OptiX OSN 7500 Intelligent Optical Switching System. Technical Manual - part 7
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Technical Manual - System Description
7 Intelligent Features
As shown in Figure 7-1, for diamond level service, a path ring (dotted line) is
predefined for an end-to-end protected service between a source node and a
destination node. The service is dual fed at the source node and selectively received
at the destination node according to the QoS. The bidirectional service is similar.
Normally, the receiving end receives service from the upper dotted line. When a failure
occurs to the link or node, the service will be switched to the lower dotted line.
You can also choose not to predefine the path ring, but to calculate two end-to-end
paths (which are not intersecting) from the edge node of the optical network. In such a
case, the service is dual fed at the source end and selectively received at the
destination end, thus guaranteeing the service of diamond level.
The receive node
selects the traffic
The source node sends the dual
traffic on rings
Figure 7-1 Networking protection for diamond level service
For gold level service, the logical virtual multiplex section (MS) ring must be
predefined. As shown in Figure 7-2, the bandwidth of Ring 1, Ring 2 and virtual ring
are specified as the user demands. They can be part of the maximum bandwidth of
the optical fiber. Half timeslots of the MS ring are used to protect another half. To
provide gold level service with M:N protection, each link of the service trail calculated
by the edge node of the optical network should belong to a virtual MS ring. By doing so,
a rapid MSP switching can be guaranteed in the case of link or node failure on the
service path. As shown in Figure 7-2, all links of the end-to-end service path belong to
either Ring 1 or Ring 2. If one node fails, the service on Ring 2 can be switched to the
protection path of the ring rapidly.l
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Protection path of the ring
Ring2
Ring1
Figure 7-2 Protection for gold level service
For silver level service, upon failure the service path is re-calculated after the
convergence of the topology. As the network convergence is time-consuming, the
service damaging or interruption time in re-routing is longer than the switching time for
the above two services.
Compared with the two services described above, the silver service has an advantage
that it does not need bandwidth reservation for recovery, thus improving the bandwidth
utilization. As shown in Figure 7-3, when the service link fails, a new path will be found
to recover the service.
There are two modes for rerouting: revertive and non-revertive. If the service reverts to
the original path when the fault is removed, it is in revertive mode; if not, it is in
non-revertive mode.
Re-calculated path
Figure 7-3 Application of silver level service
Provision of services of multiple-levels inherits the merit of fast protection switching of
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the SDH ring network, and takes advantages of high bandwidth utilization of the mesh
network.
7.2 Automatic End-to-End Service Configuration
The end-to-end service can be rapidly generated and protected by some simple
operations listed below through the NM system.
Select the source node.
Select the destination node.
Select desired bandwidth.
Select a service level.
Create a service connection automatically.
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7.3 Mesh Networking
Compared with the ring network, the mesh network features high bandwidth utilization,
network scalability, and survivability. This network topology is suitable for the area with
large and evenly distributed traffic. The mesh network has higher reliability because
there are multiple routes available between two nodes. This effectively protects the
traffic against node congestion and node failure. The one shown in Figure 7-3 is an
example of mesh networking.
7.4 Traffic Engineering
The traffic engineering control technique of the OptiX OSN 7500 allows a
load-balance traffic networkwide for convenient network planning and improved
bandwidth availability.
(1)
(2)
(1) Network without traffic engineering
(2) Network with traffic engineering
Figure 7-4 Application of traffic engineering in the network
As shown in Figure 7-4, the intelligent network featuring traffic engineering control
can:
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Avoid the congested path and node.
Avoid the high-risk path and node.
Automatically balance service load network wide.
Share the service load.
7.5 Integrated Intelligent Service Application
Generally, the intelligent service of the OptiX OSN 7500 is an application that
integrates the above intelligent features, including SLA, traffic engineering, mesh
networking and configuration of end-to-end service on the NM system.
Dynamically apply for service (SLA-supported).
