Abstract:
A routing management component is provided for distributing routing information among a hierarchical distributed routing architecture. The routing management component can function to associate levels of the routing architecture with subsets of a network address format. The routing management component can further assign routers of the routing architecture to portions of network addresses defined at least in part by the network address format. For example, a router may be assigned to route packets addressed to a network address with a first octet between a range of values. The router management component may further distribute, to the routers of the hierarchical distributed routing architecture, sections of routing information associated with their assigned portions of network addresses. Because routing information can be distributed between various routers, the memory requirements of individual routers can be reduced comparatively to systems in which a single router maintains an entire set of forwarding information.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/620,363, entitled DISTRIBUTED ROUTING ARCHITECTURE, and filed Sep. 14, 2012, which is a continuation of U.S. patent application Ser. No. 12/641,260, entitled DISTRIBUTED ROUTING ARCHITECTURE, and filed Dec. 17, 2009, now U.S. Pat. No. 8,331,371, the entireties of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Generally described, computing devices utilize a communication network, or a series of communication networks, to exchange data. In a common embodiment, data to be exchanged is divided into a series of packets that can be transmitted between a sending computing device and a recipient computing device. In general, each packet can be considered to include two primary components, namely, control information and payload data. The control information corresponds to information utilized by one or more communication networks to deliver the payload data. For example, control information can include source and destination network addresses, error detection codes, and packet sequencing identification, and the like. Typically, control information is found in packet headers and trailers included within the packet and adjacent to the payload data. 
     In practice, in a packet-switched communication network, packets are transmitted between multiple physical networks, or sub-networks. Generally, the physical networks include a number of hardware devices that receive packets from a source network component and forward the packet to a recipient network component. The packet routing hardware devices are typically referred to as routers. Generally described, routers can operate with two primary functions or planes. The first function corresponds to a control plane, in which the router learns the set of outgoing interfaces that are most appropriate for forwarding received packets to specific destinations. The second function is a forwarding plane, in which the router sends the received packet to an outbound interface. 
     To execute the control plane functionality, routers can maintain a forwarding information base (“FIB”) that identifies, among other packet attribute information, destination information for at least a subset of possible network addresses, such as Internet Protocol (“IP”) addresses. In a typical embodiment, the FIB corresponds to a table of values specifying network forwarding information for the router. In one aspect, commercial level routing hardware components can include customized chipsets, memory components, and software that allows a single router to support millions of entries in the FIB. However, such commercial level routing hardware components are typically very expensive and often require extensive customization. In another aspect, commodity-based routing hardware components are made of more generic components and can be less expensive than commercial level routing hardware components by a significant order of magnitude. However, such commodity-based routing hardware components typically only support FIBs on the order of thousands of entries. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1A  is a block diagram illustrative of one embodiment of a distributed routing environment including a router management component and a hierarchical, distributed routing component architecture; 
         FIG. 1B  is a block diagram illustrative of components of a router component utilized in accordance with the distributed routing environment of  FIG. 1A ; 
         FIGS. 2A-2C  are block diagrams illustrative of the distributed routing environment of  FIG. 1A  illustrating the routing of a received packet within the hierarchical distributed routing component architecture; 
         FIG. 3  is a flow diagram illustrative of a distributed router architecture routing routine implemented within a distributed routing environment; and 
         FIG. 4  is a flow diagram illustrative of a distributed router architecture routing routine implemented within a distributed routing environment. 
     
    
    
     DETAILED DESCRIPTION 
     Generally described, the present disclosure corresponds to a distributed routing architecture. Specifically, the present disclosure corresponds to a hierarchical distributed routing architecture including at least three logical levels, or layers, for receiving, processing and forwarding data packets between network components. In one embodiment, the three logical levels can corresponds to a core level, a distribution level and a transit level. Illustratively, the core level corresponds to one or more router components that receive an incoming packet from a network component and processes the destination address information associated with the received packet. The core level router component then identifies a distribution level router component based on a subset of the destination address associated with the received packet. The distribution level corresponds to one or more router components that receive a forwarded packet from a core level router component and further processes the destination address information associated with the received packet. The distribution level router component identifies a transit level router component based on at least a subset of the destination address associated with the received packet. Each distribution level router component is associated with, or otherwise corresponds to, a subset of the FIB associated with the distributed routing architecture. Finally, the transit level router components correspond to one or more router components that receive the forwarded packet from a distribution level router component and forward the packet “upstream” to a respective network, or network node. The mapping, or other assignment, of portions of the FIB associated with the distributed routing environment is managed by a router management component. 
