Is there a WAN accelerator in the path?   (Bluecoat, Riverbed, etc)  Did you run the ping test from both ends?   From Primary to dr and from dr to primary? 
I assume I am getting re-transmissions during replication because the network between my orginating group and the target group is not all Jumbo frames/Flow control etc? I get a steady rate of between 1.1 and 1.3% during the replication....if it goes beyond an hour (rare).  The replication does finish with out issue or it does not say it did not. I am just wondering if there is something I can do to prevent this beyond making sure the whole path (iSCSI VLAN, Data Center LAN, WAN between sites, recieving side Data Center LAN, recieving side iSCSI VLAN) is set per EQL recomendations (jumbo frames, flow control, unicast....etc)??   Thanks for any help!
Re-transmissions only during replication