CA2244570A1 - Implementing minet on layers 1 and 2 of the isdn protocol stack - Google Patents
Implementing minet on layers 1 and 2 of the isdn protocol stack Download PDFInfo
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- CA2244570A1 CA2244570A1 CA 2244570 CA2244570A CA2244570A1 CA 2244570 A1 CA2244570 A1 CA 2244570A1 CA 2244570 CA2244570 CA 2244570 CA 2244570 A CA2244570 A CA 2244570A CA 2244570 A1 CA2244570 A1 CA 2244570A1
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- peripheral
- isdn
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Abstract
A communication control system comprising a switching system peripheral controller, plural high level data link controllers (HDLCs) communicating with the peripheral controller, plural basic rate interface (BRI) line cards each communicating with a respective HDLC, at least one proprietary peripheral connected to a first BRI line card, at least one integrated services digital network (ISDN) peripheral connected to a second BRI line card, and communication channels between the peripherals and the BRI line cards, comprising data channels carrying data conforming to (i) a physical layer, (ii) a second layer conforming to an operating system interface (OSI) layer 2 ISDN standard protocol, and (iii) which selectably conforms to a layer 3 ISDN
standard protocol for operating an ISDN peripheral and a proprietary protocol for operating a proprietary peripheral.
standard protocol for operating an ISDN peripheral and a proprietary protocol for operating a proprietary peripheral.
Description
CA 02244~70 1998 - 08 - 07 1 1 P253CA
OF THE ISDN PROTOCOL STACK
FIELD OF THE INVENTION
This invention relates to communication systems and in particular to a system for implementing integrated services digital network (ISDN) services in a proprietary communication system.
BACKGROUND TO THE INVENTION
ISDN is a collection of standards which is being implemented in communication systems, which provides the capability to transmit and receive voice and digital signals in relatively broadband channels and to provide enhanced services. A first standard is referred to as ISDN-1, and describes basic rate interface (BRI) services. ISDN-1 is described in Bellcore Special Report SR-NWT-001937. A more-advanced standard, referred to as ISDN-2 provides more advanced services, which includes primary rate interface (PRI). ISDN-2 is described in Bellcore Special Report SR-NWT-002120, issue 1, May 1992.
To implement ISDN, special line circuits are required to be used in switching systems, that can communicate with peripherals such as special telephone sets using the particular communication protocol of BRI
or PRI. The communication protocol is transmitted in frames, and is comprised of three layers: a physical layer 1, a second layer referred to as layer 2, and a third layer referred to as layer 3. Layer 1 carries control signals for network and terminal termination equipment, the transmission capability of B and D
channels and the related timing and synchronization functions. Layer 2 carries link control data and layer 3 carries network control data.
While it is understood that a person skilled in the art has knowledge of the above, reference is made to the publications ITU-T Recommendations 1.430 which describes layer 1, Q.921 which describes layer 2, and CA 02244~70 1998-08-07 Q.931 which describes layer 3, by the International Telecommunication Union (ITU), dated March 1993, which are incorporated herein by reference.
Switching system manufacturers had found that they could offer services advanced from ISDN-1, using proprietary switching systems, proprietary peripheral equipment (e.g. telephone sets), and proprietary line circuits linking the switching systems and peripheral equipment. To conform such equipment to ISDN standards in order to accommodate customers who wish to use standard ISDN peripheral equipment would remove some advanced services already offered, which is undesirable since it would make the equipment less competitive.
SUMMARY OF THE INVENTION
The present invention is a communication control system which allows a user to maintain the switching system which can offer the advanced services, and use either the ISDN peripherals to obtain the restricted ISDN services conforming to ISDN standards, or use the proprietary peripherals to provide the ISDN and more advanced services.