     In one embodiment, each of the router components associated with the core level, distribution level and transit level can correspond more closely to commodity based router components/hardware. In another embodiment, the core level, distribution level and transit level router components correspond to logical router components that do not necessarily have a corresponding hardware router component. For example, one or more logical router components within each level may be implemented in the same hardware router component. Likewise, the logical router components associated with different levels of the distributed routing architecture may be implemented in the same hardware router component. In both embodiments, however, because responsibility for maintaining the FIB associated with the distributed routing environment is divided among several router components, the processing and memory restraints associated with commodity based router components/hardware can be mitigated. Various implementations, combination, and applications for dividing the FIB associated with the distributed routing environment will be described in accordance with the distributed routing environment. However, one skilled in the relevant art will appreciate that such embodiment and examples are illustrative in nature and should not be construed as limiting. 
     Turning now to  FIG. 1A , a distributed routing environment  100  for implemented a hierarchical distributed routing architecture will be described. The distributed routing environment  100  includes a router management component  102  for controlling the routing information utilized by the distributed routing environment  100 . Specifically, the router managed component  102  can receive all upstream routing information to be used by the distributed routing environment  100  and allocate the assignment of the upstream routing information among the components of the distributed routing environment  100  as will be described. In one embodiment, the router management component  102  can correspond to a computing device in communication with one or more components of the distributed routing environment  100 . Illustrative computing devices can include server computing devices, personal computing devices or other computing devices that include a processor, memory and other components for executing instructions associated with the function of the router management component  102 . In another embodiment, the router management component  102  may be implemented as a software component that is executed on one or more of the router components described below. Illustratively, the router management component  102  maintains and updates the FIB associated with the distributed routing environment  100 . Additionally, the router management component  102  can allocate responsibility for portions of the FIB entries to the various layers of the distributed routing environment  100 , as will be described below. In one embodiment, the router management component  102  can partition the FIB according to the distribution to the various router components of the distributed routing environment  100  and distribute respective portions of the FIB to be maintained in a memory associated with the various router components. 
     With continued reference to  FIG. 1A , the distributed routing environment  100  includes a first communication network  104  that transmits data packets to the distributed routing environment  100 . The first communication network  104  may encompass any suitable combination of networking hardware and protocols necessary to establish packet-based communications to the distributed routing environment  100 . For example, the communication network  104  may include private networks such as local area networks (LANs) or wide area networks (WANs) as well as public or private wireless networks. In such an embodiment, the communication network  104  may include the hardware (e.g., modems, routers, switches, load balancers, proxy servers, etc.) and software (e.g., protocol stacks, accounting software, firewall/security software, etc.) necessary to establish a networking link with the distributed routing environment  100 . Additionally, the communication network  104  may implement one of various communication protocols for transmitting data between computing devices. As will be explained in greater detail below, the communication protocols can include protocols that define packet flow information, such as network address information corresponding to the Internet Protocol version 4 (IPv4) and the Internet Protocol version 6 (IPv6) Internet Layer communication network protocols. One skilled in the relevant art will appreciate, however, that present disclosure may be applicable with additional or alternative protocols and that the illustrated examples should not be construed as limiting. 
     In communication with the first communication network  104  is a first level of the distributed routing environment  100 , generally referred to as the core layer or core level. In one embodiment, the core level corresponds to one or more logical router components, generally referred to as core level routers  106 A,  106 B, and  106 C. As previously described, within the distributed routing environment  100 , the core level routers  106 A,  106 B,  106 C receive an incoming packet from a component from the network  104  and process the destination address by identifying a distribution level router component based on a subset of the destination address associated with the received packet. Illustratively, the subset of the destination address can correspond to less than the entire destination IP address, such as the highest most values of the IP address. As previously described, the core level routers  106 A,  106 B,  106 C can correspond to logical router components implemented on one or more hardware components. In one embodiment, each logical router component can correspond with a dedicated physical router component. In another embodiment, each logical router component can correspond to a physical router component shared by at least one other logical router component in the distributed router environment  100 . In an alternative embodiment, at least some portion of the core layer may be implemented by components outside the distributed routing environment  100 . In such an embodiment, such external components would directly address a distribution level router component (described below) of the distributed routing environment  100 . 
