SONET SDH Nirmala Shenoy Information Technology Department Rochester

SONET / SDH Nirmala Shenoy Information Technology Department Rochester Institute Technology updated 1/2002 1

SONET / SDH • Scope – What is SONET/SDH – features – Signal hierarchy – Topologies – SONET components – Layers – Frames – Virtual tributaries updated 1/2002 2

SONET / SDH • 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, DS 1 (Asyn) updated 1/2002 3

SONET / SDH • What is SONET / SDH? – Single reference clock • synchronize transmissions – Predictability – Powerful frame – Transmission envelope • Multiplex channels – Multiplexed transport mechanism • Optical based Carrier System updated 1/2002 4

SONET / SDH • What is SONET / SDH? – Self healing ring topology – Consolidate and segregate traffic from different end-points – Extensive integrated OAM&P – Backward compatibility updated 1/2002 5

SONET / SDH • Signal Hierarchy – STS – Synchronous Transport Signals • support a certain base data rate- 51. 84 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 updated 1/2002 6

SONET / SDH • Sonet/SDH rates STS 1 STS-3 STS-9 STS-12 STS-18 STS-24 STS-36 STS-48 STS-96 STS-192 OC-1 OC-3 OC-9 OC-12 OC-18 OC-24 OC-36 OC-48 OC-96 OC-192 51. 840 155. 520 466. 560 622. 080 933. 120 1244. 160 1866. 230 2488. 320 4976. 640 9953. 280 updated 1/2002 STM-1 STM-3 STM-4 STM-6 STM-8 STM-12 STM-16 STM-32 STM-64 7

SONET / SDH • Configuration updated 1/2002 8

SONET / SDH • SONET topology updated 1/2002 9

SONET / SDH • Multiplexing updated 1/2002 10

SONET / SDH • 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 updated 1/2002 11

SONET / SDH • 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 updated 1/2002 12

SONET / SDH • SONET Devices • Regenerator – Repeater – improves signal quality – Operations – include layer 2 • Frame alignment, scrambling, error monitoring – Section terminating equipment updated 1/2002 13

SONET / SDH • Section – Connects two neighboring devices • Line – Connects two multiplexers (STS , Add/Drop) • Path – Connects two STS Mux/demux • Layers – likewise – path, line, section updated 1/2002 14

SONET / SDH • SONET layers updated 1/2002 15

SONET / SDH • Photonic layers – phy – Specs for optical fiber channel – NRZ encoding used • Power level • Wavelength • Pulse shape updated 1/2002 16

SONET / SDH • 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 updated 1/2002 17

SONET / SDH • 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 updated 1/2002 18

SONET / SDH • 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 updated 1/2002 19

SONET / SDH • SONET STS-1 Frame updated 1/2002 20

SONET / SDH • 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 updated 1/2002 21

SONET / SDH – first column in SPE – path overhead updated 1/2002 22

SONET / SDH • Section overhead – Alignment bytes (A 1 & A 2)– framing and synchronization – pattern F 628 hex – Identification byte (C 1)–unique id for the STS 1 frame – Parity byte (B 1) – Order-wire byte (E 1)– bytes in consecutive frames – form a communication channel between regenerators updated 1/2002 23

SONET / SDH • Section overhead – User’s byte (F 1)– bytes in consecutive frames form a channel for user needs at the section level – Management bytes (D 1, D 2 and D 3)- 3 bytes per frame in consecutive frames = 192 kbps for OAM updated 1/2002 24

SONET / SDH • Line Overhead – Pointer bytes (H 1, H 2, H 3)– 3 bytes – identify location of the payload – Line Parity byte (B 2) – Automatic Protection Switching bytes 2 bytes (K 1, K 2) – consecutive frames- 128 kbps channel to detect problems in multiplexers updated 1/2002 25

SONET / SDH • Line Overhead – Data communication channel bytes (D 4 -D 12) – consecutive frames – 576 kbps OAM at the line – Growth bytes (Z 1, Z 2) – future use – Orderwire byte (E 2) – line level updated 1/2002 26

SONET / SDH • Path Overhead – Path trace byte (J 1) – bytes in consecutive frames – path tracking – verify connection – Path parity byte (B 3) – Path signal label byte (C 2) – path id – gives the construction details of the SPE – Path Status byte (G 1) –receiver communicates its status updated 1/2002 27

SONET / SDH • Path Overhead – Path user channel byte (F 2) user needs at path level – Virtual tributary indicator (H 4) –multi-frame indicator – payload not fitting into a frame – Growth byte (Z 3, Z 4, Z 5) – reserved – updated 1/2002 28

SONET / SDH • Virtual Tributaries – Partial payload share a frame – The SPE has a number of tributaries – VT 1. 5 = 8000 frames * 3 columns * 9 rows * 8 bits = 1. 728 Mbps DS-1 service – VT 2 = 8000 frames*4 columns*9 rows * 8 bits = 2. 304 Mbps CEPT-1 updated 1/2002 29

SONET / SDH • Virtual Tributaries – VT 3 = 8000 frames * 6 columns * 9 rows * 8 bits = 3. 456 Mbps DS-1 C – VT 6 = 8000 frames*12 columns*9 rows * 8 bits = 6. 912 Mbps DS-2 updated 1/2002 30

SONET / SDH • 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 updated 1/2002 31