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Transcript
Chapter 8 Backbone Networks True-False Questions The following are possible True/False questions for tests. The statement is given and the answer is provided . The level of difficulty (easy, moderate, difficult) and the page number(s) relevant to the topic are also furnished. 1. A backbone network is a high-speed network that connects many networks 2. Answer: True Difficulty: Easy Reference: p. 265 Backbone networks typically use lower speed circuits to interconnect a series of LANs and provide connections to other backbone networks. 3. Answer: False Difficulty: Easy Reference: p. 265 A backbone network that connects many backbone networks spanning several buildings at a single location is often called an Internet backbone. 4. Answer: False Difficulty: Easy Reference: p. 265 One basic component of a backbone network is the hardware device that connects other networks to the backbone. 5. Answer: True Difficulty: Easy Reference: p. 265 Switches, routers, and gateways devices that can connect networks to the BN. 6. Answer: True Difficulty: Easy The cable to connect BNs is usually twisted pair. 7. Answer: False Difficulty: Easy Reference: p. 265 A hardware device that operates at the application layer is a router. 8. Answer: False Difficulty: Moderate Routers can only connect the same type of cable. 9. Answer: False Difficulty: Easy Reference: p. 266 Routers use network layer address to forward packets between network segments. 10. Answer: True Difficulty: Moderate Routers operate at the application layer Reference: p. 265 Reference: p. 266 Reference: p. 266 11. Answer: False Difficulty: Moderate Reference: p. 266 Routers connect two or more network segments that use the same or different data link protocols, but the same network protocol. 12. Answer: True Difficulty: Moderate Reference: p. 266 One advantage of a router is that it can choose the “best” route between networks when there is a choice. Answer: True Difficulty: Easy Reference: p. 267 13. 14. One difference between a switch and a bridge is that a router will only process messages addressed to the router, while a switch processes all messages.. Answer: True Difficulty: Easy Gateways are simpler than routers. Reference: p. 267 15. Answer: False Difficulty: Easy Reference: p. 268 Gateways connect two or more networks that use the same or different data link and the same or different network protocols. 16. Answer: True Difficulty: Moderate Reference: p. 268 One of the least common uses of gateways is to enable LANs that use TCP/IP and Ethernet to communicate with mainframes that use other protocols. 17. Answer: False Difficulty: Moderate Reference: p. 268 The terms for hardware devices, such as routers and gateways, are interchangeable among vendors. 18. Answer: False Difficulty: Moderate Reference: p. 269 Layer-3 switches switch messages based on their data link layer address. 19. Answer: False Difficulty: Easy Reference: p. 269 Routed backbones are switches that move packets based on data link layer addresses. 20. Answer: False Difficulty: Moderate The distribution layer of a backbone connects the LANs together 21. Reference: p. 271 Answer: True Difficulty: Easy Reference: p. 270 The primary advantage of a routed backbone is that it clearly segments each part of the network connected to the backbone because each segment has its own subnet addresses that can be managed separately. 22. Answer: True Difficulty: Moderate Reference: p. 272 One advantage of a routed backbone is that is requires little management. 23. Answer: False Difficulty: Easy Reference: p. 273 A routed backbone tends to be used more for large networks than VLANs. 24. Answer: False Difficulty: Easy A collapsed backbone uses a bus topology 25. 26. Reference: p. 280 Answer: False Difficulty: Easy Reference: p. 274 A room that contains a rack of equipment for a rack-based collapsed backbone is also called the main distribution facility (MDF) or central distribution facility (CDF). Answer: True Difficulty: Easy Reference: A key advantage of a chassis-based collapsed backbone is its flexibility. Answer: True Difficulty: Easy Reference: p. 275 p.279 27. A VLAN network assigns computers to LAN segments by hardware. 