Abstract:
A router for interconnecting external devices. The router comprises a switch fabric and a plurality of routing nodes coupled to the switch fabric. Each routing node comprises packet processing circuitry for transmitting data packets to, and receiving data packets from, the external devices and for transmitting data packets to, and receiving data packets from, other routing nodes via the switch fabric and control data processing circuitry capable of performing control and management functions. The control data processing circuitry comprises a first network processor for performing control and management functions associated with the router and a second network processor for performing control and management functions associated with the router. The control and management functions are dynamically allocated between the first network processor and the second network processor.

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001]     The present invention is generally directed to distributed architecture routers and, in particular, to an apparatus and method using cognitive identical code to distribute control and management plane functions (or operations) between control processors of a multiprocessor router.  
       BACKGROUND OF THE INVENTION  
       [0002]     There has been explosive growth in Internet traffic due to the increased number of Internet users, various service demands from those users, the implementation of new services, such as voice-over-IP (VoIP) or streaming applications, and the development of mobile Internet. Conventional routers, which act as relaying nodes connected to sub-networks or other routers, have accomplished their roles well, in situations in which the time required to process packets, determine their destinations, and forward the packets to the destinations is usually smaller than the transmission time on network paths. More recently, however, the packet transmission capabilities of high-bandwidth network paths and the increases in Internet traffic have combined to outpace the processing capacities of conventional routers.  
         [0003]     This has led to the development of a new generation of massively parallel, distributed architecture routers. A distributed architecture router typically comprises a large number of routing nodes that are coupled to each other via a plurality of switch fabric modules and an optional crossbar switch. Each routing node has its own routing (or forwarding) table for forwarding data packets via other routing nodes to a destination address.  
         [0004]     When a data packet arrives in a conventional routing node, a forwarding engine in the routing node uses forwarding tables to determine the destination of the data packet. A conventional Internet Protocol (IP) router uses a dedicated forwarding table for each type of traffic, such as Internet Protocol version 4 (IPv4), Internet Protocol version 6 (IPv6) and MPLS.  
         [0005]     Conventional routers use many packet processors to route data traffic through the router. However, conventional routers typically use a single control plane processor to perform control plane functions (or operations) and management plane functions (or operations). The single control plane processor handles all management functions and all routing protocols. Some prior art routers may use two control plane processors, a primary and a secondary, for redundancy purposes. But each of these processors performs the same functionality. The primary control processor performs all control and management functions, while the secondary control processor is idle and waits for a failure of the primary control processor. Thus, the redundant processors are not used to increase the aggregate processing power and do not allow optimization of resource utilization through resource allocation.  
         [0006]     Thus, the speed of control plane processing in prior art routers is limited by the processing power of a single processor. This fails to take advantage of parallel processing opportunities. To achieve high route update rates, expensive data processors must be used.  
         [0007]     Therefore, there is a need in the art for improved high-speed routers. In particular, there is a need for a high-speed router in which control and management plane functions are not bottlenecked by a single control plane processor.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention supports distribution of control plane functions (or operations) between the inbound and outbound network processors of a routing node, allows flexible resource allocation, uses standard protocols and operating system software, and provides a software solution with no additional hardware support.  
         [0009]     In an advantageous embodiment, the present invention uses standard Linux sockets and standard protocols, such as TCP and UDP, to allow cognizant, but identical, control and management plane code to run in both the inbound and outbound network processors. This allows the distribution of management and routing functions (or operations) between these two processors, thereby allowing more aggregate processing power to be applied to the control plane functions and to allow splitting the workload between these processors as necessary to meet the control plane throughput requirements.  
         [0010]     To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide a router for interconnecting external devices coupled to the router. According to an advantageous embodiment of the present invention, the router comprises: 1) a switch fabric; and 2) a plurality of routing nodes coupled to the switch fabric, wherein each of the plurality of routing nodes comprises i) packet processing circuitry capable of exchanging data packets with external devices and exchanging data packets with other ones of the plurality of routing nodes via the switch fabric and ii) control processing circuitry capable of performing control and management functions. The control processing circuitry comprises: i) a first network processor capable of performing control and management functions associated with the router; and ii) a second network processor capable of performing the control and management functions associated with the router, wherein the control and management functions are dynamically allocated between the first network processor and the second network processor.  
