1.2.1 Relay function

The Switch forwards received IP packets based on routing tables. This forwarding processing can be roughly divided into the three functions described below.

• Communication protocols

  Communication protocols are used to send and receive IP packets at the IP layer.

• Forwarding function

  The forwarding function forwards IP packets based on routing tables.

• Route control function

  The route control function exchanges routing information with other routers, determines routes, and creates routing tables.

The following figure provides an overview of IPv4 routing.

Figure 1-2: Introduction to IPv4 Routing Features