Source: http://www.google.com/patents/US6118759?dq=6985872
Timestamp: 2013-12-12 23:09:11
Document Index: 653699078

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Patent US6118759 - Network system and frame relay switch - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Advanced Patent Search | Sign inAdvanced Patent SearchPatentsA network system in which administrators of frame relay networks can recognize the quality of the ATM network suitably and manage the frame relay networks in accordance with the quality condition of the ATM network. When a frame F is transmitted from a frame relay network FR1 at a transmitting side to...http://www.google.com/patents/US6118759?utm_source=gb-gplus-sharePatent US6118759 - Network system and frame relay switchPublication numberUS6118759 APublication typeGrantApplication numberUS 08/837,558Publication dateSep 12, 2000Filing dateApr 21, 1997Priority dateOct 28, 1996Fee statusPaidPublication number08837558, 837558, US 6118759 A, US 6118759A, US-A-6118759, US6118759 A, US6118759AInventorsJunichi Katoh, Akitsugu OhyoshiOriginal AssigneeFujitsu LimitedExport CitationBiBTeX, EndNote, RefManPatent Citations (11), Referenced by (26), Classifications (11), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetNetwork system and frame relay switchUS 6118759 AAbstract A network system in which administrators of frame relay networks can recognize the quality of the ATM network suitably and manage the frame relay networks in accordance with the quality condition of the ATM network. When a frame F is transmitted from a frame relay network FR1 at a transmitting side to an IWF, a frame header in which a transmission number is stored is added to the frame F. Then, the frame F is received by a frame relay network FR2 at a transmitted side through the IWF and the ATM network. In the frame relay network FR2, a difference between the transmission number stored in the frame header of the frame F and a reception condition variable kept in the frame relay network FR2 is calculated, and the difference is stored in a quality information collection table as a number of discarded frames in the ATM network.
As shown in FIG. 15, first, the frame transmission processing part 56, with the above described method, detects the connection status of the ISDN circuit 23 (backup circuit) corresponding to the transmitted frame relay network number (the network number of the frame relay network FR2) for the frame F to be transmitted &lt;step S101&gt;.
Then, the frame transmission processing part 56 determines whether the connections between the ISDN circuit 23 to be a backup circuit and the frame relay networks FR1, FR2 are completed or not &lt;step S102&gt;. At that time, when the frame transmission processing part 56 determines that the connections between the frame relay networks FR1, FR2 and the ISDN circuit 23 are completed, the frame transmission processing part 56 advances the operation to the step S103. When the frame transmission processing part 56 determines that the connections between the frame relay networks FR1, FR2 and the ISDN circuit 23 are in a state except for completion, the frame transmission processing part 56 advances the operation to the step S104.
The header editing part 57 adds the frame header storage area 26 in front of the core header storage area 27 of the frame F (see FIG. 2), and makes the respective values in the frame header storage area 26 zero-clears &lt;step S105&gt;.
The header editing part 57 detects a transmission status variable corresponding to the transmitted frame relay network number and the DLCI number of the frame F in the continuous number management table 52 (see FIG. 10) &lt;step S106&gt;.
The header editing part 57 determines whether the transmission status variable obtained in the step S106 is 65535 which is the maximum value of 16 bits or not &lt;step S107&gt;. At that time, when the transmission status variable is 65535, the header editing part 57 restores the transmission status variable to 0 &lt;step S108&gt;, and when the transmission status variable is not 65535, the header editing part 57 adds 1 to the value obtained in the step S106 of the transmission status variable &lt;step S109&gt;.
The header editing part 57 stores the value obtained in the step S108 or in the step S109 of the transmission status variable in the transmission number storage area 26a of the frame F. With this arrangement, the transmission number of the frame F is set &lt;step S110&gt;.
The header editing part 57 stores a value, which is the same value stored in the transmission number storage area 26a in the step S110, in the continuous number management table 52 as a transmission status variable &lt;step S111&gt;.
