Abstract:
A method and apparatus embodying some aspects of a packet processing communication system. The packet processing communication apparatus comprises a packet processor and a microprocessor. The packet processor is configured to process packets belonging to a certain flow through a plurality of processing stages of a programmable data-path. The microprocessor is in communication with the packet processor and is configured to process a user-defined function in the programmable data-path on designated packets belonging to the certain flow. The packets of respective flows to be processed by the microprocessor are designated in a mapping. The designated packets processed by the microprocessor are returned to one of the processing stages of the packet processor for further processing.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to processing of network traffic, and more particularly to implementing a PON processor. 
       BACKGROUND OF THE INVENTION 
       [0002]    Passive optical networks (PON) have been developed to provide high bandwidth traffic for subscribers over an optical cable. An exemplary diagram of a typical PON  100  is schematically shown in  FIG. 1 . The PON  100  includes M optical network units (ONUs)  120 - 1 ,  120 - 2 , through  120 -M (collectively ONU  120 ), coupled to an optical line terminal (OLT)  130  via a passive optical splitter  140 . Traffic data transmission may be achieved by transmitting data over two optical wavelengths, one for the downstream direction and another for the upstream direction. Downstream transmission from the OLT  130  is broadcasted to all ONUs  120 . Each ONU  120  filters its respective data according to, for example, pre-assigned tag values. ONUs  120  transmit respective data to OLT  130  during different time slots allocated by OLT  130  for each ONU  120 . Splitter  140  splits a single line into multiple lines, for example, 1 to 32, or, in case of a longer distance from OLT  130  to ONUs  120 , 1 to 16. 
         [0003]    An ONU includes a PON processor utilized for processing downstream traffic received from the OLT and providing the contents of the downstream traffic to one or more subscriber devices. Similarly, the PON processor of the ONU is designed to receive and transmit upstream data from one or more subscriber devices to the OLT via the passive optical network. 
         [0004]      FIG. 2  shows an exemplary diagram of a PON processor  200 . The PON processor  200  typically includes a microprocessor  210 , a packet processor  220 , an Ethernet media access control (MAC) adapter  230 , a PON MAC adapter  240 , and a memory controller  250  that interacts with an external memory. The various components of the PON processor  200  communicate through an internal bus  260 . An example for a PON processor is shown in U.S. Pat. No. 7,643,753 assigned in common to the same assignee as the present application, and is hereby incorporated for all that it contains. 
         [0005]    In the architecture of the PON processor  200 , there are two logic paths: data and control. In the data path, traffic from/to the PON is processed by the packet processor  220 . The processing tasks in the data path include, for exempla, bridge learning, queuing, shaping, and reassembling of packets. Data processed by the packet processor  220  may be either an upstream flow, i.e., data sent from a subscriber device to the OLT or a downstream flow, i.e., data sent from the OLT to a subscriber device. The packet processor  220  is a dedicated piece of hardware designed to accelerate the processing of packets belonging to a certain flow. 
         [0006]    In the control path, the microprocessor  210  executes tasks that are typically related to management of connections handled by the PON processor  200 . For example, such tasks include, but are not limited to, open/close connections, control the state of a connection, identifying traffic received on a new connection, and so on. Such operations generally do not require processing of individual packets belonging to a certain flow. For example, if the microprocessor  210  identifies a packet received on a new connection, then the processing of the first packet will be performed by the microprocessor  210  and subsequence packets are handled only by the packet processor  220 . 
         [0007]    In addition to different processing tasks performed by the packet processor  220  and microprocessor  210 , each processor is programmable differently. Specifically, in order to allow fast processing of traffic, the packet processor  220  is programmable using firmware, which comprises low-level execution code (e.g., assembly or any proprietary programming language). The firmware includes instructions purposely designed to accelerate the processing tasks of the packet processor  220 . The firmware is developed by the vendor of the PON processor  200  and is integrated therein prior to the installation of the PON processor  200  in an ONU. Thus, any modifications in the firmware can be made by the vendor of the PON processor  200 . 
         [0008]    The microprocessor  210  is typically a general-purpose central processing unit (CPU) that is programmable to execute software that includes high-level programming language (e.g., C) over an operation system. Any modifications to the software of the microprocessor  210  can be performed on-site, for example, by a novice technician of the ONU, by re-programming the software of the microprocessor  210 . 
