CS4550: Computer Networks II public telecommunication networks

1. CS4550:Computer Networks IIpublic telecommunication networks

2. “public” telecom networks • US telco networks : history, business, politics • US telco networks: basic structure • cable TV networks • wireless networks • international telephone networks • future (?) - fiber to the home?

3. US telco networks : history • invention of telephone: ~1876 • Alex. G. Bell, Elisha Gray, P. Reis • original telephone patents: 1876,77 • spread of telephone companies: 1893-4 to 1901 • establishment of AT&T, its tactics, monopoly in 3 areas

4. US telco networks : history • hush-a-phone, pres. address, etc. • antitrust lawsuits : 1921, 1956, 1984 • divestiture of 1984 • other LD companies, Baby Bells, etc. • after 1984 • 1996: second divestiture and TC Act • recent events

5. US telco networks : business • generally very profitable, because - telephone service universal (in US) - local service companies often enjoy monopolies - ATT enjoyed 3 monopolies (<1984), protected by gov’t many years - ATT subsidized local service by overcharging on long distance (<84)

6. US telco networks : politics • often have had major influence on telecommunications industry - companies are very large, have many customers (voters) - telecom. essential to modern economy - control of communications is power (political, economic) - at times gov’t has protected monopolies; at times, divested them - antitrust laws

7. US telco nets : structure < 1984 • ATT enjoyed monopolies in 3 areas: - local telco service - long distance - network equipment • telco network divided into 5-level hierarchy

8. US telco nets : local loops • local loop; “end office” or central office; star topology; app. 19K in US phone twisted pair phone to l.d. switch end office phone phone

9. PBX : private branch exchange • a privately owned telephone switch; enables companies, etc. to have own private local phone network • several generations; most recent are digital, capable of data and voice • connect to public telco through a “trunk,” or higher capacity line • centrex - similar service, but owned and maintained by the telco

10. telco switch - generic design switching matrix control unit ... network interface ... ... ... trunks digital/analog devices

11. US telco nets : structure < 1984 regional switch (10) ATT l.d. structure < 84 -simple hierarchy, augmented by tandem lines -easy design, but not most efficient use of resources end office (19000)

12. US telco nets : structure < 1984 • AT&T was major telco in US, largest in world (approximations below) -70% of local telephones in US - 99% of l.d. traffic - 99% telecom equipment - 1,000,000 employees - total revenue was 2% of annual GNP of US

13. US telco nets : structure < 1984 • AT&T before 1984 • 22 BOCs (Bell Operating Companies) --> local telephone service • Western Electric --> equipment • Long lines department --> long distance service • Bell Telephone laboratories --> research lab “national resource”

14. AT&T : divestiture • background : 1956 consent decree • 1974 : US DOJ brought suit against ATT for violation of antitrust law. Charged that ATT “denied benefits of free and competitive market to purchasers of telecommunications equipment and service” • settlement negotiated after years of negotiations and softball

15. AT&T divestiture, results • 22 BOCs separated, grouped into 7 RBOCs • RBOCs to provide “equal access” • RBOCs may sell but NOT manufacture CPE • ATT retained WE, long lines, part of Bell labs • Bell labs split between ATT and RBOCs (Bellcore) • 161 LATAs defined • ATT released from 1956 decree

16. LATA local access transport area • defines boundaries local telcos cannot cross; so 3 types of calls • local (truly local) - no charge ; Monterey to Monterey • local access : toll charge to local company (Monterey to Salinas) • long distance : must use a long distance company (Monterey - San Jose)

17. AT&T since 1984 • l.d. share has decreased from 95%+ to ~60% or less, still quite profitable • employees --> ~300,000 (until 96) • ventured into computers - failed twice (ATT PC, NCR purchase) • bought out Craig McCaw’s cellular company --> cellular network • gone to all digital network • 2nd divestiture, 1996 (--> 180,000) • has agreement to merge with TCI

18. telecom since 1984 • AT&T doing well, but only 1 of several major companies • Sprint, MCI major competitors after 84 • Worldcom-MCI merger produced major telecom power • Lucent Tech. --> another power • telecom in other countries have moved towards competition, freedom • technology moved forward faster than ever before

19. telco companies today, US • ATT, Sprint, MCI-Worldcom ; GTE • original 7 RBOCs : Pacific Telesis; Nynex; Ameritech; US West ; Southwestern Bell (now SBC); Bell Atlantic; Bell South. • mergers have reduced these • SBC bought Pacific Telesis, and pending Ameritech • Nynex and Bell Atlantic merged • GTE may merge with Bell Atlantic

20. some current and future trends • all networks converging towards data networking (Internet) • i.e., voice, TV cable and internet become 1 network • TCI-ATT merger pending • Sprint-Cisco agreement on data network • will have higher bandwidth available to home & throughout

21. TV cable networks • designed for TV broadcast to homes • uses coaxial cable : 1 TV channel has 6 MHz, or 1500 voice channels; 1 cable can carry hundreds of channel • to carry voice/data, switching equipment needs to be modified. • TV networks can provide competition for voice, and higher speed internet access • ATT-TCI merger: ATT hopes to use TV cable for voice and data to penetrate home.

22. TV cable -- long distance combo ATT long distance network TV cable network

23. cellular nets : wireless phones • central station, and base stations

24. cellular nets : wireless phones • base stations communicate through radio signals with end users • competition for local phone and limited data. Has difficulties inherent in wireless media - inference, capacity, handoffs between cells; but these are being addressed. • security also more difficult

25. satellite networks : iridium, etc. • iridium project : Motorola and others; already has 80-90 satellites in orbit • other competing • will probably be expensive, but a world-wide network for voice data

26. internet telephony • already here... will get better • quality less than conventional, but as speed improves, this will too • many parts of world have poor phone penetration; this may be the way to bring service, and break nationalistic monopolies (e.g., Telmex) and US telco monopolies

27. international telco summary • US most advanced, but western Europe, Japan, Taiwan, Hong Kong, Singapore, others close • much of world - India, China, Indonesia, Mexico/Latin America - far behind; some still have monopolies (e.g. Telmex) • some leading internat’l companies: Erricson, Deutche Telecom, British Telecom, Cable and Wireless, Hong Kong Telecom, NTT Lucent Tech., MCI-Worldcom, Sprint-Cisco, ATT, GTE , SWB

28. future : fiber to the home? • high capacity of fiber has drastically altered world of telecom • breakup of ATT 1984 has also drastically improved progress • fiber to the home? some predict this, may happen; but in whatever form, we can expect higher capacity internet and telephone access... possibly through TV cable... and continued progress in communications