1. DC 10 - 1 DATACOMM John Abbott College JPC Digital Telecomm M. E. Kabay, PhD, CISSP Director of Education, ICSA President, JINBU Corp Copyright © 1998 JINBU Corp. All rights reserved

2. DC 10 - 2 Digital Telecomm l Digital CPE l ISDN l ATM l Infobahn

3. DC 10 - 3 Digital CPE l Digital PBX l Digitized Voice l T-1

4. DC 10 - 4 Digital CPE Digital PBX a hot seller today l Turns analog signal (voice) into digital pulses l Allows voice and data to be controlled from a single central switch l Digital phone converts voice to bits l Codec is Coder-Decoder (opposite of Modem)

5. DC 10 - 5 Digital CPE Digitized Voice l Pulse code modulation (PCM) – 8 Khz sampling – 8 bits/sample – 64Kbps data stream l Human hearing cannot distinguish digital and analog signals l Allows full range of digital transmission controls – error checking – signal regeneration

6. DC 10 - 6 Digital CPE T-1 l 1.544 Mbps channel l 24 channels using TDM l Applications – PCM on T-1 allows 24 voice links – need only 2 twisted pairs + special equipment – resistant to EMI (high signal-to-noise ratio) – can be highly cost-effective

7. DC 10 - 7 Digital CPE l T-1 signalling – voice runs 64 Kbps – data needs 1 parity bit/byte: 56 Kbps l Multiplexers for T-1 lines – can share single channel among several lower-speed devices – rent fractional T-1 from carrier

8. DC 10 - 8 ISDN l Integrated Services Digital Network l Channels l Rates l Services l Trends

9. DC 10 - 9 ISDN l Standards still in evolution l CCITT working on intl agreements l Expect eventual hardware interoperability

10. DC 10 - 10 ISDN ISDN Channels l Different bandwidths = channels l Bearer channel (B-channel) 64 Kbps l D-channel – signalling data @ 16 Kbps or 64 Kbps – usually used for out-of-band signalling – often relatively low usage – used for low-priority data; e.g., e-mail l A-channel : analog communications l C-channel: very low-speed data

11. DC 10 - 11 ISDN l Basic-Rate I/F (BRI) – 2 B-channels + 1 D-channel (2B+D) l Primary-Rate I/F (PRI) – US/Canada: 23 B-channels + 1 D-channel – 1.544 Mbps l European PRI: 30 B + D – 2.048 Mbps l Other channel arrangements – A+C: hybrid I/F – voice + data for non-ISDN phones/terminals

12. DC 10 - 12 ISDN Equipment Functions l TE1: Terminal Equipment Type 1 – compatible with ISDN network – e.g., ISDN-compatible phone, workstation l TE2: Terminal Equipment Type 2 – not compatible with ISDN network – requires terminal adaptor (TA) to link into ISDN

13. DC 10 - 13 ISDN Network Termination Equipment l NT1: Network Termination 1 – OSI Layer 1 – physical and electrical connection to network – can be changed if digital transmission medium changes (e.g., change to optical) l NT2: Network Termination 2 – OSI Layers 2 and 3 – e.g., PBX, LANs

14. DC 10 - 14 ISDN ISDN Services l D-channel can carry info about callers l Individualized call-forwarding for specific callers l Long-distance camp-on-busy function l Automatic routing of 800-calls to local outlet

15. DC 10 - 15 ISDN Video l Motion Pictures Experts Group (MPEG) l Developing standards for video signal compression – uncompressed requires 21 Mbps for broadcast-quality real-time digital video – MPEG II requires only 7 Mbps l Video conferencing: most of image is static – send only changes – use multirate ISDN such as 384 Kbps channels (6 B-channels)

16. DC 10 - 16 ISDN ISDN Today l Not likely to see instant conversion of all existing telecomm to ISDN l Primary Rate I/F (PRI) is about same cost as T-1: but much more flexible l Residential customers a huge market – can have voice and data on same line – but only minority of residential customers use existing analog services--so will ISDN be commercially viable?

17. DC 10 - 17 ISDN Broadband ISDN (BISDN) l In initial planning phase l Extremely high bandwidth (150 Mbps) l Real-time broadcast video services l Entertainment applications l Telecommuting applications

18. DC 10 - 18 ATM Asynchronous Transfer Mode l Protocol for implementing BISDN l Independent of bandwidth l Data chunked into cells l Being promoted by ATM Forum – founded 1991 – consortium of many players in datacomm

19. DC 10 - 19 ATM ATM Cells l 53-bytes (bytes called octets in ATM) l header: 5 octets l payload: 48 octets

20. DC 10 - 20 ATM Physical Transmission l SONET: Synchronous Optical Network l SONET line speeds defined in OC-N form – N is 51.84 Mbps – OC-1 = 51.84 Mbps – OC-3 = 155.52 Mbps l Other transmission media quite feasible

21. DC 10 - 21 ATM Routing Cells l Set up equivalent of virtual circuits l Transmission path remains fixed for a session l Headers include routing information – Virtual Channel Identifiers (VCIs) – Virtual Path Identifiers (VPIs) l Main differences from Frame Relay: – fixed cell sizes – different data formats

22. DC 10 - 22 Infobahn l Information Superhighway l NOT the current Internet l Usually refers to high-speed backbones l BISDN is chief candidate l Most of media reporting focuses on applications, not transmission channel

23. DC 10 - 23 Homework l Read Chapter 10 of your textbook in detail, adding to your workbook notes as appropriate. l Review and be prepared to define or expand all the terms listed at the end of Chapter 10 of your textbook (no hand-in required) l Answer all the exercises on page 232 of the textbook using a computer word-processing program or absolutely legible handwriting (hand in with final quiz)