Abstract:
A communication network comprises a service network configured to provide a service over access provided by an access network, and a first access system configured to access the service over the access provided by the access network, detect a loss of the access, monitor for access restoration, upon detecting the access restoration delay a first service restoration for a first delay period, and initiate the first service restoration after the first delay period.

Description:
RELATED APPLICATIONS 
     Not applicable 
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     MICROFICHE APPENDIX 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The field of the invention relates to telecommunications, an in particular, to mitigating the consequences to a service network of the failure of an access network. 
     2. Description of the Prior Art 
     Recently, service providers have begun to partner with cable multi-system operators (MSO) to provide customer access for services. Examples of services include video on demand and voice over Internet protocol (VoIP) service, as well as other services. Other times, a service provider provides its own access. In either case, access is typically considered a general service over which other services, such as VoIP, are provided. 
     Occasionally, customers lose access in the event of an access failure. For instance, equipment in the access network could fail. Other causes of access loss are possible. In the even of an access failure, most customer equipment monitors for access restoration and then initiates a restoration process. Unfortunately, if the access failure is a mass event, then a large number of customers will initiate their restoration processes simultaneously. Such a mass restoration event could possibly overload elements in the service network. 
       FIG. 1  illustrates a communication network in an example of the prior art. Communication network  100  includes service network  110  coupled to access networks  120 ,  130 ,  150  and  150  by session border controllers (SBC)  112 ,  113 ,  114 , and  115  respectively. Session border controllers are well known network elements that manage traffic flow across network borders. Access network  120  includes devices  121 ,  123 , and  122 . Access network  130  includes devices  131 ,  133 , and  132 . Access network  140  includes devices  141 ,  143 , and  142 . Lastly, access network  150  includes devices  151 ,  153 , and  152 . 
       FIG. 2  illustrates an operational situation in the prior art. To begin, device  121  has a session connection over access network  120  to SBC  112 , and in turn, to service network  110 . Likewise, device  122  has a session established with service network  110  via SBC  112  and access network  120 . Device  123  has also established a session with service network  110  over SBC  112  and access network  120 . 
     As illustrated, an access cessation event causes the loss of the service sessions established by devices  121 ,  122 , and  123 . Namely, due to the loss of access, devices  121 ,  122 , and  123  are no longer able to continue their sessions. 
     Eventually, access is restored and an access restoration signal is applied to devices  121 ,  122 , and  123 . In response to detecting the access restoration signal, devices  121 ,  122 , and  123  all simultaneously initiate service restore requests to SBC  112 . The service restore requests, on a larger scale, could crash SBC  112 . 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention helps solve the above problems and other problems staggering the initiation of a restoration process across multiple systems. In an embodiment, a communication network comprises a service network configured to provide a service over access provided by an access network, and a first access system configured to access the service over the access provided by the access network, detect a loss of the access, monitor for access restoration, upon detecting the access restoration delay a first service restoration for a first delay period, and initiate the first service restoration after the first delay period. 
     In an embodiment, the communication network further comprises a second access system configured to access the service over the access provided by the access network, detect the loss of the access, monitor for the access restoration, upon detecting the access restoration delay a second service restoration for a second delay period, and initiate the second service restoration after the second delay period. 
     In an embodiment, the first delay period is different than the second delay period. 
     In an embodiment, the access network comprises a cable network. 
     In an embodiment, the access system comprises a cable modem. 
     In an embodiment, the access system comprises a phone coupled to the cable modem. 
     In an embodiment, the service comprises Voice over Internet protocol (VoIP) service. 
     In an embodiment, the service network comprises a Voice over Internet protocol (VoIP) service network. 
     In an embodiment, a method of operating a communication network comprises, in a service network, providing a service over access provided by an access network, and in a first access system, accessing the service over the access provided by the access network network, detecting a loss of the access, monitoring for access restoration, upon detecting the access restoration delaying a first service restoration for a first delay period, and initiating the first service restoration after the first delay period. 
