Patent Publication Number: US-9847937-B2

Title: Hardware acceleration for routing programs

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This present disclosure claims priority to U.S. Provisional Patent Application Ser. No. 61/804,924 filed Mar. 25, 2013, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     As computing devices have become increasingly available and part of our everyday lives, it has become important for people to be able to interconnect some of these devices. Computing devices can be interconnected using a network, which allows data to be communicated between two devices by way of one or more intermediary devices referred to as routers. A router is a device that receives data from one device and sends the received data to another device (e.g., another router) based on a target destination of the data. The data is typically received and sent in the form of packets of data. While current routers are useful, they are not without their problems. One such problem is that it remains difficult to build routers that are relatively inexpensive, are easily changeable by users, and route data quickly. This can lead to frustration for the user of the router and a poor user experience with the router. 
     SUMMARY 
     This summary is provided to introduce subject matter that is further described below in the Detailed Description and Drawings. Accordingly, this Summary should not be considered to describe essential features nor used to limit the scope of the claimed subject matter. 
     In general, in one aspect, this specification describes a method that includes monitoring, in a router having a hardware layer and a software layer, communications between a routing determination program and a packet router. The routing determination program identifies one or more paths to each of multiple possible target destinations for packets in a network, and the packet router maintains a forwarding information base identifying selected ones of the one or more paths. The communications include the routing determination program providing to the packet router configuration data that identifies the selected ones of the one or more paths, and the routing determination program and the packet router are both part of a software layer of the router. The method also includes changing, based on the monitored communications, a packet processor to reflect the configuration data, the packet processor being part of a hardware layer of the router. 
     In general, in another aspect, this specification describes a router that includes a packet processor implemented in a hardware layer of the router, and one or more programs implemented in a software layer of the router. The one or more programs are configured to monitor communications between a routing determination program and a packet router, the communications including the routing determination program providing configuration data to the packet router. The routing determination program and the packet router are both part of the software layer of the router. The one or more programs are further configured to change, based on the monitored communications, the packet processor to reflect the configuration data. 
     In general, in another aspect, this specification describes a computer-readable memory device comprising computer-executable instructions that, when executed, implement a router to monitor, in the router, communications between a routing determination program and a packet router. The communications include the routing determination program providing configuration data to the packet router, and the routing determination program and the packet router are both part of a software layer of the router. The router is also to change, based on the monitored communications, a packet processor to reflect the configuration data, the packet processor being part of a hardware layer of the router. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the figures, the left-most digit of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different instances in the description and the figures indicate like elements. 
         FIG. 1  illustrates an example network in which the methods and apparatus for hardware acceleration for routing programs can be used in accordance with one or more embodiments. 
         FIG. 2  illustrates a router in additional detail in accordance with one or more embodiments. 
         FIG. 3  illustrates another router in additional detail in accordance with one or more embodiments. 
         FIG. 4  is a flowchart illustrating an example process for hardware acceleration for routing programs in accordance with one or more embodiments. 
         FIG. 5  illustrates an example system that can implement various aspects of the techniques described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Methods and apparatus for hardware acceleration for routing programs are discussed herein. Generally, a router operates on packets of data it receives, oftentimes receiving packets from one router and sending the received packets to another router to progress the packets towards their target destination. The router includes a software layer and a hardware layer. The software layer includes a user space implementing both a routing determination program and a call monitoring program, and a kernel space that implements a packet router. The routing determination program determines paths for packets the router may receive based on possible target destinations for packets, generates records that include the determined paths, and communicates selected ones of the determined paths to the packet router as configuration data for the packet router. The call monitoring program monitors this communication of the selected paths to the packet router, identifies the selected paths in the communication, and has the selected paths reflected in a packet processor implemented in the hardware layer. The call monitoring program provides the selected paths to the packet processor itself, or alternatively provides the selected paths via a hardware configuration program implemented in the user space. Other configuration data can also be provided to the packet router, such as data identifying packets that are to be provided to a program of the software layer rather than being sent to another router. This configuration data is similarly monitored by the call monitoring program, and reflected in the packet processor. 
