Patent Publication Number: US-2015085871-A1

Title: Dynamically scriptable ip packet processing engine

Description:
BACKGROUND 
     The present invention relates to network processing devices including routers containing IP packet processing engines. 
     When the IP protocol architecture was defined, two general categories of computer networking nodes were defined: IP hosts and IP routers. These terms are defined in IETF RFC 1122: 
     “A host computer, or simply ‘host,’ is the ultimate consumer of communication services. A host generally executes application programs on behalf of user(s), employing network and/or Internet communication services in support of this function. An Internet host corresponds to the concept of an ‘End-System’ used in the OSI protocol suite . . . An Internet communication system consists of interconnected packet networks supporting communication among host computers using the Internet protocols. The networks are interconnected using packet-switching computers called ‘gateways’ or ‘IP routers’ by the Internet community . . . ” 
     Over time, commercial IP router vendors have integrated many services beyond those originally envisioned in IETF RFC 1812 (Requirements for IP Version 4 Routers). For example, specialized network devices (e.g. IP Firewalls and HTTP load balancers) have been developed to enforce network policies on IP traffic flowing through the network according to the network operator&#39;s requirements. These enhanced “routers” provide a set of configurable packet processing functions across protocol layers 2-7. 
     Applications running on hosts do not typically interact directly with the IP routers interconnecting them unless the application itself is a routing protocol or router network management application. However, there are some well-known examples of a host application directly interacting with the intermediate routers as seen with protocols: IETF Resource Reservation Protocol (RSVP), SOCKS5 (RFC 1928), and OpenFlow. Nevertheless, the common theme in each of these is that the functions/services provided by the IP routing device are built-in and the application is simply configuring the predefined functions that the device provides. 
     SUMMARY 
     In one embodiment, the invention provides a dynamically-scriptable router including a packet input port, a packet output port, a dynamically scriptable packet processing engine, and an application interface for loading a packet processing script into the dynamically scriptable packet processing engine. 
     In another embodiment, the invention provides a method for dynamically controlling a router. The method includes the steps of providing a dynamically-scriptable router having a packet input port, a packet output port, a dynamically scriptable packet processing engine, and an application interface; and loading a packet processing script into the scriptable packet processing engine through the application interface. 
     In yet another embodiment, the invention provides a system for dynamically controlling a router. The system includes a dynamically-scriptable router including a packet input port, a packet output port, a dynamically scriptable packet processing engine, an application interface, and a controller in communication with the packet input port, the packet output port, the dynamically scriptable packet processing engine, and the application interface. The controller is configured to load a packet processing script into the scriptable packet processing engine through the application interface. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a diagram of a dynamically-scriptable router  100  according to embodiments of the invention. 
         FIG. 2  shows a diagram of a scriptable packet processing engine running as a user-space program on top of a Linux kernel. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
     In various embodiments the invention includes one or more applications which arbitrary extend the behavior of an IP router by dynamically inserting one or more packet-processing scripts into the forwarding plane of a router as shown in the diagram of  FIG. 1 . 
       FIG. 1  shows a diagram of a dynamically-scriptable router  100  according to embodiments of the invention. The router  100  includes a scriptable packet processing engine  110  having an application interface  120  (sometimes referred to as an “API”), at least one packet input port  130 , and one or more packet output ports  140 . The application interface  120  facilitates loading of packet processing scripts  150  into the packet processing engine  110  and can also transfer data such as debugging and profiling information obtained from executing scripts. The packet processing scripts  150  may include a binary downloaded program  152  (e.g. software written in languages such as C or C#) or an interpreted packet processing script  154  (e.g. written in Java, Javascript, or Python, or derivatives of scripted languages such as Cython and Jython). 
