This standard describes the implementation of standby operation for data transmission on leased circuits using GB3454 interchange circuits and GB/T 15125 25-pin connectors. This standard meets the increasing demand for the ability to provide backup facilities in situations where data transmission is no longer possible on leased lines. This standard does not exclude the use of any method to automatically switch data transmission from leased lines to backup equipment. This standard also distinguishes between answering stations and calling stations. GB/T 15123-1994 Information Processing Data Communications DTE/DCE Interface Standby Control Operation Using 25-pin Connectors GB/T15123-1994 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
Informatlon processlng-Data
communication-DTE/DCE interface back-upcontrol operation using the 25-pole connectorGB/T 15123—94
ISO 8480-1987
This standard is equivalent to the international standard ISO8480-~1987 "Information processing data communication using 25-pole connector DTE/DCE interface back-upcontrol operation".
1 Subject content and scope of application
This standard describes the use of GB3451 interchange circuits and GB/T15125 on leased circuits. 25-pin connector for data transmission.
This standard meets the increasing need to provide backup facilities in situations where data transmission is no longer possible on leased lines.
The backup facilities may be of several types:
Using a General Switched Telephone Network (GSTN) line as a backup for a two-wire leased line; using a GSTN line as a backup for a four-wire leased line; using two GSTN lines as a backup for a four-wire leased line; using one/two lines of a private switching network as a backup for a one/four-wire leased line. NOTE: Using one/two additional leased private lines as a backup for a two/four-wire leased line is a subject for further study and the above does not list all the backup facilities.
In [FE/CF In the protocol used for exchanging interface control and status information at the interface, this change of facilities should not be noticeable. It should be understood that data transmission on a used line is replaced by a backup facility only. The protocol does not include the case of manual backup calls and responses. In addition, this standard only applies to situations where control of leased and backup facilities is required at an interface. This standard does not exclude the use of any method to automatically switch data transmission over a leased line to a backup facility. In the automatic backup switch, the following situation must be distinguished: the switch of the backup facility is initiated by the ITE. In this standard, this method is called "direct backup". "Connection mode switching"; when DTE authorizes DCE, the LXCE initiates the switching of the backup facility. In this standard, this method is called "authorized mode switching". If YTE cannot control this facility through the access door, it is allowed to select this method inside the DCE during installation. This standard also distinguishes between answering stations and calling stations. Answering station:
In this station, DCE switches to the backup facility based on the received backup request (such as a personal call). Calling station:
In this station, CE must send a backup request to the called station (such as requesting the other end to switch to the backup facility). It should be noted that these switching methods can be used only at the responding end, only at the main call or both ends of the connection. These switching methods are also applicable to simple DXCE (i.e., [XCE] without backup control) which is provided at one of the two ends of the backup line only for backup purposes. For example, a call station can provide one or more independent automatic dialing GSTN lines to meet the backup requirements of a larger number of leased lines. 2 Reference standards
GB3454 Interface circuit definition table between data terminal equipment (DTE) and data circuit terminating equipment (DCE) (CCITT Recommendation V.24)
GB/T15125 Information technology Data communication 25 pin TTE/IXCE interface connector and contact number allocation (ISO2110) CCITT Recommendation V.25bis Automatic calling and/or answering equipment using 100 series interchange circuits on the common switched telephone network (CSTN).
3 Switching to standby operation
The operating state diagram is shown in Appendix A (Supplement) When the interchange circuit 108 is implemented, it should be in the \connected state. When the circuit 108 is not implemented, the 1XF operation should be operated as if the circuit 108 is stored and in the "connected" state.
