Abstract:
A method for processing messages within a telecommunication network, including receiving, by a central office (CO) from a network manager, a message packaged within a first data frame, the message conforming to a first protocol and being addressed to a customer premises equipment (CPE), wherein the CO communicates with the network manager using the first protocol, and communicates with the CPE using a second protocol, determining if the CPE to which the message is addressed supports the first protocol, when the determining is affirmative, then encapsulating the message conforming to the first protocol within a second data frame confirming to the second protocol, when the determining is not affirmative, then translating the message from the first protocol to the second protocol, and packaging the translated message within a second data frame confirming to the second protocol, and sending the second data frame to the CPE using the second protocol.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority benefit of U.S. Provisional Application No. 61/814,314, filed on Apr. 21, 2013 by inventor Toshihiko Kusano. 
     This application is a continuation-in-part of PCT Application No. PCT/IL2013/050947 entitled TELECOMMUNICATION NETWORK NODE SUPPORTING HYBRID MANAGEMENT USING A HARDWARE ABSTRACTION AND MANAGEMENT PROTOCOL CROSS-CONNECT FUNCTION, filed on Nov. 14, 2013 by inventor Toshihiko Kusano. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to telecommunication networks, and in particular to networks that are managed heterogeneously using more than one management protocol. 
     BACKGROUND OF THE INVENTION 
     Recently, software defined networking (SDN) has been recognized as a next generation network management system for packetized data communication. SDN includes a control plane, i.e., a system that makes decisions about where traffic is sent, and a data plane, i.e., a system that forwards traffic to its destination. Network devices reside in the data plane, and interface with the control plane through a control plane/data plane interface. SDN manages network devices through abstraction of lower level functionality by decoupling the control plane from the data plane. SDN enables network administrators to have programmable central control of network traffic without requiring physical access to the network&#39;s switches. SDN creates a logical network control plane where a network switch can forward packets and a separate server can run the network control plane. The decoupling allows for the control plane to be implemented using a different distribution model than the data plane. 
     Telecommunication operators are interested in adopting SDN, and the Open Networking Foundation (ONF) has standardized a protocol, OPENFLOW™, for communication between the control plane and the data plane. During the upgrade from existing management systems to SDN-based management systems, both management systems will co-exist. 
     Conventional telecommunication network nodes are configured to work with a designated management system using a designated protocol. Different management protocols are based on different distribution models, and telecommunication network nodes that operate in accordance with one distribution model generally exhibit anomalous behavior if they are managed in accordance with another distribution model. 
     As such, upgrading an existing management system to an SDN-based management system requires replacement of all deployed telecommunication nodes with nodes adapted to SDN-based management; i.e., replacement of an entire network. Such replacement is enormously expensive and time-consuming, and causes disruption of service. For access network systems, the upgrade requires replacement of entire customer premises equipment (CPE). 
     Thus it would be of advantage to find an efficient way to operate existing telecommunication network nodes in accordance with heterogeneous management systems. 
     SUMMARY OF THE DESCRIPTION 
     Embodiments of the present invention provide efficient ways to operate telecommunication network nodes in accordance with a heterogeneous management environment. Aspects of the present invention enable telecommunication network nodes to interoperate with an existing management protocol and with other protocols, including inter alia a control plane/data plane interface for supporting SDN. 
     The present invention is of particular advantage for access networks, by enabling continuous use of CPEs while upgrading a management system. Otherwise, without the present invention, operators would need to replace CPE&#39;s located at customer sites, which is a major undertaking and which entails disruption of service. In distinction, the present invention enables operators to upgrade a management system seamlessly, without having to upgrade CPEs. 