     The distributed routing environment  100  can further include a second level of logical router components, generally referred to as the distribution layer or distribution level. In one embodiment, the distribution level corresponds to one or more router components, generally referred to as distribution level routers  108 A,  108 B, and  108 C. As previously described, within the distributed routing environment  100  the distribution level routers  108 A,  108 B and  108 C receiving an incoming packet from a core routing component  102  and process the destination address by identifying a transit level router component based on at least a subset of the destination address associated with the received packet. Illustratively, the subset of the destination address can correspond to a larger subset of the destination IP address used by the core level routers  106 A,  106 B,  106 C. In this embodiment, the routing performed by the distribution level can correspond to a more refined routing of the received packet relative to the core level routing. As described above with the core level routers  106 A,  106 B,  106 C, the distribution level routers  108 A,  108 B, and  108 C can correspond to logical router components implemented on one or more hardware components. In one embodiment, each logical router component can correspond with a dedicated physical router component. In another embodiment, each logical router component can correspond to a physical router component shared by at least one other logical router component in the distributed router environment  100 . 
     In communication with the distribution level router components is a third level of router components, generally referred to as the transmit layer or transit level. In one embodiment, the transit level corresponds to one or more router components, generally referred to as transit level routers  110 A,  110 B, and  110 C. As previously described, the transit level routers  110 A,  110 B,  110 C receive the forwarded packet from a distribution level router component  108 A,  108 B,  108 C and forward the packet “upstream” to another communication network  112  node. Illustratively, each transit level router  110 A,  110 B,  110 C can be configured to communicate with one or more upstream peers such that all packets destined for an associated peer network component will be transmitted through the assigned transit level router  110 A,  110 B,  110 C (or a redundant router). As described above with the core level routers  106 A,  106 B,  106 C and the distribution level routers  108 A,  108 B and  108 C, the transit level routers  110 A,  110 B, and  110 C can correspond to logical router components implemented on one or more hardware components. In one embodiment, each logical router component can correspond with a dedicated physical router component. In another embodiment, each logical router component can correspond to a physical router component shared by at least one other logical router component in the distributed router environment  100   
     Similar to communication network  102 , communication network  112  may encompass any suitable combination of networking hardware and protocols necessary to establish packet-based communications to the distributed routing environment  100 . For example, the communication network  112  may include private networks such as local area networks (LANs) or wide area networks (WANs) as well as public or private wireless networks. In such an embodiment, the communication network  112  may include the hardware (e.g., modems, routers, switches, load balancers, proxy servers, etc.) and software (e.g., protocol stacks, accounting software, firewall/security software, etc.) necessary to establish a networking link with the distributed routing environment  100 . As described above with regard to the communication network  104 , the communication network  112  may implement one of various communication protocols for transmitting data between computing devices. One skilled in the relevant art will appreciate, however, that present disclosure may be applicable with additional or alternative protocols and that the illustrated examples should not be construed as limiting. 
     In an illustrative embodiment, the logical router components ( 106 ,  108 ,  110 ) in  FIG. 1A  may correspond to a computing device having processing resources, memory resources, networking interfaces, and other hardware/software for carrying the described functionality for each of the logical router components. With reference now to  FIG. 1B , a block diagram illustrative of components of a router component  150  utilized in accordance with the distributed routing environment  100  of  FIG. 1A  will be described. The general architecture of the router component  150  depicted in  FIG. 1B  includes an arrangement of computer hardware and software components that may be used to implement one or more logical router components  106 ,  108 ,  110 . Those skilled in the art will appreciate that the router component  150  may include many more (or fewer) components than those shown in  FIG. 1B . It is not necessary, however, that all of these generally conventional components be shown in order to provide an enabling disclosure. 
     As illustrated in  FIG. 1B , the router component  150  includes a processing unit  152 , at least one network interface  156 , and at least one computer readable medium drive  158 , all of which may communicate with one another by way of a communication bus. The processing unit  152  may thus receive information and instructions from other computing systems or services via a network. The processing unit  152  may also be associated with a first memory component  154  for recalling information utilized in the processing of destination address information, such as at least a portion of a FIB associated with the distributed routing environment  100 . The memory  154  generally includes RAM, ROM and/or other persistent memory. The processing unit  152  may also communicate to and from memory  160 . The network interface  156  may provide connectivity to one or more networks or computing systems. The at least one computer readable medium drive  158  can also correspond to RAM, ROM, optical memory, and/or other persistent memory that may persists at least a portion of the FIB associated with the distributed routing environment  100 . In an illustrative embodiment, the access time associated with the memory component  154  may be faster than the access time associated with the computer readable medium driver  158 . Still further, the computer readable medium drive  158  may be implemented in a networked environment in which multiple router components  150  share access to the information persisted on the computer readable medium drive  158 . 
