DE19913055A1 - Data links providing method for telecommunication networks with ISDN capable switching installations - Google Patents

Abstract

The terminals have a fixed virtual connection via the signaling channel of port's n/n+1 of the switching installation. The layer2 frames with SAPI and TEI evaluation are used in signaling channel, for which allocations are inputted in the switching installation per configuration and that these allocations determines what layer2 frames are issued by what port n with what SAPI/TEI value.

Description

The invention relates to telecommunications networks in which over ISDN-capable Switching data connections are provided. This includes Switching systems in public ISDN networks, such as the German one Telekom AG operates, but also ISDN-capable telecommunications systems (PBXs) for "in-house communication".

According to the prior art, terminal devices connected to the above. Plants are connected, communicate with each other only via selected connections. For this the B channels are used. In public switching systems arise connection time dependent costs.

The invention has set itself the task of developing a method with which Data connections via ISDN-capable switching facilities are available free of charge can be put.

The object is achieved in that the D channel (signaling channel) for direct Data connections is used and the assignment of the connections based on the shift 2 addresses SAPI / TEI done.

A terminal A at a port n has a connection under SAPI17 / TEI01, for example to a terminal B at a port n + 1 with the layer 2 address SAPI18 / TEI03. Under SAPI17 / TEI02, the end device is connected to several ports n + x (maximum all including the special ports 19. . .).  

The invention is illustrated by means of examples.

For data transmission according to the invention, layer 2 frames are used in a terminal A educated. These frames are given a specific layer 2 address (SAPI / TEI). The Layer 2 address can be freely determined within the permitted value range. she is stored in the terminal and in the switching center by configuration.

The user data are transmitted to the switching device (port n) using the layer 2 frame via the S ₀ bus.

The configuration in the switching device stores which layer 2 frames from which port n with which SAPI / TEI value to which port with which SAPI / TEI Value to be output.

The layer 2 address is evaluated in the switching facility. Based on the value (here SAPI17 / TEI01) and based on additional information about the source port n the control computer of the switching system recognizes the goal of the frame. The The control computer changes the layer 2 address if necessary according to the configuration on the target port n + 1 (layer 2 address used on the target port and on the target terminal, here SAPI18 / TEI03). Then the layer 2 frame is made via the internal communication system (Bus system) of the telecommunications switch to the destination port transmitted n + 1 and output accordingly here. Via the connection technology the Frame for terminal B.

The opposite direction of the connection is reversed accordingly. Terminal B also sends SAPI18 / TEI03 at n + 1. The layer 2 address is opened in the switching facility SAPI17 / TEI01 changed and output to port A at port n.

Instead of outputting the layer 2 frame at another port n + 1, it is also possible to output the layer 2 frame with a changed layer 2 address at the same port n. This enables the communication of end devices that are connected to an S ₀ bus.

To network telecommunications switching systems, there is the option of outputting the layer 2 frame via a so-called external ISDN port (exchange line S ₀ or S _2M ). If the higher-level system also works according to the solution according to the invention, plants can be networked as desired.

Furthermore, a layer 2 frame from one port n to several ports n + 1 / n + x with port-specific addresses. Instead of a point to Point connection then creates a point-to-multipoint connection.

If there is an output to all ports of a switching system / PBX, the entire network (the S ₀ buses) is connected to one another on the basis of layer 2 addresses.

A disadvantage here is the high load on the individual buses (signaling - D channels), because the data of each source is output on all ports. Just in case The application of data in the control telecontrol or telemetry area is, however so small that this disadvantage can be neglected.

In order to enable the connection of further devices, telecommunication can cation switching system any other ports can be arranged. Here are preferably the interfaces common in data transmission technology such as X.21, X.21bis, RS232 and G.703 applicable.

The dial-up ports (remote data transmission) are made using suitable adaptation circuits connected to the internal communication system of the switching device. They have also fixed virtual connections based on layer 2 addresses to the others Ports.  

If end devices that do not work according to the ISDN Layer 2 protocol are to be connected to the above dial-up ports, a Layer 2 controller (e.g. 19 ) is arranged. This controller removes layer 2 from information that is output via the port, so that data from higher layers is output without additions. Incoming information may be expanded to include layer 2 information.

In claim 9, the arrangement of a network port is described. For communication with the network, a controller must be arranged here in which the layer 2 addresses of the ports n are converted into network addresses (IP addresses). With this solution, for example, a measuring device that is connected to any S ₀ bus of a telecommunications system can be monitored by any computer in the network (LAN, intranet).

