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Sdh concept
Advantages
             of SDH over PDH.
•   High transmission rates up to 40 Gbit/s
•    Simplified add & drop function
•    High availability and capacity matching
•   Reliability
•   Future-proof platform for new services.
•   Interconnection (SONET,SDH,PDH)
What is SDH?
• The basis of Synchronous Digital Hierarchy
  (SDH) is synchronous multiplexing - data
  from multiple tributary sources is byte
  interleaved.
• In SDH the multiplexed channels are in fixed
  locations relative to the framing byte.
• De-multiplexing is achieved by gating out the
  required bytes from the digital stream.
• This allows a single channel to be ‘dropped’
  from the data stream without de-multiplexing
  intermediate rates as is required in PDH.
7/26/2012
Multiplexing Processes
– Multiplexing is composed of various processes:
   • Mapping
      –Tributaries adapted into Virtual Containers
        (VC) by adding stuffing and POH
   • Aligning
      –Pointer is added to locate the VC inside an AU
        or TU
   • Multiplexing
      –Interleaving the bytes of multiple paths
   • Stuffing
      –Adding up the fixed stuff bits to compensate
        for frequency variances
TRANSPORT OF PDH
                   PAYLOAD
SDH is essentially a transport mechanism for carrying a
   large number of PDH payloads.
• A mechanism is required to map PDH rates into the
  STM frame. This function is performed by the
  container (C).
• A PDH channel must be synchronized before it can
  be mapped into a container.
• The synchronizer adapts the rate of an incoming PDH
  signal to SDH rate.
SDH and non synchronous signal
• At the PDH/SDH boundary Bit stuffing is
  performed when the PDH signal is mapped into
  its container.

7/26/2012
STM-N frame

                              270 x N Columns



                    9xN
                   Columns

                                   STM-N VC capacity
             9
            Rows



                                                       125 μsec
                   Section
                   Overhead
7/26/2012
Concatenated Frames

                                 N-1 Columns         SDH terminology is using
                                                      X instead of N (X = N)

                                      N x 260 Columns
                  STM
                  POH
                 9 bytes
        9 Rows                   STM-Nc Payload Capacity
                                       (AU-4-Nc)
                       Fixed
                        Stuff
                       (9N-9     STM-4c = 599.040 Mbit/s
                       bytes)    STM-16c = 2396.160 Mbit/s

                                                               125 μsec

                                N x 261 Columns
7/26/2012
SDH Rates
• SDH is a transport hierarchy based on
  multiples of 155.52 Mbit/s.
The basic unit of SDH is STM-1:
STM-1 = 155.52 Mbit/s
STM-4 = 622.08 Mbit/s
STM-16 = 2588.32 Mbit/s
STM-64 = 9953.28 Mbit/s
• Each rate is an exact multiple of the lower rate therefore
  the hierarchy is synchronous.

7/26/2012
Frame Structures for Each Common
             Hierarchy Level
                 270 Columns
    STM-1

       9 Rows                          155.52 Mbit/s




                               1,080 Columns
    STM-4

       9 Rows                                            622.08 Mbit/s



                                         4,320 Columns
   STM-16

       9 Rows
                                                         2488.32 Mbit/s




   STM-64       9 rows x 17280 columns, 9953.28 Mbit/s
7/26/2012
Mapping Hierarchy

         xN            x1
                                                                                  C-4   139 Mbit/s
STM-N         AUG           AU-4   VC-4                                                 ATM
                                               x3
                                                            x1
                            x3
                                               TUG-3               TU-3   VC-3
         x1
                                                                                         44 Mbit/s
STM-0         AUG           AU-3   VC-3                                           C-3    34 Mbit/s
                                                            x7

                                          x7
                                                             x1
                                                                   TU-2   VC-2    C-2   6.3 Mbit/s
                                                    TUG-2
                                                                  x3

                                                                  TU-12   VC-12   C-12 2 Mbit/s
   xN
        Multiplexing                                        x4
                                                                  TU-11   VC-11   C-11 1.5 Mbit/s
        Aligning

