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HUAWEI OptiX OSN 8800 T64/T32 Intelligent Optical Transport Platform. Product Description - part 14

Table 5-14 OPU types and bit rates

OPU type

OPU Payload nominal bit

OPU Payload bit rate tolerance

rate

OPU0

238/239 × 1 244 160 kbit/s

±20 ppm

OPU1

2 488 320 kbit/s

±20 ppm

OPU2

238/237 × 9 953 280 kbit/s

±20 ppm

OPU3

238/236 × 39 813 120 kbit/s

±20 ppm

OPUflex for

client signal bit rate

client signal bit rate tolerance, with a

CBR client

maximum of ±100 ppm

signals

NOTE

The nominal OPUk Payload rates are approximately:1 238 954.310 kbit/s (OPU0), 2 488 320.000 kbit/s

(OPU1 Payload), 9 995 276.962 kbit/s (OPU2 Payload) and 40 150 519.322 kbit/s (OPU3 Payload).

NOTE

In Table 5-14, the ODUk consists of 3824*4 bytes. Each OPUk payload consists of 3808*4 bytes. The

238/239 of the OPU0 payload nominal rates indicate the ratio of the OPU0 payload to the ODU0 bytes.

The 238/237 and 238/236 of the OPUk payload nominal rates indicate the ratio of the OPUk payload to

the OPUk payload excluding the stuffing information. The supplementary description is as follows:

l OPU0: The ratio of the OPU0 payload to the ODU0 bytes is as follows: (3808*4)/(3824*4) = 238/239.

l OPU1: No stuffing information is added when the STM-16 is mapped to the OPU1 as payload.

l OPU2: 16 columns of stuffing information are added when the STM-64 is mapped to the OPU2 as

payload. Therefore, the ratio of the OPU2 payload to the OPU2 payload excluding the stuffing

information is as follows: (3808*4)/[(3808-16)*4] = 238/237.

l OPU3: 32 columns of stuffing information are added when the STM-256 is mapped to the OPU3 as

payload. Therefore, the ratio of the OPU3 payload to the OPU3 payload excluding the stuffing

information is as follows: (3808*4)/[(3808-32)*4] = 238/236.

5.7.3 ODUflex

The OptiX OSN 8800 supports the flexible optical data unit flexible (ODUflex) technique. Using

the ODUflex technique, the OptiX OSN 8800 can adapt itself to various services such as video,

storage, and data services, and is able to provide future IP services.

Introduction to ODUflex

OptiX OSN 8800 T64/T32/T16 of earlier versions supports only four types of ODUk mappings:

ODU0 (1.25G), ODU1 (2.5G), ODU2 (10G), and ODU3 (40G). Services can be mapped only

to fixed bandwidth. Therefore, service mapping is not flexible and bandwidth waste may result.

ITU-T defines ODUk with flexible bandwidth (ODUflex for short) to avoid bandwidth waste

caused by service mapping.

ODUflex has the following features:

l The bandwidth required for ODUflex is about N x bandwidth of each ODTUk timeslot (1

≤ N ≤ 8).

136

l The ODTUk timeslot is the basic unit of ODUk frames and each ODTUk timeslot has the

bandwidth of 1.25Gbit/s.

NOTE

l ODTUk timeslots are basic units of ODUk frame signals. That is, ODUflex signals consist of multiple

ODTUk timeslots. Each ODTUk timeslots provides 1.25 Gbit/s bandwidth. One ODU0 signal equals one

ODTUk timeslot and ODU1 signal equals two ODTUk timeslots.

For example, when a 3G-SDI service at a rate of 2.97 Gbit/s is received on the client side, the

bandwidth usage is as follows:

l When ODUflex is not used for service mapping, the mapping path is 3G-SDI -> ODU2 -

> OTU2. In this case, the service occupies all the bandwidth (10 Gbit/s) of ODU2 and

wastes about 7 Gbit/s bandwidth.

l When ODUflex is used for service mapping, the mapping path is 3G-SDI -> ODUflex ->

ODU2 -> OTU2. Only three ODTUk timeslots are occupied and the left five ODTUk

timeslots are available for other services. Each ODTUk timeslot provides 1.25 Gbit/s

bandwidth; therefore, 6.25 Gbit/s (5 x 1.25 Gbit/s) bandwidth is saved.

