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Huawei OptiX OSN 6800. Product Overview - part 5

OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

3 Functions and Features

3.9.1 Physical Clock

OptiX OSN 6800 supports the physical clock synchronization. Physical-layer synchronization

is classified into the SDH/PDH synchronization in the traditional SDH field and synchronous

Ethernet.

OptiX OSN 6800 extracts the timing signals by the following methods:

 Extracts 2M/1.5M timing signals from the external clock interface of an NE.

 Extracts timing signals from optical signals that the line board receives.

OptiX OSN 6800 extracts input and output of two 75-ohm or two 120-ohm external clock

sources.

OptiX OSN 6800 extracts three clock working modes, that is, the tracing, holdover, and

free-run modes. The timing signals from optical signals that 1.5 Mbit/s timing signals, 2

Mbit/s timing signals and the line board receives also process and transfer synchronization

status messages (SSM).

 Tracing mode: It is the normal working mode. In this mode, the local clock is

synchronized with the input reference clock signals. An ASON NE not only supports the

traditional clock tracing mode, but also supports the ASON clock tracing mode.

 Holdover mode: When all timing reference signals are lost, the clock enters into the

holdover mode. In this mode, the clock takes timing reference from the last frequency

information saved before the loss of timing reference signals. This mode can be used to

cope with an interruption of external timing signals.

 Free-run mode: When all timing reference signals are lost and the clock losses the saved

configuration data about the timing reference, the clock starts tracing the internal

oscillator of the NE.

The synchronization process of the physical clock is as follows:

 The clock processing module of each NE extracts the clock signals from the serial bit

stream on the line and selects a clock source.

 The clock phase-locked loop traces one of the line clocks and generates the system

clock.

 The system clock is used as the transmit clock on the physical layer. It is transferred to

the downstream.

The synchronous physical clock has the following features:

 The synchronous physical clock is easy to realize and is highly reliable.

 The synchronous physical clock adopts the synchronization status information (SSM) to

indicate clock quality and exclusive OAM packets to transfer the SSM.

3.9.2 PTP Clock (IEEE 1588 v2)

A Precision Time Protocol (PTP) clock complies with the IEEE 1588 v2 protocol and can

realize synchronization of frequency and time.

IEEE 1588 v2 is a synchronization protocol, which realizes frequency and time

synchronization based on the timestamp generated during the exchange of protocol packets. It

provides the nanosecond accuracy to meet the requirements of 3G base stations.

To achieve PTP clock synchronization, all NEs on the clock link should support the IEEE 1588 v2

protocol.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

3 Functions and Features

BMC Algorithm

For the PTP clock, the best master clock (BMC) algorithm is adopted to select the clock

source.

The best master clock (BMC) algorithm compares data describing two or more clocks to

determine which data describes the better clock, and selects the better clock as the clock

source. The BMC algorithm includes the following algorithms:

 Data set comparison algorithm: The NE determines which of the clocks is better, and

selects the better clock as the clock source. If an NE receives two or more channels of

clock signals from the same grandmaster clock (GMC), the NE selects one channel of

the clock signals that traverses the least number of nodes as the clock source.

 State decision algorithm: The state decision algorithm determines the next state of the

port based on the results of the data set comparison algorithm.

Clock Architecture

There are three models for the IEEE 1588 v2 clock architecture.

 OC (Ordinary Clock): A clock that has a single IEEE 1588 v2 port and the clock needs to

be restored. It may serve as a source of time (master clock), or may synchronize to

another clock (slave clock).

 BC (Boundary Clock): A clock that has multiple IEEE 1588 v2 ports and the clock needs

to be restored. It may serve as the source of time, (master clock), and may synchronize to

another clock (slave clock).

 TC (Transparent Clock): A device that measures the time taken for a PTP event message

to transit the device and provides this information to clocks receiving this PTP event

message. That is, the clock device functions as an intermediate clock device to

transparently transmit the clock and process the delay, but does not restore the clock. It

can effectively deal with the accumulated error effects resulting from the master and

slave hierarchical architecture. In this manner, the TC ensures that the clock/time

synchronization precision meets the application requirement.