3.1 Response
3.1. 1 Direct Party
After the DTE receives an incoming call, it switches circuit 116/1 [see Appendix B (Supplement), definition of new V.24 circuits] to "ON". Operation: When the DCE connected to the leased line receives a call on the spare line, it switches circuit 125 to "ON". If the DTE needs to answer the call (see note), it switches circuit 116/1 to "ON". 1CE switches circuit 107 to "OFF" until the IXF connects to the spare facility, then switches circuit 107 and circuit 117 (if used) to "ON" in order to terminate the connection with the spare facility. The DTE switches circuit 116/1 to "OFF". ECE switches circuit 107 and circuit 117 (if used) to "disconnected" until DCE is connected to the leased line, and then switches circuit 107 to "connected". When automatic disconnect is allowed on the (STN and this situation occurs, DCE switches circuit 107 and circuit 117 (if used) to "disconnected" and waits for IYTE to switch circuit 116/1 to "disconnected" before connecting to the leased line. Note: It is the responsibility of DTE to ensure that there is no difference in switching to the backup facility. 3.1.2 Authorization Mode
In this mode, DT E Authorizes the DCE to switch to the alternate facility when necessary by converting circuit 116/2 [see Appendix B (Supplement), definition of new V.24 circuits] to the "on state. If the DTE/DCE interface does not implement circuit 116/2, a DCE internal option is set during installation to enable the use of alternate facilities. In the authorized mode, circuit 117 should be doubled in the event that the DCE needs to inform the DTE of the line status. Operation: When circuit 116/2 is "on" (see note), the DCE connected to the leased line receives the call on the connected alternate line. After verifying the need to switch to the backup facility, IXCE: switches circuit 107 to *disconnected\, until DCE is connected to the backup facility, and then switches circuit 107 and circuit 117 to \connected".
When verifying the need to switch back to the leased line, DCE disconnects from the backup line and switches circuit 117 and circuit 107 to ~disconnected". When IDCE is connected to the leased line, it switches circuit 107 to "connected". DTE can also terminate the connection with the backup facility by switching circuit 116/2 to "disconnected". DCE switches circuit 116/2 to "disconnected".
Note: Because there is a risk of accidental human calls on the backup line, IKE has the responsibility to prevent switching to the backup by detecting that the communication via the leased line has failed. All judgment criteria for this may include monitoring the data flow in the corresponding direction. 3.2 Uncalled Station
3.2.1 Direct Mode
When the DTE needs to force the IXCE to initiate a request to the host station in order to switch to the backup facility, the DTE switches circuit 116/1 to "connect".
GB/T 15123--94
Operation: When DTE switches circuit 116/1 to "ON", the DCE connected to the leased line switches circuit 107 to "OFF" (see Note ①) and sends a call to the answering station on the standby line (see Note ②). After the DCE establishes a connection with the answering station on the standby facility, it switches circuit 107 and circuit 117 (if used) to "ON". In order to terminate the connection with the standby facility, the DTE switches circuit 116/1 to "OFF". The DCE also switches circuit 107 and circuit 117 (if used) to "OFF" until the DCE is connected to the leased line and then switches circuit 107 to "ON". When automatic disconnection is allowed on the GSTN and this occurs, the DCE switches circuit 107 and circuit 117 (if used) to *OFF and waits for the IDTE to switch circuit 116/1 to "OFF" before connecting to the leased line. When the call address information is not included in either the DCE or the switch, it is allowed to follow CCITT Recommendation V.25bis uses the self-calling procedure (which is not part of this standard) to establish the call. NOTE: C1) To facilitate the answering station to verify the standby request, the TXE of the calling station shall ensure that the carrier on the leased line is disconnected when it switches circuit 107 to "disconnected". This call may be a pre-determined call or a directly initiated call. In the case of predetermined calls, it can be executed by the automatic dialer in the DCE: it can also be executed in the so-called "hot line" environment, that is, the DCE occupies the line to enable the exchange to establish a dedicated connection. In the case of direct call initiation, the direct call initiation procedure described in CCITT Recommendation V.25bi is allowed to be used (this procedure is not part of this standard).
3.2.2 Authorization mode
In this mode, the DTE authorizes the DCE to switch from the leased line to the backup facilities when necessary by calling the answering station (see Note ② of Article 3.2.1). If the DTE/DCE interface does not implement circuit 116/2, an internal option of IXE is set during installation to enable the use of backup facilities.