The technical solution is explained in more detail using further examples:

Variant I (see Fig. 1 and 2)

• 1. User data are generated in the terminal ( 7 ) and transferred to the terminal adapter ( 6 ).
• 2. The terminal adapter (TA) transmits the user data to the PBX using layer 2 addresses via connection ( 5 ) and S ₀ bus 1 ( 2 ). The layer 2 address should be SAPI17 / TEI03 here.
  The functions are directly comparable with the X.31 technology for Datex-P. Parallel operation is even conceivable with the corresponding assignment of the layer 2 addresses.
• 3. The S ₀ bus 1 is connected to the frame router FR1 ( 10 ) in the PBX. In the FR1, the user channels are separated by multiplexers / demultiplexers ( 22 ).
• 4. The D channel is connected to the address multiplexer / demultiplexer ( 23 ). Here the layer 2 frames are distributed to various ports ( 24 ) according to their addresses SAPI / TEI. SAPI-0 data is always forwarded to the control system of the PBX ( 17 ). The distribution of the other layer 2 addresses can be freely configured using the control and configuration system of FR1 ( 11 ). The control and configuration system of FR1 and the control and configuration system of the switching matrix ( 14 ) are connected to the control system of the telecommunications system ( 17 ). The entire system is thereby configurable through a port ( 18 ).
  The layer 2 frames with the address SAPI17 / TEI03 are assigned to the port S ₀ -1/1 ( 24 ) in this example.
• 5. The ports ( 24 ) are connected to the switching matrix ( 15 ).
• 6. The ports S ₀ -1/1 and S ₀ -2/1 are connected to the coupling rail 1 ( 16 ). The connections between the coupling rails and the ports ( 24 ) are freely configurable by the control and configuration system of the switching matrix ( 14 ).
  Multiple connections are possible.
  For external long-distance connections (WAN), the coupling rails can also be connected to other ports:
  • 1. 6.1 X.21 port ( 19 ) - Here a connection via data line to another system in another location is possible (connection of 2 switching fields).
  • 2. 6.2 Network port ( 20 ) - with adaptation circuit for connections via networks (LAN).
  • 3. 6.3 S ₀ port for exchange ( 21 ) - For X.31 connections via appropriate adaption circuits. If the solution according to the invention is also implemented in "office technology", the switching matrixes are connected via this port.
• 7. The further data path runs from coupling rail 1 via port S ₀ -2/1 to the frame router FR2 ( 9 ) and further via S ₀ bus 2 ( 3 ) to the junction box ( 5 a) and via the terminal adapter ( 6 a) to the data terminal equipment ( 7 a).

Variant II (see Fig. 3)

Step 1 to 3 are identical to variant I.

• 1. The D channel is connected to the address multiplexer / demultiplexer ( 23 ). Here the layer 2 frames are distributed to various ports ( 24 ) according to their addresses SAPI / TEI. SAPI-0 data is always forwarded to the control system of the PBX ( 17 ).
  All other layer 2 frames are forwarded to the router ( 25 ). The control and configuration system ( 14 ) is connected to the control system of the telecommunications system ( 17 ). The entire system is thereby configurable through a port ( 18 ).
  In this example, the layer 2 frames with the address SAPI17 / TEI03 are forwarded to input C of the router ( 25 ). With the help of the control and configuration system ( 14 ), the router recognizes that layer 2 frames with the address SAPI17 / TEI03 at port C must be forwarded to port B.
  Tables are stored in the control and configuration system of the switching matrix, according to which it is determined which layer 2 frames are routed from which input to which output.
  Step 5. and continue like variant I.

Variant III (see Fig. 4 and 5)

• 1. User data are generated in the terminal ( 7 ) and transferred to the terminal adapter ( 6 ).
• 2. The terminal adapter transmits the user data to the PABX using layer 2 addresses via connection ( 5 ) and S ₀ bus 1 ( 2 ). The layer 2 address should be SAPI17 / TEI03 here.
  The functions are directly comparable with the X.31 technology for Datex-P. Parallel operation is even conceivable with the corresponding assignment of the layer 2 addresses.
• 3. The S ₀ bus 1 is connected to the input functional unit EF1 ( 26 ) in the PBX. In EF1, the user channels are separated by multiplexers / de multiplexers ( 22 ).
• 4. The D channel is connected to the functional unit address extension layer 2 addresses ( 30 ). The layer 2 address is expanded by a port address. Since the extended address is only used internally in the plant, it is not bound to any standardization. The extended frames are transmitted to the control system of the telecommunications system ( 17 ) via input filters ( 31 ) and bus system ( 29 ).
• 5. Layer 2 frames from the bus system ( 29 ) are filtered by the input filter ( 31 ) for port addresses. Only the layer 2 frames with the address of their own port are forwarded to the address extension ( 30 ).
• 6. In the case of layer 2 frames from the input filter ( 31 ), the port addresses are removed again in the functional unit ( 30 ) before they are forwarded to the multiplexer / demultiplexer ( 22 ).
  By adding the port address, each device can be assigned to each bus for the control system of the PBX ( 17 ).
  SAPI17 / TEI03 becomes SAPI17 / TEI03 / Port01.
  For long-distance traffic, a further extension of the layer 2 address with a system address is advisable.
  In this example, the routing functions are taken over by the control system of the PBX ( 17 ). A separate functional unit similar to the router ( 25 ) is also conceivable.
• 7. In the control system of the telecommunications system, routing tables are used to recognize that frame 170301 is to be forwarded to the internal S ₀ connection S ₀ 2 ( 3 ). To do this, the port address is changed. 170301 becomes 170302. The frame is then returned to the bus system ( 29 ).
  In the case of multiple connections, the frame is output in succession with different port addresses to the bus system. Several port addresses in one frame are also conceivable.
  You can work at any speed on the internal bus system.
  Special ports ( 19 , 20 , 21 ) have their own internal port addresses. The port ( 19 ) has, for example, the port address 25 (see FIG. 4). He can then also be addressed by the control system of the PABX.
• 8. The layer 2 frame is forwarded by the input filter ( 31 ) into the input functional unit EF2 ( 27 ) (own port address is 02). The port address is removed again in the functional unit address extension ( 30 ). The frame is output to the internal S ₀ connection ( 3 ) via multiplexer / de multiplexer ( 22 ) and, as already described, forwarded to the terminal.
  The addressing of the layer 2 frames can be solved as follows:
  • a) The terminal adapters ( 6 , 6 a) work with the same layer 2 address SAPI17 / TEI03.
  • b) The terminal adapters work with different addresses for the send and receive direction. A terminal adapter sends with SAPI18 / TEI2 and receives with SAPI19 / TEI4. The remote station works the other way around.
  • c) The system z. B. Router ( 25 ) changes the layer 2 address. SAPI18 / TEI2 becomes SAPI19 / TEI4. This allows the terminal adapter to work with the same address for the send and receive direction. The same addresses as in a) are not required.

