TECHNICAL FIELD

[0001] The invention herein generally relates to data networks and particularly relates to data networks using a protection switching protocol. The embodiments herein more particularly relates to an automatic protection switching for transmission systems to provide an optimized traffic switching across a protection domain.

BACKGROUND OF THE INVENTION

[0002] Communication networks carry various types of information such as voice, data, video and the like between users. A typical communication network includes many components or modules that work together to make a connection between users. For example, a communications network typically includes switches, transport lines, terminals and other conventional equipments to establish transmission path connections between users.

[0003] However errors can occur in any one of the modules of the communication network thus creating a faulty transmission path. For example, a fiber optic cable that carries signals for the network can be cut inadvertently or otherwise damaged such that it cannot acceptably carry data. To prevent errors of this nature from hindering communications, networks include redundant components so that when a working component stops functioning acceptably, a protection component can be switched into the network in place of the non-working component. Thus, the network is able to continue information transmission despite errors. This is referred to in the industry as network survivability or protection switching. Although, the use of redundant components has its applications, it is desired in the art to have an efficient method for switching signals dedicated to a faulty transmission path through an alternate transmission path to the desired customer.

[0004] A protection system generally includes an upstream end and a downstream end having one or more work entities defined for the upstream end and the downstream end and one or more protection entities associated with the work entities. The protection system also includes a plurality of multiplexed/de-multiplexed sub-entities at the upstream/downstream end. In the conventional protection switching techniques, the protection system monitors for the work entities in which a signal failure is detected to provide for protection switching. For example, if there is a signal failure in a work entity, the protection switching mechanism will protect it using one of the protect entities. However, it is absolutely of no use to protect the work entity if there are many upstream and downstream failures on the multiplexed and de-multiplexed sub-entities. In such cases, even if the work entity is protected, the majority of the end-to-end traffic will still be down as the protection domain does not cover the integrity of the sub-entities. This limitation in the existing protection switching mechanisms is due to doing a blind monitoring of the work entities involved in the linear protection group. The conventional protection switching system does not include any intelligence to take into account the health of the upstream and downstream paths/sub-entities.

[0005] In view of the foregoing, there exists a need for a method and system for providing protection switching in a communication network which has the capability to do an optimized switching based on upstream or downstream failures across a protection domain. There also exists a need to provide a mechanism to convey the upstream and downstream traffic health to the protection switching system controlling the protection domain.

[0006] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

OBJECTS OF THE INVENTION

[0007] The primary objective of the present invention is to provide a method and system for providing an optimized protection switching based on upstream or downstream failures across a protection domain.

[0008] Another objective of the present invention is to provide a method and system for providing protection switching by accounting the failures present outside the upstream end and downstream end of a protection domain.

[0009] Another objective of the present invention is to provide a method and system for providing protection switching with an optimized usage of the protection system.

[0010] Another objective of the present invention is to provide a method and system for providing protection switching with an optimized usage of the network bandwidth.

[0011] Yet another objective of the present invention is to provide a protection switching to detect failures in upstream multiplexed sub-entities and downstream de-multiplexed sub-entities.

[0012] Yet another objective of the present invention is to provide a protection switching to reconfigure the priority of the signal flow on the protection path in case of a signal failure.

[0013] Yet another objective of the present invention is to provide a protection switching which involves only less number of components, low cost and less power consumption.

[0014] These and other objectives and advantages of the present disclosure will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

[0015] The various embodiments of the present invention provide a method and system for providing protection switching in a communication network. The method comprising steps of identifying end points for protection switching, creating a linear protection switching domain including at least one work entity and one protect entity between the identified endpoints, where the end points include an upstream end and a downstream end, creating a linear protection switching group (LPSG) at each of the endpoint, defining a plurality of upstream multiplexed sub-entities at the upstream end, defining a plurality of down-stream de-multiplexed sub-entities at the downstream end, monitoring for the defects on the work entities and protect entities between the upstream end and downstream end, monitoring for a signal failure in at least one of the upstream end and downstream end of the LPSG, switching the traffic by a linear protection controller based on defects on the work entity and protect entity between the upstream end and the downstream end or user initiated external commands, generating an upstream defect indication (UDI) alarm on detecting a signal failure on the upstream end, generating a downstream defect indication alarm (DDI) on detecting a signal failure on the downstream end, feeding the upstream defect indication alarm and the downstream defect indication alarm to the protection controller and declaring a lock-out-of protection for the work entity which has atleast one of the UDI and DDI by the linear protection controller. The upstream defect indication alarm from the upstream end is transmitted to the linear protection controller through an overhead byte on the protect entities. Here the lock-out-of protection means that a particular entity will be prevented from getting protected, in other words, a particular entity will be locked out of protection switching. Hence, the LPSG while switching the traffic from work entity to protect entity will not consider the work entity that is marked as lock out of protection for protection.

