SONET / SDH. Slides Derived from: Nirmala Shenoy Information Technology Department Rochester Institute Technology

Transcription

1 Slides Derived from: Nirmala Shenoy Information Technology Department Rochester Institute Technology 1

2 Scope What is SONET/SDH features Signal hierarchy Topologies SONET components Layers Frames Virtual tributaries 2

3 What is SONET / SDH? Synchronous Optical Network ANSI (US) Synchronous Digital Hierarchy ITU-T Europe Similar and compatible A standard to be used for fibre optics Recommendation for FOTS equipment Fibre Optic Transmission Systems Can carry incompatible DS-0, DS1 (Asyn) 3

4 What is SONET / SDH? Single reference clock synchronize transmissions Predictability Powerful frame Transmission envelope Multiplex channels Multiplexed transport mechanism Optical based Carrier System 4

5 What is SONET / SDH? Self healing ring topology Consolidate and segregate traffic from different end-points Extensive integrated OAM&P Backward compatibility 5

6 Signal Hierarchy STS Synchronous Transport Signals support a certain base data rate Mbps STS 1 STS 192 different hierarchies Corresponding carrier System Optical Carrier OC-1, OC-3, OC-12, OC-48 SDH STM Synchronous Transport Module STM 1 = STS 3 6

7 Sonet/SDH rates STS 1 OC STS-3 OC STM-1 STS-9 OC STM-3 STS-12 OC STM-4 STS-18 OC STM-6 STS-24 OC STM-8 STS-36 OC STM-12 STS-48 OC STM-16 STS-96 OC STM-32 STS-192 OC STM-64 7

8 Configuration Add/drop mux STS MUX STS MUX regenerator regenerator section section line path 8

9 SONET topology SMD ADM ADM Oc-n Oc-n SMD SA DS1 DCS Oc-n ADM Oc-n Oc-n SMD SA ADM add drop multiplexer SMD- sts mu/demux DCS digital cross connect switch SA service adapter SMD ADM Oc-n ADM SMD

10 Multiplexing DS1, CEPT1 etc Service Adapters Maps into virtual tributaries STS-n DS3 Service Adapters STS-1 MUX/DMUX E/O MAN, ATM, SMDS, others Service Adapters STS-n 10

11 SONET Devices STS Multiplexer Multiplexes and de-multiplexes signals from multiple sources Path terminating equipment Maps user payload into standard frame Header goes end-to-end as part of Synchronous Payload Envelope - SPE 11

12 SONET Devices Add /Drop Multiplexer Adds signals from different sources/removes Uses header address information to identify stream and remove Line terminating Equipment Performs multiplexing, synchronization, APS 12

13 SONET Devices Regenerator Repeater improves signal quality Operations include layer 2 Frame alignment, scrambling, error monitoring Section terminating equipment 13

14 Section Connects two neighboring devices Line Connects two multiplexers (STS, Add/Drop) Path Connects two STS Mux/demux Layers likewise path, line, section 14

15 SONET layers PATH layer LINE layer Data link SECTION layer photonic layer Physical 15

16 Photonic layers phy Specs for optical fiber channel NRZ encoding used Power level Wavelength Pulse shape 16

17 Section layer Frames identifies beginning of frame Scrambling introducing 1 s to derive clock error monitoring section level Adds 9 bytes to header frame size 810 bytes Provided at all devices 17

18 Line layer Locates partial payload virtual tributaries Provides frequency justification, bit stuffing To adjust to clocking from different systems Does APS Adds 18 bytes to header Provided at the STS Mux and Add/Drop Mux 18

19 Path layer Converts to optical signals and back to electromagnetic Adds 9 bytes to header - is part of SPE Defines the payload being carried End-to-end path control Support virtual tributaries Provided at the STS Mux 19

20 SONET STS-1Frame Frame1 Frame2 Frame8000 Frame = 810 octets * 8 = 6480bits 8000 frames/sec = 6480*8000 bits/sec = 51.84Mbps 20

21 SONET Frame Matrix of nine rows 90 octets each First 3 columns (octets) three rows section overhead 9 bytes Next 6 rows line overheads 18 bytes Rest of the frame Synchronous Payload Envelope SPE 9 bytes of path overheads 21

22 first column in SPE path overhead Section overhead line overhead STS SPE Path overhead 22

23 Section overhead Alignment bytes (A1 & A2) framing and synchronization pattern F628hex Identification byte (C1) unique id for the STS- 1 frame Parity byte (B1) Order-wire byte (E1) bytes in consecutive frames form a communication channel between regenerators 23

24 Section overhead User s byte (F1) bytes in consecutive frames form a channel for user needs at the section level Management bytes (D1, D2 and D3)- 3 bytes per frame in consecutive frames = 192 kbps for OAM 24

25 Line Overhead Pointer bytes (H1, H2, H3) 3 bytes identify location of the payload Line Parity byte (B2) Automatic Protection Switching bytes 2 bytes (K1, K2) consecutive frames- 128 kbps channel to detect problems in multiplexers 25

26 Line Overhead Data communication channel bytes (D4-D12) consecutive frames 576 kbps OAM at the line Growth bytes (Z1, Z2) future use Orderwire byte (E2) line level 26

27 Path Overhead Path trace byte (J1) bytes in consecutive frames path tracking verify connection Path parity byte (B3) Path signal label byte (C2) path id gives the construction details of the SPE Path Status byte (G1) receiver communicates its status 27

28 Path Overhead Path user channel byte (F2) user needs at path level Virtual tributary indicator (H4) multi-frame indicator payload not fitting into a frame Growth byte (Z3, Z4, Z5) reserved 28

29 Virtual Tributaries Partial payload share a frame The SPE has a number of tributaries VT1.5 = 8000 frames * 3 columns * 9 rows * 8 bits = Mbps DS-1 service VT2 = 8000 frames*4 columns*9 rows * 8 bits = Mbps CEPT-1 29

30 Virtual Tributaries VT3 = 8000 frames * 6 columns * 9 rows * 8 bits = Mbps DS-1C VT6 = 8000 frames*12 columns*9 rows * 8 bits = Mbps DS-2 30

31 Summary A carrier system optical carriers Synchronous transmission - faster Time Division multiplexing High speed backbone Support for high bit rate applications? Add/Drop multiplexers Self healing rings 31