Abstract:
A device and method to allocate a secondary power supply to a Fiber-to-the-Home subscriber is disclosed. The present invention employs methods to selectively accept or rejects packets in order to conserve power of the secondary power supply while allowing critical packets to reach their destinations.

Description:
TECHNICAL FIELD OF THE INVENTION 
   The present invention relates generally to network power allocation. In particular, the present invention detects power failures and then rejects non-critical packets to reduce power consumption. 
   BACKGROUND OF THE INVENTION 
   Fiber-to-the-Home (FTTH) is one of the hottest new markets in optical networking. Utilities, cable providers, telephone companies, and other communication based entities are starting to connect homes and businesses to the Internet through fiber as opposed to coaxial cable or telephone wire. Fiber permits data transmission bandwidths of one Gigabit/second and higher. Therefore, with fiber these entities will be able to provide high bandwidth data services, such as video on demand, and voice services to the homes of subscribers. 
   These entities currently are building and retrofitting circuits to be used at subscriber homes that will convert the data traffic from an optical signal to an electrical signal. In addition, these entities are also adding a secondary power source, which in most instances is a battery backup, to the home systems to keep the home gateway open in the case of a power failure of a primary power source. This addition of a battery backup is significant. For example, in the case of an emergency where a primary power source fails, a subscriber may still use selective network resources powered by the battery backup to contact emergency services. 
   SUMMARY OF THE INVENTION 
   The present invention relates generally to network power allocation. In particular, the present invention detects power failures and then selectively rejects non-critical packets, thus conserving power. In accordance with a first exemplary embodiment of the present invention, a fiber-to-the-home (FTTH) gateway device having inputs for both the main power supply and the secondary power supply, respectively, is used to reject non-voice packets. In accordance with a second exemplary embodiment of the present invention, a FTTH gateway device having inputs for both the main power supply and the secondary power supply, respectively, rejects packets based upon priority by examining the header of each packet. In accordance with a third exemplary embodiment of the present invention, a FTTH gateway device having inputs for both the main power supply and the secondary power supply, respectively, rejects packets based upon priority by examining the contents of the packet. In accordance with a fourth exemplary embodiment of the present invention, a FTTH gateway device having inputs for both the main power supply and the secondary power supply, respectively, provides for a graceful closing of non-critical connections by sending a message to the source of non-critical packets that a power failure has occurred and that the non-critical packets did not reach their destination, such that the source of the non-critical packets will know to re-transmit at a later time. 
   Further, the FTTH gateway device of any of the above-described embodiments may also comprise a two-port or multiple port arrangement, where one port is a dedicated voice port that connects into the home telephone line or to one or more IP phones whose power may be regulated by the FTTH gateway device of the present invention. In addition, an IP telephone may have its own primary and secondary power supply. 
   The present invention provides the technical advantage of conserving the power of a secondary power supply during the failure of a main power supply. The present invention ensures that critical packets have a means to be received and/or be transmitted during a failure of the main power supply. For example, Internet Protocol (IP) telephony devices would still be operational in a power failure in accordance with the present invention. 
   While this summary has dealt with an FTTH gateway, the concept applies to other network devices such as a router. In this case, any packet manipulation (inspection, processing, management, and assembly) would be performed by a processor within the router, and the power savings would come from the cycles the processor saves by rejecting a packet after determining the packet will not be processed and forwarded out to one or more of the interfaces. Finally, any packet-based device could use these techniques to reduce power consumption. These devices include, but should not be limited to, a set top box, a cable modem, a home gateway, a hub, a switch, a wireless telephone, a base station, a line card, etc. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numbers indicate like features, components and method steps, and wherein: 
       FIG. 1  is an illustration of a conventional circuit used to supply battery backup power upon a power failure of a main power supply; 
       FIG. 2  illustrates an exemplary two-port FTTH gateway device of the present invention; 
       FIG. 3  is a flow chart of a first exemplary embodiment of the present invention, where only voice packets are accepted during failure of a main power supply; 
       FIG. 4  is a flow chart of a second exemplary embodiment of the present invention, where only high priority packets are accepted during failure of a main power supply; 
       FIG. 5  is another flow chart of the second exemplary embodiment of the present invention, where subscribers are distinguished such that different subscribers may have different service levels during failure of a main power supply; 
       FIG. 6  is another flow chart of the second exemplary embodiment of the present invention, where packets are accepted based upon the length of the power failure of the main power supply; 
       FIG. 7  is a flow chart of a fourth exemplary embodiment of the present invention, where sources of rejected packets are notified of a power failure and connections are gracefully closed for those sources; and 
       FIG. 8  is an illustration of an exemplary router in which the present invention may be implemented. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Now referring to the drawings,  FIG. 1  shows a conventional circuit  100  which includes an application-specific integrated circuit (“ASIC”)  102 , a main power supply  104  and a battery backup  106 . The ASIC  102  converts the data traffic from its optical signal to an electrical signal. In coordination with large pulldown resistor  106  and large pulldown resistor  108 , when the “Power On” signal from the main power supply  104  is low the “Battery On” signal from the battery backup  106  is high, thus utilizing the battery backup  106  when the main power supply  104  has failed. The “Power On” and “Battery On” signals are directly interfaced with the ASIC  102 . 