     Embodiments of the present invention relate to access networks that are managed by management computers that employ different management protocols. The networks include telecommunication nodes that have a central office (CO) computer that serves as the node&#39;s access point to the network, and that have one or more CPE computers connected to the CO computer by physical data links. The CO and CPE computers in the node include hardware resources that are controlled via respective hardware resource APIs. The CO computer receives messages from and sends messages to the management computers over an access network, and receives messages from and sends messages to the CPE computers over physical data links. The messages may be request messages sent by management computers to the CO computer or to the CPE computers, or reply messages sent by the CO computer or by the CPE computers to the management computers. The messages may also be autonomous messages sent by the CO computer or by the CPE computers to the management computers, notifying the management computers of events or changes of state. Each message is packaged in a data frame that conforms to an appropriate protocol. 
     In order to accommodate heterogeneous management, a CO computer must be able to receive, from a management computer over the access network, a control request message using a first protocol and being addressed to one of the CPE computers in the node, and to forward the control request message to its destination CPE computer over a physical data link using a second protocol. The CO computer identifies the protocol capabilities of the destination CPE computer, and employs a translator to translate the request message from the first protocol to the second protocol, or employs an encapsulator to encapsulate the request message within a data frame conforming to the second protocol, as appropriate, based on the protocol capabilities of the CPE computer. 
     There is thus provided in accordance with an embodiment of the present invention a method for processing messages within a telecommunication network, including receiving, by a central office (CO) computer within a telecommunication node from a network manager computer, a message packaged within a first data frame, the message conforming to a first protocol and being addressed to a customer premises equipment (CPE) computer within the telecommunication node, wherein the CO computer communicates with the network manager computer via an access network using the first protocol, and communicates with the CPE computer via a physical data link using a second protocol, determining, by the CO computer, whether or not the CPE computer to which the message is addressed supports the first protocol, when the determining is affirmative, then encapsulating, by the CO computer, the message conforming to the first protocol within a second data frame that conforms to the second protocol, when the determining is not affirmative, then translating, by the CO computer, the message from the first protocol to the second protocol, and packaging the translated message within a second data frame that conforms to the second protocol, and sending, by the CO computer, the second data frame to the CPE computer using the second protocol via the physical data link. 
     There is additionally provided in accordance with an embodiment of the present invention a central office (CO) computer within a telecommunication network node, including a connection with an access network for sending messages to and receiving messages from a network manager computer using a first protocol, the messages being packaged within data frames, a connection with a physical data link for sending messages to and receiving messages from one or more customer premises equipment (CPE) computers within the telecommunication network node using a second protocol, the messages being packaged within data frames, a translator that is operative to translate messages bi-directionally between the two protocols, an encapsulator that is operative (i) to encapsulate a message contained in a data frame conforming with the first protocol, and package the encapsulated message within a data frame conforming to the second protocol, and (ii) to decapsulate a message conforming with the first protocol from a data frame conforming to the second protocol, and package the decapsulated message within a data frame conforming to the first protocol, and a message parser that is operative (i) to parse a message received from the network manager computer over the access network, the message being addressed to one of the CPE computers within the telecommunication node and being packaged within a first data frame conforming to the first protocol, (ii) to determine whether or not the CPE computer to which the message is addressed supports the first protocol, (iii) to pass the message to the encapsulator for encapsulating the message within a second data frame conforming to the second protocol, when the determining is affirmative, and (iv) to pass the message to the translator for translating the message from the first protocol to the second protocol, and package the translated message within a second data frame conforming to the second protocol, when the determining is not affirmative. 