In the authorization mode, circuit 117 should be implemented when it is necessary for the DCE to inform the DTE of the line status. Operation: After the DTE accepts the backup call issued under the control of the DCE, it converts circuit 116/2 into "connection". When the DCE connected to the leased line decides to send an active call, it should switch circuit 107 to "disconnect" (see Note (D) of Section 3.2.1), and after the 1XE establishes a backup connection with the answering station, it should switch circuit 107 and circuit 117 to "connect". When the DCE verifies the need to switch back to the leased line, the DCF disconnects the backup line and switches circuit 117 and circuit 107 to "disconnect". After the DCE connects to the rough line, it switches circuit 107 to "connect". I)TE can also terminate the connection with the backup facility by switching circuit 116/2 to "disconnect". The DCE switches circuit 117 and circuit 107 to "open" until the DCE connects to the leased line, and then switches circuit 107 to "connect". For pre-specified calls, where the call address is contained in the DCE, the call address programming procedure described in CCITT Recommendation V.25bis may be used (this procedure is not part of this standard). 4 Contact number assignment
Sequence exchange circuit 116: contact number 14:
Interchange circuit 117 contact 16.
Note: For these two circuits, in certain areas, some equipment uses the contact numbers assigned by the manufacturer. 2
Standby request
Disconnection
Main call reverse grip
"Lazy connection"
"Connection
"Instant opening"
"New opening
GB/T 15123.-94
Appendix A
Status diagram
(supplement)
Roughly marked line operation
"disconnect"
"disconnect"
"return leased line
"disconnect"
"open
PTE clears
"disconnect
"disconnect
GSTN operation
DCE clears
"connect"
"connect"
"disconnect"
"disconnect"
Name of standby switch in "direct mode" in Figure 1
L16/1107
People calling
"Connect"
"Disconnect*
"Connect"
Standby switching
"Connect"
"Connect"
"Meet"
Call connection
"Connect"
"Open"
"Disconnect"
Call connection
"Disconnect
+Connect"
"Disconnect"
GB/T 15123--94
Block the line as if it is not allowed to be detailed in each place
"Disconnect"
Return to the leased line
"Disconnect
*Original"
Cleared by DTE
"Meet
"Disconnect"
"Connect"
"Connect
Disconnect well"
116/2107|| tt||Leased line operation allows standby
HDCE please remove
“Connect”
“Disconnect”
“Disconnect”
GSTN operation
“Connect”
“Connect”
Standby switching in Figure A2 “Authorization method” Note: 1》“CE is disconnected from the raw line before automatic calling. 2) TCE disconnects from the rough line according to the incoming call. "According to the topic
"Open*
Sensitive call connection
"Connect
"Disconnect"
"Disconnect"
B/T 15123-94
Appendix B
Recommends the newly defined interchange circuit 116
(Supplement)
The definition of the following circuits is required to be included in GB 3151. 116/1: Standby switching in direct mode; Direction: To DCE:
The signals on this circuit control the DCE to switch between normal and standby facilities. The "Connected" state connects the DCE to the standby facility. When all the data previously transmitted on circuit 103 are completely transferred to the line, the "disconnected" state disconnects the DCE from the backup facility, and then the DCF is reconnected to the normal facility. 116/2: Backup switching in authorization mode: Direction: to DCE;
The signal on this circuit controls the T3CE to switch between normal and backup facilities. The "connected\" state indicates that the DTE is ready to switch from the normal backup facility and switch the DCE to the backup facility when necessary. When all the data previously transmitted on circuit 103 are completely transferred to the line, the "disconnected" state disconnects the 1XE from the backup facility, and then the IDCE is reconnected to the normal facility. Additional remarks:
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard was drafted by the North China Institute of Computing Technology of the Ministry of Machinery and Electronics Industry. This standard is under the jurisdiction of the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Zhang Bao, Tang Wenhuan, Dai Zhenqi, and Huang Jiaying.-94
Appendix A
Status diagram
(Supplement)
Roughly marked line operation
"disconnect"
"disconnect"
"open
PTE clears
"disconnect
"disconnect
GSTN operation
DCE clears
"connect"
"connect"
"disconnect"
"disconnect"
"disconnect"||t t||Figure^1 "Direct Mode" standby switching name
L16/1107
Personal call
"Connect"
"Disconnect*
"Connect"
Standby charge
Connect"
"Connect"
"Meet"
Call connection
"Connect"
"Open"
"Disconnect"
Call connection
"Disconnect
+Connect"
"Disconnect"
GB/T 15123--94
