Modules 8 TNE

which layer provides services to allow end devices to exchange data across networks.

are the principle network layer communication protocols.

The network layer provides services to direct the 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 routers before reaching the destination host. Each router a packet crosses to reach the destination host is called a hop.

• Routing

• Addressing End Devices

• Encapsulation

• 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. After the packet is de-encapsulated by the network layer, the resulting Layer 4 PDU is passed up to the appropriate service at the transport layer.

• De-encapsulation

• Encapsulation

• Routing

• Addressing end devices

There is no connection with the destination established before sending data packets.

Operation is independent of the medium (i.e., copper, fiber-optic, or wireless) carrying the data.

is one of the primary network layer communication protocols.

How many bytes for IPv4 packet header?

• 64 bytes

• 20 bytes

• 128 bytes

• 10 bytes

Used to detect corruption in the IPv4 header

• Header Checksum

• Protocol

• Time to Live (TTL)

• Version

Contains 4 buts binary value 0100 that identify this is an IPv4 packet