ODUflex Applications

Transport of generic CBR signals

ODUflex can be used to transmit constant bit rate (CBR) services on an optical transport

network (OTN). The services whose CBRs are higher than 2.48832 Gbit/s are mapped to

an ODUflex (CBR) container in bit synchronization mode. Functions such as end-to-end

performance monitoring and protection switching are feasible on the ODUflex (CBR)

container. The overheads and monitoring management modes of ODUflex services and

traditional ODUk (k= 0, 1, 2, 3) are the same. For the application scenarios, see Figure

5-33 and Figure 5-34.

Figure 5-33 shows how ODUflex is used to transport generic CBR signals. An FC400

service occupies four ODTUk timeslots and is mapped to an ODUflex container; a 3G-SDI

service occupies three ODTUk timeslots and is mapped to an ODUflex container. In this

way, the FC400 and 3G-SDI services share the same OTU2 wavelength.

Figure 5-34 shows how ODU2 is used to transport generic CBR signals. The FC400 and

3G-SDI services are mapped to different ODU2 containers, and therefore they occupy

different OTU2 wavelengths.

Figure 5-33 Transport of generic CBR signals (ODUflex)

FC400 and 3G-SDI share a same OTU2 wavelength

FC400

(4 x ODTUk TS)

ODUflex

OTU2

OTN Network

3G-SDI

(3 x ODTUk TS)

ODUflex

Client side

WDM side

Client side

137

Figure 5-34 Transport of generic CBR signals (ODU2)

FC400 and 3G-SDI each occupy a OTU2 wavelength

Client

Line

Client

FC400

OTU2

FC400

ODU2

OTN Network

3G-SDI

OTU2

3G-SDI

ODU2

Client side

WDM side

Client side

ODUflex Implementation

Figure 5-35 shows how an ODUflex signal is mapped and multiplexed.

Figure 5-35 ODUflex mapping and multiplexing method

Client

ODUk.t

+ ODUk

ODUk

Service

s MUX

Overhead

BMP Mapping

+ ODUflex

GMP Mapping

into OPUflex

Overhead

into ODUk.ts

The client signals are mapped into an OPUflex frame using the bit-synchronous mapping

procedure (BMP) or GPF-F mapping method. The OPUflex frame changes into an ODUflex

frame after it carries an ODUflex frame header.

The ODUflex frame is mapped into N ODTUk timeslots by using the generic mapping

procedure (GMP).

Multiple ODTUk timeslots are multiplexed into a standard ODUk frame after an ODUk

frame header is inserted.

ODUflex Signal Types

Table 5-15 lists the current boards that support transmission of signals through ODUflex frames.

Table 5-15 ODUflex signal transmission

Applicable Board

Encapsulation

Client Signal Type

ODUflex

Mode

Mapping Path

TN11LOA

ODUflex(CBR)

FC400/FC800/3G-

Client signal-

SDI

>ODUflex->ODU2-

>OTU2

138

Applicable Board

Encapsulation

Client Signal Type

ODUflex

Mode

Mapping Path

TN54TOA

FC400/3G-SDI

Client signal-

>ODUflex

TN53TDX,

FC800

TN55TQX

TN53NQ2,

ODUflex->ODU2-

TN53ND2,

>OTU2

TN53NS2

5.7.4 Mapping and Multiplexing

This section describes how client signals are mapped and multiplexed on Huawei transport

equipment in addition to the mapping paths and required timeslots.

H-L Multiplexing Hierarchy

In the high-order (H) and low-order (L) multiplexing hierarchy, client signals in an OTN system

are sent to the line for transmission after the H-L multiplexing processes. For low-order

multiplexing, a client signal is multiplexed into a low order (LO) ODUk signal. For high-order

multiplexing, an LO ODUk signal is multiplexed into a high order (HO) ODUk signal, which

is then transmitted on the line. Before OptiX OSN 8800 V100R005, client signals are mapped

and multiplexed level by level. For example, to map a client signal into an ODU2 signal, the

client signal must go through the client->ODU0->ODU1->ODU2 process. However, in OptiX

OSN 8800 V100R005 and later versions, which support the H-L multiplexing hierarchy, the

mapping process is simplified as client->ODU0->ODU2.

