SONET / SDH

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SONET / SDH

• Nirmala Shenoy
• Information Technology Department
• Rochester Institute Technology

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SONET / SDH

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

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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)

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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

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SONET / SDH

• What is SONET / SDH?
• Self healing ring topology
• Consolidate and segregate traffic from different
  end-points
• Extensive integrated OAMP
• Backward compatibility

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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

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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

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SONET / SDH

• Configuration

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SONET / SDH

• SONET topology

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SONET / SDH

• Multiplexing

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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

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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

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SONET / SDH

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

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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

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SONET / SDH

• SONET layers

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SONET / SDH

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

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SONET / SDH

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

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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

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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

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SONET / SDH

• SONET STS-1Frame

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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

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SONET / SDH

• first column in SPE path overhead

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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

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SONET / SDH

• Section overhead
• Users 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

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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

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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

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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

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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

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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 frames4 columns9 rows 8 bits
  2.304 Mbps CEPT-1

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SONET / SDH

• Virtual Tributaries
• VT3 8000 frames 6 columns 9 rows 8 bits
  3.456 Mbps DS-1C
• VT6 8000 frames12 columns9 rows 8 bits
  6.912 Mbps DS-2

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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