     The memory  160  contains computer program instructions that the processing unit  152  executes in order to operate the dynamic classifier. The memory  160  generally includes RAM, ROM and/or other persistent memory. The memory  160  may store an operating system  162  that provides computer program instructions for use by the processing unit  152  in the general administration and operation of the router component  150 . The memory  160  may further include computer program instructions and other information for implementing one or more of the logical router components in the distributed routing environment  100 . For example, in one embodiment, the memory  160  includes a router module  164  that implements the functionality associated with any of the routers  106 ,  108 ,  110 . In the event that multiple logical routers are implemented by the same router component  150 , memory  160  may have each instance of a router module  164 . 
     In an illustrative embodiment, each router component  150  may be embodied as an individual hardware component for implementing one or more logical routers  106 ,  108 ,  110 . Alternatively, multiple router components  150  may be grouped and implemented together. For example, each router component  150  may correspond to an application-specific integrated circuit (ASIC) having a processing unit  152 , memory  154  and memory  160  (or other components with similar functionality). The router components  150  may share one or more components, such as the network interface  156  and computer readable medium  158 , via a common communication bus. 
     With reference now to  FIGS. 2A-2C , the processing of receiving packets by the distributed routing environment  100  will be described. With reference first to  FIG. 2A , an incoming packet is received from the communication network  104  to a core level router  106 . The core level router  106  that receives the incoming packet may be selected according to a variety of techniques including, but not limited to, load balancing, random selection, round robin, hashing, and other packet distribution techniques. Upon receipt, the core level router  106  processes destination IP address and utilizes a subset of the destination IP address to identify a second level destination router component that will perform a second level of routing. In an illustrative embodiment, the core level router  106  utilizes the most significant bits of the IP address, such as the eight most significant bits of the destination address. The selection of the subset of IP addresses corresponding to a selection of the most significant bits is generally referred to as prefix. For example, selection of the eight most significant bits corresponds to a prefix length of “8.” Selection of the sixteen most significant bits corresponds to a prefix length of “16.” One skilled in the relevant art will appreciate that the number of bits utilized by the core level router  106  may vary. Additionally, in an alternative embodiment, the core level router  106  may use different methodologies to allocate, or otherwise subdivide, the address space serviced by the distributed routing environment  100 . 
     Based on the processing of the first subset of the destination address, the core level router  106  forwards the packet to a distribution level router, in this case illustratively  108 A. As previously described, the receiving distribution level router  108 A processes the destination address of the received packet and also utilizes a subset of the destination IP address to identify a third level router component that will forward the packet to a next network destination (outside of the distributed routing environment  100 ). Similar to the core level router  106 , the receiving distribution level router can be configured to utilize a selection of the most significant bits of the IP address (e.g., the prefix) to route the packet. In an illustrative embodiment, the prefix used by the distribution level router  108 A is greater than the prefix used by the core level router  106 . Based on the processing by the distribution level router  106 A, the transit level router  110 B receives the forwarded packet and forwards the packet to a designated designation associated with the communication network  112 . 
     Turning now to  FIGS. 2B and 2C , the allocation of IP addresses or subsets of IP addresses within the distributed routing environment  100  will be described. With reference to  FIG. 2B , the core level router  106  distributes some portion of the subset of destination IP addresses to distribution level router  108 A (illustrated at  202 ). Distribution level router  108 A in turn further distributes the portions of the IP addresses to transit level routers  110 A,  110 B, and  110 C (illustrated at  204 ,  206 , and  208 ). With reference to  FIG. 2C , the core level router  106  distributes a different portion of the subset of destination IP addresses to distribution level router  108 B (illustrated at  210 ). Distribution level router  108 B in turn further distributes the portions of the IP addresses to transit level routers  110 A and  110 B (illustrated at  212  and  214 ). 
