Abstract:
A traffic management system includes a traffic monitor and a traffic manager. The traffic monitor monitors traffic at a reference point T of user network interface to produce traffic information for each connection established. The traffic-manager manages network traffic of the wide-area network based on the traffic information received from the traffic monitor. The traffic information is produced for each permanent virtual connection (PVC) or for each dedicated line.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a traffic management system of a wide-area network (WAN) and in particular to a traffic monitor and traffic management system and method for use in a frame-relay or leased-line (dedicated-line) network. 
     2. Description of the Related Art 
     In general, a WAN system is composed of a frame-relay/leased-line network and a plurality of subscriber systems. Each of the subscriber systems is provided with a router that handles a plurality of subscriber lines. The router is connected to the frame-relay/leased-line network through a digital service unit (DSU) and a terminal adapter (TA). 
     In such a network, traffic management is one of the most important management items and therefore various traffic management techniques have been proposed. For example, a routing control system disclosed in Japanese Patent Application Unexamined Publication No. 6-132959 performs centralized management regarding routers and LANs so as to reduce the network traffic. 
     A frame-relay exchange disclosed in Japanese Patent Application Unexamined Publication No. 7-307762 is provided with a table for storing a priority of a received frame for each data link connection identifier (DLCI). When the congestion exceeds a predetermined degree, a received frame having no priority is discarded so as not to discard a received from having high priority. 
     Further, there has been disclosed a method for displaying a traffic state within a network in Japanese Patent Application Unexamined Publication No. 8-181771. According to this method, a management station performs both configuration management and performance management to display easy-to-understand traffic states between network elements. 
     Although these conventional techniques can be combined to achieve a proper traffic management, such a conventional traffic monitoring system does not provide a means for monitoring the traffic of permanent virtual connection (PVC), resulting in reduced flexibility in add-on design of the subscriber system. 
     Further, the conventional traffic monitoring system is designed to monitor the traffic at a point between the TA and the router connected to the subscriber system. Therefore, in the case of the router having the TA built therein, an additional TA is needed to convert V-series interface to I-series interface. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a traffic monitor and traffic management system and method that can improve flexibility in add-on design of a subscriber system. 
     Another object of the present invention is to provide a traffic monitor and traffic management system and method that can monitor the traffic for each connection within the wide-area network. 
     According to the present invention, traffic within a wide-area network such as a frame-relay/leased-line network is monitored at a reference point T of user network interface. In other words, a traffic management system includes a traffic monitor for monitoring traffic at a reference point T of user network interface to produce traffic information for each connection, and further includes a traffic manager for managing network traffic of the wide-area network based on the traffic information received from the traffic monitor. The traffic information may be produced for each permanent virtual connection (PVC) or for each dedicated line. 
     The traffic monitor may be provided with a connector that is connected to a subscriber line at the reference point T and branches a transmission signal of the subscriber line to produce a branched transmission signal. The traffic monitor may be further provided with an interface device for detecting a frame from the branched transmission signal during a designated time period and a processor for producing the traffic information of predetermined traffic parameters for each connection based on frames detected for the designated time period. 
     The traffic information may be produced by counting the frames for each permanent virtual connection (PVC) or for each dedicated line during the designated time period for each dedicated line. The traffic information may be produced for each data link connection identifier (DLCI) included in an address field of a frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing a network configuration of a wide-area network employing a traffic management system according to an embodiment of the present invention; 
     FIG. 2 is a block diagram showing a traffic monitor according to the embodiment; 
     FIG. 3 is a diagram showing a signal format of a frame-relay frame; 
     FIG. 4 is a diagram showing a signal format of a PPP frame; and 
     FIG. 5 is a diagram showing an example of a group of traffic information stored in a traffic information memory. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a WAN system is composed of a frame-relay/leased-line network  10  and a plurality of subscriber systems. Further, a traffic monitor  20  is connected to at least one subscriber line at reference point T and produces traffic information under the control of supervisory control equipment  40 . As described later, the traffic information is summation data for predetermined items of the traffic characteristics. The traffic information obtained by the traffic monitor  20  is transferred to the supervisory control equipment  40  using simple network management protocol (SNMP) message through a local-area a network (LAN)  30  that is provided as necessary. The supervisory control equipment  40  manages the traffic of the frame-relay/leased-line network  10  based on the traffic information received from the traffic monitor  20 . 