         Mapping
7/26/2012
Containers - I.
– In SDH terminology, the original PDH payload
  with special framing is called a container (C-x)
– Various container sizes with some space for
  stuffing are defined
   • C-11 for DS1 (25 bytes = 1.600 Mbit/s)
   • C-12 for E1 (34 bytes = 2.176 Mbit/s)
   • C-2 for DS2 (106 bytes = 6.784 Mbit/s)
   • C-3 for DS3 or E3 (84 columns = 48.384
     Mbit/s)
   • C-4 for E4 (260 columns = 149.760 Mbit/s)
Virtual Containers - II.
– Various VC sizes defined:
   • With 1 byte allocated for POH
       – VC-11 for DS1 (26 bytes = 1.664 Mbit/s)
       – VC-12 for E1 (35 bytes = 2.240 Mbit/s)
       – VC-2 for DS2 (107 bytes = 6.848 Mbit/s)
   • With 1 column allocated for POH
       – VC-3 for DS3 or E3 (85 columns = 48.960 Mbit/s)
       – VC-4 for E4 (261 columns = 150.336 Mbit/s)
Tributary Unit Structure
– TUs are defined to fit into a number of columns
    • This requirement determines the size of virtual
      containers and containers
    • TU-3 adds up 3-byte pointer plus stuffing to VC-3
    • Lower TUs add up 1 byte for pointer storage
       –Organized into 4 frames (500 μs multi-frame)
       –This provides V1, V2, V3, V4 TU pointer bytes
– Lower TUs also organize POH along the multi-
  frame
    • This provides V5, J2, Z6, Z7 POH bytes
    • Lower TUs use V1, V2, V3, V4 bytes in 500 μs
      multi-frame
Adoption of 2MBPS Signal over SDH.




 IF C1C1C1-111 THEN S1 IS A JUSTIFICATION BIT




     SKG/RTTC/BBS
7/26/2012
General Structure
Order of transmission
              1st               270 columns


     2nd




       Section
       overhead                               VC Capacity
       (SOH)                                   (for AUG)




             9 columns          261 columns
 7/26/2012
STM-1 frame


                                   270 bytes

  RSOH               1   ….. 9           261Byte

            3 rows

                     pointer         Information
                                                                9 Rows
                                       Payload
MSOH
            5 rows



                     Transport                                      125 μs
                     overhead
                                     Synchronous Payload Envelope




7/26/2012
Pointer
                            4 Bytes
                       v1
      V1 & v2 points
                                              TU12
           V5
                       v2


                              v5


                                      VC-12
                                              500 μsec
                       v3




7/26/2012
STS-1 Frame                               810x64kbps=51.84Mbps
                                      810 Octets per frame @ 8000 frames/sec
                                                         90 columns

                                 A1 A2 J0      J1
                                 B1 E1 F1 B3
            1
                                 D1 D2 D3 C2
       Order of
     2 transmission              H1 H2 H3 G1
                       9 rows    B2 K1 K2 F2
Special OH octets:               D4 D5 D6 H4
                                 D7 D8 D9 Z3
A1, A2 Frame Synch
                                 D10 D11 D12 Z4
B1 Parity on Previous Frame
    (BER monitoring)             S1 M0/1 E2 N1
J0 Section trace
   (Connection Alive?)          3 Columns of        Synchronous Payload Envelope (SPE)
H1, H2, H3 Pointer Action       Transport OH        1 column of Path OH + 8 data columns
K1, K2 Automatic Protection
Switching                              Section Overhead               Path Overhead

    SKG/RTC/BBSR
    S                                  Line Overhead                  Data
STM-0 Overheads
                                                                HO Path
                              Section Overhead                  Overhead
                    Framing          Framing      RS Trace        Path Trace
                       A1               A2           J0               J1
     R-Section       BIP-8           Orderwire   User Channel       BIP-8
     Overhead         B1                E1            F1             B3
                   Data Com         Data Com      Data Com       Signal Label
                      D1               D2            D3              C2