The following describes how the TN52TOG and TN52ND2 boards map and multiplex client

signals level by level using a GE signal as an example. To map the GE signal into an ODU2

signal before sending the signal into the cross-connect board, the equipment of a version earlier

than V100R005 must perform the client-> ODU0 ->ODU1->ODU2 process, which is marked

as red in Figure 5-36.

Figure 5-36 Level-by-level mapping and multiplexing

OTU3

ODU3

OPU3

OTU2

ODU2

OPU2

OTU1

ODU1

OPU1

OTU0

ODU0

Client

Mapping

Multiplexing

139

For the equipment of V100R006C01 or a later version, boards such as the LOA board support

H-L multiplexing and can map a client signal into an ODU2 signal according to the client-

>ODU0->ODU2 process. Then the equipment sends the ODU2 signal to the cross-connect

board. The H-L multiplexing process is marked as red in Figure 5-37.

Figure 5-37 H-L mapping and multiplexing

x32

OTU3

ODU3

OPU3

OTU2

ODU2

OPU2

OTU1

ODU1

OPU1

OTU0

ODU0

Client

Mapping

Multiplexing

Mixed Mapping and Multiplexing

The equipment supports mapping and multiplexing of lower order ODUk signals into higher

order ODUk signals. For example, the equipment can map and multiplex a mixture of ODU0

and ODU1 signals into an ODU2 frame.

Each ODUk frame occupies some TS sub-timeslots. TS sub-timeslots may be occupied in the

following modes:

l Completely fixed consecutive occupation: Each ODUk signal occupies a fixed TS sub-

timeslot if hybrid mapping or multiplexing is not supported. For example, the second ODU1

channel occupies TS3 and TS4.

ODU2

ODU1

TS1-TS2

(First channel)

ODU1

TS3-TS4

(Second channel)

ODU1

TS5-TS6

(Third channel)

ODU1

TS7-TS8

(Fourth channel)

140

l Initially fixed consecutive occupation: The fixed occupation relationships will be changed

after hybrid mapping and multiplexing are supported. For example, ODU1 may occupy

TS5 and TS6.

ODU2

ODU1 (first channel)

TS1-TS2

ODU0 (first channel)

TS3

ODU0 (second channel)

TS4

ODU1 (second channel)

TS5-TS6

ODU1 (third channel)

TS7-TS8

l Flexible and inconsecutive occupation: Timeslots are assigned more flexibly. For example,

the first ODU1 channel occupies TS2 and TS4, which are inconsecutive timeslots.

ODU2

ODU0 (first channel)

TS1

ODU1 (first half of the first

TS2

channel)

ODU0 (second channel)

TS3

ODU1 (second half of the

TS4

first channel)

ODU1 (second

TS5-TS6

channel)

ODU1 (third channel)

TS7-TS8

5.7.5 TCM

Tandem connection monitoring (TCM) is used mainly when the network scale is relatively large

or when network resources are leased to different network carriers. In this case, the TCM is used

to monitor the quality of the transmission channels in a specific network area, for example, a

leased transmission network.

The TCM provides section monitoring for the ODUk (k = 0, 1, 2, 3) channel. The main functions

of TCM are as follows:

l Monitoring the tandem connection between optical UNI and UNI, and monitoring the

ODUk connection that traverses public transport network. Users monitor the quality of the

provider network with TCM, which is enabled at the interface nearest to the provider

network.

l Monitoring the tandem connection between optical NNI and NNI, and monitoring the

ODUk connection that passes through carrier network. The network provider monitors the

141

quality of local network with TCM, which is located at the interfaces on both ends of the

provider network.

l Monitoring the tandem connection of optical channels for fault location or verification of

service delivery quality.