Reference numerals

1

PABX according to the invention

2nd

Internal S ₀

Connection of the PBX; here S ₀

1

3rd

Internal S ₀

Connection of the PBX; here S ₀

2nd

4th

Internal S ₀

Connection of the PBX; here S ₀

3rd

5

Junction box for S ₀

-Equipment

6

Terminal adapter

7

Data terminal equipment z. B. flextime terminal, PC. . .

8th

FR3 frame router

9

FR2 frame router

10th

Frame router FR1

11

Control and configuration system with memory for FR1

12th

Control and configuration system with memory for FR2

13

Control and configuration system with memory for FR3

14

Control and configuration system with memory for the switching matrix

15

Switching matrix

16

Coupling rails 1-n

17th

Control system of the PBX. The standard tasks of the PBX are controlled here (connection establishment, dialing,...)

18th

Configuration connection of the PBX

19th

X.21 port with adapter circuit

20th

Network port with adaptation circuit

21

S ₀

-External / office connection

22

Multiplexer / demultiplexer B1, B2, D-channel

23

Address multiplexer / demultiplexer

24th

Ports

25th

Router

26

Input function unit (EF1) for S ₀

1 (

2nd

)

27

Input function unit (EF2) for S ₀

2 (

3rd

)

28

Input function unit (EF3) for S ₀

3 (

4th

)

29

Bus system

30th

Functional unit address extension layer 2 address with buffer memory

31

Input filter by port address

32

Layer 2 controller

Claims (11)

1. A method for providing data connections in telecommunications networks with ISDN-capable switching devices, characterized in that
that the terminals have a fixed virtual connection via the signaling channel of ports n / n + 1 of the switching device,
that layer 2 frames with SAPI and TEI values are used for this purpose in the signaling channel, for which assignments are stored in the switching device by configuration, and
that these assignments determine which layer 2 frames are output from which port n with which SAPI / TEI value to which port with which SAPI / TEI value. 2. The method according to claim 1, characterized in that the ports are n S ₀ ports or are ports which are suitable for making an S ₀ interface available to terminal devices after appropriate adaptation. 3. The method according to claim 1, characterized in that the ports are n S _2M ports or are ports that are suitable for making an S _2M interface available to terminal devices after appropriate adaptation. 4. The method according to claim 1-3, characterized in
that at least one X.21 port ( 19 ) is arranged on the switching device,
that this port is connected to the internal communication system / bus system via a suitable adaptation circuit, and
that fixed virtual connections based on layer 2 addresses to the other ports are also possible via this port. 5. The method according to claim 1-4, characterized in that an X.21bis port is arranged instead of or in addition to the X.21 port. 6. The method according to claim 1-4, characterized in that an RS232 port is arranged instead of or in addition to the X.21 port. 7. The method according to claim 1-4, characterized in that a G.703 port is arranged instead of or in addition to the X.21 port. 8. The method according to claim 4-7, characterized in
that a layer 2 controller is assigned to the ports according to claims 4 to 7,
that this controller removes layer 2 for information that is output via the port, so that the data of higher layers are output without additions, and
that incoming information is expanded by layer 2 information. 9. The method according to claim 1-4, characterized in
that a network port is arranged instead of or in addition to the X.21 port, and
that the SAPI / TEI addresses are converted into network addresses. 10. The method according to claim 1-9, characterized in
that at least 2 terminals that are connected to an S ₀ bus have a fixed virtual connection with each other,
that the terminals are to be assigned on the basis of the different layer 2 addresses, and that the switching device converts the layer 2 addresses accordingly. 11. The method according to claim 1-9, characterized in
that the number of ports that have a fixed virtual connection to one another is arbitrary, and
that a maximum of all ports are involved in this logical connection.