Abstract:
A network controller may split, via a pass-through driver, processing of transmit and/or receive network traffic handled by the network controller. Physical layer (PHY) processing and/or Medium Access Control (MAC) processing of the management traffic may be performed internally via the network controller. The pass-through driver may route at least a portion of management traffic carried via the transmit and/or receive network traffic externally to said network controller for processing. In this regard, the pass-through driver may enable routing of data and/or messages to enable performing the external processing of management traffic. An application processor may be used to perform the external processing of management traffic.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 12/190,425, filed Aug. 12, 2008; which in turn is a continuation of U.S. application Ser. No. 10/797,532, filed Mar. 3, 2004, now U.S. Pat. No.7,411,973, which claims priority to and benefit from U.S. Provisional Application Ser. No. 60/453,642, filed Mar. 11, 2003. 
    
    
     INCORPORATION BY REFERENCE 
     The above-referenced United States patent application is hereby incorporated herein by reference in its entirety. 
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     [Not Applicable] 
     MICROFICHE/COPYRIGHT REFERENCE 
     [Not Applicable] 
     BACKGROUND OF THE INVENTION 
       FIG. 1  illustrates a block diagram of a system  10  connected to a network  20  via switches  30   a ,  30   b . The system  10  includes a network interface card (NIC)  40  and an intelligent management device ( 114 D)  50 . The NIC  40  is connected to the switch  30   a  and to a host (not shown) of the system  10 . The IMD is connected to the switch  30   b  and to the host of the system  10 . The NIC includes a NIC media access control (MAC)  60  and a NIC processor  70 . The network  20  is connected to the switch  30   a  which, in turn, is connected to the NIC MAC  60 . The NIC MAC  60  is connected to the NIC processor  70  which, in turn, is connected to the host of the system  10 . The IMD  50  includes a MAC  80  and management processor  90 . The network  20  is also connected to the switch  30   b  which, in turn, is connected to the MAC  80 . The MAC  80  is connected to the management processor  90  which, in turn, is connected to the host of the system  10 . 
     The IMD  50  provides, for example, monitoring, management capabilities and remote functionality. For example, the IMD  50  can provide monitoring and management capabilities for the system  10  and can provide remote functionality to or from a device (e.g., a remote device) connected to the network  20 . 
     The IMD  50  can have one or more of the following disadvantages. For example, as illustrated in  FIG. 1 , the system  10  includes an additional dedicated connection to the network  20 . Besides the additional cost (e.g., the additional switch  30   b ) of implementing another system port, the IMD  50  is susceptible to a failure, for example, of the switch  30   b . Thus, if switch  30   b  were to fail, then the IMD  50  would no longer be accessible via the network  20 . Furthermore, because the IMD  50  is connected to the network  20 , the IMD  50  may be needlessly processing some packets carried on the network  20 . On high-speed networks, in particular, the resources of the MD  50  can be substantially consumed by such unnecessary processing, thereby reducing some resources of the IMD  50  that could have been allocated for other tasks. For example, some packets (e.g., packets that can be forwarded as received) may be processed by the IMD  50 , even though these packets need not be processed by the IMD  50 . 
     Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of ordinary skill in the art through comparison of such systems with one or more aspects of the present invention as set forth in the remainder of the present application with reference to the drawings. 
     BRIEF SUMMARY OF THE INVENTION 
     Aspects of the present invention may be found in, for example, systems and methods that interface with a management system such as, for example, an intelligent management device. In one embodiment according to some aspects of the present invention, a communications system may include, for example, a network interface card (NIC) and a management device. The management device may be coupled to the NIC. The NIC may be adapted, for example, to merge communications traffic of the management device with the NIC. 
     In another embodiment according to some aspects of the present invention, a communications system may include, for example, a first NIC, a second NIC and a manager. The first NIC and the second NIC may be coupled to a network. The manager may be coupled to the first NIC and the second NIC. The manager may initially be in two-way communications with the network via the first NIC. However, if the first NIC fails, then the manager may switch from the first NIC to the second NIC and be in two-way communications with the network via the second NIC. 
     In yet another embodiment according to some aspects of the present invention, a method of communications may include, for example, one or more of the following: providing access to and from a network for a management device via a NIC; configuring one or more filters of the NIC via one or more commands generated by an management device; filtering incoming packets via the one or more filters; and forwarding the filtered packets based upon one or more matches between information carried by the filtered packets and one or more filtering parameters. 
     In yet another embodiment according to some aspects of the present invention, a method of communications between a NIC and a management device may include, for example, one or more of the following: generating a command in the management device, the command comprising a particular sequence number; storing the command in the management device; sending the command to the NIC; executing the command in the NIC; and generating a response to the command, the response comprising the particular sequence number. In some embodiments according to the present invention, the command may also include, for example, an identifier-type field and a command structure. The response may also include, for example, an identifier-type field and a response structure. 
     In yet still another embodiment according to some aspects of the present invention, a method of remote management over a network may include, for example, one or more of the following: accessing the network via a plurality of NICs of a local server system; communicating between a local manager of the local server system and a remote manager over the network through a NIC selected by the local manager, the selected NIC being one of the plurality of NICs; managing the local server system via the local manager; and responding locally to management commands sent over the network from the remote manager. 
     These and other features and advantages of the present invention may be appreciated from a review of the following detailed description of the present invention, along with the accompanying figures in which like reference numerals refer to like parts throughout. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows a block diagram of a system connected to a network via switches. 
         FIG. 2  shows a block diagram of a system coupled to a network according to an embodiment of the present invention. 
         FIG. 3  shows a block diagram of a system coupled to a network according to an embodiment of the present invention. 
         FIG. 4  shows a flowchart illustrating an embodiment of a process for receiving and forwarding packets according to the present invention. 
         FIG. 5  shows a flowchart illustrating an embodiment of a process for handling command packets according to the present invention. 