TCM overheads are allocated in three ways: concatenation, embedding, and overlaying. OTU

frame overheads include six levels of TCM overheads, from TCM1 to TCM 6, providing the

following subfields:

l Trial trace identifier (TTI)

l bit interleaved parity 8 (BIP-8)

l Backward defect indication (BDI)

l Backward error indication and backward incoming alignment error (BEI/BIAE)

l Status bits STAT, such as LTC and LCK

The functions of TCM in the network are shown in Figure 5-38. When client services are carried

by different carrier networks, TCM overheads can be used to monitor the network quality.

Figure 5-38 Example of TCM functions

Operator B

network

Operator A

network

Domain and domain interconnect supervision (TCM3)

User

network

Lead operator QoS supervision (TCM2)

network

User QoS supervision (TCM1)

In this example, three levels of TCM overheads are used to supervise different networks.

l The user uses TCM1 to achieve QoS supervision between optical UNI and UNI.

l The lead operator uses TCM2 to achieve QoS supervision over operator networks.

l Operator A and Operator B use TCM3 to achieve QoS supervision over the local domain

and domain interconnection.

5.7.6 FEC Function

Certain OTUs, tributary boards and line boards have forward error correction (FEC) function

and advanced forward error correction (AFEC) function.

With the FEC and AFEC functions, the OSNR requirements of the system are less at the receive

end. This extends the transmission distance between the optical amplifier section and the

regenerator section.

In addition, the FEC and AFEC help to reduce bit error rate during the transmission. It also

enhances the transmission quality of DWDM networks.

142

l Standard FEC technology of the OTN network increases the FEC overheads by 7% and

realizes encoding gain 6.2 dB (BER = 1E-15).

l AFEC technology of the OTN network increases the FEC overheads by 7% and realizes

encoding gain more than 8 dB (BER = 1E-15).

NOTE

Boards that use different FEC modes cannot interoperate with each other.

5.8 WDM Technologies

This chapter describes the WDM technologies and functions implemented on the OptiX OSN

8800 T32/8800 T64.

5.8.1 DWDM and CWDM Technical Specifications

The OptiX OSN 8800 T32/8800 T64 supports two wavelength division multiplexing

technologies: dense wavelength division multiplexing (DWDM) and coarse wavelength division

multiplexing (CWDM) technologies. This section describes the technical specifications and

transmission capacity of the product using the two technologies.

There are no limits for wavelengths transmitted over G.652, G.654, and G.655 fibers used with

the OptiX OSN 8800 T32/OptiX OSN 8800 T64. To realize 40-wavelength transmission, the

wavelengths transmitted over G.653 fiber should be within 196.05 THz to 194.1 THz.

l DWDM includes 40-wavelength system and 80-wavelength system. The wavelengths are

in the C band compliant with ITU-T G.694.1.

- Each C-band 40-wavelength system with a channel spacing of 100 GHz can transmit a

maximum of 40 wavelengths. It supports services of 2.5 Gbit/s, 10 Gbit/s and 40 Gbit/

- Each C-band 80-wavelength system with a channel spacing of 50 GHz can transmit a

maximum of 80 wavelengths. It supports services of 10 Gbit/s and 40 Gbit/s.

- C-band 80-wavelength systems consist of even and odd wavelengths. The information

about odd and even wavelengths is provided below:

- C_EVEN: indicates even-numbered wavelengths. In total there are 40 even

wavelengths. The center frequency of the even wavelengths is within the range of

192.100 THz to 196.000 THz (center wavelength is within the range of 1529.55 nm

to 1560.61 nm) and the frequency spacing is 100 GHz.

- C_ODD: indicates odd-numbered wavelengths. In total there are 40 odd

wavelengths. The center frequency of the odd wavelengths is within the range of

192.150 THz to 196.050 THz (center wavelength is within the range of 1529.16 nm

to 1560.20 nm) and the frequency spacing is 100 GHz.

- The 40-wavelength system can be upgraded to the 80-wavelength system smoothly.

l CWDM with a channel spacing of 20 nm can access up to eight wavelengths. It only applies

to services rated at 2.5 Gbit/s. The wavelengths are in the C band compliant with ITU-T

G.694.2.

