GB/T 11600-1989 Use of data terminal equipment (DTE) for interfacing with asynchronous duplex V-series modems on public data networks
Some standard content:
National Standard of the People's Republic of China
GB/T11600—1989
Use of data terminal equipment (DTE) which is designed for interfacing to asynchronous duplex V-series MODEMS on public data networks Issued on August 21, 1989
Implementation on March 1, 1990
Issued by the State Administration of Technical Supervision
National Standard of the People's Republic of China
Use of data terminal equipment (DTE) which is designed for interfacing to asynchronous duplex V-series MODEMS on public data networks This standard adopts cCITT recommendation X.20bis equivalently. GB/T11600—1989
This standard is the usage of data terminal equipment (DTE) originally designed to interface with asynchronous duplex V-series modems when accessing the public data network in my country when the public data network is opened. This standard is equivalent to the English version of CCITT Recommendation X.20bis (1984). This standard takes into account:
The interface between data terminal equipment (DTE) and data circuit terminating equipment (DCE) used for start-stop transmission in public data networks has been specified in GB/T11592—1989;
Some telecommunications management departments are planning to connect the start-stop DTE originally designed to interface with start-stop transmission V-series modems to the public data network as a transitional measure; therefore, it is stipulated that:
The interface between DCE and V-series DTE using the start-stop transmission user service type in the public data network shall comply with the provisions of this standard.
1 Scope of application
This standard applies to the interface between DTE (originally designed for duplex V-series start-stop transmission modem interface) and DCE on the public data network.
This standard is limited to the data signal rate and character structure specified for start-stop transmission in GB/T11589-1989. Its applications include:
a. Circuit switching service;
Leased circuit service.
2 Interchange circuit
2.1 Functional characteristics
The functional characteristics of the relevant interchange circuit (see Table 1) conform to GB/T3454-1982. 2.2 Electrical characteristics
The electrical characteristics of the interchange circuit conform to GB/T3455-1982, and adopt the 25-pin interface connector and pin allocation in GB/T6107-1985 standard.
Approved by the State Administration of Quality and Technical Supervision on August 21, 1989 and implemented on March 1, 1990
108/1)
108/22)
GB/T11600—1989
Signal ground or public return line
Send data
Receive data
Ready to send
Data equipment ready
Connect data equipment to line
Data terminal ready
Data channel receiving line signal detector
Call indicator
Local loopback
Test indicator
Note: 1) For automatic control of direct calling facilities. 2) For switching data network services. 3) This circuit is not provided in leased circuit services. 4) The circuit is not provided for networks that do not provide automatic loop testing. 3 Use of interchange circuits
3.1 Operation of interchange circuit 107 - Data equipment ready This circuit is used to indicate the operating functions given in Table 2. Table 2
State of circuit 107
ON
OFF
OFF
Meaning in data network
Data ready (see note)
DCE clear indication
DCE clear confirmation
Note: Since there is no circuit 105, circuit 106 turns on within 0 to 20 ms after circuit 107 turns on. 3.2 Use of interchange appliances 108/1 and 108/2 3.2.1 Circuit 108/1 - Connect data equipment to the line This circuit is used instead of circuit 108/2. The operating functions given in Table 3 shall be indicated. 3.2.2 Circuit 108/2 - Data terminal prepares this circuit for use in place of circuit 108/1 and shall indicate the operating functions given in Table 4. 2
Circuit 108/1 status
ON
ON
OFF
OFF
Circuit 108/2 status
ON
OFF
OFF
3.3 Circuit 125 -
Call indicator
GB/T 11600—1989
Meaning in data network
Call request for direct call (see 3.4.1) Call acceptance
DTE clear request
DTE clear confirm (see 3.4 .4)
Meaning in data network
Call accepted
DTE clear request
DTE clear confirm (see 3.4.4)
The connected state indicates an incoming call, and the circuit is turned off when: circuit 107 is turned on; or
DCE ready is received from the network; or b.
DCE clear indication is received from the network
3.4 Operational requirements for circuits 106, 107, 108/1, 108/2 and 1093.4.1 Call request for direct call
For direct call facilities, the DTE turns circuit 108/1 to the connected state to indicate a call request. Circuit 108/2 cannot be used for this purpose.
Call Acceptance
After receiving an incoming call, DTE should change circuit 108/1 or 108/2 from disconnected to connected within 500ms to indicate call acceptance, otherwise clear the call. When DCE makes an incoming call to DTE, if DTE's circuit 108/2 is already in the connected state, DCE will regard the connected state on circuit 108/2 as a call acceptance indication. Alternatively, when DTE does not provide circuit 108/1 or 108/2, DCE should generate a call acceptance signal sent to the network as a response to the incoming call signal from the network. A DTE controllable unready signal can also be sent to the network by manual operation on DCE.
