My ISP network is core/agg mpls rings of MX960's and ACX5048's....960's connect 40 gig to 5048's using the MPC7E-MRATE in the MX960. Seems good to me so far.... Also use MX960 40 gig on MPC7E-MRATE to DC/CDN deployments of QFX5120's (pure Ethernet tagging). -Aaron