         [0011]     According to one embodiment of the present invention, the control and management functions are dynamically allocated between the first network processor and the second network processor according to a first level of activity of control and management functions in the first network processor relative to a second level of activity of control and management functions in the second network processor.  
         [0012]     According to another embodiment of the present invention, the first network processor is controlled by first control software code and the second network processor is controlled by second control software code substantially identical to the first control software code.  
         [0013]     According to still another embodiment of the present invention, the first network processor determines a first group of control and management functions allocated to the first network processor by examining a configuration register associated with the first network processor.  
         [0014]     According to yet another embodiment of the present invention, the second network processor determines a second group of control and management functions allocated to the second network processor by examining a configuration register associated with the second network processor.  
         [0015]     According to a further embodiment of the present invention, a first one of the control and management functions may be re-allocated from the first group of control and management functions to the second group of control and management functions by modifying the contents of the first configuration register and the second configuration register.  
         [0016]     Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:  
         [0018]      FIG. 1  illustrates an exemplary distributed architecture router, which distributes forwarding table lookup operations across a plurality of microengines and threads according to the principles of the present invention;  
         [0019]      FIG. 2  illustrates selected portions of the exemplary router according to one embodiment of the present invention;  
         [0020]      FIG. 3  illustrates the inbound network processor and outbound network processor according to an exemplary embodiment of the present invention; and  
         [0021]      FIG. 4  illustrates the inbound network processor and outbound network processor in greater detail according to an exemplary embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]      FIGS. 1 through 4 , discussed below, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any suitably arranged packet switch or router.  
         [0023]      FIG. 1  illustrates exemplary distributed architecture router  100 , which distributes control and management plane functions across a plurality of processors according to the principles of the present invention. Router  100  supports Layer  2  switching and Layer  3  switching and routing. Thus, router  100  functions as both a switch and a router. However, for simplicity, router  100  is referred to herein simply as a router. The switch operations are implied.  
         [0024]     According to the exemplary embodiment, router  100  comprises N rack-mounted shelves, including exemplary shelves  110 ,  120 , and  130 , that are coupled via crossbar switch  150 . In an advantageous embodiment, crossbar switch  150  is a 10 Gigabit Ethernet (10 GbE) crossbar operating at 10 gigabits per second (Gbps) per port.  
         [0025]     Each of exemplary shelves  110 ,  120  and  130  may comprise route processing modules (RPMs) or Layer  2  (L 2 ) modules, or a combination of route processing modules and L 2  modules. Route processing modules forward data packets using primarily Layer  3  information (e.g., Internet protocol (IP) addresses). L 2  modules forward data packets using primarily Layer  2  information (e.g., medium access control (MAC) addresses). In the exemplary embodiment shown in  FIG. 1 , only shelf  130  is shown to contain both route processing (L 3 ) modules and L 2  modules. However, this is only for the purpose of simplicity in illustrating router  100 . Generally, it should be understood that many, if not all, of the N shelves in router  100  may comprise both RPMs and L 2  modules.  
         [0026]     Exemplary shelf  110  comprises a pair of redundant switch modules, namely primary switch module (SWM)  114  and secondary switch module (SWM)  116 , a plurality of route processing modules  112 , including exemplary route processing module (RPM)  112   a,  RPM  112   b,  and RPM  112   c,  and a plurality of physical media device (PMD) modules  111 , including exemplary PMD modules  111   a,    111   b,    111   c,    111   d,    111   e,  and  111   f.  Each PMD module  111  transmits and receives data packets via a plurality of data lines connected to each PMD module  111 .  
         [0027]     Similarly, shelf  120  comprises a pair of redundant switch modules, namely primary SWM  124  and secondary SWM  126 , a plurality of route processing modules  122 , including RPM  122   a,  RPM  122   b,  and RPM  122   c,  and a plurality of physical media device (PMD) modules  121 , including PMD modules  121   a - 121   f.  Each PMD module  121  transmits and receives data packets via a plurality of data lines connected to each PMD module  121 .  
