SDH MAPPING AND MULTIPLEXING
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The document discusses the mapping and multiplexing of asynchronous 2048 kbps tributaries onto an STM-1 frame. It describes how the 2048 kbps signal is mapped into a VC-12 container by adding justification bytes and then into a TU-12. Multiple TU-12s carrying different tributaries are multiplexed into a TUG-2. Several TUG-2s are then multiplexed into a TUG-3, which is further multiplexed into a VC-4 container along with other TUG-3s. The VC-4 is then multiplexed with an AU-4 and pointers to form an STM-1 frame for transmission.
SDH MAPPING AND MULTIPLEXING
- 1. Niranjan B RTTC Mysore SDH MAPPING AND MULTIPLEXING
- 3. TRANSPORT OF ASYNCHRONOUS 2048 KBPS TRIBUTARIES ON STM–1 FRAME
- 5. TRANSPORT OF ASYNCHRONOUS 2048 KBPS TRIBUTARIES ON STM–1 FRAME Alternatives for Mapping 2048 Kbps Tributary on STM–1 Frame
- 7. MUTIPLEXING PRINCIPLE CONTAINER SIGNAL Container-n( n=1-4 ): A container is the information structure which forms the network synchronous information payload for a virtual container 2Mb
- 9. Asynchronous Mapping of 2048 Kbps Tributary into VC–12
- 10. STRUCTURE OF C-12 R- Fixed stuff bytes make up for the required number of bytes in the container. C & C’- Jusification control bytes S- ` Justification opportunity bit
- 11. Fixed stuff bytes R make up for the required number of bytes in the container. They are introduced after every 32nd byte of the tributary. C and C’ bytes are the justification control bytes. S is justification opportunity byte. Construction of C–12
- 12. The bit structures of C, C’ and S bytes C = C1 C2 0 0 0 0 R R C’ = C1 C2 R R R R R S1 S = S2 I I I I I I I I=Information bit of the tributary
- 13. VIRTUAL CONTAINER: VC-n Virtual Container-n(VC-n):It is the information structure used to support path layer connections in the SDH. Two types of VCs: Lower order VC-n(n=1,2) Higher order Vc-n(n=3,4) CONTAINER P O H
- 14. C-12 to VC-12 C–12 container into VC–12 virtual container by adding the path overhead (POH) bytes. The POH consists of a set of four bytes Vs, J2, Z6 and Z7, each of which is added sequentially before four C–12 containers.
- 15. V5 Byte Errordetection, path error status and signal labeling . B1-even parity bit for all the odd numbered bits of the previous VC–12. B2-even parity bit for all the even numbered bits of the previous VC–12. B3-error indication which is sent back towards path originator if more than one error is detected by the parity bits. B4- is Remote Failure Indication (RFI). It is set to ‘1’ if path failure is declared. B 5 to 7 provide signal label, e.g. “010” indicates asynchronous tributary in the container. “ 000” indicate unequipped VC–12. B 8 is path FERF (Far End Remote Failure) indication when TU–12/TU–2 path AIS or signal failure condition is being received.
- 16. V5 Byte : It provides for error detection, path error status and signal labeling
- 17. J2 Byte 16Bytes Repetitively transmit path access point identifier so that the receiver can continuously identify the tributary. J2 Byte
- 18. Z6 Byte For providing monitoring function in Tandem Z7 Byte For future use
- 19. CONTAINER P O H P T R MUX PRINCIPLE: TU-n/ AU •It is an information structure which provides adaptation between two layers: -Between lower and higher order path layers for TU -Between higher order path layer and section layer for AU POINTER is an indicator whose value defines the frame offset of a VC with respect to the frame reference of the transport entity on which it is supported
- 21. Formats of V1 and V2 bytes. V1 &V2 bytes indicate location of V5 N- NDF- New Data Flag =1001 , whenevernew TU-12 comes it is inverted, S- Trib type ,S=10 forTU12 IDID-10 bit offset of V5 bit from V2 byte
- 22. The four N bits are the New Data Flag (NDF) Their usual value is 1001. When new alignment of VC–12 is to be given, these bits are inverted and new pointer value is given in pointer bits.
