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

Mayh3m said:
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
Click to expand...
The highest on PPPoE is actually 1492 == 1500 - 8.
 
back home. It's true. My cutoff is now 1324. MTU = 1352. Back to the drawing board. :mad:
 
My IPCOP has also been coming up with different MTU sizes.

It seems to negotiating it or getting it from the modem.
 
Best info on MTU

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...
 
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.
 
NTC said:
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
Click to expand...
Ethernet - because the USB cable isn't long enough.
NTC said:
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...
Click to expand...
Both - but mainly because I was unsure.
 
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...
 
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.
 
Discovering MTU Settings

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
 
Thanks a lot, That works!!!!

I'll let Shaun know to get some sleep because that's the one he gave me!!!
 
what is an acceptable ping time

following on my previous post: what should I be looking for as a good ping time?
 
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.
 
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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
 
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).
 
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
 
[post=216568]
seburn said:
..., 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!
...
Click to expand...
[/post]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...
 
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.
 
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
 
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