The above is done by utilizing a service access point identifier (SAPI) subfield in the address field of the layer 2 protocol to identify whether an ISDN
protocol or a proprietary protocol should be used to communicate with the peripheral, and thus control operation of the ISDN or proprietary peripheral. In an embodiment of the invention, a control field of the layer 2 protocol contains functionally oriented messages in the event the SAPI subfield defines an ISDN
peripheral protocol and contains stimulus oriented messages in the event the SAPI subfield defines the proprietary peripheral protocol.
In accordance with an embodiment of the invention, a communication control system comprises: (a) CA 02244~70 1998-08-07 a switching system peripheral controller, (b) plural high level data link controllers (HDLCs) communicating with the peripheral controller, (c) plural basic rate interface (BRI) line cards each communicating with a respective HDLC, (d) at least one proprietary peripheral connected to a first BRI line card, (e) at lease one integrated services digital network (ISDN) peripheral connected to a second BRI line card, and (f) communication channels between the peripherals and the BRI line cards, comprising data channels carrying data conforming to (i) a physical layer, (ii) a second layer conforming to an operating system interface (OSI) layer
OF THE ISDN PROTOCOL STACK
FIELD OF THE INVENTION
This invention relates to communication systems and in particular to a system for implementing integrated services digital network (ISDN) services in a proprietary communication system.
BACKGROUND TO THE INVENTION
ISDN is a collection of standards which is being implemented in communication systems, which provides the capability to transmit and receive voice and digital signals in relatively broadband channels and to provide enhanced services. A first standard is referred to as ISDN-1, and describes basic rate interface (BRI) services. ISDN-1 is described in Bellcore Special Report SR-NWT-001937. A more-advanced standard, referred to as ISDN-2 provides more advanced services, which includes primary rate interface (PRI). ISDN-2 is described in Bellcore Special Report SR-NWT-002120, issue 1, May 1992.
To implement ISDN, special line circuits are required to be used in switching systems, that can communicate with peripherals such as special telephone sets using the particular communication protocol of BRI
or PRI. The communication protocol is transmitted in frames, and is comprised of three layers: a physical layer 1, a second layer referred to as layer 2, and a third layer referred to as layer 3. Layer 1 carries control signals for network and terminal termination equipment, the transmission capability of B and D
channels and the related timing and synchronization functions. Layer 2 carries link control data and layer 3 carries network control data.
While it is understood that a person skilled in the art has knowledge of the above, reference is made to the publications ITU-T Recommendations 1.430 which describes layer 1, Q.921 which describes layer 2, and CA 02244~70 1998-08-07 Q.931 which describes layer 3, by the International Telecommunication Union (ITU), dated March 1993, which are incorporated herein by reference.
Switching system manufacturers had found that they could offer services advanced from ISDN-1, using proprietary switching systems, proprietary peripheral equipment (e.g. telephone sets), and proprietary line circuits linking the switching systems and peripheral equipment. To conform such equipment to ISDN standards in order to accommodate customers who wish to use standard ISDN peripheral equipment would remove some advanced services already offered, which is undesirable since it would make the equipment less competitive.
SUMMARY OF THE INVENTION
The present invention is a communication control system which allows a user to maintain the switching system which can offer the advanced services, and use either the ISDN peripherals to obtain the restricted ISDN services conforming to ISDN standards, or use the proprietary peripherals to provide the ISDN and more advanced services.
The above is done by utilizing a service access point identifier (SAPI) subfield in the address field of the layer 2 protocol to identify whether an ISDN
protocol or a proprietary protocol should be used to communicate with the peripheral, and thus control operation of the ISDN or proprietary peripheral. In an embodiment of the invention, a control field of the layer 2 protocol contains functionally oriented messages in the event the SAPI subfield defines an ISDN
peripheral protocol and contains stimulus oriented messages in the event the SAPI subfield defines the proprietary peripheral protocol.