The header editing part 57, similarly to the frame transmission processing part 56 in the step S101, detects the connection status of the backup circuit &lt;step S112&gt;, and determines whether the connection is completed or not &lt;step S113&gt;. Then, when the determined result in the step S113 is except for the connection completion of the backup circuit, the header editing part 57 advances the operation to the step S115.
On the contrary, when the determined result in the step S113 is that the connection of the backup circuit is completed, the header editing part 57 sets "1" in the discard information storage area 26c of the frame header &lt;step S114&gt;. Then, the header editing part 57 informs the frame transmission processing part 56 of the effect that the process as to itself is finished.
When the operation in the step 114 is finished, the frame transmission processing part 56 lets the CHCs 35b, 35c and the circuit dealing unit 41 have a control signal for transmitting a frame F to the IWF 21. With this arrangement, the frame F is transmitted to the IWF 21a &lt;step S115&gt;. When the step S115 is finished, the frame transmission processing part 56 stops the operation.
As shown in FIG. 16, when a frame F is received in the IWF 21a, the conversion processing part 71 starts &lt;step S116&gt;. The conversion processing part 71 disassembles the received frame F to plural ATM cells S &lt;step S117&gt;, transmits each ATM cell to the ATM network 20 &lt;step S118&gt;.
In the ATM network 20, it is determined whether there is a congestion in the ATM network 20 &lt;step S119&gt;, and when there is a congestion, a congestion notification (EFCI) is set into the PT (see FIG. 13) in the cell header 75 of each ATM cell S &lt;step S120&gt;. Then, the ATM network 20 transmits each ATM cell S to the IWF 21 connected with the frame relay network FR2 based on the contents in the cell header 75 &lt;step S121&gt;.
Then, when the IWF 21b receives plural ATM cells S enough to assemble a frame F, the conversion processing part 71 starts and extracts the data part 76 from each ATM cell S &lt;step S122&gt;. The conversion processing part 71 assembles each data part 76 extracted in the step S122 to assemble a part from the frame header to the data of the frame F &lt;step S123&gt;. Then, the conversion processing part 71 adds the head flag 25 to the head to be a part of the frame F assembled in the step S123 and adds the FCS and the tail flag 30 to the tail to be a part of the frame F, whereby a complete frame F is assembled &lt;step S124&gt;.
The conversion processing part 71 informs the header editing part 72 of the effect that the frame F is assembled, and starts the header editing part 72 thereby &lt;step S125&gt;. Then, the header editing part 72 refers the PT stored in the cell header 75 of the ATM cell &lt;step S126&gt;, and determines whether a congestion notification (EFCI) is set in the PT or not &lt;step S127&gt;. At that time, when the EFCI is not set in the PT, the header editing part 72 advances the operation to the step S129. When the EFCI is set in the PT, the header editing part 72 stores "1" showing that there is a congestion notification in the congestion information storage area 26b of the frame F &lt;step S128&gt;. Incidentally, the header edition part 72 performs no mapping of the EFCI to the FECN in the core header of the frame F as usual. Therefore, in the frame relay network FR2, it becomes possible to separately recognize a congestion notification from the frame relay network FR1 and a congestion notification from the ATM network 20. Then, the frame F is transmitted to the frame relay network FR2 &lt;step S129&gt;.
In the frame relay network FR2, when the frame F is received by the frame relay switch 31 connected with the IWF 21, the frame reception processing part 55 starts. As shown in FIG. 17, first, the frame reception processing part 55 determines whether the frame F, which is received, (received frame F) is received from the IWF 21 or not &lt;step S130&gt;. The frame reception processing part 55, when it is determined that the received frame F is received from the IWF 21, inputs the received frame F to the quality information storage processing part 61 as a starting command and advances the operation to the step S131. On the contrary, the frame reception processing part 55, when it is determined that the received frame F is not received from the IWF 21, advances the operation to the step S144.