28. Answer: False Difficulty: Easy Reference: p. 280-281 A VLAN requires the computer manager to reconfigure the physical cables to the switch if a computer is moved from one port to another port on a switch. 29. Answer: False Difficulty: Moderate Reference: p. 280 VLANs provide faster performance compared to switched, collapsed or routed backbone architectures. 30. Answer: True Difficulty: Easy Reference: p. 280 With respect to high-speed networks, the acronym, ATM, refers to Automatic Teller Machines 31. Answer: False Difficulty: Easy Reference: p. 285 ATM is a layer 3 technology that also includes layer 2 and layer 1 technologies as part of its specification Answer: True Difficulty: Moderate ATM uses variable length cells. Reference: p. 285 32. Reference: p. 286 33. Answer: False Difficulty: Easy ATM is connection oriented. Answer: True Difficulty: Easy ATM uses permanent addresses. Reference: p. 286 34. 35. Answer: False Difficulty: Easy Reference: p. 286 A switched virtual circuit once defined is used for the current and future transmissions between two computers. Answer: False Difficulty: Easy Reference: p. 286 MULTIPLE CHOICE The following are possible multiple-choice questions for tests. The question is posed and the answer is provided under the choices. The level of difficulty (easy, moderate, difficult) and the page number(s) relevant to the topic is also furnished. 1. 2. 3. 4. Which of the following is not true about backbone networks? a. They may also be called enterprise networks if they connect all networks within an organization. b. They typically connect many networks, including LANs. c. They typically provide connections to other BNs, WANs, MANs, and the Internet. d. They may also be called campus networks if they connect many BNs spanning several buildings as a single location. e. They tend to use lower speed circuits than LANs. Answer: E Difficulty: Moderate Reference: p. 265 Which of the following is not a type of hardware device that can be used to interconnect networks? a. switches b. routers c. multiprotocol routers d. ‘dumb’ terminals e. gateways Answer: D Difficulty: Moderate Reference: p. 265-269 Switches: a. learn addresses by reading the source and destination addresses b. operate at the physical layer only c. connect two ore more network segments that use different data link protocols d. connect two or more network segments that use different network protocols e. have become more popular than layer 2 switches Answer: A Difficulty: Moderate Reference: p. 266 Routers: a. operate at the application layer b. operate only at the physical layer c. cannot connect two or more networks that use the same type of cable d. may also be called TCP/IP gateways e. operate only at the data link layer Answer: D Difficulty: Moderate Reference: p. 66 5. 6. 7. 8. 9. 10. Which of the following is not a way that a router differs from a switch? a. routers can connect two or more networks that use the same data link protocol b. routers only process messages that are specifically addressed to it c. routers operate at the network layer d. routers perform more processing on each message than switch e. routers can choose the “best” route between networks for forwarding a packet Answer:A Difficulty: Difficult Reference: p. 266 Gateways: a. process all messages, even if the messages are not explicitly addressed to them b. can translate one network protocol into another c. are less complex than bridges d. are most often used as the interface between two or more networks that have similar data link and network layer protocols e. cannot perform a routing function Answer: B Difficulty: Moderate Reference: 268 ____________ routers can understand different network layer protocols. a. Multiprotocol b. 3270 emulation c. ASCII/EBCDIC d. Asynchronous e. BridgeAnswer: A Difficulty: Easy Reference: p. 269 Which of the following is not true about Layer-3 switches? a. They switch messages based on their IP address. b. They can be used in place of routers. c. They function faster than routers. d. They have more simultaneously active ports than routers. e. They can only switch messages based on their data link layer addresses. Answer: E Difficulty: Moderate Which of the following devices is the most complex? a. Gateway b. Router c. Layer 3 switches d. Switch e. Multiprotocol router Reference: p. 269 Answer: A Difficulty: Moderate Reference: p. 267 Which of the following is not a fundamental backbone network architecture? a. Bridged backbone b. Virtual LAN c. Hubbed backbone d. Collapsed backbone e. Routed backbone Answer: C Difficulty: Easy Reference: p. 270 11. 