         FIG. 6  shows a flowchart illustrating an embodiment of a process for handling response packets according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Aspects of the present invention may be found, for example, in systems and methods that interface with a management system such as, for example, a management system including an intelligent management device (IMD). In some embodiments according to the present invention, a command protocol and format for communication between an interface card (e.g., a network interface card (NIC), a controller, an adapter, etc.) and a management system may be provided. 
     In some embodiments according to the present invention, an interface that may allow a management system to merge its traffic with that NIC (e.g., a standard NIC, a network interface controller, etc.) to provide a fully integrated management solution may be provided. The fully integrated management solution may be implemented, for example, without adding further network connections. 
     In some embodiments according to the present invention, a separate Ethernet connection port on a NIC may be provided. The separate Ethernet connection port may be, for example, a universal management port (UMP). Via this interface, a management system may see packets that it would see if it were directly connected to the network as well as many other types of packets (e.g., commands, responses, etc.) 
     In some embodiments according to the present invention, a system that passes command packets over an Ethernet interface between a management system and an UMP may be provided. 
       FIG. 2  shows an embodiment of a system  100  including an IMD  110  according to the present invention. The system  100  may be, for example, a server system, a server blade, a desktop system, a computer system, a network system, a set top box, etc.) The system  100  may include, for example, the IMD  110  and a NIC  120 . The system  100  may be coupled to a network  130  via the NIC  120 . The IMD  110  may include, for example, a management processor  140  and a media access control (MAC)  150  (e.g., a 10/100 MAC). The NIC  120  may include, for example, a NIC processor  160 , a set of filters  170 , a MAC  180  (e.g., a 10/100 MAC or UMP) and a main NIC MAC  190 . The management processor  140  may be coupled to the MAC  150  which, in turn, may be coupled to the MAC  180 . The MAC  180  may be coupled to the NIC processor  160  which, in turn, may be coupled to the main NIC MAC  190 . The NIC processor  160  may also be coupled to the set of filters  170  which, in turn, may be coupled to the NIC MAC  190 . The main NIC MAC  190  may be coupled to the network  130  via a switch  200 . 
     The system  100  may also include, for example, system sensors  210 , system controls  220 , a system interconnect  230 , a central processing unit (CPU)  240 , another CPU  250 , a system storage device  260  (e.g., a system memory) and peripheral devices  270  (e.g., disk devices, video devices, etc.) The system sensors  210  and the system controls  220  may be coupled to the IMD  110  and, in particular, may be coupled to the management processor  140 . The NIC  120 , the IMD  110 , the CPUs  240 ,  250 , the system storage device  260  and the peripheral devices  270  may each be coupled to the system interconnect  230 . In particular, the NIC processor  160  and the management processor  140  may be coupled to the system interconnect  230  via a first host connection  280  and a second host connection  290 . The host connections  280 ,  290  may be, for example, peripheral component interconnects (PCIs). 
     Other devices may be coupled to the network  130 . For example, a management console  300  may be coupled to the network  130  via a switch  310 . Other systems  320  may be coupled to the network via respective switches  330 . Although illustrated as a single switch  330 , each respective system  320  may include its own respective switch or switches  330 . Some of the other systems  320  may be identical to the system  100  illustrated in  FIG. 2  and some of the other systems  320  may be identical to the system  100  illustrated in  FIG. 3 . However, the other systems  320  need not be so limited in scope. In some embodiments, some of the other systems  320  and the system  100  may be remotely controlled (e.g., remotely monitored, remotely activated, remotely managed, remotely accessed, etc.) by the management console  300 . 
       FIG. 3  shows an embodiment of the present invention in which the system  10  is coupled to the network  130  via a plurality of NICs  120  (i.e., NIC  120 ( 1 ), NIC  120 ( 2 ), . . . , NIC  120 ( n ), where n is an integer value). Each NIC  120  may include, for example, a respective NIC processor  160 , a set of filters  170 , a first MAC  180  and a second MAC  190 . Each NIC  120  may be coupled to the network  130  via a respective switch  200 . The various components may be coupled together as described above with respect to the NIC  120  of  FIG. 2 . In addition, each NIC  120  may be coupled to the IMD  110 . In one embodiment, the second MACs  190  of the respective NICs  120  each may be coupled to the MAC  150  of the IMD  110 . 
     In operation and with reference to  FIG. 2 , the management console  300  may be in two-way communications with the system  100  and some of the other systems  320  coupled to the network  130 . The management console  300  may provide, for example, management services (e.g., remote management services) for the system  100  and some of the other systems  320 . Thus, the management console  300  may be able to pull up graphical user interfaces (e.g., windows) on its display for each of the systems that the management console  300  manages. In some embodiments, the activities performed via the management console  300  may appear seemless even though the systems being managed may be far way. 
     The IMD  110  may be in two-way communications with the management console  300  (e.g., a remote management console) via network  130 . The management console  300  may be in two-way communications with not only the IMD  110  of the system  100 , but also some of the other systems  320  coupled to the network  130 . In some embodiments according to the present invention, the IMD  110  may be in two-way communications with the management console  300  only through the NIC  120 . In various embodiments according to the present invention, the IMD  110  may not have its own direct connection to the network  130 , but instead may use the NIC  120  to access the network. The IMD  110  may provide management services for the system  100 . For example, the IMD  110  may monitor the system sensors  142  or adjust the system controls  144 . Thus, for example, the IMD  110  may monitor power supply parameters, voltage parameters, current parameters, temperature parameters, status parameters, failure parameters of various components and circuits. The system sensors  142  may also provide alerts to the IMD  110  such as, for example, that the cover of the system  100  has not been replaced, that components have been removed or failed, or that the temperature in the system  100  has exceeded particular thresholds. The IMD  110  may also adjust, activate or set system controls  144  in response to monitored parameters or in response to particular commands or requests. For example, the IMD  110  may reset power settings or parameters settings, power up the system  100  or a particular component of the system  100 , or power down the system or a particular component of the system  100 . 