     For simplicity, taking two subscriber systems  50  and  60  as an example, there will be described a traffic monitoring system according to the present invention. 
     The subscriber system  50  is connected to a router  51  that handles a plurality of subscriber lines therein and the router  51  is in turn connected to a terminal adapter (TA)  52 . The TA  52  is connected to the frame-relay/leased-line network  10  through a digital service unit (DSU)  53  that is Network Termination 1 (NT1) providing a reference point T. A router  104  having the TA built therein may be used instead of the router  51  and the TA  52 . Similarly, the subscriber system  60  is connected to a router  61  that handles a plurality of subscriber lines therein and the router  61  is in turn connected to a terminal adapter (TA)  62 . The TA  62  is connected to the frame-relay/leased-line network  10  through a digital service unit (DSU)  63  that is Network Termination 1 (NT1) providing a reference point T. A router  64  having the TA built therein may be used instead of the router  61  and the TA  62 . 
     The traffic monitor  20  is connected to each subscriber line at the reference point T through a branch cable or a tap connector and monitors the traffic of each connection through the frame-relay/leased-line network  10 . In other words, the traffic monitor  20  operates as a so-called WAN probe. 
     Traffic Monitor 
     Referring to FIG. 2, the traffic monitor  20  includes a plurality of interface (IF) modules M IF1 , M IF2  . . . M IFN , which are each connected to the physical subscriber lines at the reference point T by the branch cable or the tap connector. The respective IF modules M IF1 -M IFN  are connected to monitor processors P 1 -P N  through a selector  201 . The monitor processors P 1 -P N  are connected to a memory  202  and an analyzer  204  through a PCI (peripheral component interconnect) bus  203 . 
     Each of the IF modules M IF1 -M IFN  detects data conformable to ITU-T recommendation I.431 and produces frames of data conformable to ITU-T recommendation Q.922. The IF module can handle a plurality of channels. For example, a single IF module can handle four 1.5M-bit channels or one 6M-bit channel. 
     The IF module is provided with at least one modular jack  211  which is designed to receive a plug of the branch cable connected at the reference point T of the DSU. In the case of four 1.5M-bit channels, four modular jacks are provided. The leads of the modular jack  211  are connected to the input terminals of a transformer  212  for impedance matching and the output terminals of the transformer  212  are connected to a bipolar-to-unipolar (B/U) converter  213 . After the B/U converter  213  converts received data from bipolar to unipolar, a framer  214  detects a frame from the received data according to start and end flags to produce a Q.922 frame of data. As described later, each IF module is set to frame-relay/leased-line by downloading firmware for frame-relay/leased-line. 
     Further, the framer  214  checks FCS (frame check sequence) of the Q.922 frame and, if an error is detected, the framer  214  notifies the analyzer  204  of the number of error frames as error information. The normal frames are transferred to the selected monitor processor. 
     The respective monitor processors P 1 -P N  receive the normal frames from the IF modules M IF1 -M IFN  through the selector  201  and stores them onto a memory  202  through the PCI bus  203 . The respective monitor processors P 1 -P N  start collecting frames received from the channels depending on a monitoring start instruction received from the analyzer  204  and stop it when a monitoring stop instruction is received under the control of the supervisory control equipment  40 . In other words, the respective monitor processors P 1 -P N  collect received frames during a time interval designated by the supervisory control equipment  40 . 
     The monitor processors P 1 -P N  receive firmware for frame-relay/leased-line received from the supervisory control equipment  40  through the analyzer  204  and download the firmware to the IF modules M IF1 -M IFN . When the firmware for frame-relay is downloaded to an IF module, this IF module can be used for frame-relay monitoring. When the firmware for leased-line is downloaded to an IF module, this IF module can be used for leased-line monitoring. 
     The analyzer  204  has the following functions: SNMP (simple network management protocol) message transmission and reception; MIB (management information base) operation; frame collection; summation for each of MIB groups; frame collection control; and software/firmware program download. The MIB groups include summation groups for each link and each PVC or data link channel identifier (DLCI). 