     Having the configuration data reflected in the packet processor allows many operations of the router to be performed in the hardware layer rather than the software layer. For example, in response to receipt of a packet the packet processor can use the configuration data to determine the router that the packet is to be sent to, and send the packet to that router without involving the software layer. This increases the speed at which packets can be received, a next router identified based on the target destination, and the packet sent to the next router (e.g., because these actions can typically be performed faster by hardware than by software). This also frees a central processing unit of the router to perform operations other than routing packets. 
       FIG. 1  illustrates an example network  100  in which the methods and apparatus for hardware acceleration for routing programs can be used in accordance with one or more embodiments. The network  100  allows data to be passed from a source device  102  to a target device  104  through one or more routers, such as routers  106 ,  108 ,  110 ,  112 , and  114 . To send data from the source device  102  to the target device  104 , the source device puts the data in a data structure referred to as a packet. The packet includes the data being sent, as well as various header information that describes the packet, describes the data, and so forth. The source device  102  also associates with the packet information identifying the target device  104 , such as by including an identifier of the target device  104  in the header of the packet. The target device  104  is also referred to as the target destination for the packet. The source device  102  provides the packet to a router of the network  100  (or alternatively the source device  102  is a router of the network  100 ), and that router both determines the next router of the network  100  in a path to the target device  104  and sends the packet to that determined next router. This process continues, with each router that receives the packet determining a next router in a path to the target device  104 , and each router sending the packet to the determined next router in a path to the target device  104 , until the packet reaches the target device  104 . The target device  104  is coupled to (or alternatively is) a router of the network  100 . Although a single source device  102 , a single target device  104 , and five routers  106 - 114  are illustrated, it should be noted that the network  100  can include any number of source devices, any number of target devices, and any number of routers. 
     By way of example, the source device  102  is coupled to and provides a packet to the router  108 . The router  108  determines that the router  106  is the next router in a path to the target device  104 , and sends the packet to the router  106 . The router  106  determines that the router  114  is the next router in a path to the target device  104 , and sends the packet to the router  114 , which is coupled to and provides the packet to the target device  104 . It should be noted that this is a specific example, and that the packet can pass through any number of routers when traveling from the source device  102  to the target device  104 . 
     It should also be noted that each of the routers  106 - 114  knows or is configured with a path (or at least a next router in a path) to the target device  104 , but different routers  106 - 114  may know or be configured with different paths to the target device  104 . For example, the router  108  may know a path to the target device  104  that passes from the router  108  to the router  110  to the router  112  to the router  114 , whereas the router  110  may know a path to the target device  104  that passes from the router  110  to the router  106  to the router  114 . 
     It should further be noted that each of the routers  106 - 114  can know or be configured with a full path to the target device  104 , or alternatively with a next router in a path to the target device. Each router  106 - 114  thus need not know all paths through the network  100 . Rather, each router  106 - 114  can simply know or be configured with a next router in a path to each of multiple target devices. 
     The router  106  implements the hardware acceleration for routing programs techniques discussed herein. In one or more embodiments other routers  108 - 114  also implement the hardware acceleration for routing programs techniques discussed herein, although alternatively one or more of the routers  108 - 114  do not implement the hardware acceleration for routing programs techniques discussed herein. The router  106  includes both a software layer  120  and a hardware layer  122 . The software layer  120  includes a routing determination program  124 , a call monitoring program  126 , and a packet router  128 . The software layer  120  refers to programs or modules that are implemented as instructions to be executed or otherwise processed by a central processing unit (CPU) or other processor of the router  106  to carry out the functionality of the programs or modules. The software layer  120  includes programs or modules in software, firmware, or combinations thereof. The hardware layer  122  includes a packet processor  130 . The hardware layer  122  refers to physical components that carry out particular functionality, such as analog or digital circuits, logic components, wires or other connectors, registers, and so forth. 
     Generally, the routing determination program  124  identifies and maintains a record of one or more paths to each of multiple possible target destinations for packets. The target destination for a packet refers to the target device to which the packet is being sent. These one or more paths are also referred to as routing information bases (RIBs). From these one or more paths, the routing determination program  124  selects and maintains a record of one path for each of the multiple possible target destinations. The collection of selected paths is also referred to as a forwarding information base (FIB). The routing determination program  124  communicates the FIB to the packet router  128 . The call monitoring program  126  monitors this communication, and has the FIB reflected in (stored in a manner usable by) the packet processor  130 . The packet processor  130  uses the FIB to determine a next router to send received packets to, based on the target destinations of the packets. The routing determination program  124  and the packet router  128  need have no knowledge of, and typically have no knowledge of, the call monitoring program  126 . 