                                                    Pointer      Path Status
     AU pointer     Pointer          Pointer
                                                                     G1
                      H1               H2             H3
                     BIP-8            APS            APS        User Channel
                      B2               K1             K2             F2
                                                                 Multiframe
                   Data Com         Data Com       Data Com       Indicator
     M-Section        D4               D5             D6             H4
     Overhead      Data Com         Data Com       Data Com     User Channel
                      D7               D8             D9             F3

                   Data Com         Data Com       Data Com        APS
                     D10              D11            D12            K3

                     Sync            (REI)        Orderwire       Tandem
                      S1             (M1)            E2             N1


7/26/2012
STM-1 Section Overhead

                  A1    A1    A1    A2    A2    A2    J0               Δ - media
                                                                       dependent
      R-Section
                   B1    Δ    Δ     E1     Δ          F1
      Overhead
                   D1    Δ    Δ     D2     Δ          D3

     AU pointer   H1    H1*   H1*   H2    H2*   H2*   H3    H3   H3   H1* = 10010011

                   B2   B2    B2    K1                K2              H2* = 11111111

                   D4               D5                D6
     M-Section
     Overhead     D7                D8                D9

                  D10               D11               D12
                                                                        national use

                   S1                           M1    E2


7/26/2012
MAPPING OF VC-4 IN TO STM1

                                          270 bytes
                  9 bytes
               RSOH
Transport      3ROWS           20 BLOCKS OF 13 BYTES
Overhead                            VC-4 Path Overhead
              AU-4 POINTER
     9 rows                    Trace
              MSOH               J1       Path Overhead
                               BIP-8
              5 ROWS            B3        • J1- Path Trace
                                          • BIP-8 - Parity
                               Label
                                C2
                              Status
                                G1        • C2 - Payload Type Indicator
                               User
                                 F2
                                          • G1 - End Path Status
                             Multiframe   • F2 - User
                                H4
            Synchronous       Growth      • H4 - Use Depends On Payload
              Payload            Z3
                              Growth      • Z3-5 - Future Growth
              Envelope           Z4
                               TCM
                                 Z5
                                                           STM-1 Payload

  Asynchronous mapping of 139.264 MBPS
    7/26/2012                                                     Page-66
Payload Pointer
            Payload Pointer marks
            start of STM-1 VC-3 or
                      VC-4
                                          90 (VC-3) or 270 (VC-4) Columns
    STM-1 Frame #1


                            H1 H2 H3...

                      9
                     Rows                                         STM-1
                                                                VC-3 or VC-4

    STM-1 Frame #2                                                             125 μsec




                      9
                     Rows
                                                       STM-1 VC-3 or VC-4
                                                          POH column
                                                                               250 μsec
7/26/2012                    Section
                            Overhead
270 bytes
                   9 bytes
                RSOH
Transport       3ROWS                20 BLOCKS OF 13 BYTES
Overhead
              H1H1H1H2H2H2H3H3H3

     9 rows                          Trace
               MSOH                    J1       1   2   3   . . . . . . . . . 17 18 19 20
                                     BIP-8
               5 ROWS                 B3
                                     Label
                                      C2
                                    Status
                                      G1
                                     User
                                       F2
                                   Multiframe
                                      H4
            Synchronous             Growth
              Payload                  Z3
                                    Growth
              Envelope                 Z4
                                     TCM
                                       Z5


  Asynchronous mapping of 139.264 MBPS                                  STM-1 Payload
                                                                               Page-66
path
                     multiplex section                           multiplex section

          regenerator                 regen.           regen.              regenerator
            section                   section          section               section

                                             ADM
    TM                     REG                or                    REG                 TM
                                             DCS
   path              regen. section      multipl. section        regen. section         path
termination            termination        termination              termination       termination