- 23. The two ‘S’ bits indicate the tributary unit type. For TU–12, S bits are 10. The point value is a 0–139 decimal number coded in 10 bits which are placed in the last two bits of V1 and 8 bits of V2 byte. It is the offset of the V5 byte from the V2 byte. V3 byte is used for negative justification opportunity,. V4 Byte :This byte is reserved
- 24. PointerGeneration Usually the pointer value will remain unchanged as indicated by NDF. If due to some reason the pointer value needs to be changed, the NDF bits are inverted and the new value of the pointer takes effect. If due to some reason the pointer value is to be incremented by one byte or reduced by one byte, positive or negative justification is required.
- 25. PointerGeneration For positive justification the “ I “bits are inverted. The positive justification opportunity byte which is next to V3 byte is filled with dummy bits and in the next tributary unit, the pointer value is incremented by one. For negative justification, the D bits are inverted and V3 byte is filled with one VC–12 byte. The subsequent pointer is decremented by one in the next tributary unit.
- 26. TU–12 to TUG–12 Multiplexing
- 27. TU–12 to TUG–2 Multiplexing Tributary units (TU–12) generated from three 2048 Kbps tributaries are multiplexed to form tributary unit groups (TUG–2) TU–12s of different tributaries are already in phase synchronism. They are multiplexed byte by byte which results in 12x9 matrix of TUG–2 Note that first three bytes of TUG–2 in the upper left corner will contain the pointer bytes (V1, V2, V3, V4) of the respective TU– 12s. TUG–2 contains 108 bytes and is transported either in VC–3 or VC–4 container via TUG–3
- 29. Multiplexing of TUG–2 into TUG–3 VC12=9x4=36byte TUG2=3x 9x 4=108byte For transporting TUG–2 in VC–4 containers,
- 30. Multiplexing of TUG–2 into TUG–3 As each TUG–2 contains three 2048 Kbps tributaries, 3x7x3 = 63 tributaries can be transported by a VC–4 container.
- 31. Multiplexing is done byte by byte. TUG–3 contains 86 columns. The first two column contain fixed stuff and 3 bytes long null pointer indicator (NPI). TUG–3 can also contain VC–3 in which case
- 32. NPI bytes contain the pointer for VC–3. First three bytes of TUG–2 contain the TU–12 pointer. In TUG–3, these pointer appear in the first row of TUG–3. The first bytes of columns 3 to 23 of TUG–3 contain these pointers. (3pointers per TUG2 *7 nos of TUG2=21)
- 33. Multiplexing of TUG–3 into VC–4
- 34. Multiplexing of TUG–3 into VC–4 Three TUG–3 are multiplexed to form a VC–4 container The first column is POH. The next two columns contain fixed stuff. The rest of VC4 is formed by byte multiplexing of 3 TUG–3s. Note that all the pointer bytes of TU–12 are available in the first row in columns 10 to 72 of VC–4.
- 35. Multiplexing of TUG–3 into VC–4 6th byte of POH, called H4 byte is for the location of pointer bytes of TU–12 are fixed and known but it is not known whether these bytes are V1 or V2 or V3 or V4. This is indicated by H4 byte of POH. Thus, in a VC–4 container, VC–12 container can be located by processing H4 and the pointer bytes of TU–12s.
- 36. H4 Byte Pointer Byte X XXXX X00 V1 X XXXX X0I V2 X XXXX X10 V3 X XXXX XII V4
- 38. Multiplexing of AU–4 via AUG .The 9 bytes at the beginning of row 4 are allocated to the AU–4 pointer. The remaining 9 rows by 261 columns is allocated to VC–4. The phase of VC–4 is not fixed with respect to the AU–4. The location of the first byte of the VC–4 with respect to the AU–4 pointer is given by pointer value. The AU–4 is directly placed into AUG. One AUG gives STM–1.
