Chapter 11: Wide Area Networks

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Question 20. List some of the advantages provided by Metro Ethernet.​

Metro Ethernet provides a host of advantages, including:​ Streamlined Connections —Bridging Ethernet LANs with their native Ethernet protocols significantly streamlines the communication processes. Cost Efficiency — Metro Ethernet provides higher bandwidth at lower costs than current T-carrier and other options that rely on TDM (such as SONET). Metro Ethernet services at 10 Gbps are available with bandwidths up to 100 Gbps in the works. Scalability — Ethernet services are more easily scaled in finer increments than other high bandwidth technologies, and can be easily adjusted as subscriber needs change. familiarity—IT technicians are already familiar with Ethernet protocols and standards, which simplifies maintenance and troubleshooting. Hardware —Ethernet hardware is already widely available and less expensive to obtain the equipment needed for specific situations.

Question 11. ​What Layer 3 technology is employed by distance-vector routing protocols in which a router knows which of its interfaces a routing update and will not retransmit, or advertise, that same update on the same interface?

a. split horizon​

Question 10. At what two layers of the OSI model are LAN and WAN protocols likely to differ?​

a. ​Layer 1 d. ​Layer 2

Question 4. A MAN connection is also known as which two terms below?​

a. ​Metro Ethernet c. ​Ethernet MAN

Question 17. ​Frame relay relies on what two different types of virtual circuits?

a. ​PVC b. ​SVC

Question 5. ​What protocol is commonly used to aggregate / bond T-1 / T-3 lines?

b. MLPPP

Question 6. ​When using frame relay, what is the name of the identifier that routers use to determine which circuit to send frames to?

b. data link connection identifier

Question 22.4 ​A variety of ISDN that uses two 64-Kbps bearer channels and one 16-Kbps data channel, as summarized by the notation 2BþD.

b. ​BRI (Basic Rate Interface)

Question 18. ​The best 802.11n signal can travel approximately how far?

c. 1/4 mile

Question 23. In an ISDN connection, what is the size throughput did a single B channel provide?​

c. ​64 Kbps

Question 22.9 ​The guaranteed minimum amount of bandwidth selected when leasing a frame relay circuit. Frame relay costs are partially based on this.

c. ​CIR (committed information rate)

Question 8. In metro settings, end-to-end, carrier-grade Ethernet networks can be established via what protocol?​

c. ​Carrier Ethernet Transport

Question 19. In what type of topology is each site connected to two other sites, ​providing redundancy?

c. ​ring topology

Question 9. In ATM, a packet is called a _____________ and always consists of 48 bytes of data plus a 5 byte header.

cell

Question 24. How many channels exist in a T1 connection?​

d. 24

Question 13. In a PON system, an OLT contains a splitter that splits each port into how many logical channels?​

d. 32

Question 25. ​The DTE or endpoint device for a leased line is known as which device below?

d. ​CSU/DSU

Question 12. ​Which version of DOCSIS provides 38 Mbps per channel and requires a minimum of 4 channels to be used?

d. ​DOCSIS 3

Question 22.5 ​A connectivity device located at a telecommunications carrier's office that aggregates multiple DSL subscriber lines and connects them to a larger carrier or to the Internet backbone.

d. ​DSLAM (DSL access multiplexer)

Question 22.1 ​A special case of geosynchronous orbit in which the satellite stays directly above the equator and appears stationary from Earth. These satellites are the type used to provide satellite Internet access.

e. ​geostationary orbit

Question 22.3 ​A 4G cellular network technology that, in its latest version (called LTE-Advanced), achieves downlink data rates of up to 3 Gbps and uplink rates of up to 1.5 Gbps. AT&T and Verizon have adopted LTE for their high-speed wireless data networks.

f. ​LTE (Long Term Evolution)

Question 22.10 ​A WAN technology that sends Ethernet traffic across MAN connections.

g. ​Metro Ethernet

Question 22.8 ​A type of WAN in which each site is connected to two other sites so that the entire WAN forms a ring pattern.

h. ring topology WAN​

Question 22.7 ​An intelligent type of NIU located at the customer's demarc that can provide diagnostic information about the interface.

i. ​smart jack

Question 22.6 ​The equipment on a satellite that receives an uplinked signal from Earth, amplifies the signal, modifies its frequency, then retransmits it (in a downlink) to an antenna on Earth.

j. transponder

Question 3. If the line between the carrier and the customer experiences significant errors on a T-1, a ____________ will report this fact to the carrier.​

smart jack

Question 14. ​What is the frequency range of the C-band that is used by satellites?

C. ​3.4 - 6.7 GHz

Question 16. T-1 cables cannot utilize straight through cables using the same wiring scheme as LAN patch cables.​ True or False?

False

Question 22.2 ​A WAN technology functioning primarily at Layer 2 (although its protocols can also reach Layers 1 and 3) that was originally conceived in the early 1980s at Bell Labs and standardized by the ITU in the mid-1990s.

a. ATM (Asynchronous Transfer Mode)

Question 7. Multiplexing enables a single ____________ circuit to carry 24 channels, each capable of 64 Kbps throughput.​

T-1

Question 1. Outline the differences between a LAN and a WAN connection.​

The following list summarizes the major characteristics of WANs and explains how a WAN differs from a LAN: LANs connect nodes, such as workstations, servers, printers, and other devices, in a small geographical area on a single network, whereas WANs use networking devices, such as routers and modems, to connect networks spread over a wide geographical area. Both LANs and WANs use the same protocols from Layers 3 and higher of the OSI model. Whereas a LAN always uses packet-switched connections, a WAN can use either circuit-switched or packet-switched connections, although packet-switched connections are more common. LANs and WANs may differ at Layers 1 and 2 of the OSI model in access methods, topologies, and, sometimes, media. For example, the way DSL transmits bits over a WAN differs from the way Ethernet transmits bits over a LAN. LANs are mostly owned and operated by the companies that use them. On the other hand, WANs are owned and operated by telecommunications carriers, known as NSPs (network service providers), for example, AT&T, Verizon, Charter, and Comcast. Corporations lease WAN connections from these carriers, often with payments based on the amount of bandwidth actually used.

Question 2. List and describe the four different generations of cellular technology.​

The four generations of cell phone technology are as follows: First-generation, or 1G, services from the 1970s and 1980s were analog. Second-generation, or 2G, services, which reigned in the 1990s, used digital transmission and paved the way for texting and media downloads on mobile devices. Still, data transmission on 2G systems didn't exceed 240 Kbps. Third-generation, or 3G, services were released in the early 2000s. Data rates rose to 384 Kbps and data (but not voice) communications used packet switching. Fourth-generation, or 4G, services are characterized by an all-IP, packet-switched network for both data and voice transmission. 4G standards, released in 2008, also specify throughputs of 100 Mbps for fast-moving mobile clients, such as those in cars, and 1 Gbps for slow-moving mobile clients, such as pedestrians. WiMAX, though not strictly a cellular-based technology, is considered 4G because of its high-speed, packet-switched characteristics. Later in this section, you will learn about other 3G and 4G systems.

Question 15. A bus topology WAN is often the best option for an organization with only a few sites and the capability to use dedicated circuits.​ True or False?

True

Question 21. In a PON setup, the system is considered passive because no repeaters or other devices intervene between the carrier and the customer. True or False?

True


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