Abstract:
A system and method for reconfiguring a telecommunications network comprising a plurality of network elements is disclosed. The reconfiguration process begins by identifying a new configuration for the telecommunications network. Next, the process stores the new configuration with the old configuration for the telecommunications network. The system then identifies new connection information associated with the new configuration. The system then downloads the new connection information to the plurality of network elements. After the connection information has been downloaded, the connection information is stored with the old connection information at the plurality of network elements. Next, a message is broadcast to the plurality of network elements to activate the new configuration and deactivate the old configuration. The activation of the new connection information stored by the plurality of network elements occurs substantially simultaneously.

Description:
CROSS-REFERENCE TO OTHER APPLICATIONS 
     The following applications of common assignee contain some common disclosure as the present application: 
     U.S. Patent Application entitled “System and Method for Time Based Real-Time Reconfiguration of a Network”, filed Dec. 20, 1996, U.S. application Ser. No. 08/770,463, now U.S. Pat. No. 5,848,244. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to telecommunication network management systems. More specifically, the present invention is directed to high speed network reconfiguration. 
     2. Related Art 
     The reconfiguration of a service provider&#39;s network is becoming increasingly important. Network complexity continues to grow with the addition of network elements, the implementation of high bandwidth connections, such as OC- 12 , and the multiplexing and demultiplexing of lower bandwidth connections in and out of higher bandwidth connections. The goal of network reconfiguration is to optimize equipment usage and provide the highest possible quality service to the customer while simultaneously reducing cost. 
     Unfortunately, the current process of reconfiguring a service provider&#39;s network (“patch and roll”) is so slow, costly and has such a negative effect on network performance that the network cannot be optimized. Reconfiguration is so slow that the reconfiguration process can not keep up with equipment and circuit changes, let alone provide for management of traffic and customer demand. 
     Telecommunication service providers (e.g., MCI Telecommunications Corporation) provide a wide range of services to their customers. These services range from the transport of a standard 64 kbit/s voice channel (i.e., DS 0  channel) to the transport of higher rate digital data services (e.g., video). Both voice channels and digital data services are transported over the network via a hierarchy of digital signal transport levels. For example, in a conventional digital signal hierarchy 24 DS 0  channels are mapped into a DS 1  channel. In turn, 28 DS 1  channels are mapped into a DS 3  channel. 
     Routing of these DS 1  and DS 3  channels within a node of the network is performed by digital cross-connect systems. A node is a point of connection into a network. Digital cross-connect systems typically switch the channels at the DS 1  and DS 3  signal levels. Transmission of channels between nodes is typically provided via fiber-optic transmission systems. Fiber-optic transmission systems can multiplex a plurality of DS 3  channels into a higher rate transmission over a single pair of fibers. 
     Alternatively, a fiber-optic transmission system can implement the synchronous optical network (SONET) standard. The SONET standard defines a synchronous transport signal (STS) frame structure that includes overhead bytes and a synchronous payload envelope (SPE). One or more channels (e.g., DS 1  and DS 3  channels) can be mapped into an SPE. For example, a single DS 3  channel can be mapped into an STS- 1  frame. Alternatively, 28 DS 1  channels can be mapped into virtual tributaries (VTs) within the STS- 1  frame. 
     Various STS- 1  frames can be concatenated to produce higher rate SONET signals. For example, an STS- 12  signal includes 12 STS- 1  frames, while an STS- 48  signal includes 48 STS- 1  frames. Finally, after an STS signal is converted from electrical to optical, it is known as an optical carrier (OC) signal (e.g., OC- 12  and OC- 48 ). 
     The end-to-end path of an in-service channel within a network typically traverses a plurality of nodes. The term “in-service channel” is defined as the end to end communication channel that is providing communication service from one customer site or local exchange to another. The process of establishing the in-service channel is called “provisioning.” A new channel that has been established but is not yet carrying communications traffic is called a “provisioned channel.” The in-service channel is carried over transmission facilities that operate at various rates in the digital signal hierarchy. For example, a provisioned DS 1  channel may exist as part of a DS 3 , VT 1 . 5 , STS- 1 , STS- 12 , OC- 12 , and OC- 48  signal along parts of the end-to-end path. This results due to the switching, multiplexing and demultiplexing functions at each of the nodes. 
     “Patch and roll” is the current process of switching an in-service channel from one node to another, thereby changing the nodes traversed by the in-service channel. Patch and roll first establishes a new communications circuit by adding a new node between two existing nodes on the in-service channel, creating a “patch.” The new communications circuit is tested to obtain a good signal. After a good signal has been obtained, the in-service channel is switched over to the new circuit and the old connection is broken. In order to maintain communications, patch and roll requires that the old in-service channel be switched over one node at a time. 
