1. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Chapter 9 High-Speed Digital Access: DSL, Cable Modem, and SONET

2. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 9.1 DSL Technology ADSL Other DSL Technologies

3. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 ADSL is an asymmetric communication technology designed for residential users; it is not suitable for businesses. The existing local loops can handle bandwidths up to 1.1 MHz. ADSL is an adaptive technology. The system uses a data rate based on the condition of the local loop line.

4. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.1 DMT Upstream: 25 channels (6-30), one channel used for control, so 24 channels x 4000 Hz per channel x 15 bits/baud yields 1.44 Mbps. Theoretically. Downstream: 225 channels, one channel used for control, so 24 channels x 4000 Hz per channel x 15 bits/baud yields 13.4 Mbps. Likewise.

5. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.2 Bandwidth division

6. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.3 ADSL modem Filter often called a splitter

7. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.4 DSLAM

8. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 9.2 Cable Modem Traditional Cable Networks HFC Network Sharing CM and CMTS DOCSIS

9. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.5 Traditional cable TV network

10. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Communication in the traditional cable TV network is unidirectional. Note:

11. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.6 Second generation hybrid fiber-coaxial (HFC) network

12. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Communication in an HFC cable TV network can be bidirectional. Note:

13. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.7 Coaxial cable bands

14. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Downstream data are modulated using the 64-QAM modulation technique.. The theoretical downstream data rate is 30 Mbps. Upstream data are modulated using the QPSK modulation technique. The theoretical upstream data rate is 12 Mbps.

15. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.8 Cable modem

16. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.9 CMTS

17. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 9.3 SONET SONET Devices SONET Frame Frame Transmission Synchronous Transport Signals STS-1 Virtual Tributaries Higher-Rate Service

18. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 SONET is a synchronous TDM system controlled by a master clock. Note:

19. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.10 SONET STS Mux – multiplexes and demultiplexes SONET streams Regenerator – optical repeater but also changes SONET header information Add/drop multiplexer – can add and drop signals without changing entire mux stream

20. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.11 SONET Frame format

21. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 9.1 SONET rates STSOCRate (Mbps)SPE (Mbps)User (Mbps) STS-1OC-151.8450.1249.536 STS-3OC-3155.52150.336148.608 STS-9OC-9466.56451.008445.824 STS-12OC-12622.08601.344594.432 STS-18OC-18933.12902.016891.648 STS-24OC-241244.161202.6881188.864 STS-36OC-361866.231804.0321783.296 STS-48OC-482488.322405.3762377.728 STS-192OC-1929953.289621.6049510.912

22. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.12 STS-1 Data rate

23. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.13 Virtual Tributaries (VT) types A VT is a partial payload that can be inserted into a frame and combined with other partial payloads to fill out the frame. So instead of using all 87 payload columns of an SPE frame for data from one source, we can subdivide the SPE and call each component a VT. VT1.5 accommodates a T-1; VT2 accommodates the European CEPT-1 service at 2.048 Mbps, etc.

24. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 9.14 STS multiplexing Lower rate STSs can be multiplexed into higher-rate STS streams. Simple multiples are used to denote the stream (four STS-3s combine to create an STS-12).