The FEB is a control board for the M5 and M10 routers. The FEB communicates with the Routing Engine using a dedicated 100-Mbps link that transfers routing table data from the Routing Engine to the forwarding table in the Internet Processor II application-specific integrated circuit (ASIC). The link is also used to transfer routing link-state updates and other packets destined for the router from the FEB to the Routing Engine.The M7i Forwarding engine is a spare option with built-in Adaptive Services Module (one of the following services included with purchase: S-ES-BB, S-NAT-FW-SINGLE-BB, S-NAT-FW-MULTI-BB and S-ACCT-BB).