Output Ports switch queuing: data link buffer processing fabric line management (protocol, termination decapsulation) Buffering required when datagrams arrive from fabric faster than the transmission rate Scheduling discipline chooses among queued datagrams for transmission Network Layer 4-27 Network Layer 4-27 Output Ports  Buffering required when datagrams arrive from fabric faster than the transmission rate  Scheduling discipline chooses among queued datagrams for transmission