     In addition to responding to current conditions, the IMD  110  may also respond to requests received from the host of the system  100  or from the network  130 . In some embodiments according to the present invention, the IMD  110  may receive requests or commands from the management console  300 . In various embodiments according to the present invention, the management console  300  may provide, for example, a user input device (e.g., a keyboard, a mouse, etc.) and a user output device (e.g., a display, a graphical user interface, a video output, a graphical output, an audio output, etc.) By opening up a window in a display, a user located at the management console  300  may monitor infatuation that the IMD  110  may be receiving from the system sensors  210  or the system controls  220  or other components of the system  100 . The user may then send commands or requests to the IMD  110  to which the IMD  110  may respond. For example, the management console  300  may send a request for information to the IMD  110 . The request may be sent via the network  130  to the NIC  120 . The request may be routed through the filters  170  which may determine whether or not the request is destined for the IMD  110 . If the request had not been destined for the IMD  110 , then, for example, it may have been forwarded to the NIC processor  160  or to the host of the system  100  or elsewhere for further processing. If the request is destined for the IMD  110 , then the NIC  120  may route the request to the IMD  110 . Thus, in some embodiments according to the present invention, the IMD  110  may only receive requests or commands or data packets that are destined for the IMD  110 . 
     The IMD  110  may then analyze the request and may perform the request. For example, the request may include commands for powering down an overheated component. The IMD  110  may thus adjust one or more of the system controls  144  of the system  100 . The IMD  110  may then send a response to the management console  300  through the NIC  120  and the network  130 . The response may include, for example, graphical information for display on a monitor that the user is viewing. Thus, user seemlessly manages the IMD  110  as if the user were located at the system  100 . In some embodiments, the management console  300  may act as a dummy terminal in which keyboard strokes or other input commands (e.g., mouse interface information) are relayed to the IMD  110  which, in turn, then may send graphical information to the management console  300  which may be displayed on the monitor as alphanumeric symbols (or, for example, cursor movements) corresponding to the keystrokes (or, for example, mouse movements). 
     Referring to  FIG. 3 , the IMD  110  may be coupled to a plurality of NICs  120 . In some embodiments according to the present invention, only one of the plurality of NICs  120  provides access to and from the network  130  for the IMD  110 . The IMD  110  may select which of the NICs  120  to use as a sole connection to and from the network  130 . In some embodiments according to the present invention, the IMD  110  may have the ability to switch between using one NIC or another NIC as the sole connection to and from the network  130 , for example, at different times. This ability may enhance throughput as well as promote fault tolerance. For example, if the selected NIC is being overused by other resources of the system  100  or the network  130 , then the IMD  110  may select another NIC (e.g., a NIC that is not being overused by other resources of the system  100  or the network  130 ). In another example, if the selected NIC has failed or has been removed from the system  100 , then the IMD may select another NIC to provide a connection (e.g., a sole connection) to and from the network  130 . Furthermore, if the management console  300  determines that the selected NIC has failed or has been removed from the system  100 , the management console  300  may wait and try again or the management console  300  may broadcast the information to the other NICs of the system  100 . The IMD  110  may then be notified via the broadcasted information received from one or more of the other NICs of the system and switch to another NIC. The IMD  110  may then use the newly selected NIC to inform the management console  300  of the switch in NIC selection. 
     In some embodiments according to the present invention, the system  100  may allow, for example, the IMD  110  to merge its traffic with that of the NIC  120 . The system  100  may provide, for example, a fully integrated management solution that does not necessitate additional network connections. The NIC  120  may transmit, for example, non-command packets via the main NIC MAC  190 . The NIC  120  may receive, for example, packets via the main NIC MAC  190  and send the received packets through the set of filters  170 . The set of filters  170  may allow received packets to be passed to the IMD  110  if, for example, the received packets meet (e.g., match) at least some of the filter requirements (e.g., programmed filter parameters). The NIC  120  may receive packets from the IMD  110  that meet a particular encapsulation format and may process the packets locally. The NIC  120  may receive other types of packets from the IMD  110  that may be transmitted exactly as they were received from the IMD  110  including, for example, virtual local area network (VLAN) tag information. 
       FIG. 4  shows a flowchart illustrating an embodiment of a process for receiving and forwarding packets according to the present invention. In step  340 , the system  100  may receive packets from the network  130  via the main NIC MAC  190 . In query  350 , whether the set of filters  170  are operable may be based upon whether the set of filters  170  have been configured. The set of filters  170  may be configured, for example, via commands generated by the NIC processor  160  of the NIC  120  or the management processor  140  of the IMD  110 . If the set of filters  170  have been configured, then, in query  360 , it is determined whether the information carried by the packet satisfies (e.g., matches) one or more of the configured filter parameters. If the information carried by the packet does satisfy one or more of the configured filter parameters, then, in step  390 , the packet may be processed by the NIC processor  160  and the management processor  140  and forwarded to a destination according to the matched filter parameters. In one embodiment, with regard to layer 2 (L2) address values, the NIC  120  may forward data that may meet, for example, any of the selected perfect match filters, for example, for the L2 address. In another embodiment, the NIC  120  may limit forwarded traffic up to a particular number of VLAN networks. In yet another embodiment, the NIC  120  may filter L2 multicast or broadcast traffic and forward such traffic accordingly. In one embodiment, a broadcast packet that is determined to be an address resolution protocol (ARP) packet or other specific types of broadcast packets may be forwarded accordingly. 
     If the set of filters are not configured (query  350 ) or if the information carried by the packet does not satisfy any of the configured filter parameters (query  360 ), then, in step  370 , the packet may not reach the IMD  110 . In step  380 , the packet may be forwarded as received by the main NIC MAC  190  to the rest of the system  100 . In one embodiment, if the packets are not filtered, the receive (RX) packets including, for example, VLAN tag information may be forwarded as received via the main NIC MAC port  190 . 
     In some embodiments, the present invention may provide command packets and/or response packets transmitted and/or received by the NIC  120  having a format as set forth below. For example, the commands may be from the IMD  110  to the NIC  120  and the responses may be from the NIC  120  to the IMD  110 . 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
             