                             PTE = path terminating element
service (E1, E4..)           TM = terminal multiplexer
mapping                                                                           service (E1, E4..)
demapping                    REG = regenerator                                    mapping
                             ADM = add/drop multiplexer                           demapping
                             DCS = digital cross-connect system
                             DXC= digital cross connect
Regenerator
– A regenerator simply extends the possible
  distance and quality of a line by decomposing
  it into multiple sections
  • Replaces regenerator section overhead
  • Multiplex section and path overhead is not altered
Add-drop Multiplexer - I.
   – Add/drop multiplexer (ADM)
      • Main element for configuring paths on top of line
        topologies (point-to-point or ring)
      • Multiplexed channels may be dropped and added
      • Special drop and repeat mode for broadcast and
        survivability
      • An ADM has at least 3 logical ports: 2 core and 1 or
        more add-drop
•Ports have different                                      Optical port
roles                     Optical port    ADM(OEO)
•No switching between
the core ports
•Switching only                            Electrical port
between the add-drop
and the core ports.
Sdh concept
Uni- and Bi-directional
                     Routing
                      A                                  A
                                        A-C                             A-C

         F                          B         F                         B
                                                                 C-A
C-A


         E                          C         E                         C


                      D                                  D

             Uni-directional Ring                 Bi-directional Ring
                   (1 fiber)                           (2 fibers)
      – Only working traffic is shown
      – Subnetwork (path) or multiplex section switching for
        protection
USHR
• Working traffic is carried around the ring in
  one direction only.
• Ring capacity is sum of demands between
  nodes.
• Also called “Counter–Rotating–Ring”;
  traffic in prot. rotates opposite.
• 1:1 (USHR/L); extended to 1:N, then not
  entirely self–healing.
• 1+1 (USHR/P).
USHR-L
USHR/L
Incoming and
returning signal
routed
unidirectionally on
working ring.
On failure,
adjacent nodes
perform fold or
looping function.
Basic ADMs used
(TSI not needed).
USHR Concepts
– USHR/P = Unidirectional Self-Healing Ring / Path Switched
– 2-fiber ring topology
   • Head-end bridge, tail-end switch logical topology
        – 1+1 protection with uni-directional routing on each fiber
        – Traffic is sent in both directions on the ring on separate
           fibers
        – The better signal is selected by the receiver.
BSHR Concepts - I.
– BSHR/MS = Bi-directional Self-Healing Ring /
  Multiplex Section Switched
– 1:1, or 1:N redundancy options
– 2 fibers with shared protection configuration
   • Half the bandwidth in each direction in a link
     is reserved for the shared protection of all
     traffic in that reverse direction of the link
       –An even number of
         STM-1s are required
– 4 fibers for dedicated protection configuration
   • Bi-directional routing on 2 fibers (working
     line)
   • Each direction has a working and a protect
     fiber
BSHR Concepts - II.
– Multiple fail-over options for 4-fiber BSHR/MS
   • In normal operation traffic is sent only in the required direction
   • During fiber interruption, the traffic is routed around the break in
     opposite direction (long path)
        – Ring switching
   • Optionally if the other 2 fibers are still available, then traffic might
     be routed onto the parallel 2 fibers (short path)
        – Span switching
Multiplex Section Protection
               Switching
                           R-Section
                           Overhead
          information
          controlling
          protection                          Payload
          switching
                           M-Section
                           Overhead


– Conditions resulting in a protection switch:
   • Loss of signal, loss of frame
                                      LOS           AIS
   • Line AIS (all 1’s)
                                                          down
   • Signal degrade                    REI
                                           upstream
                                                    OCN
                                                          stream


       – Excessive BIP-24 errors in MS overhead
Path Protection Switching
R-Section               Payload
Overhead
                           VC
                          Path
                        Overhead
               STM                         Info
               Path                        controlling
             Overhead                      protection
M-Section                                  switching
Overhead                  VC
                        Payload




   – Conditions resulting in a protection switch:
      • Loss of pointer, STM or VC AIS
      • Excessive BIP errors for STM path, BIP errors for VC
        path
Automatic Protection Switching - I.

