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Lecture #6Lecture #6: Data : Data Communication Service. Communication Service.

Network Standardization.Network Standardization.C o n t e n t s C o n t e n t s Communication Services in Public Communication Services in Public

NetworksNetworks Broadband TelecommunicationsBroadband Telecommunications Network Services Network Services International Regulation:International Regulation:

Service ProvidersService Providers Standardization InstancesStandardization Instances Standardization DocumentsStandardization Documents

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The The Public NetworksPublic Networks Public networks - public services:Public networks - public services:

offered by network operators which own given offered by network operators which own given subnet (phone companies, communication subnet (phone companies, communication satellite owners, TV cable operators, etc.)satellite owners, TV cable operators, etc.)

paid and used by subscriber (customer)paid and used by subscriber (customer) Switched Multimegabit Data Service Switched Multimegabit Data Service

((SMDSSMDS) - LANs “backbone” interconnection) - LANs “backbone” interconnection::– broadband; switched, long distance networkbroadband; switched, long distance network– the connection between SMDS and LANs is the connection between SMDS and LANs is

usually DQDB MAN or short leased phone usually DQDB MAN or short leased phone lines between LANs and SMDS subnet lines between LANs and SMDS subnet

– speed ~ 45Mb/s; speed ~ 45Mb/s; peak traffic tolerantpeak traffic tolerant and and better better cost/performance ratiocost/performance ratio to leased to leased phone linesphone lines

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The The Public Networks - Public Networks - SMDSSMDS

connectionless packet delivery service connectionless packet delivery service variable length packets up to 9kB user data variable length packets up to 9kB user data

and and 8B source and destination addresses: 4bit 8B source and destination addresses: 4bit

code + up to 15 decimal digits phone number code + up to 15 decimal digits phone number (country code)+(city code)+(subscriber (country code)+(city code)+(subscriber number) - world-wide identificationnumber) - world-wide identification

option: incoming and/or outcoming address option: incoming and/or outcoming address screening for private secure communicationsscreening for private secure communications

special routing procedure for peak user traffic: special routing procedure for peak user traffic: system counter for each user accumulates system counter for each user accumulates unused time for communication and the user unused time for communication and the user has priority for peak communications has priority for peak communications

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The The Public Networks - Public Networks - X.25X.25

X.25 networksX.25 networks::– interface between public packet-switching interface between public packet-switching

networks and the subscribers networks and the subscribers

– connection oriented, based on telephone connection oriented, based on telephone

network:network:• switched virtual circuit (based on switched line)switched virtual circuit (based on switched line)

• permanent virtual circuit (based on leased line)permanent virtual circuit (based on leased line)

– specified by CCITTspecified by CCITT

– physical layer: X.21 protocol (digital physical layer: X.21 protocol (digital

signaling) or analog interface (variation of RS-signaling) or analog interface (variation of RS-

232)232)

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The The Public Networks - Frame Public Networks - Frame RelayRelay

Frame Relay ServicesFrame Relay Services::– ““virtual” leased phone lines: lower virtual” leased phone lines: lower

cost than actual leased lines but cost than actual leased lines but limited long-term average bandwidthlimited long-term average bandwidth

– connection oriented, low cost, high connection oriented, low cost, high speed (1,5 Mb/S, higher than X.25), speed (1,5 Mb/S, higher than X.25), 1.5 KB data packets1.5 KB data packets

– available virtual channels to multiple available virtual channels to multiple sites by 10-bit address, time shared sites by 10-bit address, time shared leased lineleased line

– low level protocols: low level protocols: •bad frames are just discarded;bad frames are just discarded;•detection of transmission errorsdetection of transmission errors

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Broadband Broadband TelecommunicationsTelecommunications

Broadband ISDNBroadband ISDN– unifies all information transfer unifies all information transfer

including existing:including existing:•circuit-switched phonescircuit-switched phones•packet switched frame relay and SMDS packet switched frame relay and SMDS

servicesservices•DQDBDQDB•cable TVcable TV

– and arisingand arising•multimedia (incl. CD-quality voice)multimedia (incl. CD-quality voice)•LAN interconnectionLAN interconnection•high-speed data transfer services etc.high-speed data transfer services etc.