               
               
             
           
               
                   
               
               
                 Byte 
                 31 
                 23 
                 15 
                 7 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0 
                 XXXX 
                 XXXX 
                 DA 
                 DA 
               
               
                 4 
                 DA 
                 DA 
                 DA 
                 DA 
               
               
                 8 
                 SA 
                 SA 
                 SA 
                 SA 
               
             
          
           
               
                 12 
                 SA 
                 SA 
                 BRCM Num. 
               
             
          
           
               
                 16 
                 0x5706 
                 Cmd. Seq. Num. 
               
               
                 20 
                 Cmd. Type 
                 Data Length 
               
             
          
           
               
                 24 
                 Data0 
                 Data1 
                 Data2 
                 Data3 
               
               
                 28 
                 Data4 
                 Data5 
                 Data6 
                 Data7 
               
               
                 . . . 
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                 . . . 
                 DataN 
                 Optional Padding to 32 bits 
               
             
          
           
               
                 . . . 
                 2s Complement Checksum Compensation 
               
               
                 . . . 
                 Optional Zero Pad to 64 Byte Legal Ethernet Frame 
               
               
                   
               
             
          
         
       
     
     In some embodiments, the present invention may provide for fields with definitions as set forth below.
     XXXX Padding for the purposes of this table to make protocol values align on the 32-bit rows. These bytes may not be a part of any packet.   DA Ethernet Destination Address. Value is configurable, but typically is equal to the address the receiver represents on the main interface.   SA Ethernet Source Address. Value is configurable, but typically is equal to the address the sender represents on the main interface.
 
BRCM Number
       Well-known IEEE packet type number.   
       0x5706 Packet type number used to define a packet sub-type for the BRCM number.   Cmd Type Command Type. When bit  15  of the type is set, it indicates a response packet sent from the NIC to the IMD.
 
Data Length
       This value is the length in bytes of the data payload of the command packet. This is the number of “Data” bytes in the packet. This count may not include this value or any bytes before this value. This count may not include any Padding or Checksum bytes. The checksum may sum bytes not in this count if this count is not a multiple of four.   
       Data . . . . Command payload.
 
Optional Padding to 32-bits
       If the Data portion of the command is not a multiple of four in length (i.e., Bottom two bits of Data Length field are not zero) then from one to three bytes of zero value padding may be added so that the 2s complement checksum may be calculated over full 32-bit values.
 
2s Complement Checksum Compensation
   When this value is added to the 2&#39;s complement sum of all the 32-bit words in the “Data” and “Optional Padding” areas, the resulting value may be 0xffffffff. The checksum checking may optionally be disabled at each receiver. The sender may then take advantage of this by setting this value to 0xffffffff.
 
Optional Zero Pad to 64 Byte Legal Ethernet Frame
   For frames to be compliant with IEEE 820.3, all frames are padded up to a total of 64 bytes. This is typically done automatically by most Ethernet MAC devices.   
       