- 39. Multiplexing of AU–4 via AUG
- 40. S T M -N P A Y L O A D MULTIPLE SECTION OVERHEAD REGENARATOR SECTION OVERHEAD ADMINISTRATIVE UNIT POINT 9 x N COLOUM 261 x N COLOUM 1-35-94 S T M -N P A Y L O A D MULTIPLE SECTION OVERHEAD REGENARATOR SECTION OVERHEAD ADMINISTRATIVE UNIT POINT 9 x N COLOUM 261 x N COLOUM 1-35-94 STM N FRAME STRUCTURE 622080Kbps 155520Kbps 51840Kbps 24488320Kbps STM 4 STM 1 STM 0 STM 16
- 41. 2.048 Mbps (E1) 1 2 3 32 32 Bytes 1 2 3 32 VC-12 35 Bytes POH (Lower Order) 1 2 3 32C-12 34 Bytes Stuffing Bytes Mapping of 2Mbps into STM – NMapping of 2Mbps into STM – N
- 42. TU-12 36 Bytes Pointer 9 Rows 4 Columns TU 12 is arranged Into Matrix of 9 X 4 Mapping of 2Mbps into STM – NMapping of 2Mbps into STM – N
- 43. TUG-2 9 Rows 12 Columns 9 Rows 4 Columns4 Columns4 Columns TU-12 TU-12 TU-12 Multiplexing Mapping of 2Mbps into STM – NMapping of 2Mbps into STM – N
- 44. EAGLE PHOTONICS 7 TUG-2s Stuffing Bytes 86 Columns 84 Columns TUG 3 X 7 TUG-2 TUG-3(multiplexing) Mapping of 2Mbps into STM – NMapping of 2Mbps into STM – N
- 45. HOPOH VC - 4 258 Columns Stuffing Bytes 261 Columns TUG - 3 TUG - 3 TUG - 3 86 Columns X 3 TUG–3 Mapping of 2Mbps into STM – NMapping of 2Mbps into STM – N
- 46. EAGLE PHOTONICS 261 Columns AU – 4 (Adding Pointer) POH Pay Load AU Pointer 9 Columns th Row Pay Load POH VC - 4 261 Columns 9 rows Mapping of 2Mbps into STM – NMapping of 2Mbps into STM – N mapping E1.exe
- 48. Mapping of VC–12 into VC–3 (2nd Alternate from E1 to VC-4) Up to formation of TUG–2, the process is same. From TUG–2, directly VC–3 is formed. VC–3 is further processed to form STM–1 The pointer bytes of TU–12 are present in the first row of VC–3 H4 byte of POH indicates whether the pointer bytes are V1, V2, V3 or V4
- 50. TUG-2TOVC-3
- 51. Mapping of VC–3/VC–4 into STM–1 Three VC–3s or one VC–4 can be mapped into one STM–1 frame.
- 52. TRANSPORT OF ASYNCHRONOUS 139264 KBPS TRIBUTARIES ON STM–1 FRAME Mappingof Asynchronous 139264Kbps into STM–1
- 54. TRANSPORT OF ASYNCHRONOUS 139264 KBPS TRIBUTARIES ON STM–1 FRAME 139264 Kbps stream is first organised into C–4 container of the size 9x260 (9 rows x 260cols). By adding 1 column of path overheads to this container yields VC–4 which is of the size 9x261 (9 rows x 261 columns). VC–4 is aligned into AU–4. AU–4 is mapped into AUG. One AUG gives STM–1.