         [0009]    On one hand, even a high-performance microprocessor cannot execute processing tasks as fast as dedicated processors, i.e., the packet processor  220 . On the other hand, dedicated processors are not as flexible as general-purpose CPUs. For example, if a new processing task should be performed in the data path, the firmware should be re-programmed and re-installed on the PON processor  200 . The lack of flexibility in such architectures is a major drawback for the network providers, as once the PON processors  200  are installed in the ONUs  120 , modifications to the processing tasks cannot easily be performed on-site. 
         [0010]    Thus, it would be highly advantageous to provide programmable network processors that can easily be modified and on-site. 
       SUMMARY OF THE INVENTION 
       [0011]    Certain embodiments of the invention include a network processor. The network processor comprises a packet processor for processing packets belonging to a certain flow through a plurality of processing stages of a programmable data-path; a microprocessor-data for performing one or more user-defined functions in the programmable data-path on designated packets belonging to the certain flow, wherein packets of respective flows to be processed by the microprocessor-data are designated in a flow table; a microprocessor-control for managing connections handled by the PON processor; a data-path bus for connecting the packet processor and the microprocessor-data, wherein the designated packets are transferred between the packet processor and the microprocessor-data on the data-path bus; and a control-path bus for connecting the packet processor and the microprocessor-control. 
         [0012]    Certain embodiments of the invention also include a method for processing packets in a programmable data path of a network processor. The method comprises processing, by a packet processor, packets belonging to a certain flow through a plurality of processing stages of the programmable data path; upon completion of an N th  processing stage in the data path, dispatching the packets designated in a flow table to a microprocessor-data, wherein the N th  processing stage is designated in the flow table as the processing stage that at which the packets should be dispatched; performing, by the Microprocessor-data, user-defined functions on designated packets; and returning the designated packets to the packet processor to complete the processing of such packets through remaining processing stages of the programmable data path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
         [0013]    The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings. 
           [0014]      FIG. 1  is a diagram of a PON; 
           [0015]      FIG. 2  is a schematic diagram of a PON processor; 
           [0016]      FIG. 3  is a diagram illustrating the principles of an embodiment of the invention; 
           [0017]      FIG. 4  is a block diagram of a PON processor implemented in accordance with an embodiment of the invention; and 
           [0018]      FIG. 5  is a flowchart illustrating a method for processing packets in the data-path. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    It is important to note that the embodiments disclosed by the invention are only examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others. In general, unless otherwise indicated, singular elements may be in plural and vice versa with no loss of generality. In the drawings, like numerals refer to like parts through several views. 
         [0020]      FIG. 3  shows an exemplary and non-limiting diagram of a data path. In the data path, packets belonging to a certain flow are processed by a packet processor  310  and a first microprocessor (hereinafter microprocessor-data)  320 . The firmware of the packet processor  310  is programmable to include multiple processing stages P 1  through P n . These stages may include, but are not limited to, parsing, classifying, filtering, encrypting, and routing/bridging of packets. 
         [0021]    The microprocessor-data  320  is programmable to process packets belonging to a certain flow. Specifically, the microprocessor-data  320  is designed to perform user-defined tasks (or functions) that are programmed in software (e.g., by technicians on-site) and/or tasks that require high-layer processing (e.g., layer 5 and above of the OSI model). For example, such tasks include, but are not limited to, user custom virtual local area network (VLAN) tag manipulation, packet inspection, advanced access control, quality of service (QoS), and the like. 
         [0022]    According to an embodiment of the invention, all packets belonging to a certain flow and should be processed by the microprocessor-data  320  are dispatched by the packet processor  310 . Once the processing of such packets is completed by the microprocessor-data  320 , they are returned back to the packet processor  310  to one of its processing stages. For example, in the diagram depicted in  FIG. 3 , the packets are returned either to a processing stage P n-1  (which may include encryption of packets) or processing stage P n  (which may include routing of packets through one of egresses). In addition, packets may be returned to a processing stage (illustrated by a dash line) of the packet processor  310  and then back to microprocessor-data  320  for further processing. 
         [0023]    When dispatching a packet, the packet processor  310  provides the microprocessor-data  320  with packet information including, for example, a flow-ID, a MAC address, an IP address, and a port number. The microprocessor-data  320  can use this information to retrieve packet from a memory (not shown in  FIG. 3 ). Packets processed by the microprocessor-data  320  are written back to the memory. In another embodiment, packets can be transferred between the packet processor  310  and the microprocessor-data  320  over a data-path bus (not shown in  FIG. 3 ). 