     In an illustrative embodiment, the router management component  102  ( FIG. 1 ) can allocate responsibility of subsets of IP addresses to the distribution level routers in a variety of manners. In one embodiment, the router management component  102  can allocate responsibility for the entire set of IP addresses in accordance with assignment of IP addresses equally, or substantially equally, among available routers. In this embodiment, each distribution level router  108  becomes responsible for an equal subset of IP addresses or substantially equal if the IP addresses cannot be divided equally. In another embodiment, the router management component  102  can specify specific distribution level router  108  to handle high traffic IP addresses or prefixes. In this example, the entire subset of IP addresses may be custom selected by the router management component  102 . Alternatively, only the subset of IP addresses meeting a traffic threshold may be custom selected with the remaining portions of IP address automatically distributed. 
     In still a further embodiment, multiple distribution level routers  108  may be selected for a subset of IP addresses. In this embodiment, each core level router  106  can select from multiple distribution level routers  108  based on an equal cost multi-path routing (ECMP) technique in which a specific distribution level router  108  is selected based on a standard load sharing technique. Other factors that can be utilized to select from multiple assigned distribution level router  108  include carrier preference, Internet weather, resource utilization/health reports, an allocated or determine routing cost, service level agreements (SLAs), or other criteria. 
     In one embodiment, each distribution router  108  can maintain the portion of the FIB that is associated with the subset of IP addresses assigned the respective distribution level router  108 . In another embodiment, each distribution level router  108  can maintain the entire FIB associated with the distributed routing environment  100  in a memory component, such as computer readable medium  158  ( FIG. 1B ). Once a subset of IP addresses are assigned to each respective distribution level router  108  (or otherwise updated), the applicable portions of the FIB are loaded in a different memory components, such as memory component  154  ( FIG. 1B ) utilized by the router (e.g., a routing chip level content addressable memory or a processor level cache memory). The maintenance of the applicable portions of the FIB in a memory component facilitates better router performance by faster memory access times for the applicable portion of the FIB. However, in this embodiment, the allocation of FIBs to each distribution level router  108  can be modified by loading different portions of the stored FIB from a first memory component storing the entire FIB (e.g., the computer readable medium  158 ) to the memory component maintaining the portion of the FIB allocated to the distribution level router  108  (e.g., memory component  154 ). Accordingly, this embodiment facilitates the dynamic allocation of distribution level routers  108 , the creation of redundant distribution level routers, and additional failover for distribution level routers. Additionally, one or more core level routers  106  can utilize a similar technique in performing the functions associated with the core level of the distributed routing environment  100 . 
     In still a further embodiment, as a variation to the above embodiment, each distribution level router can be allocated a larger portion of the FIB associated with the distributed routing environment  100  than is capable of being maintained in a first memory component of the router, such as memory component  154  (e.g., a processor level cache memory). If a core level router  106  routes to a distribution level router  108  and the corresponding prefixes of the destination IP address do not correspond to the FIB maintained in the first memory component of the distribution level router, the distribution level router can recall the necessary information from the larger subset of the FIB maintained in a different memory component (e.g., computer readable medium  158  ( FIG. 1B )). The FIB maintained in the first memory component (e.g., memory component  152 ) may be updated to store the prefix in the primary memory component. Alternatively, the FIB in the first memory component may not be automatically updated based on a single request, but based on increases in traffic for a given prefix. 
     In yet another embodiment, lower traffic prefixes may be assigned to multiple distribution level routers  108 . In one example, each assigned distribution level router  108  does not maintain the lower traffic routing portion of the assigned FIB in the primary memory component. Rather, routing requests for the lower traffic prefixes can be directed to a specific distribution level router based on selection techniques, such as ECMP, and can be processed by a selected distribution level router  108  based on the larger FIB maintained in a different memory component within the selected distribution level router. 
     With reference now to  FIG. 3 , a routine  300  for routing packets and implemented in a distributed routing environment  100  will be described. At block  302 , the distributed routing environment  100  obtains a routing request. As previously described, the routing request is received from a first network  102  ( FIG. 1 ) and includes information identifying a destination IP address. At block  304 , a core level router  106  corresponding to a first level of the distributed routing environment  100  is selected and receives the routing request. In an illustrative embodiment, each core level router  106  can perform the same function and can selected in accordance with standard selection techniques, including, but not limited to, random selection, round robin selection, load balancing selection and the like. 
