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Update 12/15/20011 ICSA 745 Transmission Systems Emerged Technologies Nirmala Shenoy Department of Information Technology Rochester Institute of Technology.

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Presentation on theme: "Update 12/15/20011 ICSA 745 Transmission Systems Emerged Technologies Nirmala Shenoy Department of Information Technology Rochester Institute of Technology."— Presentation transcript:

1 update 12/15/20011 ICSA 745 Transmission Systems Emerged Technologies Nirmala Shenoy Department of Information Technology Rochester Institute of Technology

2 update 12/15/20012 Emerged Technologies Scope –TI / E1 Carrier Systems –X.25 –ISDN –SS7 –FDDI

3 update 12/15/20013 Emerged Technologies Coverage –Purpose of the technology –Typical topology –Layers –PDU –Any other aspects –Conclusions

4 update 12/15/20014 T1/E1 Carriers Systems Purpose Up to 1960s telephone networks were analog 1962 – digital trunks 1980 – T1 digital carrier lines were introduced –T – telephone carrier line – copper based

5 update 12/15/20015 T1 / E1 Carrier System Purpose –Initially to carry digitized voice at 64 kbps –Voice was carried as digital signals – DS –DS was primarily based on PCM & ADPCM Time Division Multiplexing schemes –T1 was the North American Carrier –E1 was the European Carrier

6 update 12/15/20016 T1 / E1 Carrier System Purpose –T1 – can accommodate 24 64kbps voice channels – bw – Mbps –E1 – can accommodate 32 64kbps voice channels – bw – 2.048Mbps –E1 is similar to T1, but not compatible to T1

7 update 12/15/20017 T1 / E1 Carrier System Multiplexing hierarchy- T1 –DS0 – one 64kbps channel for one voice user –DS1- 24, 64kbps channels used by T1 –DS2 – 96, 64kbps channels used by T2 –7DS2 can be multiplexed into DS3 –6DS3 can be multiplexed into DS4 T1 uses DS1, but DS1 signals can be transmitted over any carrier.

8 update 12/15/20018 T1 / E1 Carrier System –Topology – similar for T1 and E1 –Typically point to point –Multiple links via cross connect switch

9 update 12/15/20019 T1 / E1 Carrier System Protocol Layer –Both T1 and E1 are in the Physical layer of the seven layer OSI model –Define connectors, signaling conventions, framing formats, etc

10 update 12/15/ T1 / E1 Carrier System Protocol Data Unit – T1 –Each voice channel gets 8 bits –24 channels make a frame = 125  sec frame –A frame has 192 bits –193 rd bit is a framing bit – synchronization –Synchronization requires 12 bits which are spread over 12 frames

11 update 12/15/ T1 / E1 Carrier System Protocol Data Unit – T1 –Signaling A & B bit signaling – in band signaling Done by bit robbing from payload –Off-hook, on-hook, ringing 8 th bit for every 6 th and 12 th frame 8 th bit is unreliable 56 kbps

12 update 12/15/ T1 / E1 Carrier System Protocol Data Unit – E1 –Each voice channel gets 8 bits –32 channels make a frame = 125  sec frame –A frame has 256 bits –32 nd byte used for control Out-of-band signaling

13 update 12/15/ T1 / E1 Carrier System Conclusions –Limited management operations –multiplexing schemes not easy –Bit stuffing problems –Stepping stones to more robust technologies Sonet/SDH


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