12. 13. 14. 15. __________ refers to the way in which backbone interconnects the network attached to it and how it manages the way in which packets from one network move though the backbone to other networks. a. Traffic architecture b. Network design c. Backbone architecture d. Distribution layer e. Core layer Answer: C Difficulty: Moderate Reference: p. 270 Which of the following is not a technology layer that is considered when designing backbone networks? a. access layer b. distribution layer c. decentralized layer d. core layer e. none of the above Answer: C Difficulty: Moderate A subnetted or hierarchical backbone can also be called: a. Bridged backbone b. Virtual LAN c. Hubbed backbone d. Collapsed backbone e. Routed backbone Reference: p. 270 Answer: E Difficulty: Moderate Reference: p. 271 _________ move packets along the backbone based on their network layer address. a. Bridged backbones b. Hubbed backbones c. Multistation access unit backbones d. Routed backbones e. NIC backbones Answer: D Difficulty: Moderate Reference: p. 271 Routed backbones: a. require a lot of management b. are not susceptible to time delays c. use data link layer addresses to move packets that leave the subnet d. require only a few set of TCP/IP addresses e. don’t need much time to establish separate subnet addresses for each LAN Answer: A Difficulty: Moderate Reference: p. 273 16. 17. 18. 19. 20. A _____________ type of BN segments (each of which has a special set of subnet addresses that can be managed by different network managers) each part of the network connected to the backbone. a. bridged backbone b. virtual LAN c. hubbed backbone d. collapsed backbone e. routed backbone Answer: E Difficulty: Moderate Reference: p. 271-273 A __________ type of BN has a star topology with one device, such as a switch, at its center. a. Bridged backbone b. Virtual LAN c. Hubbed backbone d. Collapsed backbone e. Routed backbone Answer: D Difficulty: Easy _________ have no backbone cable. a. Collapsed backbones b. Cloud routed backbones c. Hubbed backbones d. Bridged backbones e. Multistation access unit backbones Answer: A Difficulty: Easy Collapsed backbone networks: a. always use a ring topology b. are the least common type of BN used in one building c. use a star topology with one device, usually a switch d. have a great deal of cable in their backbones e. tend to have less cable, but more network devices Reference: p. 274 Reference: p. 274-275 Answer: C Difficulty: Moderate Reference: p. 274 Which of the following is an advantage of the traditional BN approach over collapsed backbone design? a. throughput is much higher in a traditional design BN b. traditional design BNs require far fewer networking devices c. traditional design BNs have much simpler network management d. much more cable is used in traditional design backbone networks e. if one networking device fails, the entire BN does not fail Answer: E Difficulty: Moderate Reference: p. 275 21. 22. 23. 24. 25. Which of the following is not true about collapsed backbones? a. performance is improved over traditional (bridged or routed) backbone networks b. each connection into the switch is a separate point-to-point circuit which supports simultaneous access by the LANs connected to the switch c. there are many more networking devices in a collapsed backbone network d. if the switch fails, so does the entire backbone network e. the backbone essentially exists in the switch; there is no backbone cable Answer: C Difficulty: Moderate Reference: p. 274-275 A rack-based collapsed backbone: a. places all network devices for one part of the building physically in the same room, often in a rack of equipment b. has an advantage of requiring less cable c. makes it more difficult to move computers from one LAN to another d. means that network capacity is always tied to the physical location of the computers e. is harder to maintain and upgrade than a BN that is not rack-based Answer: A Difficulty: Moderate Reference: p. 275 Associated with a rack-based collapsed backbone, MDF is an acronym for: a. multi-station device foundation