Configure end-to-end service on the NM system.
Calculate the requirement-satisfying best service path based on traffic engineering.
The main technology is constrained shortest path first (CSPF).
Establish general MPLS (GMPLS) signaling connection on the service path.
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8 Protection
8
Protection
This chapter describes the protection schemes, at the equipment level and network
level, provided by OptiX OSN 7500. It covers:
Equipment level protection
Network level protection
8.1 Equipment Level Protection
The OptiX OSN 7500 supports the following protection schemes at the equipment
level:
TPS protection for tributary boards
TPS protection for Ethernet boards
1+1 backup for ATM/IMA interface boards
1+1 backup for the cross-connect unit and timing unit
1+1 backup for the SCC unit
1+1 backup for the power input unit
1:N protection for the +3.3 V board power supply
Intelligent fans
Abnormality-specific board protection
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8.1.1 TPS Protection for Tributary Boards
The OptiX OSN 7500 provides 1:N TPS protection for E1, DS1, E3, DS3, E4 and
STM-1 (Electrical) services through electrical interface protection. That is, it provides
TPS protection for PQ1, PQM, PL3, PD3, SPQ4 and SEP1. To be specific, it can
support:
One 1:N (N≤4) TPS protection group for E1/T1 service
Two 1:N (N≤3) TPS protection groups for E3/DS3/E4/STM-1 service
Coexistence of the above two different TPS protection groups
8.1.2 TPS Protection for Ethernet Boards
The OptiX OSN 7500 supports 1:1 TPS protection for 100M Ethernet FE (electrical)
service, namely, 1:1 TPS protection for the EFS0.
The protection EFS0 is inserted in slot 18, and the protected EFS0 is inserted in slot
17. They work with the ETS8 and TSB8 to implement TPS protection for Ethernet FE
services.
8.1.3 1+1 Backup for ATM/IMA Interface Boards
The OptiX OSN 7500 supports 1+1 backup for ATM data boards
(ADL4/ADQ1/IDL4/IDQ1). Two ATM data boards backup each other. If either fails, the
other takes over.
8.1.4 1+1 backup for the Cross-Connect and Timing Unit
The cross-connection and timing functions are provided by the GXCS board. The
GXCS board use 1+1 backup for protecting the cross-connect unit and the timing unit
at the same time. When the active cross-connect and timing units are working
normally, the standby ones are in standby working mode, not performingthe service
cross-connection function nor providing timing to the system. They have the same
cross-connect matrix setting and clock configuration as the active units. When the
standby units receive the information indicating abnormal performance of the active
units or a switching command sent by the NM system, they will immediately take over
the job of the active units, setting themselves to the active working mode and sending
out a switchover alarm.
8.1.5 1+1 Backup for the SCC Unit
The SCC unit of the OptiX OSN 7500 is provided with 1+1 backup protection. The
standby SCC unit is in standby working mode when the active one is working
normally.
8.1.6 1+1 Backup for the Power Input Unit
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Through the two PIU boards, the OptiX OSN 7500 can access two -48 V DC inputs
that work for mutual backup. If either of them goes faulty, the other will operate to
ensure the normal operation of the equipment.
8.1.7 1:N Protection for the +3.3 V Board Power Supply
The OptiX OSN 7500 provides 1:N backup for the +3.3 V power supplies of other
boards through the power backup unit of the AUX board. When the power supply of a
board becomes faulty, the backup power will take over to ensure normal operation of
that board.
8.1.8 Intelligent Fans
The OptiX OSN 7500 adopts three intelligent fan units for heat dissipation. The power
supplies for the fans serve as backup for each other.
The intelligent fans provide the functions of stepless speed regulation and failure
detection. Once one of the fan modules goes faulty, the other two will operate at their
full speed. The running status of the fans can be indicated by the corresponding
indicators on the front panel of the fan unit.
