Input Port Functions lookup, data link forwarding line switch processing termination (protocol, fabric decapsulation) queueing Physical layer: bit-level reception Data link layer: Decentralized switching: e.g.,Ethernet given datagram dest.,lookup output port see chapter 5 using forwarding table in input port memory goal:complete input port processing at line speed' queuing:if datagrams arrive faster than forwarding rate into switch fabric Network Layer 4-22Network Layer 4-22 Input Port Functions Decentralized switching:  given datagram dest., lookup output port using forwarding table in input port memory  goal: complete input port processing at ‘line speed’  queuing: if datagrams arrive faster than forwarding rate into switch fabric Physical layer: bit-level reception Data link layer: e.g., Ethernet see chapter 5