Figure 1-3: Elements of a Network Client application Server Application Message(Frame) Client Server Computer Computer Switch Computers(and routers) 3 usually communicate Mol by sending messages Cli called frames Outside World Wireless Access point Router 88 Figure 1-3: Elements of a Network Wireless Access Point Mobile Client Router Outside World Server Computer Client Computer Switch 1 Switch 3 Message (Frame) Trunk Line Client Application Server Application 4. Computers (and routers) usually communicate by sending messages called frames