[Sorry about the null reply.] On 7/24/2014 11:51 AM, Zach Hill wrote:

Also just to reiterate I would lean more heavily on something fishing in the WAN cloud if all traffic from Site 1 to Site 2 were not seeing tcp window scaling properly, however it's only for Server A that is seeing this. Server A is able to properly TCP window scale for any local traffic.

I don't have enough data to make a detailed guess, but the broad brush is that on A, B, the router A talks to, the router B talks to, or a router in the path has got an ACL that knows A's IP or MAC address that has an unplanned affect. I'd turn off all ACL's on the path and check again and if clear, turn them back on one at a time. It is not going to be something you intended to do. One other possibility--traffic not routed by most direct, fire-wall-free route, but being detoured through a firewall. -- Requiescas in pace o email Two identifying characteristics of System Administrators: Ex turpi causa non oritur actio Infallibility, and the ability to learn from their mistakes. (Adapted from Stephen Pinker)