     There is further provided in accordance with an embodiment of the present invention a customer premises equipment (CPE) computer within a telecommunication network node, including a connection with a hardware resource that provides a physical data link for sending messages to and receiving messages from a network management computer, via a central office (CO) computer within the telecommunication network node, the messages being packaged within data frames using a first protocol when sending to and receiving from the network management computer, an encapsulator that is operative (i) to encapsulate a message contained in a data frame conforming with the first protocol, and package the encapsulated message within a data frame conforming to the second protocol, and (ii) to decapsulate a message conforming with the first protocol from a data frame conforming to the second protocol, and a message parser that is operative (i) to parse a message received from the network manager computer, the message being packaged within a data frame conforming to the second protocol, (ii) to determine whether or not the data frame includes encapsulated data conforming to the first protocol, and (iii) to conditionally pass the data frame to the encapsulator for decapsulating the encapsulated data, when the determining is affirmative. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings in which: 
         FIG. 1  is a simplified block diagram of a telecommunication network system configured for heterogeneous management, in accordance with an embodiment of the present invention; 
         FIG. 2  is a simplified block diagram of customer premises equipment (CPE), in accordance with an embodiment of the present invention; 
         FIG. 3  is a simplified block diagram of a central office (CO), with two management packagers, that uses a management control parser, in accordance with an embodiment of the present invention; 
         FIG. 4  is a simplified block diagram of a system, incorporating the CPE  FIG. 2  and the CO of  FIG. 3 , that uses a CPE management protocol control table, in accordance with an embodiment of the present invention; 
         FIG. 5  is a simplified illustration of the CPE management protocol control table of  FIG. 4 , in accordance with an embodiment of the present invention; 
         FIG. 6  is a simplified illustration of three exemplary data frames for management control messages, in accordance with an embodiment of the present invention; 
         FIG. 7  is a simplified flowchart of a method used by a CO to forward management control messages received from management systems to their intended CPEs, in accordance with an embodiment of the present invention; 
         FIG. 8  is a simplified data flow of three scenarios of use of the method of  FIG. 7 , in accordance with an embodiment of the present invention; 
         FIG. 9  is a simplified block diagram of a CPE, with two management packagers, that uses a management control parser, in accordance with an embodiment of the present invention; 
         FIG. 10  is a simplified flowchart of a method used by the management control parser of  FIG. 9 , to determine how to forward a received management control message, in accordance with an embodiment of the present invention; and 
         FIG. 11  is a simplified flowchart of a method used by the management control parser of  FIG. 3  to determine how to forward a reply message, in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present invention relate to communication networks of nodes that are under control of two different management systems. In one embodiment, the nodes are central office (CO) computers that control customer premises equipment (CPE) computers. The present invention is of particular advantage for upgrading existing systems to SDN-based systems, since it obviates the need to replace an entire existing physical infrastructure of CPEs. 
     In the discussion herein, a CO computer and a CPE computer are referred to simply as a “CO” and a “CPE”, respectively. 
