S.D.H. Training document

POH bytes - ITU-T standardization update (G.707)

9 Tb

9

Tt

261

9

B3C2G1F2H4F3K3N1

J1

VC-4 POH

.3.1.5 Path user channels: F2, F3

hese bytes are allocated for user communication purposes etween path elements and are payload dependent.

.3.1.7 Automatic Protection Switching (APS) channel: K3 (b1-b4)

hese bits are allocated for APS signalling for protection at he VC-4/3 path levels.

9.3.1.8 Network operator byte: N1 This byte is allocated to provide a Tandem Connection Monitoring (TCM) function. The details concerning the two possible implementations of the HO-TCM function are given in Annexes C and D.

9.3.1.9 Data link K3 (b7-b8) Bits 7 and 8 of K3 are reserved for a higher order path data link. The applications and protocols are outside the scope of this Recommendation.

9.3.1.10 Spare: K3 (b5-b6) These bits are allocated for future use. These bits have no defined value. The receiver is required to ignore their content.

POH bytes - ITU-T standardization update (G.707)

9 Tb

9

Tt

261

9

B3C2G1F2H4F3K3N1

J1

VC-4 POH

.3.1.5 Path user channels: F2, F3

hese bytes are allocated for user communication purposes etween path elements and are payload dependent.

.3.1.7 Automatic Protection Switching (APS) channel: K3 (b1-b4)

hese bits are allocated for APS signalling for protection at he VC-4/3 path levels.

9.3.1.8 Network operator byte: N1 This byte is allocated to provide a Tandem Connection Monitoring (TCM) function. The details concerning the two possible implementations of the HO-TCM function are given in Annexes C and D.

9.3.1.9 Data link K3 (b7-b8) Bits 7 and 8 of K3 are reserved for a higher order path data link. The applications and protocols are outside the scope of this Recommendation.

9.3.1.10 Spare: K3 (b5-b6) These bits are allocated for future use. These bits have no defined value. The receiver is required to ignore their content.

POH bytes - ITU-T standardization update (G.707)

T1523020-96(108449)

V 5

R R R R R R R R

R R R R R R R R

J 2

C1 C2 O O O O R R

R R R R R R R R

N 2

R R R R R R R R

K 4

C1 C2 R R R R R S1

S2 D D D D D D D

C1 C2 O O O O R R

R R R R R R R R

32 bytes

32 bytes

32 bytes

31 bytes

140bytes

Data bitFixed stuff bitOverhead bitJustification opportunity bitJustification control bit

DROSC

Figure 10-8/G.707 – Asynchronous mapping of 2048 kbit/s tributary

R

R

R

R

R

V5

R500 µs

R

T1523030-96(108449)

J2

N2

K4

R

Time Slot 0Time Slots 1 to 15

Time Slot 16

Time Slots 17 to 31

Time Slot 0

Time Slots 1 to 15

Time Slot 16Time Slots 17 to 31

Time Slot 0

Time Slots 1 to 15

Time Slot 16

Time Slots 17 to 31

Time Slot 0

Time Slots 1 to 15

Time Slot 16Time Slots 17 to 31

140bytes

R Fixed stuff byte

Figure 10-9/G.707 – Byte synchronous mapping for 2048 kbit/s tributary (30 channels with Common Channel Signalling or Channel Associated Signalling)

9.3.2 VC-2/VC-1 POH The bytes V5, J2, N2 and K4 are allocated to the VC-2/VC-1 POH. The V5 byte is the first byte of the multiframe and its position is indicated by the TU-2/TU-1 pointer. The position of these bytes in the multiframe is given in Figure 8-9. NOTE – Payload dependent and payload independent information is communicated by different codings in bits 5 to 7 of V5 and 5 to 7 of K4.