     Reconfiguring the network by patch and roll wastes network capacity. Since patch and roll establishes a parallel connection when switching from one node to another, the network must have additional capacity to create the second connection. Designing additional capacity into the network means additional cost for capacity that will not be providing service to the customer. 
     The current process for reconfiguring the network is too slow. Patch and roll switches one node over at a time, requiring at least two seconds, and often five seconds, to switch each node. With manual coordination, two nodes may be switched over at once. Since a network may contain upwards of 250,000 DS- 1  circuits, the time required to reconfigure the network with patch and roll renders network management nearly impossible. 
     The current process for network reconfiguration makes management of the network very difficult. Maintenance windows are time periods when the network may be reconfigured. In the Digital Data Network (DDN), there are two six-hour maintenance windows per month. Since patch and roll only allows only (at most) eighteen hundred connections to be switched in an hour, only a very small fraction of the connections in the DDN may be switched each month. Because new circuits are added constantly, network traffic, customer needs and bandwidth demands change constantly, the patch and roll method of network management is unacceptable. 
     The current process for network reconfiguration results in poor network performance. In patch and roll, it takes at least 50 milliseconds to switch each node in the in-service channel over to the provisioned channel. During this time, the in-service channel will be lost. Since patch and roll switches only one node at a time, switching the in-service channel results in numerous communication drop outs. On voice communication channels (switchnet), multiple 50 millisecond drop outs may result in a lost connection or in intermittent distortion. On the Digital Data Network (DDN), however, the 50 millisecond losses will result in dropped computer connections, data errors or software application crashes. Since many nodes may have to be switched, the patch and roll process may result in a total loss of network functionality to the customer, or greatly reduced performance. 
     In this environment, comprehensive network connection reconfiguration is difficult to accomplish. What is needed is a telecommunication network management system that can switch a large number of nodes on the in-service channel in a short time. This capability will allow network management to free up network capacity, improve customer service and increase the speed of the network. 
     SUMMARY OF THE INVENTION 
     The present invention satisfies the above mentioned needs by providing a method and system for real time reconfiguration of the network that can switch a large number of network nodes in a very short period of time. 
     The present invention is a message based system and method for reconfiguring a telecommunications network domain comprising a plurality of network elements. The reconfiguration process begins by identifying a new configuration for the telecommunications network. Next, the process stores the new configuration with the old configuration for the telecommunications network. The system then identifies new connection information associated with the new configuration. The system then downloads the new connection information to the plurality of network elements. After the connection information has been downloaded to the network elements, the connection information is stored with the old connection information at the plurality of network elements. Next, a message is broadcast to the plurality of network elements to activate the new configuration and deactivate the old configuration. The activation of the new connection information stored by the plurality of network elements occurs substantially simultaneously. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit of a reference number identifies the drawing in which the reference number first appears. The present invention will be described with reference to the accompanying drawings, wherein: 
     FIG. 1 illustrates the layers in a network management system. 
     FIG. 2 illustrates a network management system with a detailed view of a network element layer. 
     FIG. 3 illustrates the elements of a network element. 
     FIG. 4 is a flow diagram illustrating the message based process for network reconfiguration. 
     FIG. 5 is a flow diagram illustrating the connection information verification process. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides a system and method for reconfiguring a telecommunications network quickly and automatically. The present invention enables a service provider to quickly reconfigure its network at any bandwidth in sub-seconds. The process for reprovisioning an in-service channel requires a hierarchy of network levels and detailed up to date network information. The network information is combined with customer requirement information to generate a new configuration for the network at a network management level. The new configuration describes the connections that must be made and broken at the physical layer of the network to reprovision the in-service channel. The connection information may be in the form of a network map describing the desired network configuration, or in the form of a delta file describing only those connections that have changed (i.e., connections to be made and broken). 
     The connection information is downloaded from the network management down to the network physical layer, where the connection information is implemented. The old unneeded connections are broken and new connections are made substantially simultaneously, to reprovision a new in-service channel. Connection information is information describing the connections between the nodes in the network. The new in-service channel is provided quickly and with minimum impact to customer service, thereby solving the problems associated with the previous network reconfiguration process. 
     FIG. 1 illustrates a network management system  100  which is the preferred environment of the present invention. Network management system  100  preferably complies with the International Telecommunications Union (ITU) Telecommunications Management Network (TMN) standard. The TMN standard defines a layered framework for a service provider to implement its own network management process. 
