| 1: | Is Asynchronous Transfer Mode (ATM) a synchronous or asynchronous technique? Explain. |
| A1: | It is a synchronous technique. The word asynchronous in ATM is not associated with embedded start-stop techniques, but with sporadic presence of user data. |
| 2: | Name three of the advantages of digital signaling over analog signaling? |
| A2: | Better quality of service; simplified maintenance; synergy with digital switching. |
| 3: | What does FDM stand for? What rule does FDM obey? |
| A3: | FDM stands for frequency-division multiplexing and obeys the rule "some bandwidth all of the time." |
| 4: | In North America, how many voice channels are in a standard multiplexing scheme for FDM? |
| A4: | For North America, a standard voice multiplexing scheme is 12 voice channels, 4 kHz each, totaling a bandwidth from 60 to 108 kHz. |
| 5: | Describe the main phases of pulse code modulation (PCM). |
| A5: | Sampling, quantization, and coding. The first two functions are performed by a codec device, and the coding is performed by a DSU/CSU. |
| 6: | What does TDM stand for? What rule does the TDM obey? |
| A6: | TDM stands for time-division multiplexing and obeys the rule "all the bandwidth, some of the time." |
| 7: | What is the purpose of bit number 193 in TDM? |
| A7: | Bit number 193 is a framing bit; it is used for time synchronization. |
| 8: | What is a frame in TDM? |
| A8: | A frame is a sequence of time slots, each containing a sample from one of the channels. |
| 9: | What do DS1 and DS-1 stand for? What is the difference between DS1 and DS-1? |
| A9: | DS1 stands for digital service 1, which is a digital interface with a 1.544-Mbps data rate. DS-1 stands for digital signal level 1, which is a framing specification for transmitting digital signals at 1.544 Mbps on a T1 facility in the U.S. |
| 10: | What is out-of- band signaling? What is robbed bit signaling? |
| A10: | Out-of-band signaling uses frequencies outside of the normal frequency band for signaling; it is the core of SS7. In contrast, in-band signaling relies on using certain bits out of the frame format in the frequency band, which is why it is sometimes called robbed bit signaling (RBS). |
| 11: | What do CO, LEC, CLEC, and ILEC stand for? What do they have in common? |
| A11: | CO stands for central office, LEC is local exchange carrier, CLEC is competitive LEC and ILEC stands for incumbent LECs. All of them belong to the first tier of exchange carriers . |
| 12: | What is the role of tandem switches in carrier networks? |
| A12: | The secondary switch, called the tandem, provides a trunk-to-trunk switching for both LECs and IXCs. |
| 13: | What are the main caveats when the enterprise outsources service with the service provider? |
| A13: | They include the commitment of the other party and control of the information. |
| 14: | What are the three main topologies in Cisco's Ethernet to the First Mile (EFM)? |
| A14: | Ethernet over point-to-point copper ; Gigabit Ethernet over point-to-point optical fiber; point-to-multipoint optical fiber topology. |
| 15: | What does CDMA stand for? Name the 3G minimum speed requirements, as defined by ITU. |
| A15: | CDMA stands for Code Division Multiple Access. 3G, 144 kbps mobile, 384 kbps walking, 2.4 Mbps stationary. |