We have two networks, each with an MX100 acting as a one-arm VPN concentrator. These are each behind a network with an MX100 acting as a edge NAT Firewall. When sending traffic between the two concentrators, the traffic is being throttled to about 70 Mbps on a 750 Mbps synchronous circuit. However when I use an MX100 as a NAT Concentrator on one end, the traffic is as expected (roughly 350 Mbps based on other traffic). Has anyone ever run into a simlier issue where VPN traffic is being throttled?