Integrated Services Digital Network

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Broadband Broadband Telecommunications - ATMTelecommunications - ATM

ATMATM – connection oriented transmission connection oriented transmission

technology technology – short fixed-size packets - short fixed-size packets - cellscells: 5 B : 5 B

Header and 48 B PayloadHeader and 48 B Payload– cell switching instead of circuit switching cell switching instead of circuit switching

provides:provides:• up to Gb/S speed and up to Gb/S speed and • flexibility for real-time and non-real-time (but flexibility for real-time and non-real-time (but

error-free) communicationserror-free) communications• digital switching of cells replaces digital switching of cells replaces

multiplexingmultiplexing

Asynchronous Transfer Mode

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Broadband Broadband Telecommunications - Telecommunications -

ATMATM 2 standard speeds: -155 and 622 2 standard speeds: -155 and 622

(4*155) Mb/S :(4*155) Mb/S : Application:Application:

– TV/videoTV/video– phone servicesphone services– LAN backbonesLAN backbones– client-server distributed processingclient-server distributed processing

Multiple service providers over one Multiple service providers over one communication mediacommunication media

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Broadband Broadband Telecommunications - Telecommunications -

ATMATM B-ISDN over ATM - reference model:B-ISDN over ATM - reference model:

– 2 planes / 3 layers - 2 planes / 3 layers - user planeuser plane (for upper (for upper layers tasks) and layers tasks) and control planecontrol plane (connection management)(connection management)

– Physical layerPhysical layer - transparent to ATM cells, - transparent to ATM cells, specifies the media timing and signaling specifies the media timing and signaling (copper, fiber, waves etc.)(copper, fiber, waves etc.)

– ATM layerATM layer - specifies the cell header fields, - specifies the cell header fields, provides cell transport, builds virtual circuits provides cell transport, builds virtual circuits

– Adaptation-to-ATM layerAdaptation-to-ATM layer transforms transforms upper layer data into ATM cells. Resume of upper layer data into ATM cells. Resume of the public network servicesthe public network services

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Broadband Broadband Telecommunications - Telecommunications -

ATMATM ATM sublayers:ATM sublayers:– PMDPMD (Physical Medium Dependent) - (Physical Medium Dependent) -

specifies access and parameters of the specifies access and parameters of the transmission mediatransmission media

– TCTC (Transmission Convergence) - (Transmission Convergence) - transformation of cells to bitstream and transformation of cells to bitstream and packing cells from the incoming bit packing cells from the incoming bit streamstream

– SR SR (Segmentation and Reassemble) - (Segmentation and Reassemble) - transformation of packets to stream of transformation of packets to stream of cells and building packets from incoming cells and building packets from incoming cellscells

– CSCS (Convergence Sublayer) - service (Convergence Sublayer) - service interface support: high level data interface support: high level data structures, application timing, etc.structures, application timing, etc.

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Networking Services - Networking Services - SummarySummary

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Access Network Access Network ComparisonsComparisons

Narrowband dial-up modems

ISDN - BRI

ADSL(broadband)

Cable modems(broadband)

SatelliteSatellite

DownstreamData Rate

Up to 56 Kbps

56 Kbps to128 Kbps

1,5 Mbpsto 9 Mbps

500 Kbps to30 Mbps

e.g. 400 Kbpse.g. 400 Kbps

UpstreamData Rate

Up to 56 Kbps

56 Kbps to 128 Kbps

16 Kbps to 500 Kbps

99,6 Kbps to 1 Mbpsalso planning to use 28,8 Kbps

(telecommunication return)

Several possible starndardsSeveral possible starndards

Access SystemAccess System

Normal phone linesNormal phone lines

Normal phone lines with ISDN Terminal Adapters

Normal phone lines with ISDN Terminal Adapters

Normal phone lines withADSL modems

Normal phone lines withADSL modems

Cable TV networksCable TV networks

Wireless transmissionWireless transmission

Asymmetric Digital Subscriber Line

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Network ServicesNetwork ServicesNetworks provide communication connections Networks provide communication connections

between users and services. Services implement the between users and services. Services implement the logical behavior seen by users. Services are mainly logical behavior seen by users. Services are mainly Service Logic software situating in the networks Service Logic software situating in the networks elements themselves (embedded services) or in special elements themselves (embedded services) or in special service nodes (overlay services).service nodes (overlay services).

