Chapter 10 Connecting Computers

FIGURE 10.0.F01: The Xerox Alto. Photographed by Dr. Richard Smith at the Computer History Museum, California

FIGURE 10.0.F02: Physical protection of a LAN.

FIGURE 10.0.F03: A mid-20th century telegram from New York to Fargo. Courtesy of Dr. Richard Smith

FIGURE 10.0.F04: A clerk connects a teletype to a network link. Library of Congress, Prints & Photographs Division, FSA/OWI Collection, LC-USW3-032342-E

FIGURE 10.0.F05: Teletype clerks check a message on paper tape. Library of Congress, Prints & Photographs Division, FSA/OWI Collection, LC-USW3-032342-E

FIGURE 10.0.F06: A phone call makes a circuit between two phones.

FIGURE 10.0.F07: A packet network sends messages a packet at a time.

FIGURE 10.0.F08: Digital circuits self-correct minor signal glitches.

FIGURE 10.0.F09: Amplitude and wavelength.

FIGURE 10.0.F10: AM and FM waveforms.

FIGURE 10.0.F11: Basic packet format.

FIGURE 10.0.F12: A sequence diagram showing a simple ACK protocol.

FIGURE 10.0.F13: A delayed ACK yields a duplicated packet.

FIGURE 10.0.F14: The Ethernet LAN connects hosts on a bus.

FIGURE 10.0.F15: RJ-45 connectors on an Ethernet hub. Courtesy of Dr. Richard Smith

FIGURE 10.0.F16: Ethernet packet (“frame”) contents.

FIGURE 10.0.F17: MAC address format.

FIGURE 10.0.F18: Windows command to retrieve host addresses.

FIGURE 10.0.F19: Wireless protocol for avoiding collisions.

FIGURE 10.0.F20: “Hourglass” structure of network protocols.

FIGURE 10.0.F21: Each protocol layer adds a header to the packet.

FIGURE 10.0.F22: Protocol layers in ordering pizza.

FIGURE 10.0.F23: Protocol software layers on a simple LAN.

FIGURE 10.0.F24: A client requests service and the server replies.

FIGURE 10.0.F25: A directly connected printer versus sharing one across a LAN.

FIGURE 10.0.F26: Sharing files on a LAN.

FIGURE 10.0.F27: One way to delegate access to a file server.