     In one or more embodiments, additional configuration data is similarly provided to the packet router  128  by the routing determination program  124  or other program in the software layer  120 . This additional configuration data identifies, for example, types of packets or target destinations that are to be provided to the routing determination program  124  or other program in the software layer  120 , rules or criteria to determine which packets are to be provided to the routing determination program  124  or other program in the software layer  120 , and so forth. This additional configuration data thus identifies packets that are to be provided to a program of the software layer  120  rather than sent to another router. The call monitoring program  126  monitors the communication of this additional configuration data to the packet router  128 , and has this additional configuration data reflected in the packet processor  130 . Thus, received packets to be provided to the routing determination program  124  or other program in the software layer  120  are provided to such program by the packet processor  130 . 
       FIG. 2  illustrates the router  106  in additional detail in accordance with one or more embodiments. The router  106  includes the software layer  120  having a user space  202  and a kernel space  204 . The router  106  is implemented on a computing device including a CPU, memory, and an operating system. In one or more embodiments the operating system is a Linux operating system, although various other operating systems can alternatively be used. The CPU and the operating system allow programs to be run in the user space  202  or the kernel space  204 . The kernel space  204  includes programs of an operating system that manage hardware resources of the router  106 , such as access to various input/output (I/O) hardware components, memory, and the CPU. The programs in the kernel space  204  also provide protection from malicious programs, allowing some protection regarding which other programs are permitted to access the hardware resources. Other programs in the user space  202  access the programs in the kernel space  204  to use these hardware resources. The operating system is made up of multiple programs, some of which are part of the user space  202 . Other programs also operate in the user space  202 , for example programs providing various services such as Web page hosting, email or messaging services, and so forth. The user space  202  and the kernel space  204  are implemented using any of a variety of public and/or proprietary techniques. 
     The routing determination program  124  identifies one or more paths to each of multiple possible target destinations for packets in the network. The path to a target destination identifies at least a next router in the path to the target destination, and optionally identifies two or more routers in the path to the target destination. The routing determination program  124  receives paths from various sources, such as a user of the router  106 , other routers, and so forth. Various different protocols are used to describe the paths, such as open shortest path first (OSPF), routing information protocol (RIP), border gateway protocol (BGP), and so forth. Each path also has zero or more attributes (also referred to as metrics) that describe the path, such as the length of the path, the cost associated with using the path, a speed of the path, and so forth. 
     The one or more paths are also referred to as RIBs, and are maintained in an RIB collection  206 . Each RIB is a collection of paths received from a particular source or that uses a particular protocol to describe paths. The RIB collection  206  is stored in memory of the router  106 . 
     The routing determination program  124  selects, for each of multiple possible target destinations, one path from the RIB collection  206 . The routing determination program  124  uses any of a variety of public and/or proprietary techniques to select paths from the RIB collection. For example, the routing determination program  124  may select paths based on one or more attributes of the paths, or alternatively other rules or criteria. The multiple target destinations are identified in any of a variety of different manners, such as being received from a user of the router  106 , being received from another router, being inherent in the addressing protocol used to identify source devices and target devices, and so forth. 
     The collection of selected paths is also referred to as an FIB. For each target destination, a correspondence between the target destination and the selected path to that target destination is maintained by the FIB. This target destination and selected path data is used by the packet processor  130  to route packets to routers along the paths, as discussed in more detail below. 
     The routing determination program  124  communicates the FIB to the packet router  128 , which maintains the FIB as FIB  208 . The FIB  208  is stored in memory of the router  106 . The routing determination program  124  communicates the FIB to the packet router  128  in a manner than can be monitored or snooped by the call monitoring program  126 . In one or more embodiments, the routing determination program  124  communicates the FIB to the packet router  128  by invoking or calling an interface exposed by the packet router  128 , as discussed in more detail below. The routing determination program  124  communicates the FIB to the packet router  128  as commands or calls to operate on particular paths (e.g., add a path to the FIB, remove a path from the FIB, change a path in the FIB, and so forth), or alternatively commands or calls to operate on multiple paths (e.g., remove a set of multiple paths from the FIB, add a set of multiple paths to the FIB, replace the entire FIB with a new FIB, and so forth). 