b. main distribution facility c. manual data frequency d. multiplexer downstream flow e. maximum data facility Answer: B Difficulty: Moderate Reference: p. 275 A _____________ type of BN is a new type of LAN/BN architecture made possible by intelligent, high speed switches that assign computers to LAN segments via software, rather than by hardware. a. Bridged backbone b. Virtual LAN c. Hubbed backbone d. Collapsed backbone e. Routed backbone Answer: B Difficulty: Easy Reference: p. 280 Port-based VLANs use the __________ layer port number to form the VLAN groups. a. physical b. data link c. network d. transport e. application Answer: A Difficulty: Easy Reference: p. 282 26. 27. 28. 29. 30. 31. MAC-based VLANs use the _________ layer address to form the VLAN groups. a. physical b. data link c. network d. transport e. application Answer: B Difficulty: Easy Reference: p. 282 IP-based VLANs use the _______ layer address to form the VLAN groups. a. Physical b. data link c. network d. transport e. application Answer: C Difficulty: Easy Reference: p. 282 Policy-based VLANs use the _______ layer address to form the VLAN groups. a. physical b. data link c. network d. transport e. application Answer: E Difficulty: Easy Which of the following can be used for network capacity allocation? a. port-based VLANs b. MAC-based VLANs c. IP-based VLANs d. application based VLANs e. FDDI Reference: p. 282 Answer: D Difficulty: Moderate Reference: p. 282 Which IEEE standard inserts a 16-byte VLAN tag into a normal Ethernet packet? a. 802.11 b. 802.5 c. 803.3 d. 802.1q e. 802.11g Answer: D Difficulty: Moderate Reference: p. 283 Which of the following is not a way in which computers attached to a VLAN switch can be assigned to the specific virtual LANs inside them? a. IP-based b. Port-based c. MAC-based d. ATM-based e. Application-based Answer: D Difficulty: Moderate Reference: p. 280-283 32. 33. 34. 35. 36. Which of the following is not true about multi-switch VLANs? a. Several switches are used to build a VLAN b. The switches in the VLAN can send packets among themselves in a way that identifies the VLAN to which the packet belongs. c. In some multi-switch VLANs, the Ethernet packet is modified based on the emerging IEE 802.1q standard. d. In some multi-switch VLANs, a new VLAN packet encapsulates the Ethernet packet. e. All of the above are true statements. Answer: E Difficulty: Moderate Reference: p. 283 Which of the following is not true with respect to ATM? a. It uses fixed length packets, or cells. b. It is also known as Cell Relay. c. It provides no error correction to user data. (that is left to software at the source and destination) d. It is not a switched network. e. It uses a different type of addressing from traditional data link protocols because it uses virtual circuit identifiers. Answer: D Difficulty: Moderate ATM uses _______ -byte cells. a. 39 b. 44 c. 48 d. 53 e. 34 Reference: p. 286 Answer: D Difficulty: Moderate Reference: p. 286 The header of an ATM cell is comprised of _____ bytes of address and control information, such as Quality of Service. a. 3 b. 5 c. 35 d. 48 e. 53 Answer: B Difficulty: Moderate Reference: p. 286 With ATM, The path defined between sender and receiver, which is used for communication is called a ____________. a. route b. virtual circuit c. ATM path d. VLAN e. ATM LANE Answer: B Difficulty: Easy Reference: p. 286 37. 38. 39. 40. 41. 42. ATM is __________ so that all packets travel in order through the virtual circuit. a. synchronous b. connection-oriented c. sequence multiplexed d. time multiplexed e. connectionless Answer: B Difficulty: Easy Which of the following is not an ATM class of service? a. variable bit rate – real time b. variable bit rate – non-real time c. unspecified bit rate d. iso-synchronous bit rate e. available bit rate Reference: p. 286 Answer: D Difficulty: Moderate Reference: p. 286 ATM defines _________ service classes (for Quality of Service routing/switching) that enable the network to prioritize transmissions. a. three b. four c. five d. seven e. nine Answer: C Difficulty: Easy Reference: p. 287 ______ means that the data transmission rate in the circuit will vary and the application is tolerant of delays. a. Variable bit rate-real time b. Variable bit rate-nonreal time c. Available bit rate d. Unspecified bit rate e. Constant bit rate Answer: B Difficulty: Moderate Reference: p. 289 __________ means that the circuit must provide a constant, predefined data rate at all times. a. Variable bit rate-real time b. Variable bit rate-nonreal time c. Available bit rate d. Unspecified bit rate e. Constant bit rate Answer: E Difficulty: Easy ________ means that the circuit has no guaranteed data rate. a. Variable bit rate-real time b. Variable bit rate-nonreal time c. Available bit rate d. Unspecified bit rate e. Constant bit rate Answer: D Difficulty: Easy Reference: p. 282 Reference: 289 43. 