Abstract:
A method may include: (i) provisioning a first network-side interface of a first plug-in unit and a second network-side interface of a second plug-in unit as members of a network-side protection group, the first plug-in unit and the second plug-in unit integral to an adaptation layer network element; (ii) provisioning a first client-side interface of the first plug-in unit and a second client-side interface of the second plug-in unit as members of a client-side protection group; (iii) designating one of the first and second network-side interface as an active network-side interface of the network-side protection group; and (iv) designating one of the first second client-side interface as an active client-side interface of the client-side protection group, such that traffic ingressing on the active network-side interface may egress on the active client-side interface and traffic ingressing on the active client-side interface may egress on the active network-side interface.

Description:
TECHNICAL FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to networked communications and, more particularly, to systems and method for protection of an adaptation layer in a communication network. 
     BACKGROUND 
     A communication network may include network elements that route datagrams (e.g., frames, packets) through the network. Some network elements may include a distributed architecture, wherein datagram processing may be distributed among several subsystems of the network element (e.g., line cards, switches, and traffic managers). 
     In many instances, communication networks may employ link aggregation. Link aggregation (e.g., IEEE 802.1AX-2008) may generally describe the practice of using multiple network cables or ports in parallel to increase the link speed beyond the limits of any one single cable or port. Link aggregation may also be used to provide fault protection by increasing redundancy for higher availability. In link aggregation, a group or set of ports may be combined and represented as a single logical port to other components of the network system. Various switching elements of the network system may “see” the aggregated ports (known as a “link aggregation group” or “LAG”) as a single logical communication port in the routing tables or databases of network elements external to the LAG. 
     In addition, to ensure high reliability and availability in communications networks, protection switching is often used. When implemented, protection switching typically provides a primary or “working” path for a network and a redundant or “protection” path for the network. Accordingly, each path of a protection group may be monitored, and if a failure is detected on the working path, network traffic may be switched to the protection path. A LAG, because it includes a group of ports, may be used to perform protection switching, and is so often used to provide protection for Ethernet interfaces. Other protection schemes in communications networks include unidirectional path-switched ring (UPSR), birectional path-switched ring (BPSR), automatic protection switching (APS), or others. 
     A particular communication network may include a plurality of network elements for carrying Ethernet traffic between two or more clients via a synchronous optical network (SONET).  FIG. 1  depicts an example of a traditional implementation of such a communication network  1 . As shown in  FIG. 1 , communication network may include a plurality of network elements  2 , each network element  2  providing an adaptation layer interface  110   a  between Ethernet client interfaces  7  and SONET ports  6 . SONET ports  6  may be coupled to a protected SONET network  3 . Generally speaking, a network element  2  may perform datagram segmentation, reassembly, and other tasks in order to convert Ethernet packets received at an Ethernet client interface  7  to SONET frames for communication via protected SONET network  3 , and vice versa. As depicted in  FIG. 1 , a network element  2  may include a plurality of plug-in units (PIUs)  4 . A PIU  4  may have plug-in terminals so that some or all electrical and/or optical connections of the PIU  4  can be made engaging the unit with a suitable socket of network element  2 , and may generally be configured to forward datagrams between Ethernet client interface  7  and protected SONET network  3 . In some embodiments, a PIU  4  may be configured to perform datagram segmentation, reassembly, and other tasks in order to convert Ethernet packets received at an Ethernet client interface  7  to SONET frames for communication via protected SONET network  3 , and vice versa. A PIU  4  may include a port  5  configured to serve as a physical interface between its associated PIU  4  and Ethernet client interface  7 . Similarly, a PIU  4  having a port  5  may be configured to serve as a physical interface between its associated network element  2  and protected SONET network  3 . 
     In traditional implementation such as those depicted in  FIG. 1 , Ethernet client interfaces  7  may be protected (e.g., enabled for redundancy in the event of failure) using link aggregation and ports  5  comprising an Ethernet client interface  7  may comprise members of a link aggregation group  6 . In addition, protected SONET network  3  may be protecting using UPSR, BPSR, APS, or any other suitable protection scheme. However, as seen in  FIG. 1 , adaptation layer interface  110   a  may comprise a single point of failure (e.g., by way of a failure of a PIU  4 ), thus preventing end-to-end protection in network  1 . Traditional solutions to this problem include including a redundant network-side port  5  having another transmission path, ensuring that at least one of the network-side ports  5  has a path to the SONET network  3 . However, such a solution results in doubling the bandwidth requirements of a network element. 