     At block  306 , the selected core level router  106  identifies a distribution level router  108  corresponding to a second level of the distributed routing environment  100 . The core level router  108  selects the distribution level router  108  based on processing the destination IP address and utilizing a subset of the destination IP addresses (e.g., the prefix) to determine the appropriate distribution level router  108 . Illustratively, in accordance with an embodiment corresponding to the IPv4 communication protocol, the core level router  106  processing can be based on consideration of a prefix of the eight most significant bits. At block  308 , the selected distribution level router  108  identifies a transit level router  110  based on processing the destination IP address and utilizing a subset of the destination IP address to determine the appropriate transit level router  110 . Illustratively, in accordance with an embodiment corresponding to the IPv4 communication protocol, the distribution level router  108  processing can be based on a larger subset of IP address (e.g., a longer prefix such as 16 or 24 bits, as needed to select the appropriate transit level router  110 ). One skilled in the relevant art will appreciate, however, the blocks  306  and  308  may be implemented in a manner such the core level router  106  and distribution level router  108  may utilize additional or alternative attributes (including different portions of a destination IP address) of received packets in identifying the next router component to forward the received packet. 
     At block  310 , the selected transit level router  110  transmits the receive packet to the destination recipient associated, or otherwise configured, with the transit level router  110 . At block  312 , the routine  300  terminates. 
     With reference now to  FIG. 4 , another routine  400  for routing packets and implemented in a distributed routing environment  100  will be described. In an illustrative embodiment, routine  400  may be implemented in embodiments in which less than all the FIB associated with a particular distribution router  108  is maintained in a primary memory component. At block  402 , a routing request is received at a distribution level router  108 . The selection and routing to a distribution level router  108  was previously described above. Although routine  400  will be described with regard to implementation by a distribution level router  108 , one skilled in the relevant art will appreciate that at least portions of routine  400  may be implemented by other components of the distributed routing environment  100 , such as core level routers  106  or transit level router  110 . At decision block  404 , a test is conducted to determine whether the subset of the destination IP address associated with the routing request is in the portion of the FIB table maintained in the primary memory of the selected distribution level router  108 . If so, at block  406 , the distribution level router  108  obtains the transit layer routing information from the FIB maintained in the first memory component (e.g., memory component  152  ( FIG. 1B )). At block  408 , the distribution level router  108  forwards the packet to the selected transit level router  110 . 
     Alternatively, if at decision block  404  the subset of the destination IP address associated with the routing request is not maintained in the portion of the FIB table maintained in the primary memory of the selected distribution level router  108 , at block  410 , distribution level router  108  attempts to obtain additional transit routing information from a separate memory component associated with the distribution level router. At block  410 , the distribution level router  108  can update the forwarding table information maintained in the primary memory component with the information obtained from the other memory component. Alternatively, block  410  can be omitted or is otherwise optional. At block  412 , the routine terminates. 
     While illustrative embodiments have been disclosed and discussed, one skilled in the relevant art will appreciate that additional or alternative embodiments may be implemented within the spirit and scope of the present disclosure. Additionally, although many embodiments have been indicated as illustrative, one skilled in the relevant art will appreciate that the illustrative embodiments do not need to be combined or implemented together. As such, some illustrative embodiments do not need to be utilized or implemented in accordance with the scope of variations to the present disclosure. 
     Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, or steps. Thus, such conditional language is not generally intended to imply that features, elements or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements or steps are included or are to be performed in any particular embodiment. Moreover, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey utilization of the conjunction “or” in enumerating a list of elements does not limit the selection of only a single element and can include the combination of two or more elements. 
     Any process descriptions, elements, or blocks in the flow diagrams described herein and/or depicted in the attached figures should be understood as potentially representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process. Alternate implementations are included within the scope of the embodiments described herein in which elements or functions may be deleted, executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those skilled in the art. It will further be appreciated that the data and/or components described above may be stored on a computer-readable medium and loaded into memory of the computing device using a drive mechanism associated with a computer-readable medium storing the computer executable components, such as a CD-ROM, DVD-ROM, or network interface. Further, the component and/or data can be included in a single device or distributed in any manner. Accordingly, general purpose computing devices may be configured to implement the processes, algorithms, and methodology of the present disclosure with the processing and/or execution of the various data and/or components described above. Alternatively, some or all of the methods described herein may alternatively be embodied in specialized computer hardware. In addition, the components referred to herein may be implemented in hardware, software, firmware or a combination thereof. 
     It should be emphasized that many variations and modifications may be made to the above-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.