44. 45. 46. 47. 48. Used with ATM networks, MPOA is an acronym for: a. Multi-Point Overhaul Asynchronous b. Multiprocessing on Access c. Multiprotocol over ATM d. Multiplexing over Address e. Multiplexing on Asynchronous Answer: C Difficulty: Moderate Reference: p. 288 Which of the following would be least effective in improving backbone performance? a. improving the computers in the network b. changing the demand placed on the network c. adding new keyboards to the client computers d. upgrading the circuits between computers e. improving devices in the network Answer: C Difficulty: Moderate Reference: p. 293 Circuit capacity on a backbone network will not be improved by: a. going from 100Base-T Ethernet to 10Base-T Ethernet b. going from 100Base-T Ethernet to gigabit Ethernet c. adding additional circuits alongside heavily used ones d. replacing a shared circuit backbone with a switched circuit backbone e. providing a faster circuit to the server Answer: A Difficulty: Moderate Reference: p. 294 Device performance on a backbone network will not be improved by: a. using the same protocols in the backbone and the LANs b. using static routing in low to moderate traffic conditions c. ensuring that backbone devices have sufficient memory so that packets do not have to be retransmitted by the sender d. translating packets from one protocol to another as they enter the BN e. none of the above Answer: D Difficulty: Moderate Reference: p. 294 Network demand will not be reduced by: a. restricting (or moving) applications such as desktop videoconferencing b. using network devices to ensure that broadcast messages do not go to other networks c. restricting (or moving) applications such as medical imaging d. sending status information to all computers on all LANs in the backbone network e. restricting (or moving) applications such as multimedia Answer: C Difficulty: Moderate Gigabit Ethernet is not: a. the newest technology used in LANs and backbones b. rarely found in backbones at the present time c. usually run over fiber d. found in 1 GbE, 10 GbE and 40GbE formats Reference: p. 294 e. likely to replace ATM in the backbone Answer: B Difficulty: Moderate Reference: p. 284 49. Which of the following would not be part of an “ideal” backbone design for the future? a. access layer composed of 10/100 layer 2 Ethernet switches b. distribution layer composed of layer 3 Ethernet switches of 100 (or 1000) Base-T c. redundant switches d. core layer composed of layer 3 Ethernet switches running 10 (or 40) GbE over fiber e. coax cabling throughout LANs and BN Answer: E Difficulty: Moderate Reference: p. 294-295 Short Answer and Essay Questions: 1. What is a backbone network? What is typical of this kind of network? What are some business trends which we are seeing in backbone networks? What are three major technologies which are commonly seen in backbone networks? 2. Given network devices such as routers, switches and gateways, discuss three major technological trends that are helpful in explaining the differences between these devices. When might a router be useful? When might a gateway be more appropriate? 3. Describe the difference between backbone level shared media technologies and backbone level switched media technologies. Using a chart, describe two forms of shared media high speed networks and two forms of switched media technologies for high speed networks. 4. Describe and draw the topology of ATM. What are the strengths of ATM, why might ATM be slipping somewhat in the marketplace to fast ethernet? 5. List then describe 5 managerial factors to consider when selecting best practices for a backbone network design. What are six actions that you might undertake as a network manager to improve backbone performance?