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HUAWEI OptiX OSN 8800 T64/T32 Intelligent Optical Transport Platform. Product Overview - part 5

3.8 WDM Technologies

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

8800 T32/8800 T64.

3.8.1 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.

 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/s.

− 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.

 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 3-7 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.

Figure 3-7 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

1529.55nm

1535.04nm

1536.61nm

1535.82nm

10λ

1531nm

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 3-8 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.

Figure 3-8 Application of the DWDM wavelength in the CWDM system

OTU

MUX/

DEMUX

OTU

MO M1

OTU

MO M1

CWDM

DWDM

3.8.2 Nominal Central Wavelength and Frequency of the DWDM

System

Table 3-13 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

195.55

1533.07

193.55

1548.91

Wavele

Central

Wavele

Central

ngth

Frequency

Wavelength

ngth

Frequency

Wavelength

No.

(THz)

(nm)

No.

(THz)

(nm)

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

194.10

1544.53

192.10

1560.61

3.8.3 Nominal Central Wavelengths of the CWDM System

Table 3-14 Nominal central wavelengths of the CWDM system

Wavelengt

Wavelength (nm)

Wavelength

Wavelength (nm)

h No.

No.

1471

1551

1491

1571

1511

1591

1531

1611

3.8.4 Typical Application

This section describes typical PID application.

PID helps to effectively eliminate bandwidth and O&M bottlenecks on a WAN, leveraging the

features such as large capacity, high integration, versatile multi-service access, small size, and

environment-friendly design. On a WAN, a 40G/80G/120G/200G aggregation ring based on

PID boards only is recommended, eliminating commissioning while enabling quick service

provision.

Typical network 1: WAN for a small or medium-sized city

At the OTN aggregation layer, two to six aggregation rings can be deployed with two to four

NEs in each ring. A PID board(s) is used on each NE's line side. Build a 40G/80G/120G/200G

network using PID groups as required. On each aggregation ring, services are electrically

regenerated by the PID and cross-connect boards at each site. NEs at the OTN backbone layer

are interconnected with NEs on aggregation rings through PID boards. Figure 3-9 shows the

details.

Figure 3-9 WAN for a medium or large-sized city

40/80x10G

Backbone layer

Aggregation layer

200G ring

120G ring

40G/80G ring

: Router

: High-end router

: NG WDM equipment

: BRAS

: PID-installed NG WDM equipment at the aggregation layer

Typical network 2: WAN for a medium or large-sized city

At the OTN aggregation layer, 13 to 20 aggregation rings can be deployed with two to four

NEs in each ring. A PID board(s) is used on each NE's line side. Build a 40G/80G/120G/200G

network using PID groups as required. On each aggregation ring, services are electrically

regenerated by the PID and cross-connect boards at each site. NEs at the OTN backbone layer

are interconnected with NEs on aggregation rings through PID boards. Figure 3-10 shows the

details.

Figure 3-10 WAN for a medium or large-sized city

80x40G Mesh

Backbone

layer

Aggregation

layer

200G ring

40G ring

80G ring

120G ring

: Router

: High-end router

: NG WDM equipment

: BRAS

: PID-installed NG WDM equipment at the aggregation layer

3.8.5 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:

 The bandwidth required for ODUflex is about N x bandwidth of each ODTUk timeslot

(1 ≤ N ≤ 8).

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

the bandwidth of 1.25Gbit/s.

 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:

 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.

 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

3-11 and Figure 3-12.

Figure 3-11 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 3-12 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 3-11 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

Figure 3-12 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 3-13 shows how an ODUflex signal is mapped and multiplexed.

Figure 3-13 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 3-15 lists the current boards that support transmission of signals through ODUflex

frames.

Table 3-15 ODUflex signal transmission

Applicable Board

Encapsulation

Client Signal

ODUflex

Mode

Type

Mapping Path

TN11LOA

ODUflex(CBR)

FC400/FC800/3G-S

Client

signal->ODUflex->

ODU2->OTU2

TN54TOA

FC400/3G-SDI

Client

Applicable Board

Encapsulation

Client Signal

ODUflex

Mode

Type

Mapping Path

signal->ODUflex

TN53TDX,

FC800

TN55TQX

TN53NQ2,

ODUflex->ODU2->

TN53ND2,

OTU2

TN53NS2

3.8.6 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 3-14.

Figure 3-14 Level-by-level mapping and multiplexing

OTU3

ODU3

OPU3

OTU2

ODU2

OPU2

OTU1

ODU1

OPU1

OTU0

ODU0

Client

Mapping

Multiplexing

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 3-15.

Figure 3-15 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:

 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)

 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.

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