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SONET / SDH. Nirmala Shenoy Information Technology Department Rochester Institute Technology. SONET / SDH. Scope What is SONET/SDH – features Signal hierarchy Topologies SONET components Layers Frames Virtual tributaries. SONET / SDH. What is SONET / SDH?
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SONET / SDH Nirmala Shenoy Information Technology Department Rochester Institute Technology updated 1/2002
SONET / SDH • Scope • What is SONET/SDH – features • Signal hierarchy • Topologies • SONET components • Layers • Frames • Virtual tributaries updated 1/2002
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, DS1 (Asyn) updated 1/2002
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
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
SONET / SDH • Signal Hierarchy • STS – Synchronous Transport Signals • support a certain base data rate- 51.84Mbps • 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
SONET / SDH • Sonet/SDH rates STS 1 OC-1 51.840 STS-3 OC-3 155.520 STM-1 STS-9 OC-9 466.560 STM-3 STS-12 OC-12 622.080 STM-4 STS-18 OC-18 933.120 STM-6 STS-24 OC-24 1244.160 STM-8 STS-36 OC-36 1866.230 STM-12 STS-48 OC-48 2488.320 STM-16 STS-96 OC-96 4976.640 STM-32 STS-192 OC-192 9953.280 STM-64 updated 1/2002
SONET / SDH • Configuration updated 1/2002
SONET / SDH • SONET topology updated 1/2002
SONET / SDH • Multiplexing updated 1/2002
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
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
SONET / SDH • SONET Devices • Regenerator • Repeater – improves signal quality • Operations – include layer 2 • Frame alignment, scrambling, error monitoring • Section terminating equipment updated 1/2002
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
SONET / SDH • SONET layers updated 1/2002
SONET / SDH • Photonic layers – phy • Specs for optical fiber channel • NRZ encoding used • Power level • Wavelength • Pulse shape updated 1/2002
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
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
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
SONET / SDH • SONET STS-1Frame updated 1/2002
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
SONET / SDH • first column in SPE – path overhead updated 1/2002
SONET / SDH • 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 updated 1/2002
SONET / SDH • 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 updated 1/2002
SONET / SDH • 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 updated 1/2002
SONET / SDH • 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 updated 1/2002
SONET / SDH • 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 updated 1/2002
SONET / SDH • 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 updated 1/2002
SONET / SDH • Virtual Tributaries • Partial payload share a frame • The SPE has a number of tributaries • VT1.5 = 8000 frames * 3 columns * 9 rows * 8 bits = 1.728 Mbps DS-1 service • VT2 = 8000 frames*4 columns*9 rows * 8 bits = 2.304 Mbps CEPT-1 updated 1/2002
SONET / SDH • Virtual Tributaries • VT3 = 8000 frames * 6 columns * 9 rows * 8 bits = 3.456 Mbps DS-1C • VT6 = 8000 frames*12 columns*9 rows * 8 bits = 6.912 Mbps DS-2 updated 1/2002
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