     In some embodiments, the present invention may provide that command frames may not use additional L2 encapsulation techniques such as, for example, VLAN, SNAP, etc. 
     In some embodiments, the present invention may employ a transport mechanism by which reliable reception of control frames may be tracked via sequence numbers. Each command packet may be associated with a respective response packet by each carrying a common sequence number in a particular sequence number space. Accordingly, the same sequence number space may be used for command/response packets in either direction between the NIC  120  and the IMD  110 . 
       FIG. 5  shows a flowchart illustrating an embodiment of a process for handling command packets according to the present invention, for example, as executed by the IMD  110 . In step  400 , a sender of a command (e.g., the IMD  110 ) may generate a command packet. The command packet may include, for example, a sequence number with which the command packet is associated. In step  410 , the sender of the command may then store the generated command. In step  420 , the sequence space counter of the sender may then be incremented. In one embodiment, the step  420  may proceed step  400  and step  410 . In another embodiment, the command is sent from the IMD  110  to the NIC  120 . The NIC  120  may respond to the command with a response. In step  422 , the NIC  120  may receive a packet from the IMD  110 . In query  424 , a BRCM number may be detected in a particular field (e.g., an identifier-type field). If the BRCM is not detected, then, in step  426 , the packet may be processed as a management protocol frame for the management console  300 . If the BRCM is detected, then query  430  follows. In query  430 , if sender of command receives a response, then, in step  450 , the command corresponding to the received response may be deleted from storage. In one embodiment, the received response may include, for example, a particular sequence number associated with a particular command, thereby identifying the stored command which can be deleted. 
     If a response to a particular command is not received, then, in step  440 , the particular command, which has been stored, may be retransmitted. In one embodiment, the command sender may be able to retransmit any command until a response with the same sequence number is received and is processed. Accordingly, a retransmission capability is provided in the case a command packet is lost, corrupted or dropped. In another embodiment, if the sender of commands detects a particular sequence number of a response that has already been received, then the sender of commands may resend all the commands that have not had responses received that follow the latest received sequence number. In yet another embodiment, via a periodic timer, a requestor may verify commands to which have been responded. If a command has not been responded to with a response, then a retransmit of the command may be commenced. The requestor may time-out on any request without a response and may start retransmission after that timer has expired. This may be done, for example, by setting the timeout each time a command is transmitted and each time a response is received. When the timer expires, retransmit may be started if all the outstanding commands have not been responded to with corresponding responses. 
       FIG. 6  shows a flowchart illustrating an embodiment of a process for handling response packets according to the present invention as executed, for example, by the NIC  120 . In step  460 , a packet may be received. In one embodiment, a command packet may be received by a responder to commands (e.g., the NIC  120 ) from the sender of commands (e.g., the IMD  110 ). In query  462 , a BRCM number may be detected in a particular field (e.g., an identifier-type field). If the BRCM number is not detected, then, in step  464 , the packet may be forwarded to a main transmission port. If the BRCM number is detected, then, in step  470 , the sequence number carried by the command packet may be determined. For example, the NIC processor  160  may parse the command packet to determine the sequence number carried by the command packet. In query  480 , it may be determined whether the determined sequence number is the expected sequence number. If the determined sequence number is the expected sequence number, then, in step  490 , the command may be executed and a response packet may be generated that may include, for example, the expected sequence number. In one embodiment, the NIC processor  160  may configure (e.g., program), for example, one or more filters in the set of filters  170  in light of the received command packet. In step  500 , the generated response packet may be stored and returned to the sender of the command packet. In one embodiment, the responder to commands may store only the last response packet sent to the sender of commands. Thus, the latest response packet may be written over the previous response packet or the previous response packet may be deleted or invalidated. In another embodiment, the responder to commands may store one or more response packets sent to the sender of commands. 
     If the determined sequence number is not the expected sequence number (query  480 ), then, in step  510 , the stored response packet (e.g., the previously stored response packet) may be resent. In one embodiment, if the responder receives a command with a sequence number other than the one expected (e.g., the last one plus one), then the NIC  120  may not execute that command, but instead may send the response for the previously executed command. In another embodiment, the responder to commands may re-execute a command without any adverse effects (e.g., side effects). 
     In one embodiment, no more than approximately 2 15 −1 commands may be outstanding at any time, for example, due to protocol limitations. Memory limitations in the sender may become evident long before the protocol limit is reached. The responder may only keep the last response that was sent so that it might not have any retransmit memory limitations for outstanding packets. However, other limitations may become factors for consideration. 
     Since the requestor may be the only station saving the outstanding commands, the responder may be able to execute all commands more than once without any adverse effects. Accordingly, the retransmission of a command that exhibits modal effects may cause problems. These modal effects can be avoided by the design of the command packets such that repeated execution has no side effects. 
     The following are some examples of commands and responses according to an embodiment of the present invention. 
     Hello—0x0001. The Hello command may solicit a presence response from the NIC  120 . The NIC  120  may respond as long as the message is received without error. The command does not make a commitment to work further. The Hello command may be intended for use as a flush command, if needed, possibly during initial negotiation. Error Codes may include, for example, OK. 
     ID Request—0x0002. The ID Request command may indicate the IMD type and version as a string up to, for example, forty characters long. The response to the ID Request command may return the NIC type and version as a string up to, for example, forty characters long. Error Codes may include, for example, OK; UNAVAIL; BAD_ID; or FATAL 
     Reset To Default—0x0003. The Reset To Default command may request that defaults be set for settings relating to, for example, filters, flow controls, etc. This may be an equivalent state to a reset NIC. Error Codes may include, for example, OK or FATAL. 
     Set NIC&lt;-&gt;IMD Flow Control Method—0x0101. The Set NIC&lt;-&gt;IMD Flow Control Method command may set, for example, the flow control method used between, for example, the IMD  110  and the NIC  120 . In some embodiments, only symmetrical flow control may be supported in which both ends use the same method. An OK response may indicate that the NIC  120  has set itself to the same flow control method. Settings may include, for example, NONE or PAUSE. Error Codes may include, for example, OK; NOT_SUPPORTED; or FATAL. 
     Set NIC Drop Policy—0x0102. The Set NIC Drop Policy command may set the drop policy used by the NIC  120  when passing frames to the IMD  110 . Settings may include, for example, DROP or BACKPRESSURE. Responses may include, for example, DROP or BACKPRESSURE—setting now in; or DRIVER_CTL—bit set when driver is running and BACKPRESSURE mode could not be selected. Error Codes may include, for example, OK or FATAL. 
     Set NIC Port—0x0103. The Set NIC Port command may request, for example, that the NIC  120  set the main port to a particular speed. If the main port speed is already at the specified speed, then no action may be taken and the link might not be dropped. The speed may be limited, for example, by power management limitations. Setting the requested speed may jeopardize exceeding the power supply for a particular design. This may not be returned on a card or LAN-on-motherboard (LOM) that may provide enough power in all modes. The speed change may be denied due to the OS driver being loaded. The speed change may be denied because of, for example, interface limits such as Fiber or because an external “in-line” device connected that may not be controlled for some reason. Settings may include, for example, GET, 10, 100, 1000—GET requests that current state be returned with no effect; HD_FLAG—half duplex flag, invalid with 1000 setting; PAUSE—Pause Flow Control Enable Flag; or AUTO—flag indicating that a setting is a “maximum setting” to advertise for auto-negotiation, when set, the link may be dropped as the link is re-negotiated. Responses may include, for example, 10, 100, 1000—speed of link; HD_FLAG—set if link is half duplex; PAUSE—set if pause flow control is enabled; LINK_UP—flag set if link was attained in new mode; FIBER—flag set if fiber connection; PWR_LIMIT—flag set if requested speed was denied due to particular card power limitations; DRV_LIMIT—flag set if request speed was denied due to driver being loaded and forcing link type; INTF_LIMIT—flag is set if requested speed was denied due to limitations in the PHY device (e.g., Fiber that cannot support 10/100); AUTO_NEG—flag is set if link was attained using auto-negotiation; AUTO_NEG_PAR—flag is set if link was attained using auto-negotiation and parallel detection was used to detect link (AUTO_NEG may also be set if this flag is set); CAP10, CAP100, CAP1000—capability advertised by link partner (valid only if AUTO_NEG=1 &amp;&amp; AUTO_NEG_PAR=0); CAP_HD_FLAG—capability advertised by link partner (valid only if AUTO_NEG=1 &amp;&amp; AUTO_NEG_PAR=0); or CAP_PAUSE—capability advertised by link partner (valid only if AUTO_NEG=1 &amp;&amp; AUTO_NEG_PAR=0). Error Codes may include, for example, OK or FATAL. 
     Drop NIC Port Link—0x0104. The Drop NIC Port Link command may drop a link on the main port if it has not already been dropped. The link may be re-established, for example, by using the Set NIC Port command. Error Codes may include, for example, OK or FATAL. 
     Filter All Packets—0x0201. 
     