[0016] According to an embodiment of the present invention, defining LPSG at the end points comprising steps of assigning priority to the plurality of upstream multiplexed sub-entities and the plurality of downstream de-multiplexed sub-entities at each of the work entities, assigning an upstream threshold value for the upstream defect indicator and a downstream threshold value for the downstream defect indicator for each of the work entities, comparing a summation of the product of signal status and priority with the upstream threshold value at the upstream end and downstream threshold value at the downstream end and declaring the upstream defect indication alarm if the summation exceeds the upstream threshold value and a downstream defect indication alarm is declared if the summation exceeds the downstream threshold value.

[0017] According to an embodiment of the present invention, assigning priority of the plurality of sub-entities at each work entity includes specifying predetermined weightings to each sub-entity to decide on the priority of the signal traffic to provide for protection switching in case of a signal failure.

[0018] According to an embodiment of the present invention, the predetermined weightings includes at least one of user configurable values configured in accordance with service level agreements and values set through a network management system which has a complete network view.

[0019] According to an embodiment of the present invention, the linear protection controller determines the automatic lock out of protection for the work entity based on at least one of receiving an upstream defect indication alarm and receiving a downstream defect indication alarm.

[0020] According to an embodiment of the present invention, the downstream defect indication alarm is declared at the downstream end and protection decision is taken at the downstream end of the protection domain and the upstream defect indication alarm is declared at the upstream end and transmitted to the downstream end to determine a protection decision.

[0021] According to an embodiment of the present invention, the downstream end declares a downstream defect indication alarm on detecting at least one of a remote signal failure and a user configurable signal failure in at least one of the plurality of downstream de-multiplexed sub-entities.

[0022] Embodiments herein further disclose a system for providing protection switching in a communication network. The system comprising a means for identifying end points for protection switching, a linear protection switching domain including at least one work entity and one protect entity between the identified endpoints, where the end points include an upstream end and a downstream end, a linear protection switching group at each of the endpoint, a plurality of work entities defined between the upstream end and the downstream end, a plurality of sub-entities defined for each of the plurality of work entities, at least one protection entity defined for the plurality of work entities, at least one signal monitor, alarm monitor and overhead monitor for each of the plurality of work entities, protect entities and sub-entities, an upstream defect indicator for indicating signal failure in the upstream end, a downstream defect indicator for indicating signal failure in the downstream end and a linear protection controller to determine protection decision of a defective work entity. The linear protection controller issues the lock out of protection on at least one work entity in which a signal failure is detected upstream or downstream conveyed through the upstream defect indicator or downstream defect indicator respectively.

[0023] According to an embodiment of the present invention, the upstream defect indicator declares an upstream defect indication alarm to indicate a signal failure in at least one of a sub-entity associated with the upstream work entities and downstream defect indicator declares a downstream defect indication alarm to indicate a signal failure in at least one of a sub-entity associated with the downstream work entities.

[0024] According to an embodiment of the present invention, the upstream defect indicator transmits the defect indication alarm from the upstream end to the protection controller through at least one of overhead bytes on the protection entities.

[0025] According to an embodiment of the present invention, the communication network comprises at least one of a Synchronous Digital Hierarchy Network (SDH), Synchronous Optical Networking (SONET), Ethernet, Multiprotocol Label Switching (IP-MPLS) and Optical Transport Network (OTN).

[0026] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

[0028] FIG. 1 is a block diagram illustrating a system for providing protection switching over a communication network, according to an embodiment of the present invention.

[0029] FIG. 2 is a schematic diagram illustrating the generation of an upstream defect indication alarm in a linear protection switching domain according to an embodiment of the present invention.

