1. 1 ELEN 602 Lecture 7 Review of last lecture –Select Repeat ARQ –Performance of different ARQ schemes Data link layer -- framing –HDLC –PPP

2. 2 B B C C A A B C A B C A MUX (a) (b) Trunk group Multiplexing

3. 3 A C B f C f B f A f W W W 0 0 0 (a) Individual signals occupy W Hz (b) Combined signal fits into channel bandwidth Frequency Division Multiplexing

4. 4 (a) Each signal transmits 1 unit every 3T seconds (b) Combined signal transmits 1 unit every T seconds t A1A1 A2A2 t B1B1 B2B2 t C1C1 C2C2 3T3T 0T0T 6T6T 3T3T 0T0T 6T6T 3T3T 0T0T 6T6T t B1B1 C1C1 A2A2 C2C2 B2B2 A1A1 0T 1T 2T 3T 4T 5T 6T Time-division Multiplexing

5. 5 2 24 1 MUX 1 2 24 b1 2...b 23 22 frame 24... T-1 Carrier System

6. 6 North American Digital Hierarchy 28 M13 Multiplex M23 Multiplex x7 Primary Multiplex Eg. Digital Switch 24 chan PCM M12 Multiplex x4 1 DS3 44.736 Mbps DS1 1.544 Mbps DS2 6.312 MbpsDS3 44.736 Mbps Basic Digital Hierarchy

7. 7 123 4 5 123 4 5 t Timing in TDM Multiplexer

8. 8 Low-Speed Mapping Function Medium Speed Mapping Function High- Speed Mapping Function DS3 44.736 DS1 DS2 CEPT-1 CEPT-4 139.264 ATM 150 Mbps STS-1 STS-3c OC-n Scrambler E/O 51.84 Mbps High- Speed Mapping Function Mux STS-n SONET Multiplexing

9. 9 MUX DEMUX MUX DEMUX MUX DEMUX (a) pre-SONET multiplexing remove tributary insert tributary ADM remove tributary insert tributary (b) SONET Add-Drop multiplexing SONET add-drop multiplexing

10. 10 a b c 3 ADMs physical loop net OC-3n SONET Ring Network

11. 11 a b c logical fully-connected net (a) a b c 3 ADMs connected in physical ring topology OC-3n (b) Logical Networks

12. 12 a b c d a b c d (a) Dual ring (b) Loop-around in response to fault Surviving Faults in SONET

13. 13 Inter-Office Rings Metro Ring Regional Ring SONET Network Structure

14. 14 1 2 m Optical MUX 1 2 m Optical deMUX 1 2. m Optical fiber Wavelength Division Multiplexing

15. 15 (a) WDM chain network a b c d (b) WDM ring network a b c 3 ADMs Network Configuration using WDM