– APS = Automatic                                              Tributary
                                                               Channels


  Protection Switching                            STM-N Mux



   • Allows network to        MSTE              K1K2
                                               Read/Sel
                                                           K1K2
                                                           Write



     react to failed lines,
     interfaces, or
     poor signal quality
– Performed over the                 Working
                                     STM-N
                                                                      Protect
                                                                      STM-N
  entire STM-N payload
– Uses K1 and K2 bytes
  of MS Overhead
                              MSTE              K1K2
                                                Write
                                                           K1K2
                                                          Read/Sel



                                                  STM -N Mux

                                                               Tributary
                                                               Channels
Automatic Protection Switching - II.
– K1 byte:                                                     Tributary
                                                               Channels

   • Type of request (bits                        STM-N Mux

     1-4)
                              MSTE              K1K2       K1K2

   • Channel requested                         Read/Sel    Write



     (bits 5-8)
– K2 byte:
   • Channel selected (bits
     1-4)
                                     Working                          Protect
   • Architecture (bit 5)            STM-N                            STM-N


   • Mode of operation
     (bits 6-8)
       – e.g. Alarm
          Indication Signal   MSTE              K1K2
                                                Write
                                                           K1K2
                                                          Read/Sel

          (AIS), Remote
          Defect Indicator                        STM -N Mux

          (RDI)                                                Tributary
                                                               Channels
Uni- and Bi-directional APS
– Uni-directional APS
  • Only traffic on the affected fiber is switched to the
    protect line
– Bi-directional APS
  • TX and RX are both switched when channel is
    affected
Revertive and Non-revertive
           APS
– Revertive switching
  • Will restore to the working channel when WTR
    timer expires
– Non-revertive switching
  • Will not move to working channel after failure
    unless requested
Sdh concept