     In use, the scriptable packet processing engine  110  executes a program which provides extensible access to the application interface  120  using a network protocol such as TCP/IP such that an API user&#39;s computer can gain access to the application interface  120 , for example over a wired or wireless network. Packets entering the router  100  via I/O (e.g. packet input ports  130  and packet output ports  140 ) may be managed by the scriptable packet processing engine  110  itself or the packets may be managed by TCP/IP services provided by the operating system of the user&#39;s computer (which uses ports managed by the I/O itself). Within the TCP/IP session, application interface  120  commands are exchanged which extend the functions of the scriptable packet processing engine  110 , provide instructions on how to treat packets, and provide management information. The remote API user&#39;s program is typically running on a remote host, but it is also possible for the API user to be running on the same physical machine that is running the scriptable packet processing engine  110 . Scripts can be updated by sending network packets containing a script to the API or using a CLI or GUI to the API to provide manual scripts written by a user or derived from another script written by a user. 
     The router  100  may include a controller (including, e.g., a microprocessor) in communication with the packet input port, the packet output port, the dynamically scriptable packet processing engine, and the application interface. In various embodiments, the controller is configured to carry out the operations of the router  100  as disclosed herein. 
     The packet input ports  130  and packet output ports  140  can be physical devices (e.g. Ethernet port), logical devices (e.g. VLAN on a physical Ethernet port), or virtual logical devices (virtual Ethernet driver associated with a VSWITCH between virtual machines running on a general purpose computing platform), and a given router  100  may include combinations of types of packet input ports  130  and packet output ports  140 . The number of physical packet input ports  130  and packet output ports  140  on a given router  100  is generally a hundred or less, however, each physical port can support thousands of logical ports (e.g. VLANS). 
     The scriptable packet processing engine  110  can be embodied as an add-on software function to a traditional hardware-based IP packet router, software running on a general purpose computing platform (e.g. blade server), or as a software module extending a virtual hardware switch (VSWITCH) between virtual systems. When running on a general purpose computing platform, the software would typically be run in userspace along with userspace I/O device drivers. The router  100  also includes a microprocessor and memory that are in communication with the scriptable packet processing engine  110 . 
     For example,  FIG. 2  shows the scriptable packet processing engine  110  running as a user-space program on top of a Linux kernel. The user-space located engine  110  is directly managing/programming the I/O hardware, thus completely bypassing the kernel as packets flow through it. 
     The scriptable packet processing engine  110  is dynamically programmed at runtime (by one or more independent application programs) and supports multiple simultaneous independent packet processing scripts. The scripts are executed in a prioritized fashion (as requested by the applications themselves and/or as assigned by the system). A single input packet may be serviced by a variable number of scripts. For example, one application might install a script that makes copies of every packet that matches a specific UDP destination port and sends the copy over a TCP session back to the application. A second script might perform a traffic classification and shaping operation on every packet that arrives on a specific port. A third program might perform deep packet inspection processing and tag the packet (or corresponding traffic flows) with metadata that can be used by a later-executed script to record statistics, etc. 
     The packet processing scripts loaded by the application interface  120  can be defined in either a compiled language (e.g. software written in languages such as C or C#) or an interpreted scripting language such as Python, Java, or Javascript, or derivatives of scripted languages such as Cython and Jython. One advantage of using an interpreted language is that if a script is installed that contains a programming fault, the scriptable packet processing framework will catch the exception and recover gracefully (e.g. terminate the script) without affecting other scripts or packets. For performance, a JIT (Just-in-time) compilation engine can be applied to optimize the interpreted scripts. A second advantage is that these scripts can work across all ranges of devices that support this feature without any changes to the interpreted scripts. Binary compiled programs do not offer this advantage and must generally be recompiled for different hardware devices. Any hardware or software device that supports the interpreted scripting language would be able to use the script without change regardless of the underlying hardware. A third advantage is that these interpreted scripts are often easier for application developers to write, providing application developers with a resource to develop network scripts that run on devices they commonly cannot program. In addition, interpreted packet processing scripts can gain access to direct hardware I/O from userspace. 
