CS4550: Computer Networks II public telecommunication networks

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CS4550Computer Networks IIpublic
telecommunication networks

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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?

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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 ATT, its tactics, monopoly in 3
  areas

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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

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US telco networks business

• generally very profitable, because
• - telephone service universal (in US)
• - local service companies often enjoy monopolies
• - ATT enjoyed 3 monopolies (govt many years
• - ATT subsidized local service by overcharging
  on long distance (

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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 govt has protected monopolies at
  times, divested them
• - antitrust laws

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US telco nets structure

ATT enjoyed monopolies in 3 areas

- local telco service

- long distance

- network equipment

telco network divided into 5-level hierarchy

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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
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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

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telco switch - generic design
switching matrix
control unit
...
network interface
...
...
...
trunks
digital/analog devices
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US telco nets structure regional switch (10)
ATT l.d. structure -simple hierarchy, augmented by tandem
lines -easy design, but not most efficient use
of resources
end office (19000)
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US telco nets structure

ATT 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

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US telco nets structure

ATT 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

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ATT 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

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ATT 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

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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)

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ATT 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 McCaws cellular company --
  cellular network
• gone to all digital network
• 2nd divestiture, 1996 (-- 180,000)
• has agreement to merge with TCI

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telecom since 1984

• ATT 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

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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

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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

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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.

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TV cable -- long distance combo
ATT long distance network
TV cable network
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cellular nets wireless phones

• central station, and base stations

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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

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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

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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

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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 internatl companies
• Erricson, Deutche Telecom, British
  Telecom, Cable and Wireless, Hong Kong Telecom,
  NTT
• Lucent Tech., MCI-Worldcom, Sprint-Cisco, ATT,
  GTE , SWB

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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