Abstract:
An Ethernet, or more generally any packetized network system, remote management device and system operable via Ethernet connections according to non-Ethernet message instructions presented during the active idle signal period, e.g. during the inter-packet gap (IPG), which are separated from the Ethernet signalling before detection. A locally managed device includes a physical layer interface adapted to receive a secondary signal which is encoded to provide a corresponding signal while conforming to the active idle and minimum IPG requirements, and is received by a remote device managed according to the encoded signals provided from the local device during the IPG. Further embodiments provide multiple (serial) nesting of such remote devices along the Ethernet path, with the instructions to and data from the most distant such remote devices forwarded through intermediate remote devices according to the present invention.

Description:
FIELD OF THE INVENTION 
     The present invention relates to remotely managed network systems, in particular to a remotely managed packet data system having control information provided during non-data gaps between the data packets. 
     BACKGROUND OF THE INVENTION 
     Prior control of remote network system devices, such as by SNMP control, have eaten into the bandwidth available for data and other network traffic. Moreover, the management and signalling protocol for such remotely-managed network devices have been excessively cumbersome, unstable or otherwise undesirable. Such protocol control of remote devices require the same high-level network operations as required for the data exchange, and may also fail to provide available network management when the system high-level network operations becomes disabled. 
     SUMMARY OF THE INVENTION 
     The apparatus and system according to the present invention provides a Wan Management channel via “quasi-in-band signalling” to control remote network devices by physical layer interface devices having programmable access to the signal bits presented during the idle period which are added after packet-based network data (e.g. Ethernet) encoding and removed before network data decoding to remain transparent to normal system data transfer operation and bandwidth availability. 
     The system according to the present invention operates the remote devices in a stateless mode, wherein responses to received commands result in a direct remote device response, thus avoiding unstable and unpredictable system operations, especially during start-up or other transient conditions. Moreover, the added network control data signalling added does not reduce system reliability, but provides network control of enhanced reliability since the WAN management signal, being included in a data format significantly shorter than the prior network data packets, is less likely to be corrupted and thus more likely to be transferred without error. 
     Furthermore, the devices and system according to the present invention provide serial nesting of such remote devices along the Ethernet path, with the instructions to and data from each such remote device(s) forwarded through intermediate remote device(s) by successive receipt and retransmissions, or “hops” according to the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     These and further features of the present invention will be better understood by reading the following Detailed Description together with the Drawing, wherein 
     FIG. 1 is a diagram illustrating an exemplary network including one embodiment according to the present invention; 
     FIG. 2 is a data flow/format diagram of a network signal transfer in a network including and among devices according to one embodiment of the present invention; 
     FIG. 3 is a block illustration of the signalling hierarchy including the location of WAN management signalling according to one embodiment of the present invention; 
     FIG.  4 A and FIG. 4B are a timing diagrams showing the communication sequence between local and remote device(s) according to one embodiment of the present invention; 
     FIG. 5 is a block diagram of the board level implementation of one embodiment according to the present invention; and 
     FIG. 6 is a block diagram of an ASIC according to the embodiment of the present invention of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in FIG. 1, the device and system  50  according to the present invention enables the network controller  52 , via locally managed device  54  to reach across the network to interrogate control, status, and performance attributes of the remote network device  56 . The controller  52  includes a controller CPU  53  (FIGS. 4A and 4B) and additional control, such as SNMP control via progmable system  58  or equivalent. This is accomplished via a WAN management channel that exists between and independent of the network format data packets, e.g. Ethernet. When the network management is in operation via the WAN management side channel, it will have no impact on the customers data or available bandwidth. 
     As shown in FIG. 2, the WAN management channel actually uses the Inter-Packet Gap (IPG)  80 , which is the idle time between packets  81 A and  81 B, etc., being transmitted by end devices (not shown), and can be a transmission at any speed that is supported by the Ethernet (with active idle) or the particular data transfer protocol used. A WAN management channel packet frame  70  is generated to convey particular management data and commands between a sending device, e.g.  54 , and a receiving device, e.g.  56 , on the network. In one embodiment, the sending device may initially be the master, locally managed device  54  while the receiving device is the addressed remote device  56 ; in other embodiments or instances in the communication protocol (as shown in FIG.  4 A and FIG.  4 B), the reverse may be true and both combinations simultaneously may be true. 
     While the embodiments shown in FIG. 2 for simplicity provides direct connection between the WAN management channel packet sending and receiving devices, the present invention also is operable in networks with additional WAN management devices  56 - 2  . . .  56 -N addressable via a ‘hop’ value  73  in the frame  70  specifies the number of receipts and retransmissions of the contained data to be provided for the frame. Each time the frame is retransmitted, the value of the Hop  73  number is decremented by one. The process repeats until the Hop value is zero to indicate that the receiving remote device is the final destination; thereafter, the IPG data is replaced by nominal IPG idle signals. Thus, a 4-bit Hop number can specify a maximum of 15 retransmissions, or ‘hops’. 
     Prior to insertion into the active idle time, the active idle signals  83  in the TPG  80  a read by the sending device to verify that the IPG  80  comprises only idle  83  (non-data) bytes. The sending device then inserts the WAN management packet frame  70  (typically 6 each 8-bit bytes) into the iPG (typically initially having at least 12 idle 8-bit bytes) by replacing the corresponding idle bytes. The receiving device removes the WAN management packet bytes and reconstitutes the original IPG  80  to comprise only active idle signals,  83 . 