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Sdh concept

  • 2. Advantages of SDH over PDH. • High transmission rates up to 40 Gbit/s • Simplified add & drop function • High availability and capacity matching • Reliability • Future-proof platform for new services. • Interconnection (SONET,SDH,PDH)
  • 3. What is SDH? • The basis of Synchronous Digital Hierarchy (SDH) is synchronous multiplexing - data from multiple tributary sources is byte interleaved. • In SDH the multiplexed channels are in fixed locations relative to the framing byte. • De-multiplexing is achieved by gating out the required bytes from the digital stream. • This allows a single channel to be ‘dropped’ from the data stream without de-multiplexing intermediate rates as is required in PDH. 7/26/2012
  • 4. Multiplexing Processes – Multiplexing is composed of various processes: • Mapping –Tributaries adapted into Virtual Containers (VC) by adding stuffing and POH • Aligning –Pointer is added to locate the VC inside an AU or TU • Multiplexing –Interleaving the bytes of multiple paths • Stuffing –Adding up the fixed stuff bits to compensate for frequency variances
  • 5. TRANSPORT OF PDH PAYLOAD SDH is essentially a transport mechanism for carrying a large number of PDH payloads. • A mechanism is required to map PDH rates into the STM frame. This function is performed by the container (C). • A PDH channel must be synchronized before it can be mapped into a container. • The synchronizer adapts the rate of an incoming PDH signal to SDH rate. SDH and non synchronous signal • At the PDH/SDH boundary Bit stuffing is performed when the PDH signal is mapped into its container. 7/26/2012
  • 6. STM-N frame 270 x N Columns 9xN Columns STM-N VC capacity 9 Rows 125 μsec Section Overhead 7/26/2012
  • 7. Concatenated Frames N-1 Columns SDH terminology is using X instead of N (X = N) N x 260 Columns STM POH 9 bytes 9 Rows STM-Nc Payload Capacity (AU-4-Nc) Fixed Stuff (9N-9 STM-4c = 599.040 Mbit/s bytes) STM-16c = 2396.160 Mbit/s 125 μsec N x 261 Columns 7/26/2012
  • 8. SDH Rates • SDH is a transport hierarchy based on multiples of 155.52 Mbit/s. The basic unit of SDH is STM-1: STM-1 = 155.52 Mbit/s STM-4 = 622.08 Mbit/s STM-16 = 2588.32 Mbit/s STM-64 = 9953.28 Mbit/s • Each rate is an exact multiple of the lower rate therefore the hierarchy is synchronous. 7/26/2012
  • 9. Frame Structures for Each Common Hierarchy Level 270 Columns STM-1 9 Rows 155.52 Mbit/s 1,080 Columns STM-4 9 Rows 622.08 Mbit/s 4,320 Columns STM-16 9 Rows 2488.32 Mbit/s STM-64 9 rows x 17280 columns, 9953.28 Mbit/s 7/26/2012
  • 10. Mapping Hierarchy xN x1 C-4 139 Mbit/s STM-N AUG AU-4 VC-4 ATM x3 x1 x3 TUG-3 TU-3 VC-3 x1 44 Mbit/s STM-0 AUG AU-3 VC-3 C-3 34 Mbit/s x7 x7 x1 TU-2 VC-2 C-2 6.3 Mbit/s TUG-2 x3 TU-12 VC-12 C-12 2 Mbit/s xN Multiplexing x4 TU-11 VC-11 C-11 1.5 Mbit/s Aligning Mapping 7/26/2012
  • 11. Containers - I. – In SDH terminology, the original PDH payload with special framing is called a container (C-x) – Various container sizes with some space for stuffing are defined • C-11 for DS1 (25 bytes = 1.600 Mbit/s) • C-12 for E1 (34 bytes = 2.176 Mbit/s) • C-2 for DS2 (106 bytes = 6.784 Mbit/s) • C-3 for DS3 or E3 (84 columns = 48.384 Mbit/s) • C-4 for E4 (260 columns = 149.760 Mbit/s)
  • 12. Virtual Containers - II. – Various VC sizes defined: • With 1 byte allocated for POH – VC-11 for DS1 (26 bytes = 1.664 Mbit/s) – VC-12 for E1 (35 bytes = 2.240 Mbit/s) – VC-2 for DS2 (107 bytes = 6.848 Mbit/s) • With 1 column allocated for POH – VC-3 for DS3 or E3 (85 columns = 48.960 Mbit/s) – VC-4 for E4 (261 columns = 150.336 Mbit/s)
  • 13. Tributary Unit Structure – TUs are defined to fit into a number of columns • This requirement determines the size of virtual containers and containers • TU-3 adds up 3-byte pointer plus stuffing to VC-3 • Lower TUs add up 1 byte for pointer storage –Organized into 4 frames (500 μs multi-frame) –This provides V1, V2, V3, V4 TU pointer bytes – Lower TUs also organize POH along the multi- frame • This provides V5, J2, Z6, Z7 POH bytes • Lower TUs use V1, V2, V3, V4 bytes in 500 μs multi-frame
