Fig. 23.1.2 shows a use of the cloud network in describing how a gateway works. There are two networks in Fig. 23.1.2, both represented by clouds and named network 1 and network 2. A special computer called a gateway is a member of both networks so it can act as a relayer of messages sent from a computer on one network to another computer on the other network. Addresses of individual computers take the form of net number, period, computer number. The gateway has two numbers because it is on two different networks: 1.5 and 2.1.