     Network management system  100  comprises three layers  110 ,  120  and  130 . Layer  130  is designated as the network element layer (NEL). NEL  130  is a physical layer that includes the various network systems (e.g., asynchronous systems, SONET systems, etc.) used in the transport and routing of network traffic (e.g., DS 1 , DS 3 , OC-N, etc.). NEL  130  comprises network elements  131 - 136 . Examples of network elements are wideband digital cross connects (WBDXC), broadband digital cross connects (BBDXC), optical cross connects, lightwave terminating elements (LTEs), etc. The connections between the various nodes of network elements  131 - 136  in NEL  130  define the in-service channels. For simplicity, the connections between the network elements are not shown in FIG.  1 . Switching connections between the nodes in network elements  131 - 136  in NEL  130  reroutes the in-service channel, or provisions a new channel for communications service. 
     Each network element  131 - 136  in NEL  130  can be designed to provide status and connection information to the higher network management layers  110 ,  120 . This status and connection information is used by the network hierarchy to plan and implement new network configurations. In particular, network elements  131 - 136  are connected to one of domain managers  121 - 123  in domain management layer (DML)  120 . For example, FIG. 1 shows network elements  131  and  132  connected to domain manager  121 . In this manner, each domain manager  121 - 123  controls a portion of NEL  130 . In a preferred embodiment, each domain manager  121 - 123  has exclusive communication with particular network elements  131 - 136 . A “domain” is the portion of NEL  130  that is “seen” by a particular domain manager  121 - 123 . The domain of domain manager  121 - 123  may be defined by a vendor&#39;s equipment or the geographic location of the network equipment. For example, domain manager  121  can provide information to and retrieve information from network elements  131  and  132  in its domain. The information transfer may occur either periodically or upon a user&#39;s request. 
     NML  110  comprises network manager  111 . Connection information to switch network elements  131 - 136  is provided to domain managers  121 - 123  by the network manager  111  in network manager layer (NML)  110 . Additionally, network elements  131 - 136  provide status information describing the state of NEL  130  to NML  110  to enable effective network management. Network manager  111  is logically shown as a single entity. In implementation, network manager  111  may comprise one or more sites. For example, multiple service centers (not shown) can exist in different parts of the country (e.g., East Coast and West Coast). In combination, these national-level service centers provide total visibility of the physical network in NEL  130 . In the preferred embodiment, network manager  111  interacts with NEL  130  through the DML  120 . Information about the network is provided from NEL  130  to NML  110  and from NML  110  to NEL  130  through DML  120 . 
     Network manager  111  can also be split among services and/or network elements. For example, in one embodiment, a first network manager is dedicated to asynchronous parts of the network, a second network manager is dedicated to DS 1 , DS 3  and VT-n traffic, and a third network manager is dedicated to STS-n and OC-n traffic. 
     Network manager  111  can provide a user interface for the provisioning of various services. For example, a customer can indicate a desire for a DS 1  digital data service between network element  131  and network element  135 . Upon receipt of this customer request, network manager  111  determines the connection information corresponding to the desired provisioned channel. Additionally, network manager  111  may determine that the in-service channel must be rerouted because of equipment problems, bandwidth problems, to take advantage of new hardware in NEL  130 , etc. Network manager  111  then communicates the connection information to domain managers  121 - 123  that control the part of the NEL  130  necessary to set up the DS 1  connection between network elements  131  and  135 . 
     FIG. 2 illustrates the network management system, and provides a more detailed view of an exemplary network clement layer. The network element layer of FIG. 2 includes a plurality of network elements  202 - 216 , and shows the network element interconnections that carry the network communication traffic. The network element layer of FIG. 2 includes: WBDXC  202 ,  216 ; BBDXC  204 ,  214 ; and LTEs  206 - 212 . WBDXC  202 ,  216  multiplexes lower rate channels into and out of higher-rate channels for transmission to BBDXC  204 ,  214  or LTEs  206 - 212 . For the purposes of explanation, all correspondingly identified elements are the same, and will be referred to by a single reference number. It should be understood, however, that the present invention is equally applicable to any network element capable of switching nodes and re-routing a communications channel. 
     Domains  218 ,  220  are represented by dotted boxes in FIG.  2 . Domains  218 ,  220  are defined by those network elements that can be “seen” by a particular domain manager. In FIG. 2, for example, domain  218  is defined by network elements  202 - 208 , which are seen by domain manager  121 . 