         [0024]    The software executed by the microprocessor-data  320  performs fast context switching and parallel processing to reduce latencies when accessing the memory and communicating with the packet processor  310 . The software executed by the microprocessor-data  320  is coded using a high-level programming language (e.g., C), thereby the programming can be easily modified by a user. 
         [0025]    The flexibility that is provided by implementing a data path as depicted in  FIG. 3  will be understood from the following non-limiting example. In a conventional PON processor (e.g., PON processor  200 ), the firmware of the packet processor is configured with a set of rules designed for performing VLAN tag modification. VLANs are created to provide the segmentation services traditionally provided by routers in LAN configurations. Once installed in the ONU including an addition VLAN tag modification rules requires re-programming the firmware. As mentioned above, this task is performed by the vendor of PON processor. That is, the vendor should program a new version of firmware, test if the new version is operable, and send the new version of firmware to a network provider to install the ONUs with the new firmware. Therefore, even a simple modification to the firmware can take months until implemented. 
         [0026]    In the proposed data path, the software of the microprocessor-data  320  can be updated with a new rule for the VLAN tag manipulation and instructions on which flows/packets the new rule should be applied. As the software of the microprocessor-data  320  is written using a high-level programming language and can be updated by the network provider, such a software update can be performed on-site in a matter of hours. It should be appreciated that the VLAN tag manipulation is only one example and other examples will be apparent to one with ordinary skill in the art. 
         [0027]      FIG. 4  shows an exemplary and non-limiting block diagram of a PON processor  400  implemented in accordance with an embodiment of the invention. The PON processor  400  includes a packet processor  410 , a first microprocessor (hereinafter microprocessor-data)  420 , a second microprocessor (hereinafter microprocessor-control)  430 , a memory controller  440  that interacts with an external memory, an Ethernet MAC adapter  450 , and a PON MAC adapter  460 . The packet processor  410  communicates with the microprocessor-data  420 , Ethernet MAC adapter  450 , and PON MAC adapter  460  through a data-path bus  470 . The microprocessor-data  420  interfaces with a data path bus using a bus adapter  480  that utilizes a cache memory  485 . The packet processor  410 , microprocessor-data  420 , and memory controller  440  are connected through a control-path bus  490 . In certain embodiments of the invention, the PON processor  400  may include an array of packet processors  410 . 
         [0028]    In accordance with an embodiment, the data-path bus  470  transfers data at high rates and its architecture is based on a push-ahead mechanism, using a binary tree topology. The data-path bus  470  supports parallelism in read and write transactions and allows simultaneous transfer of data from/to various components. A more detailed description of the broad bus  470  can be found in U.S. Pat. No. 7,370,127 assigned in common to the same assignee as the present application, and which is hereby incorporated for all that it contains. 
         [0029]    As described in detail above, the microprocessor-data  420  operates together with the packet processor  410  in the data path to process packets belonging to a certain flow. In one embodiment, packets belonging to a designated flow can be transferred on the data-path bus  470 . In another embodiment, packets can be read and written to the external memory through the memory controller  440 . In order to accelerate the packet processing, the microprocessor-data  420  can use data cached in the memory  485 . 
         [0030]    The microprocessor-control  430  is operable in the control path and executes tasks that are typically related to management of connections handled by the PON processor  400  and to the control of the PON processor  400 . The microprocessor-control  430  does not process individual packets belonging to a certain flow. 
         [0031]    Typically, each of the microprocessor-data  420  and microprocessor-control  430  includes internal memory (not shown) that may consist of a program memory to keep the software and the operating system, a data memory to hold data of the various tasks, and a context memory to maintain instances of registers. When updating the software of, for example, the microprocessor-data  420  the new software is uploaded to its internal program memory. In a similar fashion, the packet processor  410  also includes an internal memory (not shown) that consists of a program memory, a context memory, and as data memory. The firmware of the packet processor  410  is saved in the program memory. 