     Reference is made to  FIG. 1 , which is a simplified block diagram of a telecommunication network system  100  configured for heterogeneous management, in accordance with an embodiment of the present invention. Generally, network system  100  is controlled by one or more management systems, which establish data channels, configure data forwarding rules, and operate and administer the network system. Network system  100  includes one or more telecommunication nodes. Each node includes a central office (CO) and one or more CPEs. The CO serves as an access point for the node to a communication network between the management system(s) and the nodes. The CO in the node receives requests in the form of management control messages from the management system(s). Requests may be intended for the CO or for one of the CPEs in the node. If a request is intended for a CPE in the node, then the CO forwards the request to the CPE. Generally, each CO and CPE controls one or more hardware resources, and the management control messages are implemented via APIs for the hardware resources. In response-request type network systems, a CO or CPE that receives a request sends a reply back to the management system that issued the request. 
       FIG. 1  shows two management systems, designated  110  and  120 , and referred to as management system A and management system B, respectively, which communicate with each of two telecommunication nodes, designated  130  and  140 . Management system  110  and/or  120  may use a standard resource management protocol, such as OPEN FLOW™, or a non-standard protocol. The protocol used by management system  110  is designated as “protocol A”, and the protocol used by management system  120  is designated as “protocol B”. Telecommunication nodes  130  and  140  communicate with management systems  110  and  120  over management channels. Telecommunication node  130  connects with user terminals  150  over data channels, and telecommunication node  140  connects with user terminals  160  over data channels. Telecommunication nodes  130  and  140  are managed by management systems  110  and  120 , to establish data channels, to configure data forwarding rules, and for general administration and operation. Telecommunication nodes  130  and  140  communicate with management systems  110  and  120  via specific management interfaces, and management messages are communicated using protocol A and protocol B, respectively. 
     Telecommunication node  130  includes a central office (CO), designated  132 , and referred to as CO #1, and two customer premises equipment (CPE), designated  136  and  138 , and referred to as CPE #1-1 and CPE #1-2, respectively. Telecommunication node  140  includes a central office, designated  142 , and referred to as CO #2, and two CPEs, designated  146  and  148 , and referred to as CPE #2-1 and CPE #2-2, respectively. 
     CO  132  communicates with CPEs  136  and  138  over physical data links using specific management protocols. Similarly, CO  142  communicates with CPEs  146  and  148  using specific management protocols. Generally, when a CPE is registered in a telecommunications network, it exchanges information to notify the network of the protocol that it uses. For example, IEEE 802.3ah/av and ITU-T G.983.2 each define a message exchange mechanism to notify the network of organization information specific to a CPE in a passive optical network. 
     It will be appreciated by those skilled in the art that the system shown in  FIG. 1  is an exemplary system for the purpose of explaining embodiments of the network management functionality of the subject invention. As such, although  FIG. 1  shows two management systems communicating with two telecommunication nodes each having a CO and two CPEs, the subject invention applies to any configuration of management systems, telecommunication nodes, COs and CPEs. 
     The network of  FIG. 1  may be, inter alia, a passive optical network (PON), and the CPEs may be optical network units (ONUs). 
     Reference is made to  FIG. 2 , which is a simplified block diagram of a CPE  200 , such as CPE #1-1, CPE #1-2, CPE #2-1 or CPE #2-2 of  FIG. 1 , in accordance with an embodiment of the present invention. CPE  200  includes a management packager  210 , a hardware resource API  250 , and a hardware resource  260 . Management packager  210  processes control messages received from a CO. 
     Hardware resource  260  provides a physical data link  270  for communication between CPE  200  and a CO via a CPE management protocol  280 . Data link  270  uses a logical CPE management protocol channel  290 . 