         [0028]     Additionally, shelf  130  comprises redundant switch modules, namely primary SWM  134  and secondary SWM  136 , route processing module  132   a,  a plurality of physical media device (PMD) modules  131 , including PMD modules  131   a  and  131   b,  and a plurality of Layer  2  (L 2 ) modules  139 , including L 2  module  139   a  and L 2  module  139   b.  Each PMD module  131  transmits and receives data packets via a plurality of data lines connected to each PMD module  131 . Each L 2  module  139  transmits and receives data packets via a plurality of data lines connected to each L 2  module  139 .  
         [0029]     Router  100  provides scalability and high-performance using up to M independent routing nodes (RN). A routing node comprises, for example, a route processing module (RPM) and at least one physical medium device (PMD) module. A routing node may also comprise an L 2  module (L 2 M). Each route processing module or L 2  module buffers incoming Ethernet frames, Internet protocol (IP) packets and MPLS frames from subnets or adjacent routers. Additionally, each RPM or L 2 M classifies requested services, looks up destination addresses from frame headers or data fields, and forwards frames to the outbound RPM or L 2 M. Moreover, each RPM (or L 2 M) also maintains an internal routing table determined from routing protocol messages, learned routes and provisioned static routes and computes the optimal data paths from the routing table. Each RPM processes an incoming frame from one of its PMD modules. According to an advantageous embodiment, each PMD module encapsulates an incoming frame (or cell) from an IP network (or ATM switch) for processing in a route processing module and performs framing and bus conversion functions.  
         [0030]     Incoming data packets may be forwarded within router  100  in a number of different ways, depending on whether the source and destination ports are associated with the same or different PMD modules, the same or different route processing modules, and the same or different switch modules. Since each RPM or L 2 M is coupled to two redundant switch modules, the redundant switch modules are regarded as the same switch module. Thus, the term “different switch modules” refers to distinct switch modules located in different ones of shelves  110 ,  120  and  130 .  
         [0031]     In a first type of data flow, an incoming data packet may be received on a source port on PMD module  121   f  and be directed to a destination port on PMD module  131   a.  In this first case, the source and destination ports are associated with different route processing modules (i.e., RPM  122   c  and RPM  132   a ) and different switch modules (i.e., SWM  126  and SWM  134 ). The data packet must be forwarded from PMD module  121   f  all the way through crossbar switch  150  in order to reach the destination port on PMD module  131   a.    
         [0032]     In a second type of data flow, an incoming data packet may be received on a source port on PMD module  121   a  and be directed to a destination port on PMD module  121   c.  In this second case, the source and destination ports are associated with different route processing modules (i.e., RPM  122   a  and RPM  122   b ), but the same switch module (i.e., SWM  124 ). The data packet does not need to be forwarded to crossbar switch  150 , but still must pass through SWM  124 .  
         [0033]     In a third type of data flow, an incoming data packet may be received on a source port on PMD module  111   c  and be directed to a destination port on PMD module  111   d.  In this third case, the source and destination ports are associated with different PMD modules, but the same route processing module (i.e., RPM  112   b ). The data packet must be forwarded to RPM  112   b,  but does not need to be forwarded to crossbar switch  150  or to switch modules  114  and  116 .  
         [0034]     Finally, in a fourth type of data flow, an incoming data packet may be received on a source port on PMD module  111   a  and be directed to a destination port on PMD module  111   a.  In this fourth case, the source and destination ports are associated with the same PMD module and the same route-processing module (i.e., RPM  112   a ). The data packet still must be forwarded to RPM  112   a,  but does not need to be forwarded to crossbar switch  150  or to switch modules  114  and  116 .  
         [0035]      FIG. 2  illustrates selected portions of exemplary router  100  in greater detail according to one embodiment of the present invention.  FIG. 2  simplifies the representation of some of the elements in  FIG. 1 . Router  100  comprises PMD modules  210  and  250 , route processing modules  220  and  240 , and switch fabric  230 . PMD modules  210  and  250  are intended to represent any of PMD modules  111 ,  121 , and  131  shown in  FIG. 1 . Route processing modules  220  and  240  are intended to represent any of RPM  112 , RPM  122 , and RPM  132  shown in  FIG. 1 . Switch fabric  230  is intended to represent crossbar switch  150  and the switch modules in shelves  110 ,  120  and  130  in  FIG. 1 .  