BIP-2 REI RFI Signal Label RDI

1 2 3 4 5 6 7 8

Figure 9-9/G.707 – VC-2/VC-1 POH V5

9.3.2.1 V5 byte The byte V5 provides the functions of error checking, signal label and path status of the VC-2/VC-1 paths. The bit assignments of the V5 byte are illustrated in Figure 9-9. Bits 1 and 2 are used for error performance monitoring. Note that the calculation of the BIP-2 includes the VC-2/VC-1 POH bytes but excludes bytes V1, V2, V3 (except when used for negative justification) and V4. Bit 3 is a VC-2/VC-1 path Remote Error indication (REI) (former FEBE) indication that is set to one and sent back towards a VC-2/VC-1 path originator if one or more errors were detected by the BIP-2, and is otherwise set to zero. Bit 4 is a VC-11 byte synchronous path Remote Failure Indication (RFI). This bit is set to one if a failure is declared, otherwise it is set to zero. The VC-11 path RFI is sent back by the VC-11 termination. The use and content of this bit are undefined for VC-2 and VC-12. NOTE – A failure is a defect that persists beyond the maximum time allocated to the transmission system protection mechanisms. Bits 5 through 7 provide a VC-2/VC-1 signal label Bit 8 is set to 1 to indicate a VC-2/VC-1 path Remote Defect Indication (RDI)(former FERF), otherwise it is set to zero.

9.3.2.2 Path Trace: J2 Byte J2 is used to transmit repetitively a Low Order Path Access Point Identifier so that a path receiving terminal can verify its continued connection to the intended transmitter.

9.3.2.3 Network operator byte: N2 This byte is allocated to provide a Tandem Connection Monitoring (TCM) function. The details concerning the implementation of the LO-TCM are given in Annex E.

9.3.2.4 Extended signal label: K4 (b1) This bit is allocated to an extended signal label. If the signal label in V5 bits 5 through 7 is 101 the contents of the extended signal label is valid and is described below. For all other values of V5 bits 5 through 7 the extended signal label bit is undefined and should be ignored by the receiver. The bit contains a 32 frame multiframe depicted in Figure 9-10. The multiframe alignment signal, MFAS, consists of "0111 1111 110". The extended signal label is contained in bits 12 to 19. Multiframe position 20 must contain "0". The remaining 12 bits are reserved for future standardization, should be set to all "0"s and should be ignored by the receiver. NOTE 1 – The virtual concatenation multiframe in K4 bit 2 uses the MFAS of this bit. That means that the virtual concatenation function needs to consider this bit without confirming that the V5 signal label is 101. There are no inconsistency problems since all LO virtually concatenated payloads must have an extended signal label. NOTE 2 – If at a later stage the bits reserved for future use are activated, care must be taken to ensure that a sequence of nine "1"s (imitating the MFAS) is avoided.

Multiframe alignment bitsMFAS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

0

20 21 22 23 24 25 26 27 28 29 30 31 32

MFAS

Bit number:

R R R R R R R R R R R R

Zero0Reserved bitR

Extended Signal Label

Figure 9-10/G.707 – K4 bit 1 multiframe The coding of the extended signal label is given in Table 9-13. The signal labels in Table 9-12 for the range "0" to "7" and the signal labels in Table 9-13 for the range of "08" to "FF" together forms the complete VC-1/2 signal label range of "00" to "FF".

NOTE 3 – Signal label "5" is indicated by an equipment not supporting the extended signal label receiving an extended signal label. NOTE 4 – For interworking with equipment using the ATM mapping in 10.2.5 it may be necessary to accept the V5 signal label "5" without K4 bit 1 multiframe as an equipped condition.