     The routing determination program  124  identifies paths to include in the RIB collection  206  at various times or in response to various events, such as in response to receipt of a path from another router or a user of the router  106 . The routing determination program  124  also selects paths from the RIB at various times or in response to various events. For example, the routing determination program  124  may select paths to include in the FIB at regular or irregular intervals (e.g., hourly or daily), in response to receipt of a threshold number of new paths from other routers, and so forth. The routing determination program  124  communicates changes to the FIB at regular or irregular intervals. The paths in the RIB collection  206 , as well as in the FIB, can thus change over time. 
     The packet router  128  is configured to pass packets between programs in the user space  202  and the hardware layer  122 . Some packets received by the router  106  target the routing determination program  124 , such as packets providing configuration information for the router  106 , packets providing paths to the router  106 , and so forth. The packet router  128  receives these packets from the hardware layer  122  and communicates the packets to the routing determination program  124 . The packet router  128  communicates the packets to the routing determination program  124  in various manners, such as by invoking or calling an interface exposed by the routing determination program  124 . The packet router  128  can also receive packets from the routing determination program  124  that are to be sent to another router (e.g., providing to another router an indication of paths known to the router  106 ). The routing determination program  124  communicates these packets to the packet router  128  in various manners, such as by invoking or calling an interface exposed by the packet router  128 . The packet router  128  provides these packets to the hardware layer  122 , which sends these packets to another router. 
     The packet router  128  is also configured to receive a packet (e.g., from another router), determine the next router to send the packet to based on both the target destination of the packet and the FIB  208 , and send the packet to the determined next router. However, the packet router  128  does not perform these operations in the router  106 . Rather, the packet processor  130  in the hardware layer  122  performs these operations, ignoring or bypassing the packet router  128 , as discussed in more detail below. 
     The call monitoring program  126  monitors or snoops communications between the routing determination program  124  and the packet router  128 . The call monitoring program  126  monitors communications in various manners, which vary by implementation and operating system. For example, the Linux operating system allows programs to monitor system calls, which include calls made to the packet router  128 . The routing determination program  124  uses calls, which can be referred to as NETLINK_ROUTE sockets that are based on netlink messages, to communicate the FIB to the packet router  128 . The call monitoring program  126  monitors these calls, and has the FIB that is included in these calls reflected in the packet processor  130 . 
     In one or more embodiments, the call monitoring program  126  has the FIB reflected in the packet processor  130  by sending the FIB to a hardware configuration program  210 , which in turn configures the packet processor  130  with the FIB. Configuring the packet processor  130  with the FIB refers to storing in memory of the packet processor  130  data indicating target destinations and the paths of the FIB to those target destinations in a manner that makes the stored data useable by the packet processor  130  to route packets along the paths of the FIB. 
     In embodiments in which the call monitoring program sends the FIB to the hardware configuration program  210 , the hardware configuration program  210  receives data monitored by the call monitoring program  126 , including the FIB, and configures the packet processor  130  with the received data. The hardware configuration program  210  configures the packet processor  130  directly storing the target destination and path data from the FIB as configuration data  212  in memory  214  of the packet processor  130  (e.g., by performing register writes to the packet processor  130 ). Alternatively, the hardware configuration program  210  configures the packet processor  130  by communicating with a device driver (not shown) associated with the packet processor  130 . The device driver is implemented in the kernel space  204  (or alternatively the user space  202 ), and receives from the hardware configuration program  210  the data with which the packet processor  130  is to be configured, and stores the data in memory of the packet processor  130  (e.g., by performing register writes). Use of the device driver allows the hardware configuration program  210  to operate in a more general manner, and rely on the device driver to know the appropriate memory where data is to be stored. For example, the hardware configuration program  210  can call an Add_route interface of the device driver and provide the target destination and path data as parameters. The device driver knows the locations in memory of the packet processor where the target destination and path data are to be stored. Different routers can thus use the same hardware configuration program  210 , but have different packet processors  130 . 