       
         
               
               
               
               
               
             
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Byte 
                 31 
                 23 
                 15 
                 7 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 16 
                 0x5706 
                 Cmd. Seq. Num. 
               
               
                 20 
                 0x0201 
                 4 
               
             
          
           
               
                 24 
                 0xFDFEFFFB 
                   
               
               
                 28-63 
                 0 
               
               
                   
               
             
          
         
       
     
     The Filter All Packets command may provide that packets received on the main port may be filtered and may not be delivered to the IMD  110 . The command may be used, for example, as a power-up setting and may be used with any filters (e.g., time filters) when reset or re-loaded. 
     Filter All Packets Response—0x8201. 
     
       
         
               
               
               
               
               
             
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Byte 
                 31 
                 23 
                 15 
                 7 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 16 
                 0x5706 
                 Res. Seq. Num. 
               
               
                 20 
                 0x8201 
                 4 
               
             
          
           
               
                 24 
                 0x7DFEFFFB 
                   
               
               
                 28-63 
                 0 
               
               
                   
               
             
          
         
       
     
     Filter based on settings—0x0202. Packets may be filtered according to particular filter settings (e.g., current filter settings). 
     Set Perfect Match Filter—0x0203. It may set the filters defined by Fnum to the value specified in DA. Legal values for Fnum are 0 and 1. If the “OFF” bit is set, then the specified perfect match filter may be disabled. 
     