[0030] FIG. 3 is a schematic diagram illustrating the generation of a downstream defect indication alarm in a linear protection switching domain according to an embodiment of the present invention.

[0031] FIG. 4 is a schematic diagram illustrating a linear protection controller accounting for the protection decision of the work entities, according to an embodiment of the present disclosure.

[0032] Although the specific features of the present disclosure are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

[0033] In the following detailed description, a reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.

[0034] The various embodiments of the present invention provide a method and system for providing protection switching in a communication network. The method comprising steps of identifying end points for protection switching, creating a linear protection switching domain including at least one work entity and one protect entity between the identified endpoints, where the end points include an upstream end and a downstream end, creating a linear protection switching group (LPSG) at each of the endpoint, defining a plurality of upstream multiplexed sub-entities at the upstream end, defining a plurality of down-stream de-multiplexed sub-entities at the downstream end, monitoring for the defects on the work entities and protect entities between the upstream end and downstream end, monitoring for a signal failure in at least one of the upstream end and downstream end of the LPSG, switching the traffic by a linear protection controller based on defects on the work entity and protect entity between the upstream end and the downstream end or user initiated external commands, generating an upstream defect indication (UDI) alarm on detecting a signal failure on the upstream end, generating a downstream defect indication alarm (DDI) on detecting a signal failure on the downstream end, feeding the upstream defect indication alarm and the downstream defect indication alarm to the protection controller and declaring a lock-out-of protection for the work entity which has atleast one of the UDI and DDI by the linear protection controller. The upstream defect indication alarm from the upstream end is transmitted to the linear protection controller through an overhead byte on the protect entities.

[0035] In the embodiments herein, any of the end points identified for providing protection switching can be an upstream end or a downstream end depending on the direction of signal flow. In case of a unidirectional signal flow, the end point through which the signal ingress the linear protection domain is the upstream end and the end point though which the signal egress the linear protection domain is the downstream end. If the signal flow is bidirectional, then each of the end point functions as an upstream end and a downstream end.

[0036] The LPSG is defined at the end points by assigning priority to the plurality of upstream multiplexed sub-entities and the plurality of downstream de-multiplexed sub-entities at each of the work entities, assigning an upstream threshold value for the upstream defect indicator and a downstream threshold value for the downstream defect indicator for each of the work entities, comparing a summation of the product of signal status and priority with the upstream threshold value at the upstream end and downstream threshold value at the downstream end and declaring the upstream defect indication alarm if the summation exceeds the upstream threshold value and a downstream defect indication alarm is declared if the summation exceeds the downstream threshold value.

[0037] The priority of the plurality of sub-entities at each work entity includes specifying predetermined weightings to each sub-entity to decide on the priority of the signal traffic to provide for protection switching in case of a signal failure. Here, the predetermined weightings includes at least one of user configurable values configured in accordance with service level agreements and values set through a network management system which has a complete network view.

[0038] The linear protection controller determines the automatic lock out of protection for the work entity based on at least one of receiving an upstream defect indication alarm and receiving a downstream defect indication alarm. The upstream defect indication alarm is declared at the upstream end and transmitted to the downstream end to determine a protection decision. The downstream defect indication alarm is declared at the downstream end and protection decision is taken at the downstream end of the protection domain.

[0039] The downstream end declares a downstream defect indication alarm on detecting at least one of a remote signal failure and a user configurable signal failure in at least one of the plurality of downstream de-multiplexed sub-entities. Similarly, the upstream defect indication alarm is declared on detecting a signal failure in at least one of the plurality of upstream multiplexed sub-entities.

[0040] The system for protection switching in a communication network comprises a means for identifying end points for protection switching, a linear protection switching domain including at least one work entity and one protect entity between the identified endpoints, where the end points include an upstream end and a downstream end, a linear protection switching group at each of the endpoint, a plurality of work entities defined between the upstream end and the downstream end, a plurality of sub-entities defined for each of the plurality of work entities, at least one protection entity defined for the plurality of work entities, at least one signal monitor, alarm monitor and overhead monitor for each of the plurality of work entities, protect entities and sub-entities, an upstream defect indicator for indicating signal failure in the upstream end, a downstream defect indicator for indicating signal failure in the downstream end and a linear protection controller to determine protection decision of a defective work entity. The linear protection controller issues the lock out of protection on at least one work entity in which a signal failure is detected upstream or downstream conveyed through the upstream defect indicator or downstream defect indicator respectively.

