Figure 1-5: Ethernet Switch Operation C3-is out Port 15 D4-47-55-C4B6-F9 Switching Table Port Host Switch 10 A1-44-D5-1F-A 13 B2-CD-13-5B- 2 1532D-5538A94F 16 D4-47-55-C4-B6-F9 Port 15 3 Frame to c3 Frame to c3 A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65 C3-2D-55-3B-A94F A1-sends a frame to c3 Switch sends frame to c3-
11 Figure 1-5: Ethernet Switch Operation A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65 Switch D4-47-55-C4-B6-F9 C3-2D-55-3B-A9-4F Port 15 Frame to C3… A1- sends a frame to C3- Frame to C3… Switch sends frame to C3- Switching Table Port Host 10 A1-44-D5-1F-AA-4C 13 B2-CD-13-5B-E4-65 15 C3-2D-55-3B-A9-4F 16 D4-47-55-C4-B6-F9 15 C3-2D-55-3B-A9-4F C3- is out Port 15 1 2 3
Figure 1-3: Elements of a Network Client application 消息(帧) Server Application Message(Frame) Access Switch Line 2 Client Server 6 Computer Wireless access Switch Points connect unk 3 Wireless Stations Line to switches Client Switch Outside World Wireless Access Point Router 12
12 Figure 1-3: Elements of a Network Wireless Access Point Mobile Client Router Outside World Server Computer Client Computer Switch 1 Switch 2 Switch 3 Switch 4 Message (Frame) Access Line Trunk Line Client Application Server Application 6. Wireless Access Points Connect Wireless Stations to Switches 消息（帧）
Figure 1-3: Elements of a Network Client application Server Application Message(Frame) Access Switch Line 2 Client Server Computer Routers connect networks Computer Switch to the outside world Trunk treated just like computers Line in single networks Mobile Client witch Outside Yes, single networks can4 World contain routers uuv Router 13
13 Figure 1-3: Elements of a Network Wireless Access Point Mobile Client Router Outside World Server Computer Client Computer Switch 1 Switch 2 Switch 3 Switch 4 Message (Frame) Access Line Trunk Line Client Application Server Application 7. Routers connect networks to the outside world; Treated just like computers in single networks Yes, single networks can contain routers
Figure 1-3: Elements of a Network Client Applicatio erver Application 8. Access Lines Connect Computers Access to switches(接入线) SWItch Line 2 Client Server Computer Computer Switch Switch Trunk 3 Line Mobile Switch Outside 9. Trunk Lines Connect World Switches to switches and Switches to Routers(中继线) Router 14
14 Figure 1-3: Elements of a Network Wireless Access Point Mobile Client Router Outside World Server Computer Client Computer Switch 1 Switch 2 Switch 3 Switch 4 Message (Frame) Access Line Trunk Line Client Application Server Application 8. Access Lines Connect Computers to Switches （接入线） 9. Trunk Lines Connect Switches to Switches and Switches to Routers（中继线）
Figure 1-4: Packet Switching and Multiplexing (多路复用) Breaking Communications into Small Messages is called Packet Switching, even if the Messages are frames AC AC Client AC Server AC ComputerA ACBDAC Computer C Trunk Line BD Access BD/LIne Multiplexed Packets BD Share Trunk Lines Mobile client So Packet Switching Router D Computerb Reduces the Cost of Trunk Lines 15
15 Figure 1-4: Packet Switching and Multiplexing （多路复用） Client Computer A Mobile Client Computer B Router D Server Computer C AC AC AC AC AC AC BD BD BD BD Access Line Trunk Line Multiplexed Packets Share Trunk Lines So Packet Switching Reduces the Cost of Trunk Lines Breaking Communications into Small Messages is Called Packet Switching, even if the Messages are Frames