     In embodiments in which the call monitoring program  126  itself configures the packet processor  130  with the FIB, the call monitoring program  126  configures the packet processor  130  by storing the target destination and path data from the FIB as configuration data  212  in memory  214  of the packet processor  130 , analogous to the operation of the hardware configuration program  210 . Alternatively, the call monitoring program  126  can communicate with a device driver associated with the packet processor  130  to store the target destination and path data from the FIB as configuration data  212  in memory  214  of the packet processor  130 , analogous to the operation of the hardware configuration program  210 . 
     In the illustrated example of  FIG. 2 , the call monitoring program  126  and the hardware configuration program  210  are implemented in the user space  202 . Alternatively one or both of the call monitoring program  126  and the hardware configuration program  210  are implemented in the kernel space  204 . 
     In one or more embodiments, the packet processor  130  is implemented as a hardware switch. The packet processor  130  includes the memory  214 , a controller  216 , and multiple I/O ports  218 . The FIB is reflected in the packet processor  130  by being stored as configuration data  212  (e.g., by the hardware configuration program  210 ). The I/O ports  218  can be any number of ports, such as 20, 50 or 100 ports. Each port of the I/O ports  218  receives and transmits packets of data. Incoming packets  220  are received by the I/O ports  218 . For a received packet, the controller  216  performs packet routing operations including identifying the target destination for the packet (e.g., as indicated in a header of the packet), determining the next router in the path to the target destination based on the configuration data  212 , and sending the packet to the next router as an outgoing packet  222 . As the FIB is reflected in the packet processor  130  as the configuration data  212 , given a target destination the selected path to that target destination is readily identified from the configuration data  212 . Depending on the networking protocol being used, the packet routing operations optionally also include, prior to sending the packet to the next router, adding headers or rewriting headers of the packet so that the packet is correctly sent to the next router. 
     It should be noted that the packet processor  130  performs the packet routing operations of receiving packets, determining the next routers in the paths to the target destinations of the packets, and sending the packets to the next routers independent of the software layer  120 . The packet processor  130  performs these packet routing operations ignoring the packet router  128 —the packet router  128  need have no knowledge of, and typically has no knowledge of, the packets that are received and sent by the packet processor  130 . 
     It should also be noted that the packet processor  130  differs from a network interface card. The packet processor  130  includes multiple ports, typically at least 20-30, in contrast to the single port of a network interface card. The packet processor  130  also uses the configuration data  212  to perform the packet routing operations, in contrast to network interface cards which include no such capability. 
     The call monitoring program  126  also monitors or snoops communication of configuration data other than the FIB between the routing determination program  124  and the packet router  128 . For example, in the Linux operating system the routing determination program  124  uses calls (referred to as NetDev calls) to communicate this configuration data to the packet router  128 . Any configuration data that can be communicated between the routing determination program  124  and the packet router  128  indicating the manner in which the packet router  128  is to operate can be monitored by the call monitoring program  126 , which can have the configuration data reflected in the packet processor  130 . This configuration data includes, for example, indications of packets that are to be provided to the routing determination program  124 , such as packets providing configuration information for the router  106 , packets providing paths to the router  106 , and so forth. Packets to be provided to the routing determination program  124  can be identified in different manners, such as packets that have the router  106  as a target destination, packets that are identified (e.g., in a header) as being configuration or control packets, or using various other rules or criteria. 
     The call monitoring program  126  has the monitored configuration data reflected in the packet processor  130 , such as being written as configuration data  212  by the hardware configuration program  210 . Incoming packets  220  that are to be provided to the routing determination program  124  can thus be identified by the controller  216  based on the configuration data  212 , and provided to the packet router  128  by the packet processor  130 . The packet router  128 , in turn, provides the packets to the routing determination program  124 . The packet router  128  communicates with the packet processor  130  as if the packet processor  130  were a traditional network interface card. The packet processor  130  invokes or calls an interface exposed by the packet router  128 . The packet router  128  need have no knowledge that, and typically has no knowledge that, it is communicating with hardware that performs the packet processing operations performed by the packet processor  130 . 