[0041] The communication network herein comprises at least one of a Synchronous Digital Hierarchy Network (SDH), Synchronous Optical Networking (SONET), Ethernet, Multiprotocol Label Switching (IP-MPLS) and Optical Transport Network (OTN).

[0042] FIG. 1 illustrates a system for providing protection switching in a communication network, according to one embodiment of the present disclosure. The system comprises a linear protection switching domain 103 including an upstream end 101, a downstream end 102 and a linear protection switching group at each of the upstream end 101 and the downstream end 102. A plurality of work entities 104 (Wl, Wx and Wn) and protection entities 105 (PI, Py and Pm) for the work entities 104 are defined within the linear protection switching domain 103. The plurality of work entities is defined for the upstream end 101 and similarly a plurality of work entities are defined at the downstream end 102. Further pluralities of sub-entities 106a-106f
are defined for each of the plurality of work entities 104 at the upstream end 101 and at the downstream end 102. The protection entities 105 are provided such that at least one protection entity 105 is defined for the plurality of work entities 104. The system further includes a signal monitor 107, an alarm monitor 108 and an overhead monitor 109 for each of the plurality of work entities 104, protect entities 105 and sub-entities 106. The signal monitor 107 monitors the signal flow from the plurality of sub-entities 106 to the work entities 104 of the upstream end 101 and the downstream end 102 and from the work-entities of the upstream end 101 to the downstream end 102. The alarm monitor 108 raises an upstream defect indication alarm if the signal monitor 107 reports a signal failure at the sub-entities at the upstream end 101. The alarm monitor 108 may raise a downstream defect indication alarm if the signal monitor 107 reports a signal failure at the sub-entities at the downstream end 102. The overhead monitor 109 is provided at the downstream end 102 of the linear protection switching system, which checks if any over head byte indicating an upstream fault indication is transmitted by the upstream end 101 to any of the protection entities 105 and informs the downstream end 102 of the same.

[0043] The system further comprises a linear protection controller 110 to decide on the protection decision of the work entities 104. The linear protection controller 110 takes protection decision based on at least one of the upstream defect indication alarm from the upstream end 101 and the downstream defect indication alarm from the downstream end 102.

[0044] FIG. 2 is a schematic diagram illustrating the generation of an upstream defect indication alarm in a linear protection switching domain according to an embodiment of the present invention. The linear protection switching system does an optimized switching based on upstream end 101 or downstream end 102 signal failures across the protection domain 103. The linear protection switching system conveys the upstream end 101 and downstream end 102 traffic health to the protection controller. The linear automatic protection switching group at the upstream end 101 comprises of a plurality of work entities 104 and a plurality of protect defined in the protection domain 103. The pre-defined weightings are dynamic user configurable values configured in accordance with user preferences. The assigning of pre-defined weightings to upstream multiplexed sub-entities of the work entity 104 is done manually by the network operator or done through a network management system which has a complete network view.

[0049] FIG. 3 illustrates a system diagram for generating a downstream defect indication alarm, according to one embodiment of the present disclosure. The linear automatic protection switching group at downstream end 102 comprises of a plurality of work entities 104 and a plurality of protect entities 105. Further pluralities of sub-entities are de-multiplexed in each of the work entity 104. Here El, E2, E3 En are the sub-entities which are de-multiplexed from the work entity W1 as shown in FIG. 3.

[0050] The plurality of sub-entities El, E2, E3 …..En de-multiplexed from
W1 is assigned with pre-defined weightings Dl, D2, D3....Dn. The pre-defined weightings are assigned such that the sum of the weightings is equal to 1. Further a second user configurable threshold value t2 is assigned for a downstream defect indicator for each of the work entities.

[0051] For example, the weightings assigned to the plurality of sub-entities is Dl-0.1 (for El), D2-0.3(for E2), D3 0.6(for E3) and sum of Dl, D2 and D3 is 1. In this case, the weightings assigned to sub-entity E3 is high and E3 has a highest priority compared to other sub-entities (El and E2). The pre-defined weightings assigned to the plurality of sub-entities decide priority of the traffic for each of the plurality of sub-entities at the downstream end 102.