     In an embodiment, an access system comprises an interface configured to access a service provided by a service network over access provided an access network, and a processing system configured to detect a loss of the access, monitor for access restoration, upon detecting the access restoration delay a service restoration for a delay period, and initiate the service restoration after the delay period. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The same reference number represents the same element on all drawings. 
         FIG. 1  illustrates a communication network in an example of the prior art. 
         FIG. 2  illustrates a flow diagram in an example of the prior art. 
         FIG. 3  illustrates a communication network in an embodiment of the invention. 
         FIG. 4  illustrates the operation of an access system in an embodiment of the invention. 
         FIG. 5  illustrates a flow diagram in an embodiment of the invention. 
         FIG. 6  illustrates a communication network in an embodiment of the invention. 
         FIG. 7  illustrates a flow diagram in an embodiment of the invention. 
         FIG. 8  illustrates a portion of a communication network in an embodiment of the invention. 
         FIG. 9  illustrates a computer system in an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 3-9  and the following description depict specific embodiments of the invention to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple embodiments of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. 
       FIG. 3  illustrates a communication network in an embodiment of the invention. Communication network  300  includes service network  310  coupled to access networks  320 ,  330 ,  350  and  350  by session border controllers (SBC)  312 ,  313 ,  314 , and  315  respectively. Session border controllers are well known network elements that manage session traffic flow across network borders. Access network  320  includes access systems  321 ,  323 , and  322 . Access network  330  includes access systems  331 ,  333 , and  332 . Access network  340  includes access systems  341 ,  343 , and  342 . Access network  350  also includes access systems  351 ,  353 , and  352 . 
       FIG. 4  illustrates the operation of an access system in an embodiment of the invention. To begin, the access system detects a loss of access that occurs in the access network over which the access system is provided access to a service provided by a service provider (Step  410 ). Next, the access system monitors for access restoration (Step  420 ). The access system could detect the access restoration by sensing a signal applied to an access line, receiving a control message, polling, or the like. 
     The access system determines based on the monitoring whether or not access has been restored (Step  430 ). If access has been restored, the access system delays a service restoration process for a particular delay period (Step  440 ). The period could be a randomly generated number. Optionally, the period could be programmed at the time of manufacturing or service configuration. Other sources of the delay period are possible. Upon expiration of the delay period (Step  450 ), the access system initiates the restoration process (Step  460 ). 
       FIG. 5  illustrates a system flow diagram in an embodiment of the invention. To begin, access system  321  has a session connection over access network  320  to SBC  312 , and in turn, to service network  310 . Likewise, access system  322  has a session established with service network  310  via SBC  312  and access network  320 . Access system  323  has also established a session with service network  310  over SBC  312  and access network  320 . 
     As illustrated, an access cessation event causes the loss of the service sessions established by access systems  321 ,  322 , and  323 . Namely, due to the loss of access, access systems  321 ,  322 , and  323  are no longer able to continue their sessions. 
     Eventually, access is restored and an access restoration signal is applied to access systems  321 ,  322 , and  323 . In response to detecting the access restoration signal, access systems  321 ,  322 , and  323  operate as described for  FIG. 4 . In particular, the access systems detect the access restoration. Each individual access system determines a unique delay period. Each access system then holds off on initiating their respective restoration processes until the expiration of their respective delay periods. 
     As each delay period expires, the associated access system initiates its restoration process with SBC  312 . In this manner, the restoration processes initiated by each access system are staggered. As a result, the service restoration attempts reduce the likelihood of crashing SBC  312 . 
       FIG. 6  illustrates a communication network  600  in an embodiment of the invention. Communication network  600  includes service network  610  coupled to access networks  620 ,  630 ,  650  and  650  by session border controllers (SBC)  612 ,  613 ,  614 , and  615  respectively. Session border controllers are well known network elements that manage session traffic flow across network borders. Access network  620  includes access systems  621 ,  623 , and  622 . Access network  630  includes access systems  631 ,  633 , and  632 . Access network  640  includes access systems  641 ,  643 , and  642 . Access network  650  also includes access systems  651 ,  653 , and  652 . Service network  610  also includes call control system  616 . Call control system  616  is a well known element that provides session control over calls placed to and from service network  610 . It should be understood that communication network  600  could comprise a session initiation protocol (SIP) enabled service network. 