   The “Power On” or “Battery On” signals may be monitored by a plurality of devices that respond to current power conditions, e.g. a power failure. In accordance with the present invention,  FIG. 2  illustrates a Fiber-to-the-Home gateway device (“gateway device”)  200 . The gateway device  200  includes a network interface  202 ; first and second packet inspection and assembly units  204 ,  210 ; a packet, buffering, processing and management unit  206 ; and a subscriber interface  212 . The exemplary gateway device  200  is a two-port network device. Alternatively, the gateway device  200  can be a multi-port device. 
   In normal operation, a packet is received at the network interface  202 . The network interface  202  passes the packet to the first packet inspection and assembly unit  204  such that the packet can be inspected in accordance with one or more of the exemplary embodiments of the present invention discussed below. The packet is then sent to the packet buffering, processing, and management unit  208 , where the packet is stored. The packet buffering, processing, and management unit  208  is also where packets are accepted or rejected during a power failure in accordance with the present invention as described in detail below. If accepted and released by the packet buffering, processing, and management unit  208 , the packet is passed on to the subscriber interface  212 , from which a subscriber client may receive the packet after being assembled by the second packet inspection and assembly unit  210 . The second packet inspection and assembly device  210  is also used for packets originating from the subscriber client, thus it is used for packets traveling in the reverse direction (subscriber to network) of the process flow described above. Note that the technique can apply in either direction. A subscriber client may be a personal computer, high definition television, conventional television, set top box, video converter, IP telephony device, modem, plain old telephony system (“POTS”) telephony device, wireless telephone, home gateway device, hub, switch, router, or any other device which sends and/or receives data packets. 
     FIG. 3  is a flow chart illustrating a first exemplary embodiment of the present invention, where only voice packets are accepted during a power failure of the main power supply  104 . The gateway device  200  waits for a change of the “Power On” signal in block  302 . If there is a change in the “Power On” signal, the gateway device  200  determines whether the main power supply  104  is “off,” in block  304 . If the main power supply is “off,” indicating a power failure, in block  306  non-voice packets are rejected and will not pass to or from the subscriber client(s) (home user device). This is easily accomplished in a two-port device such as the device of  FIG. 2  (or a router that can detect the status of its power source, see  FIG. 8  below), by rejecting all non-voice packets attempting to be transmitted. If, in block  304 , the main power supply is detected as “on,” then the gateway device  200  is initialized in block  308 , after which the gateway device  200  accepts all packets in block  310 . Similarly, compression operations, e.g., compress, decompress, etc., can be selectively performed on packets, also to conserve power, using the above method or methods described below. 
   A second exemplary embodiment is illustrated in the flow chart of  FIG. 4 . In accordance with the second exemplary embodiment, only “high priority” packets are accepted during a failure of the main power supply  104 . “High priority” packets may be defined in a variety of ways including packets originating from particular network addresses, i.e., IP address; virtual local area network (“VLAN”) assignments; quality of service metric; IEEE 802.1p class of service; service level agreements; and/or bandwidth allocation. The header of each packet is examined by the packet inspection and assembly units  204 ,  212  to determine whether a packet meets a pre-defined “high priority” criteria. 
   As a basic example of this embodiment,  FIG. 4  illustrates a flow chart where the gateway device  200  waits for a change of the “Power On” signal in block  402 . If there is a change in the “Power On” signal, the gateway device  200  determines in block  404  whether the main power supply  104  is “off.” If the main power supply  104  is “off,” indicating a power failure, only high priority packets are accepted and will pass to or from the subscriber client(s) in block  406 . If, in block  404 , the main power supply  104  is detected as “on,” then the gateway device  200  is initialized in block  408 , after which the gateway device  200  in block  410  accepts all packets. 
     FIG. 5  illustrates a more complex exemplary embodiment, where packets are accepted or rejected based upon a subscriber&#39;s service level agreement. In  FIG. 5 , the gateway device  200  waits for a change of the “Power On” signal in block  502 . If there is a change in the “Power On” signal, the gateway device  200  determines, in block  504 , whether the main power supply is “off.” If the main power supply is “off,” indicating a power failure, the gateway device  200  determines, in block  506 , whether the subscriber to receive the packet has a Gold service level agreement (“SLA”). For purposes of example only, it is assumed that a Gold SLA is the most premium package offer by the service provider. If the subscriber has a Gold SLA, then all packets will be accepted in block  508 . If the subscriber does not have a Gold SLA, then the gateway device  200  checks, in block  510 , whether the subscriber has a Silver SLA, some service less than the Gold SLA. If the subscriber has a Silver SLA then only voice packets and packets up to one Mbps are accepted in block  512 . If the subscriber has neither a Gold nor Silver SLA, then, in block  514  only voice packets are accepted. If the main power supply is detected as “on,” in block  504 , then the gateway device  200  accepts all packets in block  516 . 