- 56. Mapping 139264 Kbps tributary into VC–4 Each of the 9 rows is partitioned into 20 blocks consisting of 13 bytes each In each row, one justification opportunity bit(s) and five justification control bits (c) are provided (Fig.3). The first byte of each block consists of : Either eight information bits (I), i.e. W bytes; OR One justification control bit (c) plus five fixed stuff bits (R) plus two overhead bits (o), i..e x byte; OR Six information bits (I) plus one justification opportunity bit(s) plus one fixed stuff bit (R),
- 57. Alignment of VC–4 into AU–4 VC–4 is aligned into AU4, by means of AU–4 pointer.
- 58. Multiplexing of AU–4 via AUG The 9 bytes at the beginning of row 4 are allocated to the AU–4 pointer. The remaining 9 rows by 261 columns is allocated to VC–4. The phase of VC–4 is not fixed with respect to the AU–4. The location of the first byte of the VC–4 with respect to the AU–4 pointer is given by pointer value. The AU–4 is directly placed into AUG. One AUG gives STM–1.
- 59. TRANSPORT OF ASYNCHRONOUS 34368 KBPS TRIBUTARIES ON STM–1 FRAME
- 62. Asynchronous Mapping of 34368 Kbps Tributary into VC–3 One 34368 Kbps tributary can be mapped into a VC–3, C–3 container is formed first by inserting justification and fixed staff bytes. Justification makes the information bit stream and bytes synchronous to the SDH environment . In addition to the VC–3 POH, the VC–3 consists of a payload of 9x84 bytes every 125 ms. This payload is divided in three subframes, each subframe consisting of : 1431 information bits (I); two sets of five justification control bits (C1,C20; two justification opportunity bits (S1,S2); 573 fixed stuff bits (R).
- 64. VC–3 Path Overhead Bytes The VC–3 path overhead is located in the first column of 9 row by 85 column VC–3 structure. The POH consists of nine bytes denoted J1, B3, C2, G1, F2, H4, Z3, Z4, Z5
- 65. First Alternative Mapping via AU–3.
- 66. The three bytes at the beginning of row 4 are allocated to the AU–3 pointer, the remaining 9 rows by 87 column is allocated to the VC–3 and two columns of fixed stuff. The byte in each row of the two columns of fixed stuff of each AU–3 shall be the same. The phase of the VC–3 and two columns of fixed stuff is not fixed with respect to AU–3. The location of the first byte of VC–3 with respect to AU–3 pointer is given by the pointer value. As shown the three AU– 3s are byte interleaved in the AUG. One AUG gives STM–1.
- 67. Second Alternative Mapping via AU–4. VC–3 is first aligned into TU–3. The TU–3 consists of the VC–3 with a 9 byte VC–3 POH and the TU–3 pointer. The first column of the 9 row by 86 column TUG–3 is allocated to the TU–3 pointer bytes H1, H2, H3 and fixes stuff. The phase of the VC–3 with respect to TUG–3 is indicated by the TU–3 pointer. .
- 70. The AU–4 consists of the VC–4 (Payload of 9 rows by 261 columns) plus 9 bytes at the beginning of row 4 (allocated to AU–4 pointer). The phase of VC–4 is not fixed with respect to the AU–4. The location of the first byte of the VC–4 with respect to the AU–4 pointer is given by the pointer value. The AU–4 is placed directly in the AUG. One AUG gives STM–1
- 72. The AU–n pointer provides a method of allowing flexible and dynamic alignment of the VC–n within the AU–n frame Dynamic alignment means that the VC–n is allowed to “Float” within the AU–n frame. Thus, the pointer is able to accommodate differences, not only in the phases of the VC–n and the SOH, but also in the frame rates.
- 74. 4 parallel and frame synchronised STM-1 SDHsignals may be byte-interleave multiplexed togetherto forman STM-4 SDHsignal at 622.08 Mb/s (4x STM-1 bit rate). Byte-interleaved multiplexing is accomplished by taking in turn, one byte fromeach input tributary and placing it in the higherspeed output signal
- 75. Frame STM-16