Multiplex communications – Fault recovery – Bypass an inoperative switch or inoperative element of a...
Patent
1994-05-27
1996-12-03
Olms, Douglas W.
Multiplex communications
Fault recovery
Bypass an inoperative switch or inoperative element of a...
370228, 370276, H04L 1224
Patent
active
055815421
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device and a method each of performing a switching control to a standby system in a hybrid system of a duplex system and a backup line.
2. Description of the Prior Art
FIG. 13 is a block diagram showing a hybrid system including a duplex system using a packet exchange and a backup line using a public network. Referring to FIG. 13, numeral 110 represents a first packet exchange. The first packet exchange 110 exchanges frame information (packets). The first packet exchange 110 is constituted of a communication line management processor (MPR) 111, and a pair of a communication multiplexer (CMU 0 system) 112 and a communication multiplexer (CMU 1 system) 113.
The communication line management processor 111 can continue communication by processing data desirably when a transfer occurs between duplex lines.
The pair of communication multiplexers 112 and 113 are connected via different lines, respectively. Line control devices (LC) 114 and 115 are built in the communication multiplexers 112 and 113, respectively.
Numeral 120 represents a second packet exchange. The second packet exchange 120 can exchange frame information (packet), like the first packet exchange 110. The second packet exchange 120 can switch the line to the line via the first packet exchange 110 or the backup line (public network) 160.
Numeral 130 represents a third packet exchange. The third packet exchange 130 can exchange frame information (packet), like the first packet exchange 110. The third packet exchange 130 interchanges the line to the public network 160 or the host 140.
Numeral 140 represents a host. The host 140 transmits desired information in response to a request from the terminal 150. The host 140 is constituted of a CPU, a memory, and other elements. Hence a user can perform a desired communication via the terminal 150.
In such a configuration shown in FIG. 13, the hybrid system including a duplex system using a packet exchange and the backup line 160 using a public network operates in accordance with the signals shown in FIG. 14.
With a communication via the line for the communication multiplexer (CMU 0 system) 112, when the line is transferred to the communication multiplexer (CMU 1 system) 113 (refer to (1) in FIG. 14), the communication line management processor 111 requests the line control device (LC) 114 in the communication multiplexer (CMU 0 system) 112 to perform a transmission queue sweeping operation. The line control device (LC) 114 under the sweeping request outputs a transmission regulation signal frame (RNR, P frame signal) to the opposite station (the second packet exchange 120) to regulate transmission from the opposite station (the second packet exchange 120) and to verify the serial transmission number of an I-frame including data (refer to (2) in FIG. 14).
The opposite station (the second packet exchange 120), which has received the transmission regulation frame, outputs the response (RR, F-frame signal) of a normal notification signal to the line control device (LC) 114 in the communication multiplxer (CMU 0 system) 112. The line control device 114 notifies the communication line management processor 111 of the transfer data communication (refer to (3) in FIG. 14).
That is, the communication multiplexer (CMU 0 system) 112 notifies the processor 111 of the transmission serial number in a transmission waiting state before a switching operation to resume the communication.
The communication line management processor 111 notifies the line control device (LC) 115 in the communication multiplexer (CMU 1 system) 113 of transfer data to reopen the transmission (refer to (5) in FIG. 14) after the communication multiplexer (CMU 0 system) 112 (refer to (4) in FIG. 14) has swept away the transmission queue.
Thereafter, the communication multiplexer (CMU 1 system) 113, which has received the transfer data notification, reopens to accumulate the transmission queue frame corresponding to the event number from the processor 111. The co
REFERENCES:
patent: 5193086 (1993-03-01), Satomi et al.
patent: 5210740 (1993-05-01), Anzai et al.
patent: 5321394 (1994-06-01), Carlton et al.
patent: 5406564 (1995-04-01), Okita
Iwasawa Yuichi
Kato Naoto
Blum Russell W.
Fujitsu Limited
Olms Douglas W.
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