The TC is classified into peer-to-peer (P2P) TC and end-to-end (E2E) TC according to

the delay processing mechanism.

− P2P TC: When the PTP packets are transmitted to the P2P TC, the P2P TC corrects

both the residence time of the PTP packets and the transmission delay of the link

connected to the receive port. The P2P TC is mainly used in the MESH networking.

− E2E TC: When the PTP packets are transmitted to the E2E TC, the E2E TC corrects

only the residence time of the PTP packets. The E2E delay computation mechanism

between the master and slave clocks is adopted. The intermediate nodes do not

process the transmission delay but transparently transmit the PTP packets. The E2E

TC is mainly used in the chain networking.

OptiX OSN 6800 can support the OC, BC, TC, TC+OC, BC + physical-layer clock, and

TC+BC at present.

3.10 ASON Management

An automatically switched optical network (ASON) is a new-generation optical transmission

network.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

3 Functions and Features

With integration of SONET/SDH functionality, effective IP technology, large-capacity

WDM/OTN, and revolutionary network control software, ASON lays a foundation for flexible

and scalable next generation optical networks, which are easy to operate and manage, and less

expensive to operate.

Introducing ASON into WDM networks brings the following benefits:

 High reliability: Protection and restoration together improve network reliability and

service security.

 Easy to use: Network resources and topologies are easy to discover and end-to-end

services can be quickly created.

 Easy to manage: Trail resources are manageable and predictable, and services can be

automatically reverted to their original trails.

 Investment saving: A mesh network ensures higher resource usage and enables quick

expansion (plug-and-play).

 New service types: Service level agreement (SLA) ensures differentiated services.

WDM/OTN equipment is an effective service carrier. However, only the capability of

carrying services (on the transport plane) does not qualify WDM/OTN equipment as

advanced and future-oriented equipment, which also requires outstanding performance in

bandwidth usage, flexibility, manageability, maintainability, reliability, and protection

capability. It has become a trend to implement a control plane over the transport plane of the

WDM/OTN equipment.

The limitations on the WDM/OTN equipment are removed after the ASON technology is

implemented on the WDM/OTN equipment. Because of the ASON technology, the

WDM/OTN equipment features high reliability, flexibility, bandwidth utilization,

maintainability, and manageability and supports different service levels and quick deployment

of services. Further, the operability of a WDM/OTN network is highly improved because of

the features supported by the ASON technology, such as automatic discovery of resources,

traffic engineering, dynamic bandwidth adjustment, and interconnection and communication

technologies.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

4 Network Application

Network Application

About This Chapter

4.1 Networking and Applications

The OptiX OSN 6800 supports point-to-point network, chain network, ring network and

MESH network.

4.1 Networking and Applications

The OptiX OSN 6800 supports point-to-point network, chain network, ring network and

MESH network.

4.1.1 Basic Networking Modes

The OptiX OSN 6800 supports point-to-point networking, chain networking, ring networking,

and mesh networking.

Different networking modes are applied to different application scenarios. You need to select

the required networking mode according to the service requirements.

Point-to-Point Network

A point-to-point network is the basic application. It is used for end-to-end service

transmission. The other networking modes are based on point-to-point networking mode,

which is the basic network. A point-to-point network is generally used to transmit common

voice services, private line data services, and storage services.

Chain Network

The chain network with OADM(s) is suitable when wavelengths need to be added/dropped

and passed through. A chain network has similar service types as a point-to-point network, but

the chain network is more flexible than the point-to-point network. It can be applicable not

only to the point-to-point service, but also to the convergence service and broadcast service

dedicated for simple networking.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

4 Network Application

Ring Network

Network security and reliability are key factors that indicate the quality of the services

provided by network operators. Because of its high survivability, the ring network is the

dominant networking mode in MAN DWDM network planning. The ring network has the

widest application range. It can be applied to the point-to-point service, convergence service,

and broadcast service. It can diversify into complex network structures, such as tangent rings,

intersecting rings, and rings with chains.