     SUMMARY 
     According to one embodiment, a method may include provisioning a first network-side interface integral to a first plug-in unit and a second network-side interface integral to a second plug-in unit as members of a network-side protection group, the first plug-in unit and the second plug-in unit integral to a network element. The method may further include provisioning a first client-side interface integral to the first plug-in unit and a second client-side interface integral to the second plug-in unit as members of a client-side protection group. The method may also include designating one of the first network-side interface and the second network-side interface as an active network-side interface of the network-side protection group. The method may additionally include designating as a standby network-side interface of the network-side protection group the network-side interface not designated as the active network-side interface. Moreover, the method may include designating one of the first client-side interface and the second client-side interface as an active client-side interface of the client-side protection group. The method may also include designating as a standby client-side interface of the client-side protection group the client-side interface not designated as the active client-side interface. As a result, traffic ingressing on the active network-side interface may egress on the active client-side interface and traffic ingressing on the active client-side interface may egress on the active network-side interface. 
     Certain embodiments of the invention may provide one or more technical advantages. For example, methods and systems disclosed herein may provide for end-to-end protection in a communication network. 
     Certain embodiments of the invention may include none, some, or all of the above technical advantages. One or more other technical advantages may be readily apparent to one skilled in the art from the figures, descriptions, and claims included herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a block diagram of a traditional communication network; and 
         FIGS. 2-5  illustrate block diagrams of an example communication network, in accordance with certain embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 2-5  illustrates a block diagram of an example communication network  10 , in accordance with certain embodiments of the present disclosure. In certain embodiments, network  10  may comprise a network configured to provide for Ethernet datagram communication via synchronous optical networking (SONET). Network  10  may include one or more transmission media  12  operable to transport one or more signals communicated by components of network  10 . The components of network  10 , coupled together by transmission media  12 , may include a plurality of network elements  102  and a protected SONET network  101 . Network  10  may be used in a short-haul metropolitan network, a long-haul inter-city network, or any other suitable network or combination of networks. 
     Each transmission medium  12  may include any system, device, or apparatus configured to communicatively couple network elements  102  to each other, protected SONET network  101 , and/or client interfaces  110   b , and communicate information between network elements  102  and protected SONET network  101  and between network elements  102  and client interfaces  110   b . For example, a transmission medium  12  may include an optical fiber, an Ethernet cable, a T1 cable, a WiFi signal, a BLUETOOTH signal, or other suitable medium. 
     Network  10  may communicate information or “traffic” over transmission media  12 . As used herein, “traffic” means information transmitted, stored, or sorted in network  10 . Such traffic may comprise optical or electrical signals configured to encode audio, video, textual, and/or any other suitable data. The data may also be real-time or non-real-time. Traffic may be communicated via any suitable communications protocol, including, without limitation, the Open Systems Interconnection (OSI) standard and Internet Protocol (IP). Additionally, the traffic communicated in network  10  may be structured in any appropriate manner including, but not limited to, being structured in frames, packets, or an unstructured bit stream. As used herein, the term “datagram” may refer to a frame, packet, or other data structure for transmission of traffic. 
     Protected SONET network  101  may include any system configured to switch, forward, and/or route traffic between network elements  102 . Protected SONET network  101  may comprise a plurality of optical nodes each configured to provide switching, forwarding, and/or routing functionality. As its name indicates, protection SONET network  101  may employ a protection methodology to provide redundancy protection in the event of a failure. To provide protection, protected SONET network  101  may employ unidirectional path-switched ring (UPSR), birectional path-switched ring (BPSR), automatic protection switching (APS), or another suitable protection scheme. 
     A client interface  110   b  may provide an interface between a network element  102  and clients (e.g., customers) of a network provider. In addition, protected SONET network  101  may comprise a provider network. 
     Each network element  102  in network  10  may comprise any suitable system operable to transmit and receive traffic. In the illustrated embodiment, each network element  102  may be operable to transmit traffic directly to one or more other network elements  102  and receive traffic directly from the one or more other network elements  102 . Generally speaking, a network element  102  may perform datagram segmentation, reassembly, and other tasks in order to convert Ethernet packets received at a client interface  110   b  to SONET frames for communication via protected SONET network  101 , and vice versa. As shown in  FIGS. 2-5 , each network element  102  may include a management module  108 , a plurality of plug-in units (PIU)  106 , a mate-link  114  including one or more inter-PIU links, and a SONET line card  111 . 
     A PIU  106  may include any system, device, or apparatus having plug-in terminals so that some or all electrical connections of the PIU  106  can be made engaging the unit with a suitable socket of network element  102 . A PIU  106  may generally be configured to forward datagrams between a client and a SONET line card  111  via interfaces  110 . In some embodiments, a PIU  106  may be configured to perform datagram segmentation, reassembly, and other tasks in order to convert Ethernet packets received at a client interface  110   b  to SONET frames for communication via protected SONET network  101 , and vice versa. As shown in  FIGS. 2-5 , a PIU  106  may include a network-side interface  110   a  and a client-side interface  110   b.    