       FIG. 7  illustrates a system flow diagram in an embodiment of the invention. To begin, access system  621  has a session connection over access network  620  to SBC  612 , and in turn, to service network  610 . Likewise, access system  622  has a session established with service network  610  via SBC  612  and access network  620 . Access system  623  has also established a session with service network  610  over SBC  612  and access network  620 . 
     As illustrated, an access cessation event causes the loss of the service sessions established by access systems  621 ,  622 , and  623 . Namely, due to the loss of access, access systems  621 ,  622 , and  623  are no longer able to continue their sessions. 
     Eventually, access is restored and an access restoration signal is applied to access systems  621 ,  622 , and  623 . In response to detecting the access restoration signal, access systems  621 ,  622 , and  623  operate as described for  FIG. 4 . In particular, the access systems detect the access restoration. Each individual access system determines a unique delay period. Each access system then holds off on initiating their respective restoration processes until the expiration of their respective delay periods. 
     As each delay period expires, the associated access system initiates its restoration process with CCS  616 . In an example, the associated access system transmits a SIP signaling message to restore access. In this manner, the restoration processes initiated by each access system are staggered. As a result, the service restoration attempts reduce the likelihood of crashing CCS  616 . 
       FIG. 8  illustrates a portion  601  of communication network  600 , including service network  610 , access network  620 , and access system  622 . Service network  610  includes SBC  612  and CCS  616 . Access system  622  includes modem  622 A and phone  622 B. Modem  622  could be any type of device capable of interfacing communications between phone  622 A and access network  620 . Phone  622 B could be any type of communication device capable of providing phone functions and interfacing communications between modem  622 A and a user. Phone  622 A could be in communication with modem  622  over a wireline or wireless connection. Likewise, modem  622  could be in communication with access network  620  over a wireless or wireline connection, or a combination thereof. 
     In operation, modem  622 A and phone  622 B could function together to operate as described for access systems in  FIGS. 3 and 6 . In an embodiment, the entire functionality of an access system as described in  FIGS. 3 and 6  could be included in modem  622 A. In another embodiment, portions of the functionality of an access system as described in  FIGS. 3 and 6  could be distributed between modem  622 A and phone  622 B. In yet another embodiment, the entire functionality of an access system as described in  FIGS. 3 and 6  could be included in phone  622 B. 
       FIG. 9  illustrates computer system  900  in an embodiment of the invention. Computer system  900  includes interface  920 , processing system  930 , storage system  940 , and software  950 . Storage system  940  stores software  950 . Processing system  930  is linked to interface  920 . Computer system  900  could be comprised of a programmed general-purpose computer, although those skilled in the art will appreciate that programmable or special purpose circuitry and equipment may be used. Computer system  900  may use a client server architecture where operations are distributed among a server system and client devices that together comprise elements  920 - 950 . 
     Interface  920  could comprise a network interface card, modem, port, or some other communication device. Signaling interface  920  may be distributed among multiple communication devices. Interface  930  could comprise a computer microprocessor, logic circuit, or some other processing device. Processing system  930  may be distributed among multiple processing devices. Storage system  940  could comprise a disk, tape, integrated circuit, server, or some other memory device. Storage system  940  may be distributed among multiple memory devices. 
     Processing system  930  retrieves and executes software  950  from storage system  940 . Software  950  may comprise an operating system, utilities, drivers, networking software, and other software typically loaded onto a general-purpose computer. Software  950  could also comprise an application program, firmware, or some other form of machine-readable processing instructions. When executed by the processing system  930 , software  950  directs processing system  930  to operate as described for an access system as illustrated in  FIGS. 3 and 6 .