chapter 6.pdf - Network layer Chapter 6 The Network Layer...

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Network layer Chapter 6 The Network LayerThe network layer uses four basic processes: Addressing end devices- End devices must be configured with a unique IP address for identification on the network. Encapsulation - The network layer encapsulates the protocol data unit (PDU) from the transport layer into a packet. The encapsulation process adds IP header information Routing - The network layer provides services to direct packets to a destination host on another network. To travel to other networks, the packet must be processed by a router. The role of the router is to select the best path and direct packets toward the destination host in a process known as routing. A packet may cross many intermediary devices before reaching the destination host. Each router a packet crosses to reach the destination host is called a hop. De-encapsulation - When the packet arrives at the network layer of the destination host, the host checks the IP header of the packet. If the destination IP address within the header matches its own IP address, the IP header is removed from the packet.
Network Layer Protocolsthere are only two network layer protocols that are commonly implemented: Internet Protocol version 4 (IPv4) Internet Protocol version 6 (IPv6) Encapsulating IPIP encapsulates the transport layer segment or other data by adding an IP header. This header is used to deliver the packet to the destination host. The IP header remains the same from the time the packet leaves the source host until it arrives at the destination host.

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