Site To Site VPN, MTU
Posted on 2007-10-11
I have a site to site vpn set up from a Netgear to a cisco router. THe vpn is stable, i can ping, ftp, telnet, rdp, etc down the tunnel.
I have a NAS device at one end which i would like to be able to copy NFS shares to overnight, However they wont copy. The file writes to the disk then hangs and lists the share as 0 bytes.
I can transfer from Windows to NAS and back the other way, however the speed is not great. I can also tranfer from window sto windows.
I can browse the NFS shares on the NAS from the linux box but i cant transfer data.
The MTU is set to 1500 on both lans. I can ping with MTU of 1472 from windows to linux at one side hovever not back the other way.
When i ping windows to windows, or windows to NAS/NFS with 1473 i get the reply i would expect
"packet needs to be fragmented but DF set"
However when i drop the packet size to 1472, the ping request times out. This is the same to 1416. It is not untill 1415 that i get a ping response.
I am confused as to why this would happen? could this be casusing my problems due to fragemented packets? Would lowering the MTU fix this problem
thanks in adavance