Optimizing MTU for NFS
Posted on 2007-10-15
I have been configuring a site to site VPN using a cisco router (with the help of some experst on EE)
I now have the vpn tunnel functioning and stable, the networks are also routing fine. I have had to lower the MTU settings to get the data trasfer to work.
My quiestion is that is there a way of optimising this especially for NFS transfer? or is it more trial and error.
I have been changing MTU and MSS values and the trasfer does work, however it appears to stall and then retry, so the amount of data jumps in big blocks. It seems as if the retry time gets larger and larger untill it hangs completely.
We have found that at different MTU settings the data only writes the file header and hangs, other times it stops at 800k?
I can ping the down the VPN with packet sizes of upto 1472. I am using a cisco 878 on an SDSL line, to a Netgear router. We are copying from a Redhat server to a Ready NAS device.