Mesh Network

Mesh networks have no node bottleneck and ensure unblocked services through alternative

routes during equipment failure. In a mesh network, more than one route is available between

two nodes. The mesh network has high service transmission reliability, and the mesh topology

is a mainstream networking mode for ASON networks. Mesh networking features flexibility

and scalability. It is widely used in ASON networks.

4.1.2 Typical Networking

The OptiX OSN 6800 can be networked with other WDM and SDH or SONET equipment to

achieve a complete transport solution.

Figure 4-1 shows the typical networking.

Figure 4-1 Typical networking

OptiX OSN

6800

OptiX OSN

3800

OptiX OSN

3800

6800

OptiX OSN

6800

OptiX OSN

3800

6800

OptiX OSN

6800

OptiX OSN

6800

:OADM

:OTM

WSS Grooming Solution

ROADM in wavelength selective switch (WSS) mode is applicable to intra-ring grooming

and inter-ring grooming.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

4 Network Application

At a network node, ROADM in WSS mode can freely change the add/drop status or

pass-through status of a wavelength, and does not interrupt a service in the change process.

ROADM can work with tunable lasers to flexibly groom wavelengths.

WSS enables output of any wavelength through any port. A port in WSS mode can be used as

either a port for local wavelength adding or dropping or a multi-directional MS port. WSS can

work with WSS or a coupler to build ROADM, as shown in Figure 4-2.

Figure 4-2 Functional diagram of a WSS-based ROADM node

4/8

…

OAU

WSD9

WSM9

OAU

WSM9

WSD9

OAU

…

4/8

WSS realizes colorless wavelength add/drop. Users can set the add/drop or pass-through state

of wavelengths on the NMS. In addition, the dynamic wavelength status can be adjusted

remotely and the services can be fast provisioned.

WSS supports the wavelength grooming in multiple directions and the multi-dimensional

ROADM structure. With WSS, the wavelength resources of multi-directional node on a ring

with chain or intersecting rings network are reconfigurable, as shown in Figure 4-3.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

4 Network Application

Figure 4-3 Inter-ring grooming ROADM solution

East

South

West

South

West

North

GE Ethernet Convergence Solution

The equipment provides Ethernet Layer 2 convergence boards, such as the TBE, L4G, LEM24,

LEX4, to achieve local FE-to-GE convergence and GE-to-GE/10GE network-wide

convergence. For details, see Figure 4-4.

Service convergence may be local convergence or network-wide multi-level convergence.

 Generally, for local convergence, multiple local client-side ports access services at the

same time but there is still idle bandwidth. If the service routes are the same or partially

the same, the services can be forwarded to the same port based on the VLAN

information and then send to the line side. For details, see station C in Figure 4-4.

 If the service volume is low after convergence or service routes are not completely the

same, a Layer 2 convergence board on the transmission trail, such as the L4G and TBE,

can combine the converged services and locally added services, and assign a route to the

combined services. This process is referred to multi-level convergence. For details, see

station B in Figure 4-4.

 A level-1 convergence node has the same functions as a local convergence node, except

for that the local convergence node converges services from multiple client-side ports to

the system side, while the level 1 convergence node converges services from multiple

system-side ports to the client side. For details, see station A in Figure 4-4.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

4 Network Application

Figure 4-4 GE Ethernet convergence solution

Centralized/distributed cross-

connections

Centralized/distributed cross-

connections

L4G/TBE

LDG B

L4G/LOG

1*GE or 10GE

Level-1 convergence node

TBE/L4G

LDG

L4G/LOG

5G DWDM

Level-2 convergence node

Z*GE or FE

2.5G

Centralized/distributed cross-

C/DWDM

connections

2.5G

C/DWDM

CWDM

X*GE

LDG/LOG L4G ECOM

Local convergence node

Y*GE

WDM ASON Solution

The equipment supports the ASON control plane. With the ASON control plane and WDM

features such as ROADM, FOADM, and optical wavelength/sub-wavelength protection, the

equipment provides an ideal WDM ASON solution.