     Reference is made to  FIG. 3 , which is a simplified block diagram of a CO  300 , such as CO #1 or CO #2 of  FIG. 1 , with two management packagers  310  and  320 , that uses a management control protocol parser  340 , in accordance with an embodiment of the present invention. Management packagers  310  and  320  are referred to as management packager A and management packager B, respectively. Management packagers  310  and  320  process control messages received from management systems, such as management systems  110  and  120  of  FIG. 1 . CO  300  includes an encapsulator  333 , a translator  337 , and management protocol parser  340 , the operations of which are described below. CO  300  includes a hardware resource API  350 , and a hardware resource  360 . 
     CO  300  communicates with CPEs over data link  270  via CPE management protocol  280 . Data link  270  uses logical CPE management protocol channel  290 . 
     Reference is made to  FIG. 4 , which is a simplified block diagram of a system, incorporating CPE  200  of  FIG. 2  and CO  300  of  FIG. 3 , that uses a CPE management protocol control table  400 , in accordance with an embodiment of the present. Generally, a CPE supports a single management packager, whereas a CO may support more than one management packager, such as management packagers  310  and  320 . However, in some cases a CPE may also support more than one management packager, such as CPE  600  shown in  FIG. 9 , which is discussed below. 
       FIG. 4  shows that management control messages are forwarded from CO  300  to hardware resource  260 , using physical data link  270  between CO  300  and CPE  200 , through logical CPE management protocol channel  290 . 
       FIG. 4  shows that management packagers A and B access CPE management protocol control table  400  in order to process management control messages that they receive from management systems  110  and  120 . 
     Reference is made to  FIG. 5 , which is a simplified illustration of the CPE management protocol control table  400  of  FIG. 4 , in accordance with an embodiment of the present invention. Control table  400  includes a field  410  with a CPE identifier, a field  420  with a management package type, and a field  430  with a management protocol forwarding rule. 
     Processing Requests 
     Reference is made to  FIG. 6 , which is a simplified illustration of three exemplary data frames for packaging management control messages, in accordance with an embodiment of the present invention. A first data frame  510  includes a destination address  511 , a source address  512 , a protocol A header  513 , protocol A data  514  and a flag  515 . A second data frame  520  includes a protocol B header, protocol B data and a flag  525 . A third data frame  530  includes a protocol B header, a protocol A header, protocol A data and a flag  535 . The flags  515 ,  525  and  535  have respective settings referred to as “NATIVE”, “TRANSLATED” and “ENCAPSULATED”. Use of these flags is described below. 
     When a management packager in a CO receives a message from one of the heterogeneous management systems, it first determines if the message is being sent to the CO itself, to control the CO, or if instead the message is being sent to a CPE via the CO. If the message is being sent to a CPE via the CO, then the management packager invokes a procedure that uses a method with special rule-based logic for forwarding messages. 
     Reference is made to  FIG. 7 , which is a simplified flowchart of a method  1000  used by CO  300  to forward management control messages received from management system  110  to their destination CPEs, in accordance with an embodiment of the present invention. The method of  FIG. 7  includes separate branches for destination CPEs of type A, type B and type AB, as determined from CPE management protocol control table  400 . It will be appreciated by those skilled in the art that the relevant flowchart for forwarding management control messages received from management system  120  is similar to that of  FIG. 7 , but with “A” and “B” reversed at the middle branch and right branch from operation  1030 , and with “B” replaced by “A” at operations  1050  and  1070 . 
     When management packager  310  in CO  300  receives a message from management system A for destination CPEs of type A, CO  300  forwards the message to the CPE, preserving the protocol in use. When management packager  310  in CO  300  receives a message from management system A for destination CPEs of type B, the protocol is translated from protocol A to protocol B by a translator (element  337  of  FIG. 4 ), and the translated message is then forwarded to the destination CPE. When management packager  310  in CO  300  receives a message from management system A for destination CPEs of type AB, CO  300  encapsulates protocol A in protocol B by an encapsulator (element  333  of  FIG. 4 ), and the encapsulated message is then forwarded to the destination CPE. The thus-processed protocol is forwarded to a hardware resource (element  260  of  FIG. 4 ), using a physical data link (element  270  of  FIG. 4 ) between the CO and the CPE through a logical CPE management protocol channel (element  290  of  FIG. 4 ). 