In accordance with an embodiment of the invention, a communication control system comprises: (a) CA 02244~70 1998-08-07 a switching system peripheral controller, (b) plural high level data link controllers (HDLCs) communicating with the peripheral controller, (c) plural basic rate interface (BRI) line cards each communicating with a respective HDLC, (d) at least one proprietary peripheral connected to a first BRI line card, (e) at lease one integrated services digital network (ISDN) peripheral connected to a second BRI line card, and (f) communication channels between the peripherals and the BRI line cards, comprising data channels carrying data conforming to (i) a physical layer, (ii) a second layer conforming to an operating system interface (OSI) layer
2 ISDN standard protocol, and (iii) which selectably conforms to a layer 3 ISDN standard protocol for operating an ISDN peripheral and a proprietary protocol for operating a proprietary peripheral.
BRIEF INTRODUCTION TO THE DRAWINGS
A better understanding of the invention will be obtained by considering the detailed description below, with reference to the following drawings, in which:
Figure l is a block diagram of a communication control system in accordance with the prior art, Figure 2 is a block diagram of a communication control system in accordance with an embodiment of the present invention, Figure 3 is an illustration of a data packet used in an ISDN layer 2 protocol, Figure 4 is a block diagram of mixed types of devices that can be used with the present invention, and Figure 5 illustrates an arrangement of protocols in accordance with another embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Figure l is a block diagram of pertinent parts of an example proprietary communication switching system, a type sold as SX2000tm PBX by Mitel CA 02244~70 1998-08-07 Corporation. A description of details of this system may be found in U.S. Patent 4,510,597 issued April 9, 1985 invented by Conrad Lewis, U.S. Patent 4,615,028 issued September 30, 1986, invented by Conrad Lewis and Gino Totti, and in U.S. Patent 4,616,360 issued October 7, 1986, invented by Conrad Lewis and are incorporated herein by reference.
In summary, a main control complex 1 controls a peripheral control complex 3. The main control complex is comprised of a main processor which communicates with and controls a peripheral controller in the peripheral control complex 3 via a message switch, and controls a circuit switch which switches signals between peripherals which signals pass through a peripheral switch system in the peripheral control complex.
Peripherals such as proprietary digital telephone sets 5 generate and receive signals via line circuits 7, which interface the peripheral switch system in the peripheral control complex. Each line circuit is comprised of a microprocessor which communicates with the peripheral switch system, and which interfaces a high level data link controller (HDLC) 11. The HDLC 11 interfaces a multiplexer 13, which interfaces plural digital network interface (DNI) circuits 15 to which the peripherals 5 are connected.
The DNI circuits 15 can be type MT8972B digital subscriber interface circuits sold by Mitel Corporation, specification version MTS23 of which is incorporated herein by reference.
In operation, the peripherals (below referred to as telephone sets, for convenience) generate signals (stimuli) which are received by the associated DNI
circuits. The DNI circuits are scanned via the multiplexer 13 for control messages generated by the telephone sets. These messages are routed, through the CA 02244~70 1998-08-07 HDLC 11 and the microprocessor 9 to the peripheral control complex, and subsequently to the main control complex. Control messages are also routed in the reverse direction.
In addition, the DNI circuits 15 are scanned for the presence of connected telephone sets, and status information is sent to the main control complex.
ScAnn;ng is needed in order to allow sharing of the DHLC
11 between several DNI circuits 15.
In order to provide specialized and advanced services, the DNI circuits 15 communicate with the telephone sets using proprietary protocols. Software or firmware programs to implement these protocols are stored in the DNI circuits, one referred to as MILAP, which corresponds to the ISDN protocol layer 2, and another referred to as MINET, which differs from the ISDN layer 3 protocol in several ways. One of the differences is that the MINET protocol is stimulus in nature, to operate to the design of the proprietary telephone sets 15. The MINET protocol has no relationship to the state of a telephone call, and the network layer concepts associated with call routing, used in layer 3, are not implemented. The DNI circuit does not support ISDN peripherals.
Reference is now made to Figure 2, which is a block diagram of an embodiment of the present invention.