[0052] The downstream health (Td) is calculated as the summation of the product of signal status Bx and pre-defined weightings Dx i.e. Td=DI*B1+ D2*B2+ D3*B3+....+ Dn*Bn.

Where, Bx=l when there is a remote defect indication on sub-entity Ex's peer receive end or when there is a signal failure (if there is a user configurable criteria of signal failure) else the signal status Bxr 0.

[0053] If the downstream health Td is greater that t2 (downstream threshold limit), the downstream end raises a downstream defect indication alarm. The downstream defect indication alarm is invoked to indicate a signal failure in at least one of the plurality of downstream multiplexed sub-entities. The downstream defect indication alarm is declared at the downstream end 102 and the downstream defect indication alarm is fed to the linear protection controller 110 to take necessary protection action. The pre-defined weightings are dynamic user configurable values configured in accordance with user preferences. The assigning of user configurable weightings to downstream multiplexed sub-entities of the work entity 104 is done manually by the network operator or done through a network management system which has a complete network view.

[0054] FIG. 4 is a schematic diagram illustrating a linear protection controller accounting for the protection decision of the work entities, according to an embodiment of the present disclosure. The protection switching system in a communication network includes a linear protection controller 110 to which the upstream defect indication alarm and the downstream defect indication alarm is fed to determine the protection decision of the work entities 104. The linear protection controller determines the automatic lock out of protection for the work entity based on at least one of receiving an upstream defect indication alarm or receiving a downstream defect indication alarm.

[0055] The user initiated external commands (401) are fed as input to the linear protection controller 110. The external commands (401) include the conventional forced switch command, manual switch command, exerciser command and lockout (henceforth called as manual lockout). The linear protection controller 110 is also provided with inputs such as UDI computed at the upstream end for each of the work entities and DDI computed at the downstream end for each of the work entities (402), signal status for each of the work entities and protect entities (403) and overhead bytes carrying the APS protocol message (404) . The linear protection controller 110 then issues an automatic lock out of protection on at least one work entity in which a signal failure is detected conveyed by atleast one of UDI and DDL The aggregate lock out external command is the subtotal of the automatic lockout and manual lock out command based on the presence of other external commands (401) in the linear protection switching system. If the external command does not include any of the forced switch, manual switch and exerciser command, then the aggregate lockout is at least one of the manual lockout and the automatic lockout. If the external command includes any of the forced switch command, manual switch command and exerciser command, then the aggregate lockout is just the manual lockout and the automatic lockout is ignored.

[0056] According to an embodiment of the present invention, if the signal failure in at least one of the work entity associated with at least one of the upstream end and downstream end of the LPSG is restored, then the defect indicator associated with the work entity ceases to declare the defect indication alarm. Thus the defect indication alarm will not be transmitted to the protection controller. The protection controller then issues a clear out command for the lock-out of protection, when it does not receive the defect indication alarm. The lock out over the work entity is then cleared and the traffic through the work entity is regained.

[0057] The method and system for providing linear protection switching in a communication network according to the present disclosure is adapted to do an optimized switching based on upstream or downstream failures across the protection domain. The automatic linear protection switching of the embodiments herein provides optimized usage of the protection system and the network bandwidth. The linear protection switching according to the present invention enables to identify a work entity with a signal failure on the upstream or downstream end and routes the protection entity to protect against a signal failure on another work entity whose upstream and downstream paths are clean or to carry extra traffic on itself. The linear protection switching system reconfigures the priority of the network such that the protection path is redirected to a communication path with low priority so as to optimize the bandwidth usage.

[0058] The linear protection switching according to the present invention is cost effective as it includes only less number of components, consumes only less power and is faster as compared to the conventional protection switching.

[0059] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

[0060] Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the disclosure with modifications. However, all such modifications are deemed to be within the scope of the claims.