When the operation is advanced to the step S131, the quality information storage processing part 61 receives a frame F from the frame reception processing part 55 so as to start. First, the quality information storage processing part 61 takes the DLCI number out from the core header of the received frame F and detects the transmitted frame relay network number in the transmitted frame relay network number retrieval table 53 (see FIG. 11) &lt;step S132&gt;.
The quality information storage processing part 61 takes the transmission number stored in the transmitting number storage area 26a of the received frame F out. Then, the quality information storage processing part 61 detects the receiving status variable corresponding to the transmitted frame relay network number and the DLCI number of the received frame F, which the numbers are obtained in the step S132, in the continuous number management table 52 (see FIG. 10) &lt;step S133&gt;.
The quality information storage processing part 61 determines whether the transmission number obtained in the step S133 is over the receiving status variable obtained in the step S133 or not &lt;step S134&gt;. The quality information storage processing part 61, when the transmission number is larger than the receiving status variable, obtains a number of ATM network discarded frames by using the following (expression 1) &lt;step S135&gt;. Then, the operation is advanced to the step S137.
On the contrary, the quality information storage processing part 61, when the transmission number is smaller than the receiving status variable, obtains a number of ATM network discarded frames by using the following (expression 2) &lt;step S136&gt;. Then, the operation is advanced to the step S137.
Then, the quality information storage processing part 61 retrieves the quality information collection table 49 (see FIG. 7), and adds the number of ATM network discarded frames, which the number is obtained in the step 135 or in the step 136, to the number of ATM network discarded frames, which the number is stored in relation to the transmitted frame relay network number and the DLCI number of the received frame F &lt;step S137&gt;.
The quality information storage processing part 61 retrieves the continuous number management table 52, and stores the transmission number of the received frame F, which the transmission number is obtained in the step 133, in the storage area of the receiving status variable corresponding to the transmitted frame relay network number and the DLCI number &lt;step S138&gt;.
The quality information storage processing part 61 determines whether "1" is stored in the congestion information storage area 26b of the received frame F or not &lt;step S139&gt;. When "1" is not stored in the congestion information storage area 26b, the quality information storage processing part 61 finishes the operation, and shifts to the operation of the step S141 by the frame reception processing part 55. When "1" is stored in the congestion information storage area 26b, the quality information storage processing part 61 retrieves the quality information collection table 49, and adds 1 to a value of the frequency of ATM network congestion notification reception, which the value is stored in relation to the transmitted frame relay network number and the DLCI number of the received frame F &lt;step S140&gt;. Then, the quality information storage processing part 61 finishes the operation, and shifts to the operation of the step S141 by the frame reception processing part 55.
When the operation is advanced to the step S141, the frame reception processing part 55 determines whether "1" is stored in the discard information storage area 26c of the received frame F or not. When "1" is not stored in the discard information storage area 26c, the frame reception processing part 55 deletes the frame header storage area 26 of the received frame F &lt;step S142&gt;, and the operation is advanced to the step S144.
On the contrary, when "1" is stored in the discard information storage area 26c, the frame reception processing part 55 discards the received frame F &lt;step S143&gt;. With this arrangement, it is prevented that frames F are transmitted to the terminal 22b repeatedly.
The quality condition analyzing part 58 starts when this operation is performed. The quality condition analyzing part 58, as shown in FIG. 18, makes the transmitted frame network number 0 &lt;step S301&gt;, and makes the DLCI number 0 &lt;step S302&gt;. Then, the quality condition analyzing part 58 sets the transmitted frame network number and the DLCI number obtained in the steps S301 and S302 as retrieval keys. The quality condition analyzing part 58 makes the values of work areas a1, a2, b1 and b2 (not shown) set in the MMs 34a, 34b for its own process zero-clear &lt;step S303&gt;.