     FIG. 3 further illustrates WBDXC  202 . WBDXC  202  comprises: disk  302 ; main CPU  304 ; supervisor CPUs  306 ,  308 ; and I/O cards  310 - 316 . I/O cards  310 - 316  further comprise I/O processors  318 - 324 , and I/O ports  326 - 332 . Disk  302  stores configuration information describing the configuration of and management and operating system software for WBDXC  202 . Main CPU  304  accesses disk  302 , controls shelf processors  306 ,  308 , runs software and communicates with domain manager  121 . Main CPU  304  also manages the high level operation of WBDXC  202 . Some of the management functions of main CPU  304  are, for example, providing the user interface, keyboard interface, disk drive interface, tape drive interface, etc. Main CPU  304  also provides communication to the hierarchy of network management layers  110 ,  120  above. 
     Shelf processors  306 ,  308  supervise and control individual I/O cards  310 - 316  on a particular “shelf” of a WBDXC  202 . A shelf comprises a plurality of I/O cards of the same type and configuration (e.g., 16 DS- 3  I/O cards). Shelf processors  306 ,  308  provide shelf supervision, shelf performance monitoring, restore and remove functionality and control (i.e., removal and addition of shelf hardware) and equipment state changes. Shelf processors  306 ,  308  provide the interface between the I/O cards  310 - 316  on a particular shelf and the main CPU  304 . 
     I/O cards  310 - 316  comprise I/O processors  318 - 324  and I/O ports  326 - 332 . I/O cards  310 - 316  are supervised by a particular shelf processor  306 ,  308 . I/O cards  310 - 316  on the same shelf have the same number of ports, and handle the same density channel (i.e., DS 1 , DS 3 , OC- 12 , etc.). I/O cards  310 - 316  receive connection and switching commands from shelf processors  306 ,  308 . I/O cards  310 - 316  also provide port status information to shelf processor  306 ,  308 . I/O processors  318 - 324  control the sending and receiving of the actual communication signals. Ports  326 - 332  are the communications ports to which the fiber or telecommunications lines are connected in WBDXC  202 . Ports  326 - 332  may be DS 1 , DS 3 , VT 1 . 5 , etc. in density. Ports  326 - 332  are the nodes between which the connections are switched, and provide the signals that go out on the network cabling. 
     FIG. 4 is a flow chart which illustrates the process of message based network reconfiguration. The network reconfiguration process begins at step  402 . After step  402 , network manager  111  downloads the connection information to domain manager  121  at step  404 . In the preferred embodiment, the network is reconfigured one domain at a time. Reconfiguring multiple domains at the same time may cause excessive in-service channel drop out due to the time lag between when the network elements of different domains switch their connections. Assume, for example, a domain in New York and a domain in California are part of the same in-service channel to be reconfigured by a network manager in New York. After the network elements are reconfigured, the network manager broadcasts a message to implement the new connection information. Because of the distance between New York and California, the network elements in New York would necessarily implement the new connection information much sooner than the network elements in California. Since a new in-service channel is not re-established until the new configuration is implemented, the time lag between the New York and California domains causes a longer drop out in the in-service channel. To minimize in-service channel downtime, the network is reconfigured one domain at a time. In situations where the lag time is not unacceptably long, however, more than one domain may be reconfigured at a time. 
     The connection information that is downloaded to the network elements defines the desired configuration of the network, and can either describe the desired configuration of the total network (i.e., all of the connections in the network), or a list of the changes to be made to the current network configuration (i.e., a “delta” file). The connection information can be in the form of a network map of the connections between the network elements, a series of TL- 1  commands that switch the network element connection, or a database of connection information. 
     Domain manager  121  downloads connection information at step  406  to those network elements that will be reconfigured after network manager  111  has downloaded the connection information at step  404 . Domain manager  121  downloads only that connection information to each network element to which it applies. Alternatively, domain manager  121  may download all of the domain connection information network elements  202 - 208 , and each network element implements only that connection information which applies to it. 
     WBDXC  202  verifies the connection information at step  408  after it has received the connection information from domain manager  121 . WBDXC  202  verifies that the ports and port IDs specified by the connection information exist, that the hardware exists to support the proposed connections, that the ports specified by the connection information are in the correct state, that the connection information has the correct syntax, that the connection information is not corrupted, etc. If the connection information is successfully verified in step  408 , the connection information is determined to be valid at step  410 . If the connection information is not successfully verified in step  408 , the connection information is determined to be invalid at step  410 . In the case of a WBDXC  202  the verification and validation steps are performed by main CPU  304 . 