     As also shown in FIG. 2, in the present exemplary embodiment, the WAN management side channel frame  70  format contains a Start of Frame delimiter byte  71 , Command/Response value  72 , Address value  74 , Data byte  75 , Frame (error) Check value  76  and End of Frame delimiter byte  77 . The Address field  74  of the WAN management frame  70  will contain a value between 0 and 4096. 
     Upon power up, the local agent  54  will establish the presence of a remotely WAN manageable device  56  by querying the local interface for remote device information as provided on various accessible registers, described below. The local agent  54  will follow a request/response protocol as shown in FIG.  4 A and FIG. 4B, with only one request typically, e.g.  91 , outstanding at any specific time. After a predetermined time-out the software can issue a duplicate request or new request if no response was received. The hardware will package the request into a WAN management frame for transmission on the media between data packets, devices with WAN management must remain compatible with non-WAN management devices such as other media converters, hubs, and switches. 
     The local agent  54  is able to read ( 95 ) from the remote device  56  the following type of information: device serial number, model number, hardware rev, date of manufacturing, connector type, link status and all registers and counters that are accessible. Moreover, the user is able to over-ride local switch setting available on a the remote unit. The read of the remote device is provided by a local agent read command,  93  of FIG.  4 B. 
     The WAN management channel packet is to be transmitted during the interframe idle period  80  which comprises the interpacket gap (IPG), which is specified to be a minimum of 12 bytes by the IEEE 802.3 standard in the present exemplary embodiment. To minimize and eliminate interference with user data the management packet is to be transmitted directly following a data (e.g. Ethernet) packet. If there is no Ethernet traffic to be inserted therebetween, then WAN management packet(s) ( 70 ) may be generated at any time (after the first three idle bytes) during the idle period. If user data (a non-idle byte) is received (or detected, typically by a non-match of the idle signal at the physical layer) during transmission of the management packet then the transmission of the WAN management packet is terminated (aborted) immediately to allow the Ethernet Traffic to flow through unaltered. 
     Example commands ( 72 ) typically include: 
     Read Command  93 : are issued by the local agent  54  to read the contents of a location on the remote device. The Data Byte is ignored on Read Commands. 
     Write Command,  91 : are issued by the local agent  54  to write a value to a location on the remote device. The Data Byte contains the 8-bit value being written. 
     Response Commands  92 : are issued by the remote device  56  in response to either a Read or Write command. The Notify Response includes the register location being read and contents after any write operation has occurred. 
     Alarm Notification  94 : are issued by the remote device in response to the contents of an alarm register changing unexpectedly. The Alarm Indication includes the register location and contents after any change has occurred. 
     Alarm indications are initiated and issued by remote device(s) and are sent as specific data words. 
     The novel and inventive features according to the present invention can be further appreciated with regard to the OSI hierarchical model  200  of packet data as shown in FIG.  3 . Since the WAN management frame  70  appears between packets during the time allotted for active idle signals, the WAN management frame  70  is separated early in the model, at the physical layer  204  (as compared to earlier system management techniques which are inserted and extracted at a higher, e.g. transport  212  or session  214 , layers.) The corresponding IEEE 802.3 standard model  220  provides sublayers, including a physical coding layer  228  which includes transacting (e.g. inserting or removing) the management frame  70  within the sublayer  228 B. Thus, the existence of the WAN management frame  70  is invisible above OSI physical layer  204 . 
     The board level block diagram  100  for one embodiment of the present invention local device is shown in FIG. 5, wherein an Application Specific Integrated Circuit (ASIC)  102 , with the necessary clock oscillator  104 , PROM  106 , user option switches  108 , signal LEDs  110  and controller backplane interface and data buffer  112  are connected to provide the structure and functionality according to the present invention described elsewhere. The data buffer  112  and an EEPROM  114  communicate ( 95 ) with the controller ( 52 ). The PHY (physical layer) circuits  120 A and  120 B communicate between WAN and LAN media, and provide the access to the idle and WAN management frame signals, e.g. during the IPG via a secondary channel as provided by typical physical layer interlace devices. 
     The internal structure  150  of an ASIC incorporating the features of the embodiment  100  of FIG. 5 is shown in diagram  150  of FIG.  6 . 
     The number of bits comprising the constituent bytes and/or words of the frame  70  may also include greater and lesser values. Moreover, the specific implementation of the structure according to the present invention as illustrated by the exemplary configurations of FIGS. 1-6 incorporates the technology available to one of ordinary skill in the art, as well as their equivalents and future improvements which may provide apparatus operable according to the present claimed invention. For instance, other structural implementation of adding signalling at the physical or MAC layer of the sending device and recovering (and optionally removing) signalling in the sending device at the physical or MAC layer is within the scope of the present invention. Moreover, the network media is not limited to twisted pair (TP), fiber-optic, coaxial cable, etc., and includes any media, including wireless, by which the network may be configured and made operable according to the present invention with appropriate PHY elements  120 A and  120 B. Further modifications and substitutions by one of ordinary skill in the art and according to the present invention are within the scope of the present invention, which is not to be limited except by the claims which follow.