System and method for performing cut-through forwarding in an atm network supporting lan emulation

Abstract

System and method in a network processor for performing cut-through forwarding of LANE packets without incurring the overhead associated with LANE protocol stack assisted routing. A content addressable memory (CAM) stores LEC uplink information including mapping between MAC destination addresses and VCC information. The network processor also stores LEC information table for corresponding VLAN identifiers and LECs. The LEC information table includes LEC ID information for the VLAN ID. For a LANE packet received from Ethernet and outbound to ATM destination, the network processor determines the LEC ID for the packet and then performs a CAM lookup to determine VCC information for the packet. The packet is then forwarded using the LEC ID and VCC information. For a LANE packet received from an ATM source and outbound to the Ethernet, the network processor determines the interface address of the packet. Based on the interface address, the network processor determines if the packet is a echoed or loopback packet or if its destination is the network processor itself. The packet is then routed to via the Ethernet if it is not a loopback or echo packet and the destination is not the network processor.