Embedded servicesEmbedded services are implemented as integral are implemented as integral parts in switches, routers and mobile exchanges. parts in switches, routers and mobile exchanges. Examples of these are Plain Old Telephone Services Examples of these are Plain Old Telephone Services (POTS), ISDN connectivity and supplementary services, (POTS), ISDN connectivity and supplementary services, Mobile connectivity services and Intelligent Network Mobile connectivity services and Intelligent Network services in SSCP network elements.services in SSCP network elements.

Overlay servicesOverlay services are implemented in external are implemented in external switches or computers which are connected to the switches or computers which are connected to the existing access or basic networks. Examples of these existing access or basic networks. Examples of these are Voice and Multimedia services, GSM messaging are Voice and Multimedia services, GSM messaging services and overlay Intelligent Networks.services and overlay Intelligent Networks.

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Network ServicesNetwork Services

delay (S)

10

10

1 (S)

10

10

10 (mS)

Batch Processing

Electronic Mail

ONLINE

RPCVoice

TransactionProcessing

File Transfer

InteractiveMultimedia

TV HDTV

Compressed VIDEO

Animation

Virtual Reality

10k 100k 1M 10M 100M 1G 10G b/S

speed

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Networks and ServicesNetworks and ServicesThe service provision through networks is usually The service provision through networks is usually

divided vertically into divided vertically into infrastructureinfrastructure, , (value (value added) servicesadded) services and and contentscontents. .

– Infrastructure servicesInfrastructure services mean selling generic point to mean selling generic point to point or multipoint connections “pipes” to the point or multipoint connections “pipes” to the customers. This is a typical product of a public network customers. This is a typical product of a public network operator.operator.

–Value Added Networks (VAN)Value Added Networks (VAN) are products that are products that provide more complex behavior (called service logic) on provide more complex behavior (called service logic) on the network than simple “pipes”. Electronic mail, WWW the network than simple “pipes”. Electronic mail, WWW and Intelligent Network voice services are value added. and Intelligent Network voice services are value added. Mobile network voice services are often considered Mobile network voice services are often considered generic, but here we would like to consider mobility as a generic, but here we would like to consider mobility as a strong added value component.strong added value component.

–Content ServicesContent Services are digital information available or are digital information available or sold through networks. The digital (also called sold through networks. The digital (also called multimedia) contents are usually combined with some multimedia) contents are usually combined with some service logic controlling their retrieval.service logic controlling their retrieval.

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Networks and ServicesNetworks and ServicesThe increasing role of value added The increasing role of value added

services and digital contents available services and digital contents available through networks will introduce new through networks will introduce new players:players:

–Network OperatorsNetwork Operators are the traditional players owning are the traditional players owning public networks and selling infrastructure and value public networks and selling infrastructure and value added services. They may have also content services added services. They may have also content services available e.g. in their Cable TV networks.available e.g. in their Cable TV networks.

–Service ProvidersService Providers create and sell value added create and sell value added services on top of the existing networks. Service services on top of the existing networks. Service providers do not usually own complete networks, but providers do not usually own complete networks, but may own and operate certain network parts such as may own and operate certain network parts such as base stations.base stations.

–Content ProvidersContent Providers which own digital contents and sell which own digital contents and sell them using also networks as their distribution channels.them using also networks as their distribution channels.

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International Network International Network Regulation - Service Regulation - Service

ProvidersProviders Common carriers (USA, >2200 approved by Common carriers (USA, >2200 approved by

Federal Communication Commission: AT&T, Federal Communication Commission: AT&T, Bell, GTE...)Bell, GTE...)