8.1.9 Abnormality-Specific Board Protection
1. Power Failure during Software Loading
Application program and data have the check function. When software loading is
interrupted, the basic input/output system (BIOS) will not start the unfinished program
and data until they are successfully loaded.
2. Over-voltage and Under-voltage Protection
The power board is designed with a lightning protection component to effectively
reduce the damages that may be possibly caused by transient high-voltage such as
lightning. When the voltage is over low, this board will automatically reset the center
processing unit (CPU) and the software will reinitialize the chips. The software will
provide a mirror protection for important memories that may affect the services. When
the voltage is not stable, which causes the memory value to change, the values can
be recovered to normal. In addition, when the voltage is too low, the power system will
automatically cut off the active power to protect the system.
3. Board Temperature Check
The temperature detection circuit is provided on the boards that generate much heat,
such as optical interface board and GXCS board. When the ambient temperature
detected is too high, an alarm is generated to remind the maintenance personnel to
clean the fans.
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8.2 Network Level Protection
8.2.1 SDH Trail Protection
The OptiX OSN 7500 can implement linear MSP and the MSP ring.
1. Linear MSP
Linear MSP is mainly used in the chain network. The OptiX OSN 7500 supports 1+1
and 1:N (N ≤14) protection schemes. In the 1:N protection mode, extra services can
be transmitted on the protection facility. In the linear MSP scheme, the switching time
is less than 50ms as specified in ITU-T Recommendation G.841.
2. MSP Ring
The OptiX OSN 7500 supports two-fiber MS shared protection ring, with the switching
time less than 50ms, as specified in ITU-T Recommendation G.841.
In line with ITU-T Recommendation G.841, the OptiX OSN 7500 supports four-fiber
MS shared protection ring, which provides ring switching and span switching in
addition to the similar functions of the two-fiber bidirectional MSP.
8.2.2 SDH SNCP
The OptiX OSN 7500 supports SNCP as required by ITU-T Recommendation G.841.
Even multiple service switching events occur at the same time, the switching time can
still be less than 50ms.
8.2.3 Protection for Interworking Service in Rings
As required by ITU-T Recommendation G.841, the OptiX OSN 7500 supports
protection for interworking services in rings, even in the rings with different protection
schemes (such as SNCP or MSP).
8.2.4 Fiber-shared Virtual Path Protection
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STM-64
STM-16
STM-16
SNCP
MSP
Figure 8-1 Fiber-shared virtual path protection
As shown in Figure 8-1, in the fiber-shared virtual path protection, one STM-16,
STM-4, or even STM-1 optical path is logically divided into lower-order or higher-order
paths, which are then combined with other links to form the path-level rings. The
path-level rings can be set with protection schemes such as path protection (PP), MSP,
SNCP, and non-protection (NP).
8.2.5 MS-Shared Optical Path Protection
In the MS-shared optical path protection, an optical interface can be configured with
multiple MSP groups, so that MSP rings can share the same fiber and optical interface.
This function is conditioned on the optical board’s capability of processing multiple
sets of independent K bytes. SL64 of the OptiX OSN 7500 support a maximum of four
sets of K bytes and SL16 support two.
Figure 8-2 shows the networking for two-fiber MS-shared optical path protection that
the OptiX OSN 7500 supports.
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MS-shared ring
OptiX OSN
STM-16/64
OptiX OSN
7500
7500
STM-4/16/64
MS-shared ring
STM-4/16/64
STM-4/16/64
MSP ring 1
STM-16
STM-64
X
MSP ring 2
STM-16
STM-16
Figure 8-3 Two lower-speed lines share one higher-speed line
The OptiX OSN 7500 also supports the line units at the same speed to form a
bidirectional sharing protection, as shown in Figure 8-4. In this case, the west STM-16
line units can only add part of VC-4 into the MSP ring group.
MSP ring 1
STM-16
STM-16
X
MSP ring 2
STM-16
STM-16
Figure 8-4 Sharing protection of the lines with the same speed
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