  • 14. Adoption of 2MBPS Signal over SDH. IF C1C1C1-111 THEN S1 IS A JUSTIFICATION BIT SKG/RTTC/BBS
  • 16. General Structure Order of transmission 1st 270 columns 2nd Section overhead VC Capacity (SOH) (for AUG) 9 columns 261 columns 7/26/2012
  • 17. STM-1 frame 270 bytes RSOH 1 ….. 9 261Byte 3 rows pointer Information 9 Rows Payload MSOH 5 rows Transport 125 μs overhead Synchronous Payload Envelope 7/26/2012
  • 18. Pointer 4 Bytes v1 V1 & v2 points TU12 V5 v2 v5 VC-12 500 μsec v3 7/26/2012
  • 19. STS-1 Frame 810x64kbps=51.84Mbps 810 Octets per frame @ 8000 frames/sec 90 columns A1 A2 J0 J1 B1 E1 F1 B3 1 D1 D2 D3 C2 Order of 2 transmission H1 H2 H3 G1 9 rows B2 K1 K2 F2 Special OH octets: D4 D5 D6 H4 D7 D8 D9 Z3 A1, A2 Frame Synch D10 D11 D12 Z4 B1 Parity on Previous Frame (BER monitoring) S1 M0/1 E2 N1 J0 Section trace (Connection Alive?) 3 Columns of Synchronous Payload Envelope (SPE) H1, H2, H3 Pointer Action Transport OH 1 column of Path OH + 8 data columns K1, K2 Automatic Protection Switching Section Overhead Path Overhead SKG/RTC/BBSR S Line Overhead Data
  • 20. STM-0 Overheads HO Path Section Overhead Overhead Framing Framing RS Trace Path Trace A1 A2 J0 J1 R-Section BIP-8 Orderwire User Channel BIP-8 Overhead B1 E1 F1 B3 Data Com Data Com Data Com Signal Label D1 D2 D3 C2 Pointer Path Status AU pointer Pointer Pointer G1 H1 H2 H3 BIP-8 APS APS User Channel B2 K1 K2 F2 Multiframe Data Com Data Com Data Com Indicator M-Section D4 D5 D6 H4 Overhead Data Com Data Com Data Com User Channel D7 D8 D9 F3 Data Com Data Com Data Com APS D10 D11 D12 K3 Sync (REI) Orderwire Tandem S1 (M1) E2 N1 7/26/2012
  • 21. STM-1 Section Overhead A1 A1 A1 A2 A2 A2 J0 Δ - media dependent R-Section B1 Δ Δ E1 Δ F1 Overhead D1 Δ Δ D2 Δ D3 AU pointer H1 H1* H1* H2 H2* H2* H3 H3 H3 H1* = 10010011 B2 B2 B2 K1 K2 H2* = 11111111 D4 D5 D6 M-Section Overhead D7 D8 D9 D10 D11 D12 national use S1 M1 E2 7/26/2012
  • 22. MAPPING OF VC-4 IN TO STM1 270 bytes 9 bytes RSOH Transport 3ROWS 20 BLOCKS OF 13 BYTES Overhead VC-4 Path Overhead AU-4 POINTER 9 rows Trace MSOH J1 Path Overhead BIP-8 5 ROWS B3 • J1- Path Trace • BIP-8 - Parity Label C2 Status G1 • C2 - Payload Type Indicator User F2 • G1 - End Path Status Multiframe • F2 - User H4 Synchronous Growth • H4 - Use Depends On Payload Payload Z3 Growth • Z3-5 - Future Growth Envelope Z4 TCM Z5 STM-1 Payload Asynchronous mapping of 139.264 MBPS 7/26/2012 Page-66
  • 23. Payload Pointer Payload Pointer marks start of STM-1 VC-3 or VC-4 90 (VC-3) or 270 (VC-4) Columns STM-1 Frame #1 H1 H2 H3... 9 Rows STM-1 VC-3 or VC-4 STM-1 Frame #2 125 μsec 9 Rows STM-1 VC-3 or VC-4 POH column 250 μsec 7/26/2012 Section Overhead
  • 24. 270 bytes 9 bytes RSOH Transport 3ROWS 20 BLOCKS OF 13 BYTES Overhead H1H1H1H2H2H2H3H3H3 9 rows Trace MSOH J1 1 2 3 . . . . . . . . . 17 18 19 20 BIP-8 5 ROWS B3 Label C2 Status G1 User F2 Multiframe H4 Synchronous Growth Payload Z3 Growth Envelope Z4 TCM Z5 Asynchronous mapping of 139.264 MBPS STM-1 Payload Page-66
  • 25. path multiplex section multiplex section regenerator regen. regen. regenerator section section section section ADM TM REG or REG TM DCS path regen. section multipl. section regen. section path termination termination termination termination termination PTE = path terminating element service (E1, E4..) TM = terminal multiplexer mapping service (E1, E4..) demapping REG = regenerator mapping ADM = add/drop multiplexer demapping DCS = digital cross-connect system DXC= digital cross connect
  • 26. Regenerator – A regenerator simply extends the possible distance and quality of a line by decomposing it into multiple sections • Replaces regenerator section overhead • Multiplex section and path overhead is not altered
  • 27. Add-drop Multiplexer - I. – Add/drop multiplexer (ADM) • Main element for configuring paths on top of line topologies (point-to-point or ring) • Multiplexed channels may be dropped and added • Special drop and repeat mode for broadcast and survivability • An ADM has at least 3 logical ports: 2 core and 1 or more add-drop •Ports have different Optical port roles Optical port ADM(OEO) •No switching between the core ports •Switching only Electrical port between the add-drop and the core ports.