National PTTs (government monopoly)National PTTs (government monopoly) ISPs (ISPs (Internet Service Providers) mostly private) mostly private Satellite Communication Services Providers - Satellite Communication Services Providers -

usually divisions of National PTTs (big usually divisions of National PTTs (big countries, KPN (the Netherlands), India, etc.) - countries, KPN (the Netherlands), India, etc.) - – TV/Radio broadcasting, TV/Radio broadcasting, – Military/Navy area, Military/Navy area, – Data CommunicationsData Communications

• example: Intersat (geostationary orbit)example: Intersat (geostationary orbit)• terrestrial receivers:VSATs (Very Small Aperture Terminals) terrestrial receivers:VSATs (Very Small Aperture Terminals)

(“dishes”)(“dishes”)• Sat-To-Sat communicationsSat-To-Sat communications

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International Network Regulation International Network Regulation - Main Standardization Instances - Main Standardization Instances

CCITTCCITT (after 1993 (after 1993 ITU-T) - International ) - International consultative committee for telegraphs and consultative committee for telegraphs and telephones - intergovernmental organization telephones - intergovernmental organization (US presented by the Department of States)(US presented by the Department of States)

ISO - Union of the national standardization - Union of the national standardization

instances instances ((ANSI, DIN, SFS, ANSI, DIN, SFS, БДСБДС …) …) divided in divided in TCs (for computers TC97, now TCs (for computers TC97, now JTC1 and subcommittees: for telecommunications and subcommittees: for telecommunications JTC1/SC6))

IEEE, , ACM

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Organizations in Organizations in interna-tional interna-tional

standardizationstandardization ITUITU-International Telecommunication -International Telecommunication

UnionUnion

JTCI-ISO/IECJTCI-ISO/IEC Joint Technical Committee 1 Joint Technical Committee 1

ISOISO-International Organization for -International Organization for

StandardizationStandardization

IECIEC-International Electronical Committee-International Electronical Committee

ISOCISOC-Internet Society-Internet Society

ATM ForumATM Forum

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Organizations in Organizations in regional regional

standardizationstandardization ETSIETSI - European Telecommunications - European Telecommunications Standards InstituteStandards Institute

T1T1 - Committee for telecommunications - Committee for telecommunications Industry Association (USA)Industry Association (USA)

TIATIA - Telecommunications Industry Association - Telecommunications Industry Association (USA)(USA)

IEEEIEEE - Institute of Electrical and Electronics - Institute of Electrical and Electronics Engineer (USA)Engineer (USA)

TTCTTC- Telecommunications Technology Council - Telecommunications Technology Council (Japan)(Japan)

RCRRCR - Research & Development Center for - Research & Development Center for Radio Systems (Japan)Radio Systems (Japan)

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Main Standardization Main Standardization Instances of the InternetInstances of the Internet

IAB (Internet Activity Board, 1983 ARPANET; (Internet Activity Board, 1983 ARPANET;

later Internet Architecture Board) split in later Internet Architecture Board) split in

1989 into 1989 into

IRTF (Internet Research Task Force), (Internet Research Task Force),

IETF (Internet Engineering Task Force) (Internet Engineering Task Force)

++ ISOC (Internet SOCiety) (Internet SOCiety)

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Standardization Standardization DocumentsDocuments ISOISO adoption procedure passes: adoption procedure passes:

– Committee Draft Committee Draft – Draft International Standard Draft International Standard – International StandardInternational Standard

ISO issued >5000 standards incl. OSIISO issued >5000 standards incl. OSI IABIAB (Internet standardization) (Internet standardization)

– RFCs: series of technical reports (>2500 up to now : series of technical reports (>2500 up to now e.g. e.g. RFC 2022RFC 2022: about PGP with MIME coding, : about PGP with MIME coding, RFC RFC 26942694: about DNS algorithm extensions): about DNS algorithm extensions)

– formal process: formal process: • RFC RFC (professional interest to the RFC) (professional interest to the RFC)• Proposed Standard Proposed Standard (working implementation (working implementation

independently tested by several different institutions) independently tested by several different institutions) • Draft StandardDraft Standard

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Switched Multimegabit Data Service (SMDSSMDS) - LANs “backbone” interconnection

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The Public Networks – SMDS packet

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ATM packet

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ATM - reference model

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ATM sublayers