1. 2.5 1 University of CalgaryCS 441 2.5 ISDN & ATM Integrated Services Digital Network (ISDN) +telephone, fax, computer, video, security +narrowband ISDN +broadband (B-ISDN) Asynchronous Transfer Mode (ATM) +asynchronous packet switching +voice, music, images, video, data +ATM protocol layers +ATM switching +SONET

2. 2.5 2 University of CalgaryCS 441 Integrated Services Digital Networks - ISDN The Public Switched Telephone Network +telephones in POTS become more complex supporting voice, video and data Digital TDM Switching +digital TDM replaces analog FDM Subscriber Loop (digitized voice, etc) +full duplex digital transmission from the user to end office switch (TDM with PCM) Control Signaling +common channel signaling over a packet switched network embedded in the PSTN for control, routing, monitoring, AIN services

3. 2.5 3 University of CalgaryCS 441 Principles & Goals of ISDN - late 1950s early 60s evolve from the existing PSTN to support voice, text, video and data => worldwide support both switched and non-switched (dedicated line) applications basic bandwidth unit is 64Kb/ s ~ digitized voice intelligence within the network - AIN services layered protocol architecture close to OSI enable varied physical configurations across regional and national boundaries

4. 2.5 4 University of CalgaryCS 441 The User / Customer Interface ISDN Interface ISDN CO packet switched network phone terminal PBX security system LAN circuit switched network other networks

5. 2.5 5 University of CalgaryCS 441 ISDN User Interface Standards - Architecture B Channel - 64 kb/ s +circuit switched, packet switched, leased line digital voice, fast data, Fax, degraded video D Channel - 16 or 64 kb/s +carries signaling information to control B channel circuit switched calls +can carry low bandwidth telemetry +low speed data, videotex, teletex, terminals H Channel(s) 384 or 1536 or 1920 kb/ s +user info at higher rates, customed groups packaged for each user

6. 2.5 6 University of CalgaryCS 441 ISDN Channel Structures Basic Service => residential & small offices +Rate is 192 kb/ s +composition : two B & one D + overhead Primary Service => larger customers +T1 rate is 1.544 (or 2.048 in europe) Mb/ s +composition : 23 B channels, 1 D channel (other variations supported)

7. 2.5 7 University of CalgaryCS 441 Broadband ISDN & ATM Today vastly larger bandwidths are desired by many classes of users => >600Mb/ s Users also require packet switching, ie, connectionless support May require fibre optical cables Asynchronous Transfer Mode (ATM) developed to support packet & circuit switching, mixed voice, video, data

8. 2.5 8 University of CalgaryCS 441 B-ISDN Transmission Services Full duplex 155.52 Mb/ s => likely satisfy most Asymetrical from subscriber to the network at 155 Mb/ s, and 622.08 Mb/ s back Full duplex 622.08 Mb/ s => multiple video session distribution, multiple video conferences

9. 2.5 9 University of CalgaryCS 441 B-ISDN & ATM Protocol Architecture B-ISDN and higher layer protocols ATM adaptation layer (AAL) convergence sublayer (CS) and segmentation / reassembly (SAR) sublayer ATM layer physical layer = TC and PMD sublayers transmission convergence (TC) and physical medium dependant (PMD) eg SONET

10. 2.5 10 University of CalgaryCS 441 ATM Network Interfaces UNI (ISDN) MUX DeMUX phone computer PBX video LAN ATM Network Access Control

11. 2.5 11 University of CalgaryCS 441 Asynchronous Transfer Mode vs Synchronous Transfer Mode - STM STM ~ TDM as in current PSTN A B C A B C A B C A B C mainframe A B C

12. 2.5 12 University of CalgaryCS 441 ATM Multiplexing A A A A A A A B A A A A A B A A A A A B A A A A mainframe A B C A heavy transmission, B occasional, C sleeping

13. 2.5 13 University of CalgaryCS 441 ATM Cells vs Frames 5 byte header 48 bytes data F Header variable length data CRC F frame = 64 - 1500 bytes long cell = 53 bytes long

14. 2.5 14 University of CalgaryCS 441 The ATM Cell Structure GFC VPI VPI VCI VCI VCI PT CLP HEC 48 bytes of Data

15. 2.5 15 University of CalgaryCS 441 Classes of Services (AALs) Constant Bit Rate (CBR) Services +voice or DSn emulation, includes mechanisms for recovering source timing info,... Variable Bit Rate (VBR) Real Time +raw compressed (ie bursty) real time video,... Variable Bit Rate (VBR) Non-Real Time +multimedia email,... Available Bit Rate (ABR) +Web browsing,... Unspecified Bit Rate (UBR) +file transfers,...

16. 2.5 16 University of CalgaryCS 441 ATM Adaptation Layer-AAL => class of service ATM designed so that Adaptation Layer functions are executed in the UNI - the user network interface Two sublayers: +=> CS convergence layer divides arbitrarily long packets into fixed length PDUs +=> SARsegmentation reassemblydivides above PDUs into 48 byte packets (cells) user data CS PDU SAR PDU CS PDU SAR PDU...