  • 29. Uni- and Bi-directional Routing A A A-C A-C F B F B C-A C-A E C E C D D Uni-directional Ring Bi-directional Ring (1 fiber) (2 fibers) – Only working traffic is shown – Subnetwork (path) or multiplex section switching for protection
  • 30. USHR • Working traffic is carried around the ring in one direction only. • Ring capacity is sum of demands between nodes. • Also called “Counter–Rotating–Ring”; traffic in prot. rotates opposite. • 1:1 (USHR/L); extended to 1:N, then not entirely self–healing. • 1+1 (USHR/P).
  • 31. USHR-L USHR/L Incoming and returning signal routed unidirectionally on working ring. On failure, adjacent nodes perform fold or looping function. Basic ADMs used (TSI not needed).
  • 32. USHR Concepts – USHR/P = Unidirectional Self-Healing Ring / Path Switched – 2-fiber ring topology • Head-end bridge, tail-end switch logical topology – 1+1 protection with uni-directional routing on each fiber – Traffic is sent in both directions on the ring on separate fibers – The better signal is selected by the receiver.
  • 33. BSHR Concepts - I. – BSHR/MS = Bi-directional Self-Healing Ring / Multiplex Section Switched – 1:1, or 1:N redundancy options – 2 fibers with shared protection configuration • Half the bandwidth in each direction in a link is reserved for the shared protection of all traffic in that reverse direction of the link –An even number of STM-1s are required – 4 fibers for dedicated protection configuration • Bi-directional routing on 2 fibers (working line) • Each direction has a working and a protect fiber
  • 34. BSHR Concepts - II. – Multiple fail-over options for 4-fiber BSHR/MS • In normal operation traffic is sent only in the required direction • During fiber interruption, the traffic is routed around the break in opposite direction (long path) – Ring switching • Optionally if the other 2 fibers are still available, then traffic might be routed onto the parallel 2 fibers (short path) – Span switching
  • 35. Multiplex Section Protection Switching R-Section Overhead information controlling protection Payload switching M-Section Overhead – Conditions resulting in a protection switch: • Loss of signal, loss of frame LOS AIS • Line AIS (all 1’s) down • Signal degrade REI upstream OCN stream – Excessive BIP-24 errors in MS overhead
  • 36. Path Protection Switching R-Section Payload Overhead VC Path Overhead STM Info Path controlling Overhead protection M-Section switching Overhead VC Payload – Conditions resulting in a protection switch: • Loss of pointer, STM or VC AIS • Excessive BIP errors for STM path, BIP errors for VC path
  • 37. Automatic Protection Switching - I. – APS = Automatic Tributary Channels Protection Switching STM-N Mux • Allows network to MSTE K1K2 Read/Sel K1K2 Write react to failed lines, interfaces, or poor signal quality – Performed over the Working STM-N Protect STM-N entire STM-N payload – Uses K1 and K2 bytes of MS Overhead MSTE K1K2 Write K1K2 Read/Sel STM -N Mux Tributary Channels
  • 38. Automatic Protection Switching - II. – K1 byte: Tributary Channels • Type of request (bits STM-N Mux 1-4) MSTE K1K2 K1K2 • Channel requested Read/Sel Write (bits 5-8) – K2 byte: • Channel selected (bits 1-4) Working Protect • Architecture (bit 5) STM-N STM-N • Mode of operation (bits 6-8) – e.g. Alarm Indication Signal MSTE K1K2 Write K1K2 Read/Sel (AIS), Remote Defect Indicator STM -N Mux (RDI) Tributary Channels
  • 39. Uni- and Bi-directional APS – Uni-directional APS • Only traffic on the affected fiber is switched to the protect line – Bi-directional APS • TX and RX are both switched when channel is affected
  • 40. Revertive and Non-revertive APS – Revertive switching • Will restore to the working channel when WTR timer expires – Non-revertive switching • Will not move to working channel after failure unless requested