         [0036]     PMD module  210  comprises physical (PHY) layer circuitry  211 , which transmits and receives data packets via the external ports of router  100 . PMD module  250  comprises physical (PHY) layer circuitry  251 , which transmits and receives data packets via the external ports of router  100 . RPM  220  comprises inbound network processor (NP)  221 , outbound network processor (NP)  223 , and medium access controller (MAC) layer circuitry  225 . RPM  240  comprises inbound network processor (NP)  241 , outbound network processor (NP)  243 , and medium access controller (MAC) layer circuitry  245 .  
         [0037]     Each network processor comprises a plurality of microengines capable of executing threads (i.e., code) that forward data packets in router  100 . Inbound NP  221  comprises N microengines (μEng.)  222  and outbound NP  223  comprises N microengines (μEng.)  224 . Similarly, inbound NP  241  comprises N microengines (μEng.)  242  and outbound NP  243  comprises N microengines (μEng.)  244 .  
         [0038]     Two network processors are used in each route-processing module to achieve high-speed (i.e., 10 Gbps) bi-directional operations. Inbound network processors (e.g., NP  221 , NP  241 ) operate on inbound data (i.e., data packets received from the network interfaces and destined for switch fabric  230 ). Outbound network processors (e.g., NP  223 , NP  243 ) operate on outbound data (i.e., data packets received from switch fabric  230  and destined for network interfaces).  
         [0039]     According to an exemplary embodiment of the present invention, each network processor comprises N=16 microengines that perform data plane operations, such as data packet forwarding. Each RPM also comprises a single RISC processor (not shown) that performs control plane operations, such as building forwarding (or look-up) tables. According to the exemplary embodiment, each microengine supports eight threads. At least one microengine is dedicated to reading inbound packets and at least one microengine is dedicated to writing outbound packets. The remaining microengines are used for forwarding table lookup.  
         [0040]     In order to meet the throughput requirements for line rate forwarding at data rates up to 10 Gbps, it is necessary to split the data plane processing workload among multiple processors, microengines, and threads. The first partitioning splits the workload between two network processors—one operating on inbound data packets from the network interfaces to the switch and the other operating on outbound data packets from the switch to the network interfaces. Each of these processors uses identical copies of the forwarding table from its own memory space. This eliminates memory contention problems.  
         [0041]     According to the principles of the present invention, the control and management plane functions (or operations) of router  100  may be distributed between inbound (IB) network processor  221  and outbound network processor  223 . The architecture of router  100  allows distribution of the control and management plane functionality among many processors. This provides scalability of the control plane in order to handle higher control traffic loads than traditional routers having only a single control plane processor. Also, distribution of the control and management plane operations permits the use of multiple low-cost processors instead of a single expensive processor. For simplicity in terminology, control plane functions (or operations) and management plane functions (or operations) will hereafter be collectively referred to as control plane functions.  
         [0042]      FIG. 3  illustrates inbound network processor  221  and outbound network processor  223  according to an exemplary embodiment of the present invention. Inbound (IB) network processor  221  comprises control plane processor  310 , microengine(s)  222 , and configuration registers  315 . Outbound (OB) network processor  223  comprises control plane processor  320 , microengine(s)  224 , and configuration registers  325 . Inbound network processor  221  and outbound network processor  223  are coupled to shared memory  350 , which stores forwarding table information, including forwarding vectors and trie tree search tables.  
         [0043]     Control and management messages may flow between the control and data planes via interfaces between the control plane processors and data plane processors. For example, control plane processor  310  may send control and management messages to the microengines  222  and control plane processor  320  may send control and management messages to the microengines  224 . The microengines can deliver these packets to the local network interfaces or to other RPMs for local consumption or transmission on its network interfaces. Also, microengines may detect and send control and management messages to their associated control plane processor for processing. For example, microengines  222  may send control and management plane messages to control plane processor  310  and microengines  224  may send control and management messages to control plane processor  320 .  