       
         
               
               
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Byte 
                 31 
                 23 
                 15 
                 7 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 16 
                 0x5706 
                 Cmd. Seq. Num. 
               
               
                 20 
                 0x0203 
                 8 
               
             
          
           
               
                 24 
                 DA 
                   
               
             
          
           
               
                 28 
                 DA 
                 OFF 
                 FNum 
               
             
          
           
               
                 28 
                 Checksum 
                   
               
               
                 32-63 
                 0 
               
               
                   
               
             
          
         
       
     
     Set Perfect Match Filter Response 0x8204. 
     Set Broadcast Filter—0x0205. The Set Broadcast Filter command may be set if broadcast frames should be forwarded to the IMD  110 . Settings may include, for example, ON. Error Code may include, for example, OK or FATAL. 
     Set ARP Filter—0x0206. The Set ARP Filter command may be set if ARP frames should be forwarded to the IMD  110 . Settings may include, for example, ON. Error Code may include, for example, OK or FATAL. 
     Get Statistics—0x0301. The Get Statistics command may request a response with the requested statistics in it. Results may include, for example: 
     
       
         
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
               
               
               
             
               
               
             
               
             
           
               
                   
               
             
             
               
                 u64_t IfHCInOctets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_ifhcinoctets. */ 
               
               
                   
                 /* 
                 This is the number of octets received on the interface, including framing 
               
             
          
           
               
                   
                 characters. */ 
               
             
          
           
               
                 u64_t IfHCOutOctets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_ifhcoutoctets. */ 
               
               
                   
                 /* 
                 This is the number of octets that have been transmitted on the interface. */ 
               
             
          
           
               
                 u64_t IfHCInUcastPkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_ifhcinucastpkts. */ 
               
               
                   
                 /* 
                 This is the number of frames received on the wire that were not dropped due 
               
             
          
           
               
                   
                 to errors that have Unicast Ethernet destination addresses. */ 
               
             
          
           
               
                 u64_t IfHCInMulticastPkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_ifhcinmulticastpkts. */ 
               
               
                   
                 /* 
                 This is the number of frames received on the wire that were not dropped due to 
               
             
          
           
               
                   
                 errors that have multicast Ethernet destination addresses. */ 
               
             
          
           
               
                 u64_t IfHCInBroadcastPkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_ifhcinbroadcastpkts. */ 
               
               
                   
                 /* 
                 This is the number of frames received on the wire that were not dropped due to 
               
             
          
           
               
                   
                 errors that have the broadcast Ethernet destination addresses. */ 
               
             
          
           
               
                 u64_t IfHCOutUcastPkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_ifhcoutucastpkts. */ 
               
               
                   
                 /* 
                 This is the number of packets transmitted that have unicast destination addresses. */ 
               
             
          
           
               
                 u64_t IfHCOutMulticastPkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_ifhcoutmulticastpkts. */ 
               
               
                   
                 /* 
                 This is the number of packets transmitted that have multicast destination addresses. */ 
               
             
          
           
               
                 u64_t IfHCOutBroadcastPkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_ifhcoutbroadcastpkts. */ 
               
               
                   
                 /* 
                 This is the number of packets transmitted that have the broadcast destination 
               
             
          
           
               
                   
                 address. */ 
               
             
          
           
               
                 u32_t Dot3StatsCarrierSenseErrors; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_dot3statscarriersenseerrors. */ 
               
               
                   
                 /* 
                 This is the number of times a false carrier has been detected on the internal 
               
             
          
           
               
                   
                 PHY device. This is indicated from the PHY by asserting RXER while 
               
               
                   
                 RXDV is low when the RXD pins are at a state of 0x0e. */ 
               
             
          
           
               
                 u32_t Dot3StatsFCSErrors; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_dot3statsfcserrors. */ 
               
               
                   
                 /* 
                 A IfInErrors value is the sum of this value and &lt;b&gt;Dot3StatsFCSErrors&lt;/b&gt; and 
               
             
          
           
               
                   
                 &lt;b&gt;Dot3StatsAlignmentErrors&lt;/b&gt;. */ 
               
             
          
           
               
                 u32_t Dot3StatsAlignmentErrors; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_dot3statsalignmenterrors. */ 
               
               
                   
                 /* 
                 This is the number of frames received on the wire that have an odd number of 
               
             
          
           
               
                   
                 nibbles and fail FCS check and are of legal length. */ 
               
             
          
           
               
                 u32_t Dot3StatsSingleCollisionFrames; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_dot3statssinglecollisionframes. */ 
               
               
                   
                 /* 
                 This is the number of collisions that were followed by successful packet 
               
             
          
           
               
                   
                 transmits. This is the same as the number of packets that were transmitted 
               
               
                   
                 with only one collision. */ 
               
             
          
           
               
                 u32_t Dot3StatsMultipleCollisionFrames; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_dot3statsmultiplecollisionframes. */ 
               
               
                   
                 /* 
                 This is the number of packets that have transmitted with more that one collision. */ 
               
             
          
           
               
                 u32_t Dot3StatsDeferredTransmissions; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_dot3statsdeferredtransmissionsl. */ 
               
               
                   
