This is kind of a WAN issue and kind of a VPN issue, so hopefully I'm posting this in the right area.
I have two sites:
- Site A: Cisco ASA 5510 with 6Mb connection to the Internet
- Site B: Cisco 2801 with T1 connection to the internet
Site A and B are connected with a L2L IPSEC VPN.
The problem I'm having is that whenever a sustained data transfer is sent over the VPN (from Site A to B) the bandwidth usage hits the roof and the packet latency jumps from about 8ms to 400ms.
I've read about this sort of thing happening with an inappropriately sized TCP Window, however I don't see any options on the ASA to adjust the TCP Window size. I kind of think it has something to do with thedisparate Internet connection speeds on both ends but there doesn't seem to be any bandwidth-shaping options for the VPN connection on the ASA.
At Site B I've replace the router (Cisco 1721 with a 2801) and the CSU/DSU WIC in the routers to no avail.
Any ideas or suggestions would be appreciated - Thanks!