Table 9-13/G.707 – VC-1/2 Extended Signal label byte coding

MSB b12 b13 b14 b15

LSB b16 b17 b18 b19

Hex code (Note 1)

Interpretation

0 0 0 0 …

0 0 0 0

0 0 0 0 …

0 1 1 1

00 … 07

Reserved (Note 2)

0 0 0 0 1 0 0 0 08 Mapping under development (Note 3) 0 0 0 0 1 0 0 1 09 ATM mapping, see 10.2.3 to 10.2.5 0 0 0 0 1 0 1 0 0A Mapping of HDLC/PPP [12], [13] framed signal

according to 10.3 0 0 0 0 1 0 1 1 0B Mapping of HDLC/LAPS [15] framed signals

according to 10.3 0 0 0 0 1 1 0 0 0C Virtually concatenated test signal, O.181 specific

mapping (Note 4) 0 0 0 0 1 1 0 1 0D Flexible Topology Data Link mapping (Note 5) 1 1 1 1 1 1 1 1 FF Reserved

NOTE 1 – There are 242 spare codes left for future use. NOTE 2 – Vales "00" to "07" are reserved to give a unique name to non-extended in Table 9-12 and extended signal labels. NOTE 3 – Value "02" is only to be used in cases where a mapping code is not defined in the above table. By using this code the development or experimental activities is isolated from the rest of the SDH network. There is no forward compatibility if a specific signal label is assigned later. If that is done the equipment that has used this code must either be reconfigured to use that new specific signal label or be recycled. NOTE 4 – Any virtually concatenated mapping defined in Recommendation O.181 or its successors which does not correspond to a mapping defined in Recommendation G.707 falls in this category. NOTE 5 – This mapping is under study and the signal label provisionally allocated.

9.3.2.5 Low Order Virtual Concatenation: K4 (b2) This bit is allocated for the lower order virtual concatenation string. The bit is multiframed in 32 frames to form a 32-bit string. This is function is described in subclause 11.4.

9.3.2.6 Automatic Protection Switching (APS) channel: K4 (b3-b4) These bits are allocated for APS signalling for protection at the lower order path level. This function is for further study.

9.3.2.7 Reserved: K4 (b5-b7) Bit 5 to 7 of K4 are reserved for an optional use described in VII.2 of Appendix VII. If this option is not used, these bits shall be set to "000" or "111". A receiver is required to be able to ignore the contents of these bits. The use of the optional function is at the discretion of the owner of the trail termination source generating the K4 byte.

9.3.2.8 Data link: K4 (b8) Bit 8 of K4 is reserved for a lower order path data link. The applications and protocols are outside the scope of this Recommendation.

TEST - Principles of PDH Multiplexing 1. Select all the CEPT bit rates among those listed below.

a) 1,5 Mbit/s b) 2 Mbit/s c) 9,6 Mbit/s d) 8 Mbit/s e) 34 Mbit/s f) 6 Mbit/s g) 45 Mbit/s h) 140 Mbit/s

2. In a 2Mbit/s signal, it is possible to transmit 30 user channels. How many channels can be transmitted in a 140Mbit/s signal ? a. 1800 b. 1880 c. 1920 d. 2020 e. 2100

3. Which block of bits in a PDH signal is responsible for the synchronization On the multiplex receive side ? a. Justification opportunity bits (JB) b. Tributary bits (TB) c. Service bits (D+N) d. Frame Alignment Signal (FAS) e. Justification control bits (CB)

4. Which method is used for PDH multiplexing ?

a. Byte-by-byte multiplexing b. Bit-by-bit multiplexing c. Word-by-word multiplexing d. Frame-by-frame multiplexing

5. A 2 Mbit/s signal shall be accessed in a 140 Mbit/s signal. How many demultiplex operations have to be carried out ? a. none b. one c. two d. three

TEST - Characteristic of SDH multiplexing

1. Which is the smallest transmission module in the SDH and what

capacity does it have a) SDH-1 (155 Mbit/s) b) STM-1 (140 Mbit/s) c) PTM-1 (155 Mbit/s) d) STM-1 (155 Mbit/s) e) ISDN ( 64 kbit/s)

2. Which of the frames below corresponds to an STM ?

C

B

A S

3. How

a) 2b) 2c) 2d) e)

PTR

S

S

S

S

S

S

S

S Payload

F

E

D

PTR

SOH Payload

S

P

S

S

many bytes does the payload block

430 byte 349 byte 239 byte

81 byte 72 byte

TR

Payload

PTR PTR

Payload

PTR

PTR

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

of the STM-1 frame contain ?