     The packet router  128  also receives packets from the routing determination program  124  that are to be sent to another router, as discussed above. The packet router  128  provides these packets to the hardware layer  122  by invoking or calling an interface exposed by the packet processor  130 . This interface exposed by the packet processor  130  is an interface expected by the packet router  128  to be exposed by a network interface card. The packet processor  130  receives these packets, and the controller  216  sends them to the identified router as an outgoing packet  222 . 
     In one or more embodiments, the routing determination program  124  also communicates with the packet router  128  requesting various status information. Various status information can be requested, such as packet count (a number of packets received or sent over some time period). The call monitoring program  126  monitors such communications, and in response to a request for status information, obtains the requested status information from the packet processor  130  and returns the requested status information to the routing determination program  124 . The call monitoring program  126  itself obtains the status information from the packet processor  130 , or alternatively the call monitoring program  126  communicates a request to the hardware configuration program  210  to obtain the status information from the packet processor  130 . The status information is obtained by requesting the status information from the packet processor  130  (e.g., a request communicated to the controller  216 ), or alternatively by performing a read of the proper memory location (e.g., by performing a register read) of the memory  214  where the status information is stored. 
     The obtained status information is returned to the routing determination program  124  by the call monitoring program  126 . Thus, the routing determination program  124  receives status information from the packet processor  130  via the call monitoring program  126 , without having knowledge that the packet processor  130  is performing the packet processing operations rather than the packet router  128 . It should be noted that care can be taken so that the routing determination program  124  receives a response to the status information request from the call monitoring program  126  rather than from both the call monitoring program  126  and the packet router  128 . In one or more embodiments, an entity (such as a NetDev module) represents network devices to various programs or modules of the router  106 , and a NetDev module is included in the router  106  (e.g., as part of a driver in the kernel space  204 ). The NetDev module receives status information from one or both of the packet router  128  and the packet processor  130 , and provides a single response (e.g., the status information received from the packet processor  130 ) to the call monitoring program  126 . The NetDev module can drop or otherwise ignore the other received status information (e.g., from the packet router  128 ), so the routing determination program  124  receives a response to the status information request from the call monitoring program but not the packet router  128 . 
       FIG. 3  illustrates the router  106  in additional detail in accordance with one or more embodiments. The router  106  includes the software layer  120 , the hardware layer  122 , the RIB collection  206 , and the FIB  208  as discussed above. However, in the example of  FIG. 3  the router  106  also includes a service program  302 . The service program  302  provides various services or functionality to other devices or to the router  106 , such as Web page hosting services, communications services (e.g., email or text messaging), additional path determination or other packet routing functionality, and so forth. The service program  302  optionally communicates with the packet router  128 , providing configuration data identifying packets that are to be provided to the service program  302 , such as packets of particular types, packets having particular target destinations, and so forth. The service program  302  also optionally provides configuration data to the packet router  128  identifying how particular types of packets are to be handled by the packet router  128  (e.g., how the packet router  128  is to determine where to send the packets or otherwise how to handle the packets). 
     The call monitoring program  126  also monitors or snoops communications between the service program  302  and the packet router  128 . The service program  302  uses calls, for example NetDev calls, to communicate the configuration data to the packet router  128 . Any configuration data that can be communicated between the service program  302  and the packet router  128  can be monitored by the call monitoring program  126 , which can have the configuration data reflected in the packet processor  130 . The call monitoring program  126  has the configuration data reflected in the packet processor  130  in various manners, analogous to the reflection of configuration data from the routing determination program  124  in the packet processor  130  as discussed above. 
     Incoming packets  220  that are to be provided to the service program  302  can thus be identified by the controller  216  based on the configuration data  212 , and provided to the packet router  128  by the packet processor  130 . The packet router  128 , in turn, provides the packets to the service program  302 . Additionally, incoming packets  220  that are to be handled in a particular manner as indicated by the configuration data from the service program  302  can thus be identified by the controller  216  based on the configuration data  212 , and handled as indicated by the configuration data  212 . 
