How is MTU size determined for File and Print Sharing ?

How is MTU size determined for File and Print Sharing ?

We are having some performance problems across our VPN tunnels. One of the
areas we are investigating is MTU size. Does anyone know how I can determine
the size of the packets that our servers are producing ?

Windows 2000 sp3 and sp4 servers
and
Windows 2003 sp2 servers

Thanks,

Ken

If you need to be 100% sure, I eould use a packet analyzer like
Ethereal, or Microsoft's Network Monitor.

Ken Hack wrote:
> How is MTU size determined for File and Print Sharing ?
>
> We are having some performance problems across our VPN tunnels. One of the
> areas we are investigating is MTU size. Does anyone know how I can determine
> the size of the packets that our servers are producing ?
>
> Windows 2000 sp3 and sp4 servers
> and
> Windows 2003 sp2 servers
>
> Thanks,
>
> Ken

Sorry for the delay in getting back but thanks for the info

"DKMortensen" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> If you need to be 100% sure, I eould use a packet analyzer like
> Ethereal, or Microsoft's Network Monitor.
>
> Ken Hack wrote:
>> How is MTU size determined for File and Print Sharing ?
>>
>> We are having some performance problems across our VPN tunnels. One of
>> the
>> areas we are investigating is MTU size. Does anyone know how I can
>> determine
>> the size of the packets that our servers are producing ?
>>
>> Windows 2000 sp3 and sp4 servers
>> and
>> Windows 2003 sp2 servers
>>
>> Thanks,
>>
>> Ken
>

by default MTU is 1500 for all ethernet connections. If you are doing
traffic over a VPN connection, you should lower that, maybe to 1400 to avoid
fragmentation.
http://www.winguides.com/registry/display.php/280/


--
Regards,
Andrei Ungureanu
www.eventid.net
Test our new EventReader!
http://www.altairtech.ca/eventreader...lt2.asp?ref=au

"Ken Hack" <(E-Mail Removed)> wrote in message
news:%(E-Mail Removed)...
> Sorry for the delay in getting back but thanks for the info
>
> "DKMortensen" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) oups.com...
>> If you need to be 100% sure, I eould use a packet analyzer like
>> Ethereal, or Microsoft's Network Monitor.
>>
>> Ken Hack wrote:
>>> How is MTU size determined for File and Print Sharing ?
>>>
>>> We are having some performance problems across our VPN tunnels. One of
>>> the
>>> areas we are investigating is MTU size. Does anyone know how I can
>>> determine
>>> the size of the packets that our servers are producing ?
>>>
>>> Windows 2000 sp3 and sp4 servers
>>> and
>>> Windows 2003 sp2 servers
>>>
>>> Thanks,
>>>
>>> Ken
>>
>
>

I am trying to determine which setting to use to optimize this and then how
to monitor the performance change. I think I have 2 choices to optimize,
one is to set the MTU at 1472 at which level packets no longer fragment
across the VPN, but reduces performance for LAN connections or Enabling
Path MTU Discovery on Windows (EnablePMTUDiscovery) to optimize both. But in
the case of EnablePMTUDiscovery does this not increase overhead and does it
really work ?

Thanks,

Ken


"Andrei Ungureanu" <contact me via www.itboard.ro> wrote in message
news:%23A7Ur%(E-Mail Removed)...
> by default MTU is 1500 for all ethernet connections. If you are doing
> traffic over a VPN connection, you should lower that, maybe to 1400 to
> avoid
> fragmentation.
> http://www.winguides.com/registry/display.php/280/
>
>
> --
> Regards,
> Andrei Ungureanu
> www.eventid.net
> Test our new EventReader!
> http://www.altairtech.ca/eventreader...lt2.asp?ref=au
>