Operation of Interchanging Circuits 109 and 106
DCE changes circuit 109 to the connected state together with circuit 107. Circuit 106 is placed in the connected state within 0 to 20ms after circuit 107 appears in the connected state. Regardless of whether circuit 108 is turned off or on, when the DCE sends a DCE clear indication signal (see 3.4.4), circuits 109 and 106 are turned off. 3.4.4DCE Clear Indication/DTE Clear Confirmation The DCE Clear Indication is transmitted to the DTE by turning circuit 107 off. When providing DTE Clear Confirmation, within 100ms after the DCE Clear Indication is issued on circuit 107, the DTE turns circuit 108/1 or 108/2 off to give a DTE Clear Confirmation signal. Otherwise, the DCE may consider the DTE to be in an uncontrollable unready state before 108/1 or 108/2 is turned off, or before the DCE is manually operated to generate a ready signal. Circuit 108/1 should always be able to give a DTE Clear Confirmation. Alternatively, when the DTE does not turn circuit 108/2 off as a DTE Clear Confirmation, a Clear Confirmation will be automatically generated in the DCE as a response to receiving a Clear Indication from the network. And the DTE is considered to be in a ready state. In the case where the DTE wishes circuit 107 to be disconnected only as a response to circuit 108/1 or 108/2 being disconnected, the DCE shall not turn circuit 107 disconnected as a DCE clear indication, and in this case, no DCE clear indication is transmitted to the DTE via the interface. In this case, the required DTE clear confirmation signal shall be automatically generated in the DCE as a response to the receipt of the clear indication signal from the network. Before circuit 108/1 or 108/2 is turned off, the DTE may be considered to be in an uncontrollable unready state. 3.4.5 Centrally controlled multipoint operation
Since circuits 106 and 109 are always in the connected state, the rules for transmission must be determined by the end-to-end control procedures of each DTE. 4 Call progress signal and information provided by the DCE Call progress signal and information provided by the DCE V series DTE cannot process. 5 Fault Detection and Isolation
5.1 Fault Status of Interchange Circuits
If the DTE or DCE cannot determine the status of circuits 107, 108/1 or 108/2 and possibly circuits 103 and 104, it shall be interpreted as an OFF state or a binary 1 state (circuits 103 and 104) as specified in the relevant electrical interface specification. 5.2 DCE Fault Status
If the DCE cannot provide service for a specified time (e.g., loss of the incoming line signal), it shall convert circuit 107 to the OFF state, the value of which is network-dependent. 5.3 Test Loops
The definition of test loops and the principles of maintenance testing using test loops are provided in the relevant standards. 5.3.1 DTE Test Loop - Type 1 Loop
This loop is used as a basic test of DTE operation and the transmitted signal is looped back in the DTE for verification. The loop should be established in the DTE as close as possible to the DTE/DCE interface. When the DTE is in the loop 1 test state:
a. Connect circuit 103 to circuit 104 within the DTE; b. Circuit 103 provided to the DCE must be in the binary 1 state; circuit 108/1 or 108/2 can be in the pre-test state, c.
If circuits 140 and 141 are provided, they must be in the disconnected state. d.
In addition, the states of other interchange circuits are not specified, but they should allow normal operation as much as possible. Loop 1 can be established from the data transfer phase or from the idle phase. If the loop is established from the data transfer phase, then during the test, the DTE will still operate normally and the DCE can continue to deliver data to the DTE. Any errors that occur during the loop test are the responsibility of the DTE to recover. If the loop is established from the idle phase, the DTE should continue to monitor circuit 125 to give priority to incoming calls over routine tests. 5.3.2 Local Test Loops - Type 3 Loops The local test loop (Type 3 loop) is used to test all or part of the operation of the DTE, interconnecting cabling, and the local DCE, as discussed below. Loop 3 may be established from any state, where permitted by national testing regulations. When testing leased circuits and short-term testing, the DCE shall continue to provide the circuit with the line state existing before the test (e.g., data transfer or ready state) on the line-switched connection. Where this is not feasible (e.g., certain cases of loop 3a) or is not required (e.g., long-term testing in line-switched applications), the DCE shall terminate existing calls. Manual control shall be provided at the DCE to activate the test loop. If automatic activation is provided on the loop, it shall be controlled by circuit 141. The exact arrangement of the test loop within the DCE is a matter of national choice. However, at least one of the local test loops described below shall be implemented. 5.3.2.1 Loop 3dWww.bzxZ.net
This loop tests the operation of the DTE, including the interconnecting cabling, by returning the transmit signal to the DTE for verification. This loop is established within the local DCE, but does not include the generator and load of the interchange circuit. 4
When the DCE is in the loop 3d test state:
a. Circuit 103 is connected to circuit 104;
b. Circuits 107 and 142 are placed in the on state. GB/T11600—1989
Note: When the test loop 3d is working, the effective length of the interconnection cable is doubled. Therefore, to ensure the correct operation of loop 3d, the maximum DTE/DCE interface cable length should be half of the normal length suitable for the data signal rate used. 5.3.2.2 Loop 3c