         [0044]     Inbound network processor  221  operates under the control of control software stored in memory  330 , such as cognitive code  335 . Similarly, outbound network processor  223  operates under the control of control software stored in memory  340 , such as cognitive code  345 . According to the principles of the present invention, cognitive code  335  and cognitive code  345  are identical software loads.  
         [0045]     Network processors  221  and  223  in router  100  share routing information in the form of aggregated routes stored in shared memory  350 . Network processors  221  and  223  are interconnected through Gigabit optical links to the switch modules (SWMs). Multiple SWMs can be interconnected through 10 Gbps links via Rack Extension Modules (REXMs). The management and routing functions/operations of router  100  are implemented in inbound network processor  221  and outbound network processor  223  in each RPM of router  100 .  
         [0046]     In order to meet the bi-directional 10 Gbps forwarding throughput of the RPMs, two network processors—one inbound and one outbound—are used in each RPM. Inbound network processor  221  handles inbound (IB) packets traveling from the external network interfaces to switch fabric  230 . Outbound network processor  223  handles outbound (OB) packets traveling switch fabric  230  to the external network interfaces. In an exemplary embodiment of the present invention, control plane processor (CCP)  310  comprises an XScale core processor (XCP) and microengines  222  comprise sixteen microengines. Similarly, control plane processor (CCP)  320  comprises an XScale core processor (XCP) and microengines  224  comprise sixteen microengines.  
         [0047]     The primary management and control plane functions of router  100  are management via Command Line Interface (CLI), management via Simple Network Management Protocol (SNMP), Standard Routing and Label Distribution Protocols, Internal Route Distribution using a proprietary protocol, and Forwarding Table Management (FTM). These functions can run in either inbound network processor  221  or outbound network processor  223 , or in both.  
         [0048]     According to the principles of the present invention, control functions/operations may be distributed between inbound network processor  221  and outbound network processor  223  because both processors execute identical cognitive code, namely cognitive code  335  and cognitive code  345 . Each of inbound network processor  221  and outbound network processor  223  determines whether it is the inbound or outbound network processor by examining configuration register  315  and configuration register  325 , respectively. Configuration files allow each processor to determine the functions (or operations) mapped to it and its role relative to those functions, typically a master role or a slave role. Thus, each one of inbound network processor  221  and outbound network processor  223  becomes cognitive of its position in the system and its role. Use of a single software load for both processors reduces the number of separate software loads that must be managed, thus reducing configuration management complexity.  
         [0049]      FIG. 4  illustrates inbound network processor  221  and outbound network processor  223  in greater detail according to an exemplary embodiment of the present invention. The primary management and control plane functions performed by control plane processors  310  and  320  are illustrated in  FIG. 4 , along with the interfaces between network processors  221  and  223  that facilitate the distribution of the functions.  
         [0050]     As can be seen in  FIG. 4 , all of the major functions may be distributed across inbound network processor  221  and outbound network processor  223 . In inbound network processor  221 , the major functions comprise Simple Network Management Protocol (SNMP) manager  410 , Command Line Interface (CLI) manager  415 , standard Routing Protocols, Label Distribution Protocols, and Proprietary protocols manager  420 , Routing Information Base (RIB) manager  425 , Address Resolution Protocol (ARP) manager  430 , Neighbor Discovery Protocol (NDP) manager  435 , and Forwarding Table (FT) manager  440 . In Outbound network processor  223 , the major functions comprise Simple Network Management Protocol (SNMP) manager  460 , Command Line Interface (CLI) manager  465 , standard Routing Protocols, Label Distribution Protocols, and Proprietary protocols manager  470 , Routing Information Base (RIB) manager  475 , Address Resolution Protocol (ARP) manager  480 , Neighbor Discovery Protocol (NDP) manager  485 , and Forwarding Table (FT) manager  490 . According to the exemplary embodiment, inbound network processor  221  and outbound network processor  223  communicate via sockets  401 - 408  and sockets  451 - 458 .  
         [0051]     According to an advantageous embodiment of the present invention, router  100  may use the control function partitioning shown in TABLE 1.  