The quality condition analyzing part 58 retrieves the quality information collection table 49 (see FIG. 7) by using the retrieval keys set in the steps S301 and S302, detects the number of ATM network discarded frames, which the number is stored correspondingly to the retrieval key, and then sets the number in the work area a1 &lt;step S304&gt;.
The quality condition analyzing part 58 retrieves the quality information cumulative table 50 (see FIG. 8) by using the above mentioned retrieval keys, and adds the number of ATM network discarded frames, which the number is obtained in the step S304, to the total of ATM network discarded frames, which the total is stored correspondingly to the retrieval keys &lt;step S305&gt;.
The quality condition analyzing part 58 retrieves the threshold storage table 51 (see FIG. 9) by using the above mentioned retrieval keys, and detects the discard frequent occurrence threshold stored correspondingly to the retrieval keys &lt;step S306&gt;.
The quality condition analyzing part 58 determines whether the number of ATM network discarded frames, which the number is stored in the work area a1 in the step S304, is over the discard frequent occurrence threshold obtained in the step S306 or not &lt;step S307&gt;. When the number of ATM network discarded frames is over the discard frequent occurrence threshold, the quality condition analyzing part 58 informs the caution output part 60 of the effect that many frames are discarded, the transmitted frame relay network number and the DLCI number. Then, the operation is advanced to the step S308. On the contrary, when the number of ATM network discarded frames is smaller than the discard frequent occurrence threshold, the quality condition analyzing part 58 advances the operation to the step S309.
When the operation is advanced to the step S308, the caution output part 60 performs the caution output process. Concretely, as shown in FIG. 19, the caution output part 60, first, determines whether a notification from the quality condition analyzing part 58 indicates a frame discard frequent occurrence or not &lt;step S401&gt;.
When the notification indicates the frame discard frequent occurrence, the caution output part 60 outputs a caution message, which many frames F are discarded, to the system console 38 in the ATM network 20 corresponding to the transmitted frame relay network number and the DLCI number which are inputted from the quality condition analyzing part 58 &lt;step S402&gt;. Then, the operation is returned to the step S309 by the quality condition analyzing part 58 via the step S403.
The quality condition analyzing part 58 retrieves the quality information collection table 49 by using the above mentioned retrieval keys, and detects the frequency of ATM network congestion notification reception, which the frequency corresponds to the retrieval key. Then, the frequency of ATM network congestion notification reception is set in the work area b1 &lt;step S310&gt;.
The quality condition analyzing part 58 retrieves the quality information cumulative table 50 (see FIG. 8) by using the above mentioned retrieval keys, and adds the frequency of ATM network congestion notification reception, which the frequency is obtained in the step S310, to the total of ATM network congestion notification reception, which the total is stored correspondingly to the retrieval key &lt;step S311&gt;.
The quality condition analyzing part 58 retrieves the threshold storage table 51 by using the above mentioned retrieval key, and detects the reception frequent occurrence threshold stored correspondingly to the retrieval key &lt;step S312&gt;.
The quality condition analyzing part 58 determines whether the frequency of ATM network congestion notification reception, which the frequency is set in the work area b1 in the step S309, is over the reception frequent occurrence threshold obtained in the step S312 or not &lt;step S313&gt;. When the frequency of ATM congestion notification reception is over the reception frequent occurrence threshold, the quality condition analyzing part 58 informs the caution output part 60 of the status of the congestion notification reception frequent occurrence, the transmitted frame relay network number and the DLCI number. Then, the operation is advanced to the step S314. On the contrary, when the frequency of ATM congestion notification reception is smaller than the reception frequent occurrence threshold, the quality condition analyzing part 58 advances the operation to the step S315.