[0061] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

CLAIMS
What is claimed is:

1. A method for providing protection switching in a communication network, the method comprising:

identifying end points for protection switching;

creating a linear protection switching domain including at least one work entity and one protect entity between the identified endpoints, where the end points include an upstream end and a downstream end; creating a linear protection switching group (LPSG) at each of the endpoint; defining a plurality of upstream multiplexed sub-entities at the upstream end; defining a plurality of down-stream de-multiplexed sub-entities at the downstream end;

monitoring for the defects on the work entities and protect entities between the upstream end and downstream end;

monitoring for a signal failure in at least one of the upstream end and downstream end of the LPSG;

switching the traffic by a linear protection controller based on defects on the work entity and protect entity between the upstream end and the downstream end or user initiated external commands;

generating an upstream defect indication (UDI) alarm on detecting a signal failure on the upstream end;

generating a downstream defect indication alarm (DDI) on detecting a signal failure on the downstream end;

feeding the upstream defect indication alarm and the downstream defect indication alarm to the protection controller; and

declaring a lock-out-of protection for the work entity which has atleast one of the UDI and DDI by the linear protection controller;

wherein the upstream defect indication alarm from the upstream end is transmitted to the linear protection controller through an overhead byte on the protect entities.

2. The method of claim 1, defining LPSG at the end points comprising steps of:
assigning priority to the plurality of upstream multiplexed sub-entities and the
plurality of downstream de-multiplexed sub-entities at each of the work
entities;

assigning an upstream threshold value for the upstream defect indicator and a downstream threshold value for the downstream defect indicator for each of
the work entities;

comparing a summation of the product of signal status and priority with the upstream threshold value at the upstream end and downstream threshold value at the downstream end; and

declaring the upstream defect indication alarm if the summation exceeds the upstream threshold value and a downstream defect indication alarm is declared if the summation exceeds the downstream threshold value.

3. The method according to claim 2, wherein assigning priority of the plurality
of sub-entities at each work entity includes specifying predetermined weightings to each sub-entity to decide on the priority of the signal traffic to provide for protection switching in case of a signal failure,

wherein the pre-determined weightings includes at least one of: user configurable values configured in accordance with service level agreements; and

values set through a network management system which has a complete network view.

4. The method of claim 1, wherein the linear protection controller determines
the automatic lock out of protection for the work entity based on at least one
of:

receiving an upstream defect indication alarm; and receiving a downstream defect indication alarm.

5. The method of claim 1, wherein the downstream defect indication alarm is declared at the downstream end and protection decision is taken at the downstream end of the protection domain and the upstream defect indication alarm is declared at the upstream end and transmitted to the downstream end to determine a protection decision.

6. The method according to claim 1, wherein the downstream end declares a downstream defect indication alarm on detecting at least one of a remote signal failure and a user configurable signal failure in at least one of the plurality of downstream de-multiplexed sub-entities.

7. A system for providing protection switching in a communication network, the system comprising:

a means for identifying end points for protection switching;

a linear protection switching domain including at least one work entity and one protect entity between the identified endpoints, where the end points include an upstream end and a downstream end;

a linear protection switching group at each of the endpoint;

a plurality of work entities defined between the upstream end and the downstream end;

a plurality of sub-entities defined for each of the plurality of work entities;

at least one protection entity defined for the plurality of work entities;

at least one signal monitor, alarm monitor and overhead monitor for each of the plurality of work entities, protect entities and sub-entities;

an upstream defect indicator for indicating signal failure in the upstream end;

a downstream defect indicator for indicating signal failure in the downstream
end; and

a linear protection controller to determine protection decision of a defective work entity;

wherein the linear protection controller issues the lock out of protection on at least one work entity in which a signal failure is detected upstream or downstream conveyed through the upstream defect indicator or downstream defect indicator respectively.

8. The system of claim 7, wherein the upstream defect indicator declares an upstream defect indication alarm to indicate a signal failure in at least one of a sub-entity associated with the upstream work entities and downstream defect indicator declares a downstream defect indication alarm to indicate a signal failure in at least one of a sub-entity associated with the downstream work entities.

9. The system of claim 7, wherein the upstream defect indicator transmits the defect indication alarm from the upstream end to the protection controller through overhead bytes on the protection entities.

10. The system of claim 7, wherein the communication network comprises at least one of a Synchronous Digital Hierarchy Network (SDH), Synchronous Optical Networking (SONET), Ethernet, Multiprotocol Label Switching (IP-MPLS) and Optical Transport Network (OTN).