What should my MTU size be?

[frontosa]

Hey Guys

I am on a 20mb adsl2+ connection and on a zyxel vdsl router.... My current MTU is currently on 1492 is this fine? what will be the best?

 

[$m@Rt@$$]

Hey Guys

I am on a 20mb adsl2+ connection and on a zyxel vdsl router.... My current MTU is currently on 1492 is this fine? what will be the best?

If you don't have too much experience regarding that don't change it. It will screw you over 1492 is most people's default and should be fine.

 

[Franna]

Test your xDSL settings here:
http://netalyzr.icsi.berkeley.edu/

 

[Rickster]

1492 here.

 

[PsyCLown]

I think 1500 is what it is meant to (default) be but since you are dialing a PPPoE account it takes 8 bits for the Ethernet something or other hence why it is 1492.

I remember reading something like that somewhere. Perhaps someone can confirm this and explain it a bit more in detail?

 

[Pada]

Here are some cryptic info about overheads associated with ADSL and TCP/IP: http://maxolasersquad.com/network/chapter18.html

So you basically start at an MTU 1500 on Ethernet level, then PPPoE takes up 8 bytes, which is why you need to set your MTU to 1492.

You can always go and play around with your computer's MTU sizes instead, because it could be that your computer is sending TCP packets of 1500 bytes, which then gets broken up into one of 1492 bytes and another one of 8 bytes by your ADSL modem...

 

[patrick123]

If you are using VPN the setting might have to adjusted from 1492 even further to cater for the VPN overheads as well. (Usually this can be achieved in the VPN config file)

 

[noswal]

This should help in explanation http://www.dslreports.com/faq/6266