When the operation is advanced to the step S314, the caution output part 60 performs the caution output process. Concretely, as shown in FIG. 19, the caution output part 60 determines whether a notification from the quality condition analyzing part 58 indicates the congestion notification reception frequent occurrence or not via the step S401 &lt;step S403&gt;. At that time, when the notification indicates the congestion notification reception frequent occurrence, the caution output part 60 outputs a caution message that many congestion notifications are received to the system console 38 from the ATM network 22 corresponding to the transmitted frame relay network number and the DLCI number inputted from the quality condition analyzing part 58 &lt;step S404&gt;. Then, when the operation in the step S404 is finished, the operation returns to the step S315 by the quality condition analyzing part 58.
The quality condition analyzing part 58 retrieves the quality information collection table 49 by using the above mentioned retrieval keys, and makes the number of ATM network discarded frames and the frequency of ATM network congestion notification reception, which the number and the frequency are stored correspondingly to the retrieval keys. At the same time, the set contents in the work areas a1, b1 are made zero-clear &lt;step S316&gt;.
The quality condition analyzing part 58 adds 1 to the DLCI number used as the retrieval key (at the current time, the DLCI number becomes 1 from 0) &lt;step S317&gt;. With this arrangement, the retrieval keys are varied in a manner that the transmitted frame relay network number becomes 0 and the DLCI number becomes 1.
The quality condition analyzing part 58 determines whether the value, to which 1 is added in the step S317, of the DLCI number is larger than the maximum value of the DLCI number corresponding to the transmitted frame network number 0 or not &lt;step S318&gt;. At that time, when the value of the DLCI number is larger than the maximum value of the DLCI number, the quality condition analyzing part 58 advances the operation to the step S319. On the contrary, when the value of the DLCI number is smaller than the maximum value of the DLCI number, the quality condition analyzing part 58 returns the operation to the step S304 and repeats the operation from the step S304 to the step S317. Then, when the operation is finally advanced to the step S319, the work area a2 is set with the cumulative value of the numbers of ATM network discarded frames, which the numbers correspond to all DLCI numbers belonging to the transmitted frame relay network number 0. The work area b2 is set with the cumulated value of the frequencies of ATM network congestion notification reception, which the frequencies correspond to all DLCI numbers belonging to the transmitted frame relay network number 0.
The quality condition analyzing part 58 determines whether the backup circuit connection status is in the backup circuit connection completion or not &lt;step S320&gt;. When the backup circuit connection status is in a state except for the backup circuit connection completion, the quality condition analyzing part 58 advances the operation to the step S321. When the backup circuit connection status is in the backup circuit connection completion, the quality condition analyzing part 58 advances the operation to the step S324.
The quality condition analyzing part 58 compares the value set in the work area a2 (the cumulative value of the numbers of ATM network discarded frames) with the first connection threshold, and compares the value set in the work area b2 (the cumulative value of the frequencies of ATM network congestion notification reception) with the second connection threshold. With this arrangement, the quality condition analyzing part 58 determines whether one of the cumulative values is over the threshold to be compared or not &lt;step S322&gt;.
The quality condition analyzing part 58 compares the value set in the work area a2 (the cumulated value of the numbers of ATM network discarded frames) with the first disconnection threshold, and compares the value set in the work area b2 (the cumulated value of the frequencies of ATM network congestion notification reception) with the second disconnection threshold. With this arrangement, the quality condition analyzing part 58 determines whether both the cumulated values are lower than the thresholds to be compared or not &lt;step S325&gt;.
When the operation is advanced to the step S323, the backup processing part 59 starts so as to perform the backup process shown in FIG. 21. That is, the backup processing part 59, first, determines whether the message inputted thereto is the backup connection message or not &lt;step S501&gt;. At that time, when it is determined that the message is the backup connection message, the backup processing part 59 advances the operation to the step S502. When it is determined that the message is not the backup connection message, the backup processing part 59 advances the operation to the step S506.