     Scenarios that use each of these branches A, B and AB, are described in what follows. 
     Reference is made to  FIG. 8 , which is a simplified data flow of three scenarios of use of the method  1000 , in accordance with an embodiment of the present invention. In a first example scenario, shown at the top of  FIG. 8 , protocol A is used for messaging between the management system and the CO, and for messaging between the CO and the destination CPE. Specifically, management system A (element  110 / 1  of  FIG. 8 ) forwards a management control message to CPE #1-1 (element  200 / 1  of  FIG. 8 ) via CO #1 (element  300 / 1  of  FIG. 8 ). Management packager A (element  310 / 1  of  FIG. 8 ) in CO #1 receives the management message (operation  1010  of  FIG. 7 ), and performs a message forwarding procedure in accordance with method  1000  of  FIG. 7  to process the message appropriately. At operation  1020  the procedure looks up CPE #1-1 in CPE management protocol control table  400  of  FIG. 5 , and identifies the type  420  of CPE #1-1 as being “A”, and identifies the management protocol forwarding rule  430  of CPE #1-1 as being “Forward Protocol A”. At operation  1030  the procedure branches to the “A” branch, which leads to operation  1040 . At operation  1040  the procedure forwards the message to CPE #1-1 to its hardware resource (element  260  of  FIG. 4 ). The format of the packet corresponds to frame  510  in  FIG. 6 . Flag  515  of frame  510  is set to “NATIVE”, which corresponds to use of protocol A. 
     The protocol identifier that is defined as part of a standardized control protocol format, such as IEEE P1904.1 or ITU-T G.984, may be used as the flag with a “NATIVE” setting, without inserting the flag into protocol A header  513 , for cases where the CPE only supports such protocol. 
     In a second example scenario, shown in the middle of  FIG. 8 , protocol A is used for messaging between the management system and the CO, and protocol B is used for messaging between the CO and the destination CPE. Management system A (element  110 / 2  of  FIG. 8 ) forwards a management control message to CPE #1-2 (element  200 / 2  of  FIG. 8 ) via CO #1 (element  300 / 2  of  FIG. 8 ). Management packager A (element  310 / 2  of  FIG. 8 ) in CO #1 receives the management message (operation  1010  of  FIG. 7 ), and performs a message forwarding procedure in accordance with the method of  FIG. 7  to process the message. At operation  1020  the procedure looks up CPE #1-2 in CPE management protocol control table  400  of  FIG. 5 , and identifies the type  420  of CPE #1-2 as being “B”, and identifies the management protocol forwarding rule  430  of CPE #1-2 as being “Translate protocol A to protocol B”. At operation  1030  the procedure branches to the “B” branch, which leads to operation  1070 , where the procedure branches further to operation  1080 . At operation  1080  the message is forwarded to a translator (element  337 / 2  of  FIG. 8 ), which translates protocol A to protocol B while maintaining the context. In accordance with an embodiment of the present invention, the translator is operative to use designated rules based on correspondence of actions and parameters in protocols A and B. The rule is generally telecommunication system and network operator specific, and is configured in accordance with a network operator&#39;s setting. The format of the packet corresponds to frame  520  in  FIG. 6 . Flag  525  of frame  520  is set to “TRANSLATED”, which corresponds to translation of protocol A to protocol B. 
     If, at operation  1070 , a received protocol A message does not have a corresponding protocol B message to translate, then the received message is discarded at operation  1090 . 
     The protocol identifier that is defined as part of a standardized control protocol format, such as IEEE P1904.1 or ITU-T G.984, may be used as the flag with a “TRANSLATED” setting, without inserting the flag into protocol A header  513 , for cases where the CPE only supports such protocol. 
     In a third example scenario, shown at the bottom of  FIG. 8 , protocol A is used for messaging between the management system and the CO, and protocol B is used for messaging between the CO and the destination CPE. However, although protocol B is used for messaging between the CO and the destination CPE, the management control message is addressed to a management packager A in the destination CPE. The CPE may include, for example, two management packagers, A and B. 