At the core layer of a network, a mesh network is built with WSS/ROADM for wavelength

rerouting. At network edges, ring and chain networks are built with traditional FOADM,

OTM, or PLC ROADM, as the service volume is low and fiber resources are insufficient. For

details, see Figure 4-5.

An ASON network provides the same protection solutions as a traditional network does. In

addition, GMPLS and WSS together provide wavelength rerouting for services under no

protection or 1+1 protection on a mesh network. This helps improve survivability of services.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

4 Network Application

Figure 4-5 WDM ASON solution

PLC ROADM

OTM

OLA

FOADM

WSS ROADM

1+1 Protection

Non-protection

Services

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

5 About the ASON

About the ASON

About This Chapter

The ASON, the automatically switched optical network, is a new generation of the optical

transmission network, all called ASON optical network. This section describes some basic

concepts of the ASON and application of the ASON software.

The electrical-layer ASON for the OptiX OSN 6800 is used only in specified offices.

5.1 Overview

The ASON software provided by Huawei can be applied to the OptiX OSN series products to

support the evolution from traditional network to ASON network. It complies with the ITU

and IETF ASON/GMPLS-related standards.

5.1 Overview

The ASON software provided by Huawei can be applied to the OptiX OSN series products to

support the evolution from traditional network to ASON network. It complies with the ITU

and IETF ASON/GMPLS-related standards.

5.1.1 Background and Advantages

Compared with the WDM network, the transmission network that applies the new ASON

technology shows advantages in service configuration, bandwidth utilization and protection

schemes.

In the traditional transmission network, the WDM transmission equipment functions as fibers.

Currently, the WDM transmission equipment also carries services. As a result, more

requirements are for the operability of the WDM equipment. The traditional network has the

following problems:

 The service configuration is complex and capacity expansion or service provision takes a

long period.

 The bandwidth utilization is of a low rate and low efficiency. In a ring network, half of

the bandwidth should be reserved.

 Just a few protection schemes are available and the performance of self-healing

protection is poor.

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OptiX OSN 6800 Intelligent Optical Transport Platform

Product Overview

5 About the ASON

The ASON has been developed to solve these problems. This technology involves signaling

switching and a control plane to enhance its network connection management and recovery

capability. It supports end-to-end service configuration and the service level agreement

(SLA).

Service Configuration

Traditional WDM networks are generally chains and rings. The trails and timeslots of their

services are manually configured ring by ring and point by point, which consumes a lot of

time and effort. As networks become increasingly large and complicated, this service

configuration mode cannot meet the rapidly increasing user demands.

The ASON successfully solves this problem by end-to-end service configuration. To configure

a service, you only need to specify its source node, sink node and protection type; the network

automatically performs the required operations.

Bandwidth Utilization

Traditional WDM optical transmission networks have a large amount of resources reserved

and lack advanced service protection, and the restore and routing functions. In contrast, with

the routing function the ASON can provide protection by reserving fewer resources, thus

increasing network resource utilization.

Protection and Restoration

Chain and ring are the main topologies used in a traditional WDM network. Optical line

protection or board-level protection are the main protection schemes for the services. In

ASON, mesh is the main topology. Besides protections, the dynamic restoring function is

available to restore the services dynamically. In addition, when there are multiple failures in a

network, the services can be restored as many as possible.

According to the difference in the service restoration time, multiple service types are defined

in ASON networks to meet different customer requirements.

5.1.2 Features of the ASON

As a new technology on the transmission network, the ASON has its own features.

Compared with the traditional network, the ASON has the following features:

 Supports the route calculation strategy that is based on optics parameters and eliminates

the route that does not comply with optics parameters automatically.

 Supports the automatic adjustment of wavelengths during rerouting or optimization,

which solves the wavelength conflict problem. (For OTN network)

 Wavelengths can be automatically allocated for newly created services.

 Configures end-to-end services automatically.

 Discovers the topology automatically.

 Provides mesh networking that enhances the survivability of the network.

 Supports different services which are provided with different levels of protection.

 Provides traffic engineering and dynamically adjusts the network logic topology in real

time to optimize the configuration of network resources.

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