17. 2.5 17 University of CalgaryCS 441 ATM Layers User Data AAL Cell Cells ATM switches TC SONET

18. 2.5 18 University of CalgaryCS 441 Physical Layers TC => transmission convergence sublayer +generates and receives frames, packs cells into frames, computes ATM header CRC, ie HEC, and inserts in each cell, on receipt checks HEC for each cell, discards if error, bit scrambling to avoid SONET framing pattern,... +based on SONET or DS3 or ??? PMD => physical medium dependant sublayer +bit transfer between two nodes, wave shapes, timing recovery, line coding,... +ATM independant of this layer

19. 2.5 19 University of CalgaryCS 441 Access Control & Policing sustained information rate (SIR) = 8 Mb/s maximum burst length of 64 kbytes bursty data tokens at 8 million per second buffered tokens < 64 K data (with virtual token) => SIR & Burst length enable sizing buffers in switches

20. 2.5 20 University of CalgaryCS 441 Virtual Paths & Virtual Circuits VC1 VC3 VC1 VC2 VC3 VC2 SONET Pipe VP1 VP2 VC establishment: PVCs = permanent virtual channels SVCs = switched virtual channels

21. 2.5 21 University of CalgaryCS 441 Virtual Circuits & Virtual Paths ATM Switch Virtual Path Virtual Circuits

22. 2.5 22 University of CalgaryCS 441 ATM Switching an ATM switch receives a cell reads VPI/ VCI reads output port and new VPI/ VCI for the next link from routing table write the new VPI/ VCI into cell buffers cell on destination output port +above must be done in 3 microseconds at OC-3 rates (155 Mb/ s) +above must be done in 1/ 3 microsecond at OC-24 rates (1.2 Gb/ s)

23. 2.5 23 University of CalgaryCS 441 ATM Switch Requirements 1 gigabit/second ~= 150 million bytes / second => 3 million cells / second => 1/ 3 usec per cell => in one second receive 3 million cells => 150 million bytes of buffer storage

24. 2.5 24 University of CalgaryCS 441 SONET Optical Channel Rates OC-151.84 Mb/ s OC-3 =>155.52 Mb/ s=> ATM OC-9466.56 Mb/ s OC-12=>622.08 Mb/ s=> ATM OC-18933.12 Mb/ s OC-24=>1244.16 Mb/ s=> ATM OC-36 1866.24 Mb/ s OC-48 =>2488.32 Mb/ s=> ATM

25. 2.5 25 University of CalgaryCS 441 OC-3 SONET Frames = 2430 bytes at 155 Mb/ s 1B 1B 1B 125  sec 270 bytes 53 byte cell nine rows 53 byte cell transport overhead

26. 2.5 26 University of CalgaryCS 441 OC-N SONET Frames = N * 51.84 Mb/ s 1B 1B 1B 125  sec N * 90 bytes row 1 row 2 row 9

27. 2.5 27 University of CalgaryCS 441 DS3 Frame ~ 44 Mb/s A1 A2 P Z ATM Cell 13-14 nibble trailer ~ 125  sec ~ 690 bytes

28. 2.5 28 University of CalgaryCS 441 Cellular Radio paging systems +one way, ~ 30 bytes +1 Mb/s satellite can handle 240,000/minute cellular phones (analog but going digital) +advanced mobile phone system (AMPS) +10-20 km diameter cells, 0.6-3 watt xmitters +832 (30Khz) send channels in 824-849Mhz +832 (30Khz) receive channels in 869-894Mhz +control, paging, signaling, data channels +half each to an A carrier and to a B carrier +21 control and 45 data channels per cell +phone scans control channels for strongest +sends 32 bit serial # & 34 bit phone # /15 min +mobile, base stations, mobile switching office

29. 2.5 29 University of CalgaryCS 441 Personal Communications Services (PCS) cordless phone that goes anywhere in the world microcells, 50-100 meters in diameter, 0.25 watt massive infrastructure - 40,000 cells per cellular cell USA auction PCS 1.7-2.3 Ghz spectrum - $7.7billion PCS in US, PCN (personal comm net) elsewhere handoff from cell to cell as in cellular (~300ms) requries location independent unique addresses across world, system must keep track of locations

30. 2.5 30 University of CalgaryCS 441 Satellite Communications geosynchronous equatorial ~36,000 km, <=180 +C band,3.7-4.2 GHx down, 5.9-6.4 GHz up +Ku band, 11.7-12.2 down, 14.0-14.5 up +Ka band 17.7-21.7 down, 27.5-30.5 up +typical sattelite ~ 12-20 transponders +round trip transit time ~ 300 ms +VSAT is 2 trips using hub ~ 540 ms low orbit satellite ~750 Km, - LEO +Iridium - 77 (now 66), 6 polar orbits (big atom) +voice, data, paging, fax, navigation worldwide +1628 mobile cells, 174 full duplex channels each +L band 1.6 GHz, 200MHz total bandwidth +competes with PCS