     FIG. 6  illustrates yet another exemplary variation of the second embodiment, where packets are accepted or rejected based upon the type of packet and duration of the power failure. In  FIG. 6 , the gateway device  200  waits for a change of the “Power On” signal in block  602 . If there is a change in the “Power On” signal, the gateway device  200  determines, in block  604 , whether the main power supply  104  is “off.” If the main power supply  104  is “off,” indicating a power failure, the gateway device  200  determines, in block  606 , whether the main power supply  104  has been “off” for less than one minute. If the main power supply  104  has been “off” for less than one minute, all packets are accepted in block  608 . This prevents the gateway device  200  from going into a full fault recovery when the power failure is de minimum. If the main power supply  104  has been “off” for more than one minute, the gateway device  200  determines in block  610  if the main power supply  104  has been “off” for less than five minutes. If the main power supply  104  has been “off” for more than one minute but less than five minutes, then voice, web pages (HTTP), and e-mail packets are accepted in block  612 . If the main power supply  104  is “off” for more than five minutes, then only voice packets are accepted in block  614 . If the main power supply is detected as “on” in block  604 , then, in block  616  the gateway device  200  accepts all packets. This method allows the gateway device  200  to adapt to the power failure based upon the severity of the power failure as measured by the duration of the power failure, thus, intelligently conserving battery backup power. 
   In a third exemplary embodiment, the same methods of the second embodiment are employed as illustrated in  FIGS. 4-6 ; however, the contents, not solely the header, of each packet are examined at the packet inspection and assembly units  204 ,  212 . 
     FIG. 7  illustrates a fourth exemplary embodiment, where the source of a rejected packet is sent a message indicating the same. In  FIG. 7 , the gateway device  200  waits for a change of the “Power On” signal in block  702 . If there is a change in the “Power On” signal, the gateway device  200  determines, in block  704 , whether the main power supply  104  is “off.” If the main power supply  104  is “off,” indicating a power failure, the gateway device  200  determines, in block  706 , whether the main power supply  104  has been “off” for less than one second. If the main power supply  104  has been “off” for less than one second, normal operation continues in block  708 . This prevents the gateway device  200  from prematurely sending messages of a power failure when the power failure is de minimus. If the main power supply  104  has been “off” for more than one second, the gateway device  200  sends a message in block  710  indicating the power failure to the source (sender) of the packet. If the main power supply  104  is detected as “on” in block  704 , then the gateway device  200  determines, in block  712 , whether a power failure message was previously sent. If a power failure message had not been previously sent, the normal operation resumes in block  714 . If a power failure message was previously sent, then in block  716  a message indicating that power has been restored is sent to the source of the previously rejected packet. After the message indicating that power has been restored has been sent, normal operation resumes in block  714 . 
   In addition to the gateway device  200 , the present invention may also be implemented in a router as shown in  FIG. 8 . Router  850  which includes a processor  852 , a memory  854 , a packet memory  856 , and one or more interfaces  858 . In this exemplary embodiment, “Battery On” and/or “Power On” propagated on a line  860 , where the line  860  may also propagate data packets. Alternatively, “Battery On” and/or “Power On” signals may be directly connected to processor  852 . “Battery On” and/or “Power On” signals are monitored by the processor  852  either through a direct connection (such as interrupts) or by polling the “Battery On” and/or “Power On” signals on the line  860  to verify if such signals have changed. The above described methods of the present invention are performed in the router  850  by the processor  852 . 
   Although the present invention has been described in detail with reference to specific exemplary embodiments thereof, various modifications, alterations and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, the above device and method of the present invention may be implemented at the home of a subscriber, at a curb-side router servicing many subscribers, or using computer code in a computer program product. 
   In addition, the device and method of the present invention may be implemented under a variety of distributed networks protocols and is not limited to the transmission control protocol/Internet protocol (TCP/IP) or the network interface protocol MAC. Further, the device and method of the present invention may be used for packets being received as well as packets being sent from a subscriber, such that a subscriber&#39;s own transmissions may not circumvent the selective packet acceptance methods of the present invention. The term “packet” as used in the above description is intend to be interpreted as any piece of data or group of data, irrespective of size, which is in a form to be transmitted or received. It is intended that the invention be limited only by the appended claims.