     A network-side interface  110   a  may include any suitable system, apparatus, or device configured to serve as an interface between a network element  102  and SONET line card  111 . A client-side interface  110   b  may include any suitable system, apparatus, or device configured to serve as an interface between a network element  102  and a transmission medium  12  communicatively coupling such network element  102  to a client. An interface  110  (e.g., a network-side interface  110   a  and/or a client-side interface  110   b ) may enable its associated network element  102  to communicate with protected a SONET line card  111  or a client, as applicable, using any suitable transmission protocol and/or standard. An interface  110  may be implemented using hardware, software, or any combination thereof. For example, an interface  110  may comprise an Ethernet port, an optical port, or any other suitable port. 
     Client-side interfaces  110   b  of a network element  102  and their corresponding transmission media may be grouped into a client-side protection group  116 . A client-side protection group  116  may provide path redundancy in the event of a link failure (e.g., a failure of transmission media  12 , a client-side interface  110   b , or another component of a network  10 ) that prevents communication between two points via a particular client-side interface  110   b  or transmission medium  12  of the client-side protection group  116 . For example, a particular client-side interface  110   b  and associated transmission medium  12  of a client-side protection group  116  may be designated as an active member of the client-side protection group  116  while other client-side interfaces  110   b  and transmission media  12  are designated as standby members. In the event of a failure preventing communication via the active client-side interface  110   b  and/or transmission medium  12 , a protection switch may occur whereby a standby client-side interface  110   b  and transmission medium  12  of the client-side protection group  116  is re-designated as active. A client-side protection group  116  may be implemented in accordance with any suitable protocol and/or standard. In some embodiments, a client-side protection group  116  may be implemented as a link aggregation group (LAG). A LAG may include any suitable number of member client-side physical interfaces  110  and may combine its member ports using link aggregation such that the member ports are represented as a single logical port to components of network  10  external to the LAG. 
     Network-side interfaces  110   a  of a network element  102  and their corresponding transmission media may be grouped into a network-side protection group  118 , which may server as an adaptation layer, as shown in  FIGS. 2-5 . A network-side protection group  118  may provide path redundancy in the event of a link failure (e.g., a failure of transmission media  12 , a network-side interface  110   a , or another component of a network  10 ) that prevents communication between two points via a particular network-side interface  110   a  or transmission medium  12  of the network-side protection group  118 . For example, a particular network-side interface  110   a  and associated transmission medium  12  of a network-side protection group  118  may be designated as an active member of the network-side protection group  118  while other network-side interfaces  110   a  and transmission media  12  are designated as standby members. In the event of a failure preventing communication via the active network-side interface  110   a  and/or transmission medium  12 , a protection switch may occur whereby a standby network-side interface  110   a  and transmission medium  12  of the network-side protection group  118  is re-designated as active. A network-side protection group  118  may be implemented in accordance with any suitable protocol and/or standard, including without limitation the protection scheme discussed below with reference to the operation of management module  108 . 
     A management module  108  may include any system, device, or apparatus configured to maintain protection groups  116  and  118 , including configuring various interfaces  110  as active or standby interfaces in order to provide redundancy protection for a network element  102 . For example, management module  108  may designate one network-side interface  110   a  of a network element  102  as active and other network-side interfaces  110   a  of the network element as standby. Similarly, management module  108  may designate one client-side interface  110   b  of a network element  102  as active and other client-side interfaces  110   b  of the network element as standby. In addition, a management module may provision a path within a network element  102  between a then-presently active network-side interface  110   a  and a then-presently active client-side interface  110   b  via one or more PIUs  106  and, if necessary, a mate link  114 . During operation, a management module  108  may perform a protection switch to provision a new active network-side interface  110   a  different from the then-present network-side interface  110   a , and/or provision a new active client-side interface  110   b  different from the then-present client-side interface  110   b . Such protection switch may occur in the event of a failure or other event that may prevent traffic communication to and/or from network element  102  using the then-present active interfaces  110  (e.g., failure of an active interface  110 , failure of a transmission medium  12  interfacing with an active interface  110 , failure of a PIU  106  upon which an active interface is located, etc.). 
     A SONET line card  111  may include any system, device, or apparatus configured to serve as a communication interface between network-side interfaces  110   a  and protected SONET network  101 . As depicted in  FIGS. 2-5 , a SONET line cars may include a plurality of interfaces  110   c , allowing for redundant paths to be established between network elements  102 . A SONET line card interface  110   c  may enable its associated network element  102  to communicate with protected SONET network  101  and/or a network-side interface  110   a , using any suitable transmission protocol and/or standard. An interface  110  may be implemented using hardware, software, or any combination thereof. For example, an interface  110  may comprise an Ethernet port, an optical port, or any other suitable port. SONET line card  111  may be an integral part of a SONET switch  1112 , as shown in  FIGS. 2-5 . 