     The analyzer  204  produces traffic information based on the normal frames and the error information. The traffic information includes the items of traffic characteristics, for example, the respective total numbers of octets, frames, error octets and error frames for each link; the respective total numbers of octets, frames, error octets and error frames for each PVC or DLCI; and the respective total numbers of octets, frames, error octets and error frames for OSI (open systems interconnection) layers  3 ,  4  and upper layers such as TCP and UDP. 
     The analyzer  204  includes a device driver  221  connected to the PCI bus  203 . The device driver  221  gets implementation information of the IF modules M IF1 -M IFN  including channel name, channel rate, and type information (frame-relay or leased-line). The device driver  221  receives the Q.922 frames collected for a designated time interval from the memory  202  and combines each Q.922 frame with the corresponding channel name and information of the monitor processor from which that frame is input to produce frame data for each Q.922 frame. 
     A traffic parameter summation processor  222  performs summation for each of MIB groups based on the frame data received from the device driver  221  and stores the traffic information obtained by the summation operation onto a traffic information memory  223 . In this embodiment, the traffic parameter summation processor  222  performs summation for each DLCI or leased line with respect to the above items. 
     An SNMP agent  224  uses a SNMP message to transmit the traffic information for a designated time interval to the supervisory control equipment  40  in response to a Get request. Further, the SNMP agent  224  transmits a trap indicating that something unusual has occurred to the supervisory control equipment  40 . When receiving a Set request from the supervisory control equipment  40 , a setting controller  225  performs the setting of the IF modules M IF1 -M IFN  as described before. 
     Referring to FIG. 3, there is shown a format of frame-relay frame (Q.922 frame). The frame is composed of a start flag  31  followed by an address field  32  consisting of a high-order octet and a low-order octet. The address field  32  includes the DLCI. The address field  32  is followed by an information field  33 , a FCS  34  and an end flag  35 . Such a frame-relay frame can be received and detected by an IF module to which the firmware for frame-relay has been downloaded. 
     Referring to FIG. 4, there is shown a format of PPP (point to point protocol) frame received from a leased line. The frame is composed of a start flag  41  followed by an address field  42 , a control field  43  and a protocol field  44 . The protocol field  44  is followed by an information field  45 , a FCS  46  and an end flag  47 . Such a PPP frame can be received and detected by an IF module to which the firmware for leased-line has been downloaded. 
     Summation Operation 
     The traffic parameter summation processor  222  performs the summation operation for each group of MIB under the control of the supervisory control equipment  40 . More specifically, when the supervisory control equipment  40  designates a channel to be checked and a time interval, the traffic parameter summation processor  222  performs the above-mentioned summation processing of frames collected for each DLCI of the designated channel at the designated time intervals. 
     When receiving the frame data from the device driver  221 , the traffic parameter summation processor  222  extracts the DLCI value from the address field of each received Q.922 frame and counts the traffic parameters (normal frames, error frames, normal octets and error octets) which have been collected for each DLCI during the designated time interval. The respective total numbers of normal frames, error frames, normal octets and error octets are stored as a group of traffic information onto the traffic information memory  223 . In this manner, a group of the traffic information for the designated time interval is sequentially stored in the traffic information memory  223 . Assuming that the summation operation is performed at 10-minute intervals, an example will be described hereinafter. 
     Referring to FIG. 5, in the case where a designated channel is monitored from 0:10 am to 0:20 am on Jan. 1 st  1998, the traffic information memory  223  counts the above information parameters for each detected DLCI to produce a group of traffic information for that time interval, for example, 380000 normal frames for DLCI=16 and 20651 normal frames for DLCI=17. 
     The traffic information memory  223  transmits the traffic information to the supervisory control equipment  40  in response to the Get request from the supervisory control equipment  40  or by polling. The supervisory control equipment  40  edits and processes the traffic information received from the traffic a monitor  20  to display the traffic characteristics for each DLCI on screen. Based on the traffic characteristics for each DLCI in the frame-relay/leased-line network  10 , the traffic control and additional line design can be easily made.