Chapter 4 - Networking and the Internet - Section 4.4 - Internet Protocols - Questions & Exercises - Page 203: 1

The link layer receives the message and hands it to the network layer. The network layer determines the direction in which the message should be forwarded and gives the message back to the link layer to be forwarded. The higher layers are not required for routing, although advanced routers may use the transport or application layers to provide additional services such as selective filtering or tiered quality of service.

The link layer receives the message and hands it to the network layer. The network layer determines the direction in which the message should be forwarded and gives the message back to the link layer to be forwarded. The higher layers are not required for routing, although advanced routers may use the transport or application layers to provide additional services such as selective filtering or tiered quality of service.