                               TABLE 1                                   FUNCTION   MASTER   SLAVE                           SNMP   OB NP 223   IB NP 221           CLI   OB NP 223   IB NP 221           RP, LDF, prop.   IB NP 221   OB NP 223           FTM   IB NP 221   OB NP 223                      
 
         [0052]     This configuration distributes the management functions to outbound network processor (OB NP)  223  and the routing protocol and forwarding table manager functions to inbound network processor (IB NP)  221 . However, this partitioning of functionality can easily be changed by re-configuring configuration registers  315  and  325 .  
         [0053]     SNMP agent functions operate on OB NP  223 , with processes in IB NP  221  providing SWM and Network Interface communication functions, as well as SMUX Peers or AgentX Servers to complete commands relating to the functionality of IB NP  221 . VTYSH Subagent functions associated with CLI operate on OB NP  223 , with IB NP  221  providing SWM and Network Interface communications functions, as well as VTYSH Servers to complete commands relating to the functions of IB NP  221 . RP, LDP, and proprietary protocols operate on IB NP  221 , with OB NP  223  providing Network Interface and SWM communications functions. Routes learned by OB NP  223  are sent to IB NP  221  for processing and FTM building. IB NP  221  builds the tables used by the microengines of both IB NP  221  and OB NP  223 . OB NP  223  maintains Forwarding Descriptors in local memory, as commanded by IB NP  221 .  
         [0054]     In router  100 , IB NP  221  receives data from the network interfaces and sends data to the switch modules, but cannot send data to the network interfaces and cannot receive data from the switch modules. OB NP  223  receives data from the switch module and sends data to the network interfaces, but cannot send data to the switch modules and cannot receive data from the network interfaces. Due to this asymmetrical communication scheme, inter-processor communications are required so that both processors may participate in all major control functions.  
         [0055]     IB NP  221  and OB NP  223  communicate using standard Linux sockets  401 - 408  and  451 - 458 . Standard IP protocols, such as User Datagram Protocol (UDP) or Transmission Control Protocol (TCP) are used on these communications links. Routing, label, forwarding, and management information are exchanged over these links.  
         [0056]     TABLE 2 below lists the threads applicable to all distributed control functions. These threads run in both IB NP  221  and OB NP  223 . The distribution of functions may be scaled to more than two network processors by including additional pairs of In and Out Services Sockets, along with associated threads and queues for each additional processor.  
                   TABLE 2                       THREAD   FUNCTION                   T-Main State Loop   Initialize and control all threads       T-Collector   Communicate with higher layer protocols       T-Reader   Read data from the other NP through the socket           interface. There are copies of this for both           Incoming and Outgoing Services       T-Writer   Write data to the other NP through the socket           interface. There are copies of this thread           for both the Incoming and the Outgoing           Services.                  
 
         [0057]     The main loop is a state machine (T-Main State Loop) that controls the other functional threads and the communication channels. The T-Collector thread receives data from higher level protocols through a pipe and delivers it to the functional module (e.g., FT manager  440 ,  490 ). The functional distribution model allows each network processor to request services from the other network processor. The local network processor receives requests for services from the remote network processor via the In Services Socket and sends requests for services to the remote NP via the Out Services Socket.  
         [0058]     There are read (T-Reader) threads and write (T-Writer) threads associated with each of the sockets. In the case of Incoming Services, requests are received from the remote network processor via the associated T-Reader thread and responses to the requests are sent to the remote network processor via the T-Writer thread. The remote processor initiates transactions through the In Services Socket. In the case of Outgoing Services, requests are sent to the remote network processor via the associated T-Writer thread and responses to the requests are received from the remote network processor via the T-Reader thread. The local processor initiates transactions through the Out Services Socket.  
         [0059]     This invention enables smaller, cheaper network processors to be used in parallel to achieve higher control plane throughput. The exemplary embodiment described herein uses two network processors, but could be expanded to more processors and does not require specialized network processors. This present invention may be used to provide high control plane processing power at a relatively low cost, thus allowing cheaper, higher performance routers to be built.  
         [0060]     Although the present invention has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present invention encompass such changes and modifications as fall within the scope of the appended claims.