1. Utilization of High Bandwidth Channels Martin Weiss

2. Slide 2 Objectives of this Meeting u Describe multiplexing techniques u Identify the elements of the public telephone network u Describe the organization of the public telephone network

3. Slide 3 Frequency Division Multiplexing Line 6 Line 5 Line 4 Line 3 Line 2 Line 1 Time Frequency Guard Band Transmission Bandwidth

4. Slide 4 Time Division Multiplexing Frequency Time 123456123456  Framing Samples from Lines

5. Slide 5 North American Digital Multiplex Hierarchy u Common transmission rates –DS0 = 64 kbps –DS1 = 1.544 Mbps = 24 DS0's –DS3 = 44.736 Mbps = 28 DS1's = 672 DS0's

6. Slide 6 ITU Digital Multiplex Hierarchy u Common transmission rates –E0 = 64 kbps –E1 = 2.048 Mbps = 30 E0's –E2 = 8.448 Mbps = 120 E0's –E3 = 34.368 Mbps = 480 E0's –E4 = 139.264 Mbps = 1920 E0's –E5 = 565.148 Mbps = 7680 E0's

7. Slide 7 Structure of Digital Transmission - T1 u Data is organized into Frames u Frames are delimited by a Framing Bit u Frames of frames, called Superframes, are also defined

8. Slide 8 Structure of a T1 Frame    Channel 1Channel 2Channel 3Channel 24F u Frame length –24 channels * 8 bits/channel = 192 Bits –Add 1 framing bit = 193 Bits

9. Slide 9 123456789101112 111111000000 Frame Number Value of Framing Bit Normal T1 Superframe Structure

10. Slide 10 ESF Frame Structure Frame Number Contents of Framing Bit 123456789101112 DDC0DCCD0D1D 19202122 DDC1DCCD0D1D 1314151617182324 D - Data Link Bits C - CRC-6 Bits

11. Slide 11 Components of a T1 Line CSU IXC Network U S E R LEC 2 Network LEC 1 Network CSU U S E R User's CPE

12. Slide 12 Structure of the Public Network u Technical structure –Telephone network structure –Equipment requirements and configuration u Organizational Structure (US) –Local access –Long distance

13. Slide 13 Initial Network Structure

14. Slide 14 Intermediate Network Structure Central Office

15. Slide 15 Expansion of the Intermediate Structure Central Office Central Office Central Office Central Office

16. Slide 16 Toll Offices Central Office Central Office Central Office Central Office Toll Office

17. Slide 17 Switching Hierarchy (Pre- Divestiture) Regional Center Sectional Center Primary Center Toll Center Central Office Local Tandem Office High Usage Trunks

18. Slide 18 Components of the Public Network Local Loop Switch Multiplexer Switch Multiplexer Transmission System PBX Local Loop Trunk Lines Signalling

19. Slide 19 Structure of the Public Network (1950s) Inside Wire Local Loop Central Office Tandem Office Tariffed and Regulated Interstate Network StateFederal

20. Slide 20 Structure of the Public Network (1970s) Tariffed and Regulated Inside Wire Local Loop Central Office AT&T’s Tandem Office OCC’s Tandem Office 2 wire 4 wire PCA Interstate Network Interstate Network StateFederal

21. Slide 21 Structure of the Public Network (1980s) Tariffed and Regulated Local Loop Central Office “Dominant” IXC’s POP “Non-Dominant” IXC’s POP 4 wire Enhanced Service Provider InterLATA Network InterLATA Network State Federal

22. Slide 22 Structure of the Public Network (Early 1990s) Tariffed and Regulated Local Loop LEC Central Office “Dominant” IXC’s POP “Non-Dominant” IXC’s POP 4 wire Enhanced Service Provider CAPs/Cable TV/Wireless Operator Services Providers To IXC InterLATA Network InterLATA Network State Federal

23. Slide 23 Structure of the Network (Late 1990s) Local Loop LEC Central Office IXC’s POP Enhanced Service Provider CAPs CATV Wireless IXC Operator Services Providers To IXC InterLATA Network State Federal InterLATA Network LEC’s POP

24. Slide 24 Telephone Competition (1893-1912) Local Loop Central Office Tandem Office Interstate Network Local Loop Central Office Tandem Office Bell System Non-Bell Company Local Franchise

25. Slide 25 Telephone Competition (1912-1921) Local Loop Central Office Tandem Office Interstate Network Local Loop Central Office Bell System Non-Bell Company Tariffed and Regulated State

26. Slide 26 Signalling in the Telephone Network u Traditional signalling u Modern signalling u Intelligent Network services

27. Slide 27 Traditional Signalling u Terminal to Switch u Switch to Switch

28. Slide 28 In-Band Signalling Signalling Path and Message Path

29. Slide 29 Out-of-Band Signalling Message Path Signalling Path

30. Slide 30 ITU Signalling System 7 (SS7) u New generation of signalling system u More capable than SS6 (CCIS) u The Integrated Services Digital Network (ISDN) requires SS7

31. Slide 31 SS7 Services: The Intelligent Network u Extensive Application of SS7 Technology u Custom Local Access Subscriber Services (CLASS) u Advanced Intelligent Network Services –More sophisticated applications of IN services