4. Which multiplex technique is used in the SDH ?

a) Byte-by byte multiplexing b) Bit-by bit multiplexing c) 5 bit / 6 bit multiplexing d) Any multiplex technique

5. How many telephone channels can theoretically be transmitted in an STM-16 signal if there is one 140 Mbit/s signal per STM-1 frame ? a) 1920 b) 7680 c) 10350 d) 25670 e) 30720

TEST - Mapping 1. Which of the information bits listed below are n o t transmitted

in a container ? a) D- and N- bits b) Fixed Justification Bits c) Service Bits d) Overhead Bits e) Justification Opportunity Bits

2. Which Containers are recommended for CEPT signals ? a) C – 4 b) C – 3 c) C – 2 d) C – 12 e) C – 11

3. Which is the difference between the Virtual Container “VC” and the Container “C” ? a) Container = Virtual container + Path Overhead b) Virtual Container = Container + Section Overhead c) Virtual Container = Container + Path Overhead d) There is no difference e) Virtual Container = STM-1 + Container

4. In which case is the Null Poiter Indication transmittedin the TUG-3 ?

a) When a 34 Mbit/s PDH signal is transmitted in the TUG3 b) When 21 x 2 Mbit/s PDH signals are transmitted in the TUG3

5. How many 34 Mbit/s signals can be transmitted in a VC-4 signal at maximum ? a) one b) two c) three d) four e) five

6. What is the difference between an AU-4 and an STM-1 ? a) AU-4 = STM-1 + POH b) AU-4 = STM-1 + SOH c) STM-1 = POH + SOH d) STM-1 = AU-4 + SOH f) There is no difference

7. Which of the signals listed below can be found in a VC-4 ? a) 1 x 140 Mbit/s b) 3 x 34 Mbit/s c) 63 x 2 Mbit/s d) 2 x 34 Mbit/s + 21 x 2 Mbit/s

8. Describe the precise path of a two Mbit/s signal into tha STM-1.

a) C3 – VC3 – TU3 – TUG3 – VC4 – AU4 – STM1 b) C12 – VC12 – TU12 – TUG2 – TUG3 – VC4 – AU4 – STM1 c) C12 – VC12 – TU12 – TUG12 – VC4 – AU4 – STM1 d) C4 – VC4 – AU4 – STM1 e) C12 – VC12 – TU12 – TUG3 – VC4 – AU4 – STM1

TEST - Pointer 1. Where can you find the AU-4 pointer in the STM-1 frame ?

a) In one of the two SOH blocks b) In the AU-4 pointer block c) In the Payload d) There is no AU-4 poiter in the STM-1 frame

2. How many TU-3 pointer bytes can be found in a VC-4 ?

a) only 6 H

H

H

b) 3 H

c) 5 H

d) 9

H

H

H

3. Which of the 9 AU pointer bytes are used

H “ “ H H HHYY

1

H

HH

HH

1

H

H

H

1

H

H

H

H

for

1

H

1 1

H

H

the

1

AU-4 pointer ?

1

2

2

2

2

2

2 2

2

3

3 3

3

3

3

3

3 3

3

3 3 1” 1”

4. What kind of information can be found in the H1 and H2 byte of the AU-4 pointer ?

a) New Data Flag (= beginning of a new pointer value) b) D-Bit (= display for a major alarm) c) 10 – Bit pointer value (= address of a VC-4) d) N – Bit (= display for a minor alarm) e) SS – Bits (= type of VC-4 contents)

5. What is the H3 byte of the TU-3 ponter used for ?

a) Service channel d) H3 Byte is meaningless b) Pointer address e) Negative Justification c) Signaling