Then, the backup processing part 59 determines whether the connection performed in the step S502 is achieved or not &lt;step S503&gt;. When it is determined that the connection is not achieved, the backup processing part 59 returns the operation to the step S502 while adjusting the connection timing &lt;step S504&gt;. The backup processing part 59 repeats the operation of the step S502 and the step S503 until it determined that the backup circuit connection is successes in the step S503. When it is determined that the backup circuit connection is successes, the backup processing part 59 advances the operation to the step S504.
The backup processing part 59 disconnects the ISDN circuit 23 connecting the transmitted frame relay network corresponding to the transmitted frame relay network number which is inputted and the frame relay network belonging to itself in accordance with the switch procedure of the ISDN circuit 23 &lt;step S508&gt;. When the operation in the step S508 is finished, the operation of the backup processing part 59 is finished and the operation is returned to the step S326 by the quality condition analyzing part 58.
Then, the quality condition analyzing part 58 determines whether the value of the transmitted frame relay network number which 1 is added in the step S326 is larger than the maximum value of the transmitted frame relay network number &lt;step S327&gt;. When the value of the transmitted frame relay network number is smaller than the maximum value, the quality condition analyzing part 58 returns the operation to the step S302 and repeats the operation from the step 302 to the step S326 until the transmitted frame relay number is over the maximum value in the step S327. Then, when it is determined that the frame relay number is over the maximum value, the operation of the quality condition analyzing part 58 is finished.
The command receiving part 63 in the frame relay switch 31 is in a state waiting for a command from the system console 38, and performs the command receiving process when a command is inputted from the system console 38 &lt;step S601&gt;.
Then, the command receiving part 63 determines whether the command received in the step S601 is a change command for the first and second connection thresholds and/or the first and second disconnection thresholds (connection/disconnection threshold change command) or not &lt;step S602&gt;. When the command is the connection/disconnection threshold change command, the command receiving part 63 waits that the changed first and second connection thresholds and the changed first and second disconnection thresholds (changed connection/disconnection threshold) are inputted from the system console 38, and inputs the connection/disconnection threshold change command and the changed connection/disconnection threshold to the quality information management processing part 62. Thereafter, the operation of the command receiving part 63 is finished.
On the contrary, when the command received in the step S601 is not the connection/disconnection threshold change command, the command receiving part 63 determines whether the received command is the change command for the discard frequent occurrence threshold and/or the reception frequent occurrence threshold (frequent occurrence threshold change command) or not &lt;step S603&gt;. Then, when the command is not the frequent occurrence threshold change command, the operation is finished. When the command is the frequent occurrence threshold change command, the command receiving part 63 waits that the change frequent occurrence threshold is inputted from the system console 38. Then, the command receiving part 63 inputs the frequent occurrence threshold change command and the changed frequent occurrence threshold to the quality information management processing part 62, and stops the operation.
In the step S604, the quality information management processing part 62 starts. The quality information management processing part 62 determines whether the command inputted from the command receiving part 63 thereto is the connection/disconnection threshold change command or not &lt;step S605&gt;. At that time, when the quality information management processing part 62 determines that the command is the connection/disconnection threshold change command, it retrieves the threshold management table 48 and changes the threshold in the corresponding storage area to the changed connection/disconnection threshold inputted thereto &lt;step S606&gt;. With this arrangement, the values of the first and second connection thresholds and the first and second disconnection thresholds are changed.
When the operation is advanced to the step S607, the quality information management processing part 62 determines whether the command inputted thereto is the frequent occurrence threshold change command or not. At that time, when the quality information management processing part 62 determines that the command is not the frequent occurrence change command, the operation thereof is finished. When the quality information management processing part 62 determines that the command is the frequent occurrence change command, it retrieves the threshold storage table 51 and changes the discard frequent occurrence threshold and/or the reception frequent occurrence threshold stored in the corresponding storage area to the change frequent occurrence threshold &lt;step S608&gt;. When the operation in the step S608 is finished, the operation of the quality information management processing part 62 is finished. With this arrangement, the fourth operation in the frame relay switch 31 is finished.