     The packet router  128  can also receive packets from the service program  302  that are to be sent to another router or device. The packet router  128  provides these packets to the hardware layer  122  by invoking or calling an interface exposed by the packet processor  130 . This interface exposed by the packet processor  130  is an interface expected by the packet router  128  to be exposed by a network interface card. The packet processor  130  receives these packets, and the controller  216  sends them to the identified router or device as an outgoing packet  222 . 
     Thus, as can be seen from the discussion herein, configuration data communicated to the packet router  128  is monitored by the  126 , which has the configuration data reflected in the packet processor  130 . The configuration data is any configuration data indicating to the packet router  128  how to handle particular types of packets, rules or criteria to apply in handling packets, and so forth. 
       FIG. 4  is a flowchart illustrating an example process  400  for hardware acceleration for routing programs in accordance with one or more embodiments. Process  400  is described in the form of a set of blocks that specify operations to be performed, and the operations are not necessarily limited to the order shown. The operations performed by the set of blocks in process  400  are performed by a router, such as the router  106  of  FIG. 1 ,  FIG. 2 , or  FIG. 3 . 
     At block  402 , communications between a routing determination program and a packet router are monitored. Both the routing determination program and the packet router are implemented in a software layer of a router. The communications include configuration data being provided by the routing determination program to the packet router, such as an FIB as discussed above. 
     At block  404 , a packet processor implemented in a hardware layer of the router is changed, based on the monitored communications, to reflect the configuration data. The configuration data is reflected in the packet processor by being written in memory of the packet processor as discussed above. 
     At block  406 , packet routing operations are performed in the hardware layer by the packet processor. The packet routing operations include receiving packets, determining the next routers in the paths to the target destinations of the packets, and sending the packets to the next routers as discussed above. These packet routing operations are performed in the hardware layer, independent of the software layer. 
     The techniques discussed herein support various usage scenarios. Routers using existing routing determination programs and packet routers can be used with the techniques discussed herein without alteration—no changes need be made to accommodate the packet processor. Neither the routing determination program nor the packet router need be customized to operate with the packet processor, yet can be readily changed as desired by a user of the router without interfering with the techniques discussed herein. The techniques discussed herein provide a low-cost solution to having the packet routing operations of receiving packets, determining the next routers in the paths to the target destinations of the packets, and sending the packets to the next routers independent of the software layer performed in hardware (and thus faster than if performed in software), without having customized software programs or hardware packet processors. Performing the packet routing operations in hardware also frees the CPU of the router to perform other operations, rather than being heavily occupied with performing the packet routing operations. 
       FIG. 5  illustrates an example system  500  that can implement various aspects of the techniques described herein. System  500  can be implemented in a variety of different devices, such as one or a combination of a media device, computer device, television set-top box, video processing and/or rendering device, Ethernet interface, switch, appliance device, gaming device, electronic device, vehicle, workstation, smart phone, tablet, and/or in any other type of computing device. System  500  can be implemented as a System-on-Chip (SoC). 
     System  500  can include electronic circuitry, a microprocessor, memory, input-output (I/O) logic control, communication interfaces and components, other hardware, firmware, and/or software needed to run a device. System  500  can also include an integrated data bus (not shown) that couples the various components of the system for data communication between the components. A wireless communication device that includes system  500  can also be implemented with many combinations of differing components. 
     In this example, system  500  includes various components such as an input-output (I/O) logic control  502  (e.g., to include electronic circuitry) and a microprocessor  504  (e.g., any of a microcontroller or digital signal processor). System  500  also includes a memory  506 , which can be any type and/or combination of RAM, low-latency nonvolatile memory (e.g., Flash memory), ROM, one-time programmable memory, and/or other suitable electronic data storage. The memory  506  includes the software layer  120  of a router, which includes a routing determination program, call monitoring program, and packet router as discussed above. Alternately or additionally, system  500  may comprise a memory interface for accessing additional or expandable off-chip memory, such as an external Flash memory module. System  500  can also include various firmware and/or software, such as an operating system  508 , which can be computer-executable instructions maintained by memory  506  and executed by microprocessor  504 . System  500  may also include other various communication interfaces and components, communication components, other hardware, firmware, and/or software, and so forth. 
     System  500  also includes a hardware layer  122  of a router. The hardware layer  122  includes a multi-port packet processor that performs packet routing operations as discussed above. 