     Although  FIGS. 2-5  depict management modules  108  as independent of other components of their respective network elements  102 , in some embodiments one or management modules may reside on PIUs  106  and/or other components of network elements  102 . Management modules  108  may be implemented in hardware, firmware, or software. 
     Various protection switching events are depicted in  FIGS. 2-5 .  FIG. 2  depicts a network element  102  during “normal” operation in which no failures are present preventing communication via any interface  110  of the network element  102 . Accordingly, management module  108  of the particular network element  102  may designate any of network-side interfaces  110   a  as the active network-side interface  110   a , and any of the client-side interfaces  110   b , as the active client-side interface  110   b , thereby establishing a path  120  for communication of traffic through network element  102 . As shown in  FIG. 3 , in the event of a protection switching event occurring that prevents communication via the then-present active client-side interface  110   b  depicted in  FIG. 2  (e.g., a failure of the then-present active client-side interface  110   b  or a transmission medium  12  coupled thereto, or other suitable failure event), management module  108  may initiate a protection switch re-designating the other client-side interface  110   b  from standby to active, thus providing a redundant communication path  120  through the network element  102 . Alternatively or in addition, as shown in  FIG. 4 , in the event of a protection switching event occurring that prevents communication via the then-present active network-side interface  110   a  depicted in  FIG. 2  (e.g., a failure of the then-present active network-side interface  110   a  or a transmission medium  12  coupled thereto, or other suitable failure event), management module  108  may initiate a protection switch re-designating the other network-side interface  110   a  from standby to active, thus providing a redundant communication path  120  through the network element  102 . Alternatively or in addition, as shown in  FIG. 5 , in the event of a protection switching event occurring that prevents communication via both the then-present active network-side interface  110   a  and the then-present active client-side interface  110   b  depicted in  FIG. 2  (e.g., a failure of the then-present active client-side interface  110   b  or a transmission medium  12  coupled thereto coupled with a failure of the then-present active network-side interface  110   a  or a transmission medium  12  coupled thereto, or a failure of a PIU  106  upon which the active network-side interface  110   a  and client-side network interface  110   b  reside), management module  108  may initiate a protection switch re-designating the other network-side interface  110   a  from standby to active, thus providing a redundant communication path  120  through the network element  102 . 
     To support the above-described protection of a network element  102 , an element of protected SONET network  101  (e.g., a SONET switch fabric or other suitable element) may be configured to, when communicating traffic to a network element  102 , broadcast such traffic to all interfaces  110   a  of a network-side protection group  118 . The active interface  110   a  of the network-side protection group  110  may further forward the traffic, while the standby interfaces  110   a  of the network-side protection group  118  may simply ignore or drop broadcast traffic received from protected SONET network  101 . 
     Modifications, additions, or omissions may be made to network  10  without departing from the scope of the disclosure. The components and elements of network  10  described may be integrated or separated according to particular needs. Moreover, the operations of network  10  may be performed by more, fewer, or other components. 
     A component of network  10  may include an interface, logic, memory, and/or other suitable element. An interface receives input, sends output, processes the input and/or output, and/or performs other suitable operation. An interface may comprise hardware and/or software. 
     Logic performs the operations of the component, for example, executes instructions to generate output from input. Logic may include hardware, software, and/or other logic. Logic may be encoded in one or more tangible computer readable storage media and may perform operations when executed by a computer. Certain logic, such as a processor, may manage the operation of a component. Examples of a processor include one or more computers, one or more microprocessors, one or more applications, and/or other logic. 
     A memory stores information. A memory may comprise one or more tangible, computer-readable, and/or computer-executable storage medium. Examples of memory include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), database and/or network storage (for example, a server), and/or other computer-readable medium. 
     Modifications, additions, or omissions may be made to network  10  without departing from the scope of the invention. The components of network  10  may be integrated or separated. Moreover, the operations of network  10  may be performed by more, fewer, or other components. Additionally, operations of network  10  may be performed using any suitable logic. As used in this document, “each” refers to each member of a set or each member of a subset of a set. 
     Certain embodiments of the invention may provide one or more technical advantages. A technical advantage of one embodiment may be that alarm indication signals that typically originate from maintenance end points may be transmitted in the event that equipment upon which the maintenance end points have experienced a fault, thus reducing the occurrence of unnecessary alarms. 
     Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure, as defined by the following claims.