     Compared to existing routers for which control is limited to setting of parameters, the dynamically-scriptable router  100  disclosed herein is fully programmable and can be configured to perform arbitrary functions using arbitrary lists of instructions. A particular script may add a new behavior to the router  100 , for example creating a new event such as the transmission of a signaling packet when a certain type of timeout occurs. Furthermore, the arbitrary functions of the dynamically-scriptable router  100  disclosed herein are inserted at run-time, in contrast to the pre-programmed functions that are hardwired into known routers. Finally, the scriptable packet processing engine  110  allows scripts to pass information about a given packet to subsequent scripts (e.g. a retransmission packet) and to also modify the sequence of scripts to be applied to each packet. 
     For the dynamically-scriptable router  100 , a manufacturer or vendor of such a router supplies an environment in a programmable system and each user supplies the functionality they need by providing arbitrarily complex programs to the scriptable packet processing engine  110  via the application interface  120 . Thus, instead of being limited to providing parameters for a few preordained functions as on known routers, a user can make use of the full array of commands available in known programming (e.g. C or C#) or scripting (e.g. Java, Javascript or Python, or derivatives such as Cython and Jython) languages. In addition, in various embodiments a script may add functionality to the router  100  by adding new primitives. 
     In addition to being able to perform adding arbitrary functions, the router  100  disclosed herein is stateful and includes memory that can be read and written to by the scripts. With this capability, the scripts that are run on the packet processing engine  110  can perform functions on the packets that require knowledge of previous packets. While some known systems have a limited amount of memory, e.g. a counter to gather statistics, this memory is for specific uses and is not made available for general use, and therefore is not equivalent to a stateful system. Thus, known routers, which are stateless, cannot take into account packet information which came through the router previously. For example, a http request might have its URL split between two packets but a stateless router would be unable to act on the whole URL since the router would be unable to store the first part of the URL until the second part became available. 
     While known packet processing engines have software that is coded into the device, this software cannot be used to introduce new protocols and the device cannot be reconfigured at runtime. For example, a packet processing program that provides Ethernet encapsulation and IP header encapsulation cannot be simply reconfigured (other than providing a new software image while the device is offline) to process IPSEC header encapsulation. However, with a scriptable packet processing engine such as that disclosed herein, new packet processing protocols can be provided with the existing software images and without requiring offline reconfiguration or addition of new firmware, by merely reconfiguring the existing software with a script introduced at runtime and without interrupting packet forwarding. These scripts can be changed in real-time to quickly update the packet processing protocols of the platform using a variety of scriptable and compiled programming languages, as discussed above. 
     Accordingly, the following are some examples of services that can be provided by scripts running in the packet processing engine  110 :
     Perform protocol decoding of a packet arriving on an input port, perform lookups in existing state tables, update state tables, modify the packet by adding/removing/updating headers or the packet payload, and then forward the resulting packet to an output port   Make a copy of a packet arriving on an input port to an output port   Classify traffic into a category and apply traffic policing/shaping   Scan payload of TCP session vs. known patterns   Perform DPI analysis on packets and tag with the pdu and flows with metadata   Collect various statistics for export   Perform protocol-specific load balancing (e.g. GTP-C decoding) and tunneling of traffic for subsequent processing   Applying/Removing an IP tunneling encapsulation (e.g. MPLS, IPSEC, L2TP, GRE) to traffic matching a pattern   Perform line rate test tool packet generation and packet validation   Perform policy-based IP forwarding   Apply a packet-filtering operation   Perform IP-reassembly   Process packets following IP-reassembly   Tunnel traffic matching specific patterns to a remote application process (or operating system kernel) for additional processing   

     In other embodiments, the dynamically scriptable packet processing engine  110  can be programmed to collect debugging and profiling information from executing scripts and to return this information via the application interface  120 . Scripts (also called plugins) inserted into the packet processing engine  110  can run in both single-threaded mode of operation with a single thread allocated to processing the packets, or a multi-threaded mode of operation that allows multiple threads to concurrently process packets in parallel by any individual running script. 
     Various features and advantages of the invention are set forth in the following claims.