VPN connection problem

[exactiv]

Hi there.

I have two D-Link DFL700 VPN firewalls, one in our HQ, one in a branch office.

They both have a VPN connection configured, and they connect successfully.

The problem is, if I try to copy a file from a machine at the branch office, to the file server in the HQ the connection is very poor. Doing a simple ping test shows significant packet loss from the branch to the HQ.
BUT... If I do the same test from the HQ to the branch the connection is perfect, no packet loss. If I copy a file from the HQ to a machine in the branch office it works perfectly.

Any help or suggestions would be most appreciated.

 

[Serbtastic]

What is the upload speed at the branch office? And how many concurrent users? If you try this test at off hours from the branch office (when there are no users around) do you get better speeds?

 

[sah2129]

Barring an ISP problem or diffeences between upstream and downstream speeds there are two things I would look at. First I would check the port speed and duplex settings of your uplink. If that's not it, I would also look into the MTU settings on the VPN routers. I have had issues where a router in the middle did not allow the fragmentation of packets. Try setting the MTU on the external interfaces to 1476. That setting will reserve enough room for the IPSec header to be added without forcing the packet to be fragmented.