This loop is used to test the operation of the DTE and includes the interconnection cable and the generator and load of the DCE interchange circuit. Except that circuit 103 is looped back to 104 and includes the interchange circuit generator and load, the remaining configuration is the same as the configuration given for loop 3d in clause 5.3.2.1. The comments concerning input impedance limitations of interface cable lengths and loads are not applicable here. 5.3.2.3 Loop 3b
This loop is used to test the operation of the line coding, control logic and circuitry of the DTE and DCE. It includes all DCE circuitry except line signal conditioning circuitry (e.g., impedance matching transformers, amplifiers, equalizers). The delay between the transmission and reception of test data is several octets (see Note). The configuration is the same as that given for loop 3c in clause 5.3.2.2, except for the location of the loop return point. NOTE: In some networks the setting of loop 36 will cause the clearing of existing connections. 5.3.2.4 Loop 3a
This loop is used to test the operation of the DTE and DCE. The loop should include the maximum number of circuits used in the operation of the DCE, including in particular the line signal conditioning circuitry. It will be recognized that in some cases it may be necessary to include various devices (e.g., attenuators, equalizers or test loop switches) in the loop path to properly terminate the subscriber line while loop 3a is under test. The configuration is the same as that given for loop 3b in clause 5.3.2.3, except for the location of the loop return point. NOTE: In some networks the setting of loop 3a will cause the clearing of existing connections. 5.3.3 Network Test Loops Type 2 Loops
Network test loops (test loops 2) shall be used by the test centre of the telecommunications administration to test the operation of leased circuits or subscriber lines and the DCE in whole or in part, as discussed below. Where permitted by national testing principles, the DTE may use loop 2 as follows: a. In the case of a circuit-switched network, to test the operation of the network connection including the far-end DCE during the data transfer phase. After completion of the network loop test, it shall be possible to re-enter the data transfer phase, b. In the case of leased circuits, to test the operation of the line including the far-end DCE during the idle phase. While the test is in progress, the DCE places circuits 107 and 109 in the open state. Circuit 104 is placed in the binary "1" state. Circuit 142 is placed in the on state. The loop may be controlled manually by a switch on the DCE, or automatically by the network. The method used for loop control and for providing automatic control is a matter of national choice.
In the event of a conflict between a call request and loop activation, the loop activation command will have priority and the call request will be abandoned. The exact means of testing the loop within the DCE is a matter of national choice. One of the following network test loops should be implemented. 5.3.3.1 Loop 2b
This loop is used by the test center of the telecommunications administration and/or the remote DTE to test the operation of the subscriber line and all circuits of the DCE except the interchange circuit generator and load.
When the DCE is in the loop 2b test state:
a. Connect circuit 104 to circuit 103 within the DCE; b. At the interface, the DCE places circuit 104 in the binary 1 state and places circuit 109 in the disconnected state, or alternatively provides an open circuit or power disconnected state on circuits 104 and 109; places circuits 106, 107, and 125 to the DTE in the disconnected state; c.
d. Places circuit 142 to the DTE in the connected state. 5.3.3.2 Loop 2a
GB/T11600—1989
The test center or remote DTE of the telecommunications administration department uses this loop to test the operation of the subscriber line and the entire DCE. Its configuration is the same as that given for loop 2b in clause 5.3.3, except for the location of the return point. 5.3.4 Subscriber line test loop—Class 4 loop The telecommunications administration department provides a subscriber line test loop (Class 4 loop) for line maintenance. 5.3.4.1 Loop 4a
This loop is only provided in the case of a 4-wire subscriber line. The telecommunications administration department uses loop 4a as a maintenance line. When the sending and receiving line pairs are connected together, the resulting circuit cannot be assumed to be normal. Loop 4a can be established inside the DCE or in a separate device.
When the DCE is in the loop 4a test state:
Circuit 104 to the DTE is set to the binary 1 state; a.
Circuits 106, 107 and 125 to the DTE are set to the disconnected state, b.
Circuit 142 to the DTE is set to the connected state. c.
5.3.4.2 Loop 4b
This loop is used by telecommunications authorities to test the operation of subscriber lines including line signal conditioning circuits within the DCE. When the receive and transmit circuits are connected at this point, loop 4b provides a connection that can be considered normal, however, since the DCE does not implement complete signal regeneration, some performance impairment is expected. Except for the location of the return point, its configuration is the same as that given for loop 4a in 5.3.4.1. Additional Notes
This standard was proposed by the Ministry of Posts and Telecommunications of the People's Republic of China. This standard is technically coordinated by the Data Communication Technology Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the 30th Institute of the Ministry of Electronics. 6
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