would think of is the command test to figure out what your MTU should be, not what it actually is.

Download Dr.TCP or TCP Optimiser to change the MTU. The recommended value (for iBurst) is 1352, so changing it to 1365 should be okay.

[Roman4604]

What does your setup look like ... where are you trying to change the mtu?

I use a D-Link router which has mtu set to 1392 and my xbox logins into Live no problem.

[PDonut]

Hey, k a few questions...

This MTU business... i dont really understand it that much but it seems important, anyways, im getting iburst soon and i've already bought a router for it and i see in the router's setup menu you can change the MTU.
Is this just for the router or would it apply to the iburst UTD aswell (are they the same thing)?


Also i see questions bout using Xbox live. Was wondering if they use Iburst and the 360 to connect to xbox live? i mean.. is it actually possible to use iburst to play network games on your 360?

[Local_Teddy]

hi everybody im pleading for help here, my cusin just moved in with me and he has a xbox 360 and we are having a very hard time trying to get connected to xbox live, I have a 5102G adsl Router, we plugged it in, there is a problim:
Network adapter: wired
Ip Address: confirmed
DNS: confirmed
MTU: FAILED!!!!!
OK now im not sure how to fix this, i can get into my router settings but i don't no what i have to change, im little scared to change stuff because there are other PC's connected to the router and i don't want to mess anything up for them. PLZ PLZ PLZ HELP!!!