     Reference is made to  FIG. 9 , which is a simplified block diagram of a CPE  600 , with two management packagers  610  and  620 , that uses a management control parser  640 , in accordance with an embodiment of the present invention. CPE  600  may have multiple CPUs each running with different management protocols. For example, one CPU may use a standard management protocol for access systems, such as the protocol defined in IEEE P1904.1, Service Interoperable Ethernet PON (SIEPON) or the protocol defined in ITU-T G.984, Gigabit PON; another CPU may use a management protocol such as OpenFlow; and CPE  600  uses a single protocol for communication between CPE  600  and the CO. When CPE  600  receives a management control message, management control parser  640  invokes a procedure that uses a method to determine how to forward a received management control message. 
     Reference is made to  FIG. 10 , which is a simplified flowchart of a method  1100  used by management control parser  640  to determine how to forward a received management control message, in accordance with an embodiment of the present invention. At operation  1110 , management control parser  640  receives a management control message, packaged within a data frame (elements  510 ,  520  and  530  of  FIG. 6 ). At operation  1120  the method branches depending on the flag (elements  515 ,  525 ,  535  of  FIG. 6 ) setting in the received data frame. If the flag setting is “ENCAPSULATED”, then at operation  1130  the received message is passed to an encapsulator (element  633  of  FIG. 9 ). The encapsulator decapsulates a protocol A message (element  538  of  FIG. 8 ) from the received message. Thereafter, at operation  1140  the decapsulated message is forwarded to management packager A (element  610  of  FIG. 9 ). Otherwise, if the flag is “NATIVE” or “TRANSLATED”, then the method branches at operation  1120  directly to operation  1140  where the received message is forwarded to management packager B (element  620  of  FIG. 9 ), without additional processing. 
     Referring back to  FIG. 8 , in the third example scenario management system A (element  110 / 3  of  FIG. 8 ) forwards a management control message to CPE #1-3 (element  200 / 3  of  FIG. 8 ). Management packager A (element  320 / 3  of  FIG. 8 ) in CO #1 receives the management message (operation  1010  of  FIG. 7 ), and performs a message forwarding procedure in accordance with the method of  FIG. 7  to process the message. At operation  1020  the procedure looks up CPE #1-3 in CPE management protocol control table  400  of  FIG. 5 , and identifies the type  420  of CPE #1-3 as being “AB”, which means that CPE #1-3 supports management protocol A in one CPU in the CPE, but the CPE only supports management protocol B for communication between CPE #1-3 and the CO. Also at operation  1020 , the procedure identifies the management protocol forwarding rule  430  of CPE #1-3 as being “Encapsulate protocol A in protocol B”. Encapsulation avoids unnecessary translation, and preserves the original message sent from management system A. At operation  1030  the procedure branches to the “AB” branch, which leads to operation  1050 . At operation  1050  a decision is made whether to encapsulate the message within protocol B, or whether to forward the message in its native protocol. This decision may be based, inter alia, on the protocols used with previous messages, or by a default setting of the system or of the CPE. If the decision at operation  1050  is to encapsulate the message (“YES”), then the method branches to operation  1060 . At operation  1060  the message is forwarded to an encapsulator (element  333 / 3  of  FIG. 8 ), which encapsulates protocol A in protocol B. The format of the packet corresponds to frame  530  in  FIG. 6 . Flag  535  of frame  530  is set to “ENCAPSULATED”, which corresponds to encapsulation of protocol A in protocol B. In this case, the protocol data B segment of frame  530  actually carries protocol header A and protocol data A. If instead the decision at operation  1050  is to forward the message in its native protocol (“NO”), then the method branches to operation  1040 , in which case the message is forwarded to the CPE in its native form, within a packet that corresponds to frame  510  in  FIG. 6 . 
     The three example scenarios shown in  FIG. 8  relate to messages transmitted from management system A. Analogous examples apply to messages transmitted from management system B to (i) a CPE of type B, (i) a CPE of type A, and (iii) a CPE of type AB, respectively. In total, for the case of two management protocols there are eight scenarios, summarized in TABLE I below. 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                 Message Forwarding Scenarios 
               