Block the line as if it is not allowed to be detailed in each place
"Disconnect"
Return to the leased line
"Disconnect
*Original"
Cleared by DTE
"Meet
"Disconnect"
"Connect"
"Connect
Disconnect well"
116/2107|| tt||Leased line operation allows standby
HDCE please remove
“Connect”
“Disconnect”
“Disconnect”
GSTN operation
“Connect”
“Connect”
Standby switching in Figure A2 “Authorization method” Note: 1》“CE is disconnected from the raw line before automatic calling. 2) TCE disconnects from the rough line according to the incoming call. "According to the topic
"Open*
Sensitive call connection
"Connect
"Disconnect"
"Disconnect"
B/T 15123-94
Appendix B
Recommends the newly defined interchange circuit 116
(Supplement)
The definition of the following circuits is required to be included in GB 3151. 116/1: Standby switching in direct mode; Direction: To DCE:
The signals on this circuit control the DCE to switch between normal and standby facilities. The "Connected" state connects the DCE to the standby facility. When all the data previously transmitted on circuit 103 are completely transferred to the line, the "disconnected" state disconnects the DCE from the backup facility, and then the DCF is reconnected to the normal facility. 116/2: Backup switching in authorization mode: Direction: to DCE;
The signal on this circuit controls the T3CE to switch between normal and backup facilities. The "connected\" state indicates that the DTE is ready to switch from the normal backup facility and switch the DCE to the backup facility when necessary. When all the data previously transmitted on circuit 103 are completely transferred to the line, the "disconnected" state disconnects the 1XE from the backup facility, and then the IDCE is reconnected to the normal facility. Additional remarks:
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard was drafted by the North China Institute of Computing Technology of the Ministry of Machinery and Electronics Industry. This standard is under the jurisdiction of the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Zhang Bao, Tang Wenhuan, Dai Zhenqi, and Huang Jiaying.-94
Appendix A
Status diagram
(Supplement)
Roughly marked line operation
"disconnect"
"disconnect"
"open
PTE clears
"disconnect
"disconnect
GSTN operation
DCE clears
"connect"
"connect"
"disconnect"
"disconnect"
"disconnect"||t t||Figure^1 "Direct Mode" standby switching name
L16/1107
Personal call
"Connect"
"Disconnect*
"Connect"
Standby charge
Connect"
"Connect"
"Meet"
Call connection
"Connect"
"Open"
"Disconnect"
Call connection
"Disconnect
+Connect"
"Disconnect"
GB/T 15123--94
Block the line as if it is not allowed to be detailed in each place
"Disconnect"
Return to the leased line
"Disconnect
*Original"
Cleared by DTE
"Meet
"Disconnect"
"Connect"
"Connect
Disconnect well"
116/2107|| tt||Leased line operation allows standby
HDCE please remove
“Connect”
“Disconnect”
“Disconnect”
GSTN operation
“Connect”
“Connect”
Standby switching in Figure A2 “Authorization method” Note: 1》“CE is disconnected from the raw line before automatic calling. 2) TCE disconnects from the rough line according to the incoming call. "According to the topic
"Open*
Sensitive call connection
"Connect
"Disconnect"
"Disconnect"
B/T 15123-94bzxZ.net
Appendix B
Recommends the newly defined interchange circuit 116
(Supplement)
The definition of the following circuits is required to be included in GB 3151. 116/1: Standby switching in direct mode; Direction: To DCE:
The signals on this circuit control the DCE to switch between normal and standby facilities. The "Connected" state connects the DCE to the standby facility. When all the data previously transmitted on circuit 103 are completely transferred to the line, the "disconnected" state disconnects the DCE from the backup facility, and then the DCF is reconnected to the normal facility. 116/2: Backup switching in authorization mode: Direction: to DCE;
The signal on this circuit controls the T3CE to switch between normal and backup facilities. The "connected\" state indicates that the DTE is ready to switch from the normal backup facility and switch the DCE to the backup facility when necessary. When all the data previously transmitted on circuit 103 are completely transferred to the line, the "disconnected" state disconnects the 1XE from the backup facility, and then the IDCE is reconnected to the normal facility. Additional remarks:
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard was drafted by the North China Institute of Computing Technology of the Ministry of Machinery and Electronics Industry. This standard is under the jurisdiction of the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Zhang Bao, Tang Wenhuan, Dai Zhenqi, and Huang Jiaying.
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