6. Which of the numbers below are valid addresses for a VC-4 a) 27 b) 782 c) –25 d) 0 e) 33 f) 720 g) 5,3 h) 783

7) Which pointers are active during the transmission of a 2 Mbit/s signal ?

a) AU-4 pointer f) SOH pointer b) TU-3 pointer g) VC-4 pointer c) TUG-3 pointer h) VC-12 pointer d) TUG-2 pointer i) TU-12 pointer e) TU-2 pointer j) No pointer is used

8) How many TU-12 pointer bytes are used for the transmission of 21 x 2 Mbit/s ?

a) 4 b) 42 c) 84 d) 64

TEST - Overhead 1. Which of the following functions are fulfilled by an averhead ?

a) Error monitoring b) Positive justification c) Frame alignment d) Path trace

2. Can the “path trace” vary on the individual line sections ?

Section Section Section 140 Mbit/s 140 Mbit/s MUX 1 REG 1 REG 2 MUX 2

3. What is the difference between RSOH and MSOH ?

a) Only regenerators can access the RSOH b) In every STM-1 frame, the MSOH is transmitted twice, whereas the

RSOH is transmitted only once. c) All SDH multiplexers and regenerators can access the RSOH; the MSOH

is accessed only by multiplexers.

4. The bytes B1, B2 and B3 serve to…. ?

a) report back errors b) detect errors by means of the parity code c) transmit order-wire channels

5. Which of the statements below relating to the POH of the VC-12 are correct ?

a) Every multiframe VC-12 has a POH b) Only the first VC-12 container in the VC-4 contains a POH c) Every VC-12 transmits the entire POH

6. What is the C2 byte in the POH of the VC-4 ?

a) Frame alignment signal b) STM-1 frame alignment c) User/application channel d) Signal identification (ID) e) Path status / trace

7. Pick from the statement below the information contained in a VC-3 (as per C” byte) a) 3 x 34 Mbit/s b) 1 x 34 Mbit/s c) TUG with ANSI signals d) 1 x 140 Mbit/s

8. Which of the bytes listed below can be contained in a VC-12 POH ?

a) J1 b) C1 c) C2 d) B3 e) J2 f) F1 g) Z6/Z7 h) V1/V2 i) V5 j) K1/K2 k) D1-D12 l) S1

9. How many STM-1 frames are required to trnsmit the entire VC-12 POH ?

a) 1 b) 2 c) 3 d) 4 e) 5

TEST - MONITORING 1. What is the maximum number of bit errors which can be counted in the B1

byte during one second

a) 128.000 b) 640 c) 512.000 d) 32.000 e) 64.000

2. Which byte is used for bit error monitoring on multiplex sections ?

a) B1 b) B2 c) B3

3. In which direction is “Section AIS” transmitted ?

a) In the forward direction b) In the backward direction c) In both directions

4. What purpose does FEBE serve ?

a) It indicates errors to the receiver. b) It indicates to the transmitter that a BER grater than 10 exp –6 was

detected c) FEBE has no function; it is merely used to verify the local LED d) It prevents the AIS from being forwarded

5. Which tipe of FERF exist ?

a) Regenerator FERF b) Section FERF c) Path FERF d) PDH – FERF

TEST - RESULTS TEST - Principles of PDH Multiplexing

1) b; d; e; h 2) c 3) d 4) b 5) d

TEST - Characteristic of SDH multiplexing

1) d 2) E 3) b 4) a 5) e

TEST - Mapping

1. a; c 2. a; b; d 3. c 4. b 5. c 6. d 7. a; b; c; d 8. b

TEST - Pointer

1) b 2) d 3) H1; H2; H3,H3,H3 4) a; c; e 5) e 6) a; b; d; e; f 7) a; i 8) c

TEST - Overhead

1) a; c; d 2) (no) 3) c 4) b 5) a 6) d 7) b; c 8) e; g; I 9) d

TEST - Monitoring

1) e 2) b 3) a 4) b 5) b; c