     One or more of the methods or techniques described above can take the form of a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer-readable medium can be any apparatus that can tangibly store the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device). Examples of a computer-readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD. However, computer-readable medium exclude signals, signal transmission, and carrier waves. 
     Further aspects of the present invention relates to one or more of the following clauses. 
     A method includes monitoring, in a router having a hardware layer and a software layer, communications between a routing determination program and a packet router. The routing determination program identifies one or more paths to each of multiple possible target destinations for packets in a network, and the packet router maintains a forwarding information base identifying selected ones of the one or more paths. The communications include the routing determination program providing to the packet router configuration data that identifies the selected ones of the one or more paths, and the routing determination program and the packet router are both part of the software layer of the router. The method also includes changing, based on the monitored communications, a packet processor to reflect the configuration data, the packet processor being part of the hardware layer of the router. 
     In the method, the configuration data comprises for each of the multiple possible target destinations, a selected one path to the target destination. 
     The method further includes, independent of the software layer of the router, receiving packets by the packet processor and also, for each received packet, identifying a next router based on both a target destination of the packet and the configuration data, and sending the packet to the next router. 
     In the method, the configuration data further identifies types of packets or target destinations of packets to be provided to the routing determination program by the packet processor. 
     The method further includes the packet processor providing a received packet to the routing determination program in response to the configuration data in the packet processor indicating the received packet is to be provided to the routing determination program. 
     The method further includes monitoring, in the router, additional communications that are between a service program and the packet router, the additional communications including the service program providing additional configuration data to the packet router, the service program being part of the software layer of the router. The method further includes changing, based on the monitored additional communications, the packet processor to reflect the additional configuration data. 
     The method further includes the packet processor providing a received packet to the service program in response to the additional configuration data in the packet processor indicating the received packet is to be provided to the service program. 
     In the method, the routing determination program is implemented in a user space of the software layer, and the packet router is implemented in a kernel space of the software layer. 
     In the method, the monitoring is performed by a call monitoring program implemented in the user space of the software layer. 
     In the method, the changing includes writing the configuration data to memory of the packet processor. 
     A router includes a packet processor implemented in a hardware layer of the router, and one or more programs implemented in a software layer of the router. The one or more programs are configured to monitor communications between a routing determination program and a packet router, the communications including the routing determination program providing configuration data to the packet router. The routing determination program and the packet router are both part of the software layer of the router. The one or more programs are further configured to change, based on the monitored communications, the packet processor to reflect the configuration data. 
     In the router, the configuration data includes one or more paths of a forwarding information base. 
     In the router, the packet processor is configured to, independent of the software layer of the router, receive packets and for each packet identify a next router based on both a target destination of the packet and the forwarding information base, and send the packet to the next router. 
     In the router, the configuration data includes identification of types of packets or target destinations of packets to be provided to the routing determination program by the packet processor. 
     In the router, the packet processor is configured to provide a received packet to the routing determination program in response to the configuration data in the packet processor indicating the received packet is to be provided to the routing determination program. 
     A computer-readable memory device includes computer-executable instructions that, when executed, implement a router to monitor, in the router, communications between a routing determination program and a packet router. The communications include the routing determination program providing configuration data to the packet router, the routing determination program and the packet router both being part of a software layer of the router. The router is also to change, based on the monitored communications, a packet processor to reflect the configuration data, the packet processor being part of a hardware layer of the router. 
     For the computer-readable memory device, the configuration data includes one or more paths of a forwarding information base. 
     For the computer-readable memory device, the router is further to, independent of the software layer of the router, receive packets by the packet processor and also, for each received packet, identify a next router based on both a target destination of the packet and the forwarding information base, and send the packet to the next router. 
     For the computer-readable memory device, the configuration data includes identification of types of packets or target destinations of packets to be provided to the routing determination program by the packet processor. 
     For the computer-readable memory device, the router is further to monitor, in the router, additional communications that are between a service program and the packet router. The additional communications include the service program providing additional configuration data to the packet router, the service program being part of the software layer of the router. The router is also to change, based on the monitored additional communications, the packet processor to reflect the additional configuration data. 
     Although the subject matter has been described in language specific to structural features and/or methodological operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or operations described above, including orders in which they are performed.