HUAWEI OptiX OSN 8800 T64/T32 Intelligent Optical Transport Platform. Product Overview - part 6
ODU2
ODU1 (first channel)
TS1-TS2
ODU0 (first channel)
TS3
ODU0 (second channel)
TS4
ODU1 (second channel)
TS5-TS6
ODU1 (third channel)
TS7-TS8
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
3.9 Clock Feature
OptiX OSN 8800 T32 and OptiX OSN 8800 T64 support the physical layer clock and PTP
clock to realize the synchronization of the clock and the time.
The physical clock extracts the clock from the serial bit stream at the physical layer to realize
the synchronization of the frequency.
The Precision Time Protocol (PTP) clock complies with the IEEE 1588 v2 protocol. IEEE
1588 v2 is a synchronization protocol, which realizes time synchronization based on the
timestamp generated during the exchanging of protocol packets. It provides the nanosecond
accuracy to meet the requirements of 3G base stations.
3.9.1 Physical Clock
OptiX OSN 8800 T32 and OptiX OSN 8800 T64 support the physical clock synchronization.
Physical-layer synchronization is classified into the SDH/PDH synchronization in the
traditional SDH field and synchronous Ethernet.
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OptiX OSN 8800 T32 and OptiX OSN 8800 T64 extract 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.
Pick-up clock signals from the line side of SDH unit.
OptiX OSN 8800 T32 and OptiX OSN 8800 T64 extract input and output of two 75-ohm or
two 120-ohm external clock sources.
OptiX OSN 8800 T32 and OptiX OSN 8800 T64 extract 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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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 8800 T32 and OptiX OSN 8800 T64 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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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.
In addition, the OptiX OSN 8800 is also capable of cross-connecting services at the SDH
layer. Therefore, WDM ASON equipment can be networked with WDM ASON equipment or
SDH ASON equipment to enable cross-connections at multiple granularities and multiple
layers, as shown in Figure 3-16.
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Figure 3-16 Flexible networking and multi-layer service cross-connections
OptiX OSN 8800
OptiX OSN 8800
Wavelength
OptiX OSN 8800
OptiX OSN 8800
OptiX OSN 9500
ODUk
VCk
OptiX OSN 8800
OptiX OSN 7500
OptiX OSN 6800
OptiX OSN 3500
Wavelength Link
ODUk Link
VCk Link
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4
Network Application
About This Chapter
4.1 Networking and Applications
The OptiX OSN 8800 T32 and OptiX OSN 8800 T64 support the point-to-point networking,
chain networking, ring networking, and mesh networking. It can be networked with other
WDM and SDH equipment to realize a complete transport solution.
4.1 Networking and Applications
The OptiX OSN 8800 T32 and OptiX OSN 8800 T64 support the point-to-point networking,
chain networking, ring networking, and mesh networking. It can be networked with other
WDM and SDH equipment to realize a complete transport solution.
4.1.1 Basic Networking Modes
The OptiX OSN 8800 supports point-to-point networking, chain networking, ring networking,
and mesh networking. It can be networked with other WDM and SDH or SONET equipment
to realize a complete transport solution.
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 for a scenario where 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 applicable to the
convergence service and broadcast service dedicated for simple networking.
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Ring Network
Network security and reliability are key factors that indicate the quality of the services
provided by network operators. Because of the high survivability, ring network is a dominant
networking mode in MAN DWDM network planning. The ring network has the widest
application range. It can be applicable 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 ring with chain.
Mesh Network
A large number of nodes are connected by straight routes on a 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.
Thus, the mesh network has high service transmission reliability, and the mesh topology is a
mainstream networking mode for ASON networks. The mesh networking features flexibility
and scalability. It is widely used in ASON networks.
4.1.2 Typical OTN Networking
The OptiX OSN 8800 can be jointly used not only with the OptiX OSN 6800 or OptiX OSN
3800 to form a complete OTN end-to-end network, but also with the OptiX BWS 1600G or
OptiX Metro 6100 to form a WDM network. The OTN or WDM network is then used to
transmit the services from the NG SDH/PTN or data communication equipment. In this
manner, the OptiX OSN 8800 T32 and OptiX OSN 8800 T64 implement a complete transport
solution.
Typical OTN Networking
When working with the OptiX OSN 6800, the OptiX OSN 8800 T32 and OptiX OSN 8800
T64 can form an OTN network or a DWDM ring to transport or add/drop services on the
WDM line. Figure 4-1 shows the typical OTN networking.
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Figure 4-1 Typical OTN networking
OptiX OSN
8800 T16
OptiX OSN
6800
OptiX OSN
DWDM Ring
8800 T32
OptiX OSN
OptiX OSN
Interconnection
8800 T64
3500
at client side
OptiX OSN
3500
OptiX OSN
SDH Ring
OptiX OSN
DWDM Ring
6800
OptiX OSN
6800
OptiX OSN
3500
6800
OptiX OSN
3500
:OADM
:ADM
WSS Grooming Solution
ROADM in wavelength selective switch (WSS) mode is applicable to intra-ring grooming
and inter-ring grooming.
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
4/8
…
…
…
…
OAU
OAU
WSD9
WSM9
OAU
WSM9
WSD9
OAU
…
…
…
…
4/8
4/8
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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.
Figure 4-3 Inter-ring grooming ROADM solution
C
D
B
East
South
A
West
South
E
West
North
F
Application of Electrical-Layer Grooming
The OptiX OSN 8800 grooms services by means centralized cross-connections.
The OptiX OSN 8800 supports ODUflex, ODU0, ODU1, ODU2, and ODU3
cross-connections. GE, 2.5G, and 10G services can share bandwidth to improve bandwidth
utilization. As shown in Figure 4-4, a GE service and a 2.5G service share a wavelength.
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Figure 4-4 Application of electrical-layer grooming
Optical-Electrical Convergence Solution
At the service access end, the equipment cross-connects multi-rate services to 40G channels
for transmission. At a service pass-through station, the equipment fast transmits services by
means of ROADM optical cross-connections. At the service receive end, the equipment drops
40G services from the line by processing electrical-layer cross-connections. If a wavelength
conflict occurs during optical-layer cross-connections, the equipment can convert
wavelengths by means of electrical-layer cross-connections. In addition, when the
transmission distance exceeds the limit, electrical regeneration can be used. As shown in
Figure 4-5, the wavelengths of two services conflict. In this case, wavelengths can be
converted by means of electrical-layer cross-connections. When the performance of the line
deteriorates and results in bit errors, electrical regeneration can be used to transmit services.
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Figure 4-5 Application of electrical-layer grooming
Wavelength conflict
Optical
Bit errors
Layer
Grooming
Electrical
Layer
Grooming
STM-1/GE/2.5G/10G&40G
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 4-6.
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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