ost to the other located in different networks. 2. Logical Addressing  In order to identify each device on internetwork uniquely, the network layer defines an addressing scheme. The sender & receiver’s IP address is placed in the header by the network layer. Such an address distinguishes each device uniquely and universally. - Segment in the Network layer is referred to as Packet.  - Network layer is implemented by networking devices such as routers 3. Routing The network layer protocols determine which route is suitable from source to destination. This function of the network layer is known as routing. 4. Fragmentation and Reassembly The network layer must send data down to the data link layer for transmission. The data or information that the network layer receives is in the form of a packet and the data that data link layer forwards is called a frame. The network layer has the responsibility of Fragmentation and reassembly because some data link layer technologies have limits on the length of any message that can be sent. If the packet of data that the network layer has to send is too large, the network layer must break the packet up, send each packet to the data link layer, and then have pieces reassembled once they arrive at the network layer on the destination system.