• ACK—acknowledgment

• Cat 5—Category 5

• Cat 5 E—Category 5 Enhanced

• CDMA—code division multiple access

• coax—coaxial cable

• CTS—Clear to Send

• DDOS—distributed denial of service

• GSM—Global System for Mobile Communication

• IP—Internet Protocol

• LAN—local area network

• MAC—media access control

• NAK—negative acknowledgment

• OSI—Open Systems Interconnect

• PAN—personal area network

• PARC—Palo Alto Research Center

• RJ-45—registered jack 45

• RTS—Request to Send

• TCP—Transmission Control Protocol

1. R1.     For each of the six types of attacks, give an example of how the attack occurs on a network.

2. R2.     Summarize and compare the three techniques for transmitting information on communications networks.

3. R3.     Explain how a typical acknowledgment protocol works, and why it pro-vides reliable data transmission. How can the protocol produce duplicate packets?

4. R4.     Briefly describe the different types of Ethernet LAN systems in use.

5. R5.     Describe the fields in an Ethernet packet.

6. R6.     Explain how collisions are handled on a wireless LAN. Compare it to how collisions are handled on a wired Ethernet LAN.

7. R7.     Explain the relationship between layers of software in the network protocol stack and headers appearing in a packet.

8. R8.     List the seven layers in the OSI protocol model in order from lowest to highest.

9. R9.     Give examples of client/server and peer-to-peer network applications.

10. R10.   Describe a typical approach to resource sharing on a network. What is the delegation problem?

Note: Some exercises are marked with restrictions. Exercises marked “Small LANs only” should only be performed on a small LAN where the student has permission to perform the assignment, often a household LAN.

1. E1.     (Small LANs only.) Identify a small, local network that you use. Ideally, it should be a household network with at least one node. Determine the node’s make and model. Visit the manufacturer’s website and determine whether it provides switch, hub, and/or wireless interconnection between endpoints (switches and hubs are described in Section 10.4). Which is it?

2. E2.     Using a host computer connected to a network, determine the following:

   1. Manufacturer of the host’s equipment

   2. Host’s MAC address

   3. The vendor who assigned the MAC address. (Determine this from the “vendor unique address” in the MAC address.)

3. E3.     (Small LANs only.) Identify a small, local network that you use. It should contain only a few hosts and no more than two network nodes. Do the following:

   1. Identify a physical perimeter that provides some protection to that network.

   2. Draw a diagram of the hosts, nodes, and links.

4. E4.     Given the maximum size of an Ethernet packet (Figure 10.13), calculate the packet efficiency.

5. E5.     Many early timesharing computers provided connections across LANs and other networks. Many of these computers accepted data typed at a keyboard one character at a time. Thus, many of the messages sent to these systems contained no more than 1 byte’s worth of actual data, after all headers were removed. If we transmit the smallest possible Ethernet packet, and it only contains 1 byte of data, what is the packet efficiency?