             
          
           
               
                   
                 Destination 
                 Source 
                   
               
               
                 CPE Type 
                 CPE Packager 
                 Management System 
                 Flag 
               
               
                   
               
               
                 A 
                 A 
                 A 
                 NATIVE 
               
               
                 A 
                 A 
                 B 
                 TRANSLATED 
               
               
                 B 
                 B 
                 A 
                 TRANSLATED 
               
               
                 B 
                 B 
                 B 
                 NATIVE 
               
               
                 AB 
                 A 
                 A 
                 NATIVE 
               
               
                 AB 
                 A 
                 B 
                 ENCAPSULATED 
               
               
                 AB 
                 B 
                 A 
                 ENCAPSULATED 
               
               
                 AB 
                 B 
                 B 
                 NATIVE 
               
               
                   
               
             
          
         
       
     
     As such, it will thus be appreciated by those skilled in the art that the present invention enables heterogeneous management, wherein plural management systems using plural management protocols send control messages over an access network to a CPE in a telecommunication node. In turn, this enables seamless upgrading of existing management systems to SDN-based management systems, by accommodating both an existing management protocol and an SDN-based management protocol. 
     Processing Replies 
     In request-response control systems, a CPE (element  136  of  FIG. 1 ) receiving a management control message via a CO (element  132  of  FIG. 1 ) sends a reply message via the CO to the management system that sent the control message. In addition, autonomous messages may also be sent from a CPE via a CO to a management system, such messages being notifications of event and status changes. Referring back to TABLE I above, for the case of two management protocols there are eight possible scenarios. In order for CPE  200  to properly generate a reply to a request message, management packager A (element  210  of  FIG. 2 ) of CPE  200  saves the flag value (elements  515 ,  525 ,  535  of  FIG. 5 ) of the data frame with the request message, and sets the same flag value in the data frame for the reply. In order for CPE  600 , with two management packagers A and B, to properly generate a reply, the flag set by management packager A for a reply to a message received from management system A will be either “NATIVE” or “ENCAPSULATED”, and the flag set by management packager B for the reply will be “TRANSLATED”. The reply is sent from the CPE to the CO. 
     In this regard it is noted that translator  337  ( FIGS. 3 and 4 ) is bi-directional, and translates “southbound” and “northbound” messages oppositely from one protocol to another, as necessary. The term “southbound” refers to communication to a lower layer facility, e.g., from a management system to a CPE, and the term “northbound” refers for communication to a higher layer facility, e.g., from a CPE to a management system. 
     Reference is made to  FIG. 11 , which is a simplified flowchart of a method  1200  used by management control protocol parser  340  to determine how to forward a reply message to management system A, in accordance with an embodiment of the present invention. At operation  1210  management protocol parser  340  receives a reply message from a CPE, the reply being packaged within a data frame (elements  510 ,  520 ,  530  of  FIG. 6 ). At operation  1220  the method branches depending on the setting of the flag in the data frame (elements  515 ,  525 ,  535  of  FIG. 6 ). If the flag is set to “NATIVE”, then at operation  1230  management protocol parser  340  forwards the message to management packager A (element  310  of  FIG. 3 ). If the flag is set to “TRANSLATED”, then at operation  1240  management protocol parser  340  forwards the message to a translator (element  337  of  FIG. 3 ). In this regard it is noted that a CPE may set the data frame flag to “TRANSLATED” for an autonomously generated message, when the CPE intends the message to be used by management system A (element  120  of  FIG. 1 ). If the flag is set to “ENCAPSULATED”, then at operation  1250  management protocol parser  340  forwards the reply message to an encapsulator (element  333  of  FIG. 3 ). The encapsulator decapsulates the protocol A message (element  538  of  FIG. 8 ) from the reply message. The decapsulated message is then forwarded to management packager A (element  320  of  FIG. 3 ). 
     When the CPE and the CO use a single protocol for messaging then, for the case of “NATIVE” and “TRANSLATED”, the protocol identifier that is defined as part of a standardized control protocol format, such as IEEE P1904.1 or ITU-T G.984, may be used as the flag with “NATIVE” and “TRANSLATED” setting, without inserting the flag into protocol A header  513 , for cases where the CPE only supports such protocol. 
     Again, it will be appreciated by those skilled in the art that although the discussion above relates to a reply sent to management system A, an analogous method is used for a reply sent to management system B. When a management packager (elements  310  and  320  of  FIG. 3 ) receives a reply that is formatted in the appropriate protocol, it processes the reply and sends it to the appropriate management system (elements  110  and  120  of  FIG. 1 ). 
     Having read the above description, it will be appreciated by those skilled in the art that the present invention enables telecommunication operators to implement flexible management system and network device upgrade strategies in accordance with their business models. 
     In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific exemplary embodiments without departing from the broader spirit and scope of the invention as set forth in the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.