DWDM wavelengths can be transported in the window of CWDM 1531 nm to 1551 nm to

expand the CWDM system capacity. Figure 5-39 shows the expansion of wavelength allocation.

With this expansion scheme, a CWDM system can transmit a maximum of 26 DWDM

wavelengths at 100 GHz channel spacing. If the DWDM wavelength is 50 GHz in channel

spacing, a CWDM system can transmit a maximum of 50 DWDM wavelengths.

143

Figure 5-39 DWDM wavelength expansion and allocation in the CWDM system

CWDM

DWDM

DWDM over CWDM

wavelengths

1529.55nm

1471nm

1530.33nm

1531.12nm

1531.90nm

1491nm

1532.68nm

1533.47nm

1511nm

1534.25nm

1511nm

1529.55nm

1535.04nm

1536.61nm

1535.82nm

1531nm

10λ

1535.61nm

1545.32nm

1551nm

16λ

1546.12nm

1545.32nm

1546.92nm

1547.72nm

1571nm

1557.36nm

1548.51nm

1549.32nm

1550.12nm

1591nm

1550.92nm

1551.72nm

1552.52nm

1553.33nm

1611nm

1554.13nm

1554.94nm

1555.75nm

1556.55nm

1557.36nm

Figure 5-40 shows the equipment configuration in which DWDM wavelengths are transported

in the window of CWDM 1531 nm to 1551 nm. The DWDM wavelengths need to pass through

the DWDM MUX/DEMUX and CWDM MUX/DEMUX. Hence, the optical amplifier unit

needs to be configured in between.

144

Figure 5-40 Application of the DWDM wavelength in the CWDM system

OTU

MUX/

DEMUX

OTU

MO M1

OTU

MO M1

CWDM

DWDM

5.8.2 Nominal Central Wavelength and Frequency of the DWDM

System

Table 5-16 Wavelengths and frequencies of a C-band 80-channel (spacing of 50 GHz) system

Wavele

Central

Wavele

Central

ngth

Frequency

Wavelength

ngth

Frequency

Wavelength

No.

(THz)

(nm)

No.

(THz)

(nm)

196.05

1529.16

194.05

1544.92

196.00

1529.55

194.00

1545.32

195.95

1529.94

193.95

1545.72

195.90

1530.33

193.90

1546.12

195.85

1530.72

193.85

1546.52

195.80

1531.12

193.80

1546.92

195.75

1531.51

193.75

1547.32

195.70

1531.90

193.70

1547.72

195.65

1532.29

193.65

1548.11

195.60

1532.68

193.60

1548.51

145

Wavele

Central

Wavele

Central

ngth

Frequency

Wavelength

ngth

Frequency

Wavelength

No.

(THz)

(nm)

No.

(THz)

(nm)

195.55

1533.07

193.55

1548.91

195.50

1533.47

193.50

1549.32

195.45

1533.86

193.45

1549.72

195.40

1534.25

193.40

1550.12

195.35

1534.64

193.35

1550.52

195.30

1535.04

193.30

1550.92

195.25

1535.43

193.25

1551.32

195.20

1535.82

193.20

1551.72

195.15

1536.22

193.15

1552.12

195.10

1536.61

193.10

1552.52

195.05

1537.00

193.05

1552.93

195.00

1537.40

193.00

1553.33

194.95

1537.79

192.95

1553.73

194.90

1538.19

192.90

1554.13

194.85

1538.58

192.85

1554.54

194.80

1538.98

192.80

1554.94

194.75

1539.37

192.75

1555.34

194.70

1539.77

192.70

1555.75

194.65

1540.16

192.65

1556.15

194.60

1540.56

192.60

1556.55

194.55

1540.95

192.55

1556.96

194.50

1541.35

192.50

1557.36

194.45

1541.75

192.45

1557.77

194.40

1542.14

192.40

1558.17

194.35

1542.54

192.35

1558.58

194.30

1542.94

192.30

1558.98

194.25

1543.33

192.25

1559.39

194.20

1543.73

192.20

1559.79

194.15

1544.13

192.15

1560.20

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