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Network Layer Introduction Routing protocols ICMP Network-layer functions Recall : two network-layer functions - Forwarding : move packets from routers' input to appropriate router output -> data plane - Routing : determine route taken by packets from source to destination -> control plane Two approaches to structuring network control plane - per-router control (tranditional, still popular) - lo..

IP Internet Protocol The Internet network layer - host, router network layer functions : physical layer -> link layer -> network layer ( routing protocols, IP protocol, ICMP protocol ) -> transport layer (TCP, UDP) IP datagram format - IP header : 5 x 32bits ( 5 x 4bytes = 20Bytes + options ) - IP payload : data Header component -- -- ver : IP protocol version number [ 4 bits ] -- head.len : Hea..

Input port queuing - Fabric slower than input ports combined -> queuing may occur at input queues - queuing delay and loss due to input buffer overflow! ( Ideally multiple packets can be transferred in parallel, as long as their output ports are different ) -> 이상적으로 output port 가 다른 패킷들은 동시에 전송될 수 있다. - Head- of-the-Line (HOL) Blocking : queued datagram at front of queue prevents others in queue..