     After WBDXC  202  has determined that the connection information is invalid at step  410 , WBDXC  202  transmits an alarm at step  422 . The alarm is transmitted to domain manager  121  which manages the domain of the WBDXC  202 . Domain manager  121  then relays the alarm to network manager  111 , and the alarm is handled by network manager  111  at step  424 . 
     After network manager  111  receives an alarm from WBDXC  202 , network manager  111  takes steps to handle it at step  424 . Network manager  111  may handle an alarm in different ways. If network manager  111  receives only a few network element alarms in response to downloaded connection information, network manager  111  may download supplementary connection information to bypass those connections which caused network element alarms. The supplementary connection information would be downloaded to domain manager  121  and WBDXC  202 , causing WBDXC  202  to bypass those connections that caused the alarms. 
     Alternatively, if network manager  111  receives a large number of network element alarms, it may broadcast commands to roll back all the downloaded connection information, thereby restoring the network to its previous configuration. Commands to remove the downloaded connection information are sent to domain manager  121  and then downloaded to the affected network elements to restore the previous network configuration. The decision whether to terminate the reconfiguration process or to continue the reconfiguration process is made at step  426 . If network manager  111  determines that the reconfiguration process can proceed, then the reconfiguration process continues at step  412 . If, on the other hand, network manager  111  determines that the reconfiguration process cannot proceed, the reconfiguration process is terminated at step  428 . 
     After the connection information has been determined to be valid at step  410 , WBDXC  202  transmits a “download successful” message at step  412 . The download successful message indicates that the connection information has been verified and the connection information is ready to be implemented at WBDXC  202 . The download successful message is transmitted from WBDXC  202  to domain manager  121 . Domain manager  121  then either transmits each download successful message it receives from the network elements in its domain  218  to network manager  111 , or consolidates all of the download successful messages into a single download successful message and transmits it to network manager  111 . 
     After network manager  111  receives the download successful message at step  414 , network manager  111  verifies that a download successful message has been received from all the network elements that received connection information. Alternatively, this verification can be done at the domain manager level. After all necessary download successful messages have been received from the network elements, network manager  111  broadcasts a command to implement the new connection information at step  416 . The command to implement the new connection information is transmitted through domain manager  121  and distributed to the network elements that will be switching connections. The new connection information is implemented by switching the connections at the network elements that receive the command to implement the connection information. All of the network elements, therefore, are switched substantially simultaneously and the old in-service channel is removed and the new in-service channel is created. 
     Switching all of network elements involved in reconfiguring the network at the same time results in only one interruption of the in-service channel. This allows the network to be reconfigured without the need for additional capacity and solves most of the problems with the patch and roll process. The WBDXC  202  implements the new connection information at step  418 , as soon as it receives the command to implement the new connection information. The implementation of the new connection information comprises breaking the old connections and making the new connections substantially simultaneously, so that a new in-service channel is created and the old one is destroyed. This results in the creation of a new in-service channel while interrupting the in-service channel only one time. After WBDXC  202  has implemented the new connection information at step  418 , the reconfiguration process is completed at step  420 . 
     FIG. 5 further illustrates the verification process of step  408 . The verification process is performed at WBDXC  202  and begins at step  502 . The connection information is downloaded from domain manager  121  and copied onto disk  302  or RAM associated with main CPU  304 . The downloaded connection information does not replace the current configuration (i.e., the network element configuration information is maintained) on WBDXC  202 . The current configuration information on the network element is maintained so that if the downloaded connection information is rolled back due to a verification problem, the current network element configuration is preserved. 
     At step  504 , main CPU  304  checks the validity of the connection information for syntax correctness, verifies the port number on WBDXC  202  is in the correct state, that the port number is valid, and other tests which ensure that the new connection information can be implemented. If the connection information is determined to be valid at step  506 , the verification process continues to step  508 . 
     If, on the other hand, the connection information is determined to be invalid, WBDXC  202  transmits an alarm at step  514 . The verification process is then terminated at step  516  after the alarm has been transmitted at step  514 . After the termination of the verification process, the reconfiguration process continues at step  424 . 
     If the connection information has been determined to be valid at step  506 , the connection information is downloaded from main CPU  304  to shelf processors  306 ,  308 . The main CPU  304  can either download only that connection information which pertains to a particular shelf processor, or download all of the connection information received from domain manager  121 . 
     Shelf processor  306  then download the appropriate connection information to I/O processors  318 - 324  at step  510 . After the connection information has been downloaded to I/O processors  318 - 324 , the verification process terminates at step  512 . After the termination of the verification process, the reconfiguration process continues at step  410 . 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the relevant art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.