                 /* 
                 This is the number of packets that were delayed in transmission because they 
               
             
          
           
               
                   
                 had to wait for a RX packet to complete. */ 
               
             
          
           
               
                 u32_t Dot3StatsExcessiveCollisions; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_dot3statsexcessivecollisions. */ 
               
               
                   
                 /* 
                 This is the number of packets that have been dropped due to having 16 collisions 
               
             
          
           
               
                   
                 in a row. */ 
               
             
          
           
               
                 u32_t Dot3StatsLateCollisions; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_dot3statslatecollisions. */ 
               
               
                   
                 /* 
                 This is the number of packets that have been dropped due to having a 
               
             
          
           
               
                   
                 collision received after the 64-byte collision window. */ 
               
             
          
           
               
                 u32_t EtherStatsCollisions; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_etherstatscollisions. */ 
               
               
                   
                 /* 
                 This is the number of collisions that have been detected on the interface. */ 
               
             
          
           
               
                 u32_t EtherStatsFragments; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatsfragments. */ 
               
               
                   
                 /* 
                 This is the count of frames less than 64 bytes with bad FCS. */ 
               
             
          
           
               
                 u32_t EtherStatsJabbers; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatsjabbers. */ 
               
               
                   
                 /* 
                 This is the number of frames received that exceed the programmed MTU 
               
             
          
           
               
                   
                 size and have bad FCS. */ 
               
             
          
           
               
                 u32_t EtherStatsUndersizePkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatsundersizepkts. */ 
               
               
                   
                 /* 
                 This is the number of frames received that are less than 64 bytes in length. */ 
               
             
          
           
               
                 u32_t EtherStatsOverrsizePkts; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_dot3statsframestoolong. */ 
               
               
                   
                 /* 
                 This is the number of frames received that exceed the programmed MTU size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsRx64Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected form emac_rx_stat_etherstatspkts64octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames received of 64 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsRx65Octetsto127Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatspkts65octetsto127octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames received of 65 bytes to 127 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsRx128Octetsto255Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatspkts128octetsto255octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames received of 128 bytes to 255 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsRx256Octetsto511Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatspkts256octetsto511octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames received of 256 bytes to 511 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsRx512Octetsto1023Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatspkts512octetsto1023octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames received of 512 bytes to 1023 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsRx1024Octetsto1522Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatspkts1024octetsto1522octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames received of 1024 bytes to 1522 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsRx1523Octetsto9022Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_etherstatspkts1523octetsto9022octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames received of 1523 bytes to 9022 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsTx64Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected form emac_tx_stat_etherstatspkts64octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames transmitted of 64 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsTx65Octetsto127Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_etherstatspkts65octetsto127octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames transmitted of 65 bytes to 127 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsTx128Octetsto255Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_etherstatspkts128octetsto255octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames transmitted of 128 bytes to 255 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsTx256Octetsto511Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_etherstatspkts256octetsto511octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames transmitted of 256 bytes to 511 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsTx512Octetsto1023Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_etherstatspkts512octetsto1023octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames transmitted of 512 bytes to 1023 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsTx1024Octetsto1522Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_etherstatspkts1024octetsto1522octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames transmitted of 1024 bytes to 1522 bytes in size. */ 
               
             
          
           
               
                 u32_t EtherStatsPktsTx1523Octetsto9022Octets; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_etherstatspkts1523octetsto9022octets. */ 
               
               
                   
                 /* 
                 This is the number of good frames transmitted of 1523 bytes to 9022 bytes in size. */ 
               
             
          
           
               
                 u32_t XonPauseFramesReceived; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_xonpauseframesreceived. */ 
               
               
                   
                 /* 
                 This is the number of good MAC control frames received of pause type with 
               
             
          
           
               
                   
                 a back-off value of zero. This register increments regardless of flow control state. */ 
               
             
          
           
               
                 u32_t XoffPauseFramesReceived; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_xoffpauseframesreceived. */ 
               
               
                   
                 /* 
                 This is the number of good MAC control frames received of pause type with 
               
             
          
           
               
                   
                 a back-off value other than zero. This register increments regardless of 
               
               
                   
                 flow control state. */ 
               
             
          
           
               
                 u32_t OutXonSent; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_outxonsent. */ 
               
               
                   
                 /* 
                 This is the number of MAC Control pause packets of value 0xffff that 
               
             
          
           
               
                   
                 have be transmitted. */ 
               
             
          
           
               
                 u32_t OutXoffSent; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_tx_stat_outxoffsent. */ 
               
               
                   
                 /* 
                 This is the number of MAC Control pause packets of value 0 that have 
               
             
          
           
               
                   
                 be transmitted. */ 
               
             
          
           
               
                 u32_t MacControlFramesReceived; 
               
             
          
           
               
                   
                 /* 
                 Collected from emac_rx_stat_maccontrolframesreceived. */ 
               
               
                   
                 /* 
                 This is the number of good MAC control frames received that are not 
               
             
          
           
               
                   
                  of pause type. */ 
               
             
          
           
               
                 Error Codes may include, for example, OK or FATAL. 
               
               
                   
               
             
          
         
       
     
     While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Therefore, it is intended that the present invention not be limited to the particular embodiments disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.