         [0032]    In accordance with an exemplary embodiment of the invention, the microprocessor-data  420  and microprocessor-control  430  are high-performance MIPS 74KEC RISC microprocessors. The microprocessor-control  430  is designed to perform time-consuming and complex processing tasks, thus it runs a complete operating system (e.g., Linux). In order to perform fast context switching and parallel processing the microprocessor-data  420  does not run an operating system. 
         [0033]    The Ethernet MAC adapter  450  includes a plurality of Ethernet interfaces for interfacing with a plurality of subscriber devices. These interfaces may be, but are not limited to, 100 Mbit Ethernet, 1 Gigabit Ethernet, 10 Gigbit Ethernet, and the like. The Ethernet MAC adapter  450  is capable of receiving upstream data flow from subscribe devices and transmitting downstream data to subscribers. The PON MAC adapter  460  processes traffic in accordance with the various PON modes that include, but are not limited to, a Gigabit PON (GPON), a Broadband PON (BPON), an Ethernet PON (EPON), or any combination therefore. The PON MAC adapter  460  handles received downstream data flows and transmits upstream data flows. Either upstream or downstream data flows are respectively forwarded to or received from the packet processor  410  via the data-path bus  470 . 
         [0034]    As discussed above, the firmware of the packet processor  410  is programmable to include multiple processing stages that may include, but are not limited to, parsing, classifying, filtering, encrypting, and routing/bridging of packets. In accordance with an embodiment, one or more of the processing stages can be performed by the microprocessor-data  420 . The user can define that certain flows will be processed, in part, by the microprocessor-data  420 . That is, one or more of the functions will be performed by the microprocessor-data  420  instead of the packet processor  410 . With this aim, the user should program the software of the microprocessor-data  420  with the functions to be performed. In addition, the user should designate in a flow table the flows (by the flow-ID) that should be processed by the microprocessor-data  420  and at which processing stage that packets belonging to the designated flow Should be dispatched to microprocessor-data  420 . The flow table is typically kept in the internal memory of the packet processor  410 . 
         [0035]    The operation of the programmable data path comprising the packet processor  410  and the microprocessor-data  420  is further illustrated in  FIG. 5 . At S 510 , an incoming packet is parsed and classified to determine the flow-ID of the packet. At S 520 , it is checked if the flow-ID is designated in the flow table as required processing by the microprocessor-data  420 , and if so, at S 530 , it is determined at which processing stage that packet should be dispatched to the microprocessor-data  420 . At S 540 , the packet is processed by the packet processor  410 , which at S 550  transfers the packet to the microprocessor-data  420  at the processing stage determined at S 530 . As mentioned above, packets can be transferred directly through the data-path bus or retrieved from the external memory. In the latter embodiment, the packet processor  410  provides the microprocessor-data  420  with the packet information. At S 550 , once the processing of the microprocessor-data  420  is completed, processing results are returned to the packet processor  410  that may update the packet accordingly. Alternatively, the microprocessor-data  420  may transfer the packet to the packet processor  410  or write the processed packet in the external memory. If S 520 , results with a NO answer, execution terminates. 
         [0036]    It should be noted that some packets belonging to a certain flow can be processed by the microprocessor-data  420  and some not. Therefore, it is important to maintain the order of packets output from the processor  200  as their input order. In accordance with an embodiment of the invention, packets per flow are reordered (to their input order) by the egress. 
         [0037]    The architecture of a specific embodiment depicted in  FIG. 4  is of a PON processor. However, a person with ordinary skill in the art can easily adapt the teachings disclosed herein to implement a network processor for access networks other than PONs. 
         [0038]    The principles of the invention can be implemented as hardware, firmware, software or any combination thereof. Moreover, the software is preferably implemented as an application program tangibly embodied on a program storage unit, a non-transitory computer readable medium, or a non-transitory machine-readable storage medium that can be in a form of a digital circuit, an analogy circuit, a magnetic medium, or combination thereof. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units (“CPUs”), a memory, and input/output interfaces. The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be either part of the microinstruction code or part of the application program, or any combination thereof, which may be executed by a CPU, whether or not such computer or processor is explicitly shown. In addition, various other peripheral units may be connected to the computer platform such as an additional data storage unit and a printing unit. 
         [0039]    The foregoing detailed description has set forth a few of the many forms that the invention can take. It is intended that the foregoing detailed description be understood as an illustration of selected forms that the invention can take and not as a limitation to the definition of the invention. It is only the claims, including all equivalents that are intended to define the scope of this invention.