The proprietary communication system including the main control complex 1 and the peripheral control complex, as in the prior art, is maintained. However, the DNI
circuits 7 are replaced with basic rate interface (BRI) line circuits 17.
The BRI line circuits 17 are comprised of a microprocessor 9, but instead of an HDLC 11, plural HDLCs 19 interface the microprocessor 9. Instead of DNI
circuits 15, BRI circuits 21 compatible with ISDN
CA 02244~70 1998-10-29 standards are used, each interfacing a corresponding HDLC circuit 19. Scanning is not used. Having one HDLC
circuit 19 for each BRI circuit 21, and no scanning, conforms to the ISDN standard.
S The proprietary system manufacturer's telephone sets have their internal physical interfaces changed to be compatible with the ISDN basic rate interface standards (S interface). Now either or both the proprietary telephone sets 5A and ISDN telephone sets 23 can be connected to corresponding BRI circuits 21.
The MILAP protocol used to correspond between the line circuit and the telephone set, which corresponds to layer 2 of the ISDN standard, is changed to comply with the aforenoted Q.921 standard for layer 2, except in one regard, to be described below. In addition, the BRI line circuit stores both the proprietary MINET protocol as well as the ISDN Q.931 for layer 3.
Figure 3 illustrates an example of a format of a frame of data 24 transmitted in accordance with layer 2 protocol. The frame is comprised of first and last flag fields each comprised of beginning and end 0 bits with six 1 bits between, at least one address field, at least 1 control field, and frame check sequences (FCS). Part of the address field is a service access point identifier (SAPI) subfield 25.
In accordance with the ISDN standard, the SAPI
value identifies a point at which data link layer services are provided by data link layer entity type to a layer 3 of management entity. Thus the SAPI specifies a data link layer entity type that should process a datalink layer frame and also a layer 3 or management entity which is to receive information carried by the data link layer frame. The following SAPI values were allocated by Q.921:
CA 02244~70 1998-08-07 SAPI VALUE Related Layer 3 or Management Entity 0 Call control procedures 1 - 15 Reserved for future standardization 16 Packet communication in X.25 level 3 procedures 17 - 31 Reserved for future standardization 63 Layer 2 management procedures All others Not available for level 2 procedures In accordance with an embodiment of the present invention, one of the SAPI values in this layer 2 protocol identifies conformance with the ISDN Q.931 S protocol at layer 3, and value of the same bit or group of bits identifies conformance with the proprietary MINET protocol at layer 3. These bits in the layer 2 protocol can be established at the time of installation of whichever sets 5A or 23, by the installer programming the data stored in the BRI line circuits 21, or in the factory, with the correct line circuit being plugged into the line card 17 at a connector which corresponds to the correct telephone set 5A, 23 at the time of installation of the telephone sets.
The control messages supported by the above should include both the stimulus oriented messages used with the proprietary telephone sets 5A, and the functionally oriented messages as required in layer 3 and described in the Q.931 standard. Some examples of the latter type of message are call setup messages, disconnect messages, etc.
CA 02244~70 1998-10-29 Figure 4 illustrates peripherals connected via a single ISDN circuit terminating at a PBX, in accordance with the present invention. A computer 26, requiring a wide bandwidth e.g. to communicate video and/or data, operates using the ISDN protocol. The protocol stack used to communicate via the communication control system is shown adjacent the computer, and is comprised of the physical layer, layer 2 conforming to ISDN Q.921, and layer 3 conforming to ISDN Q.931.
The communication control system can also communicate with proprietary telephone set 5A, using the protocol stack shown next to the telephone set 5A, comprised of the physical layer, layer 2 conforming to ISDN Q.921, and layer 3 conforming to the proprietary protocol MINET.
It may be seen that devices that conform to ISDN
layers 1 and 2 can be mixed, since the SAPI field identifies what protocol to use for layer 3. Services such as enhanced telephone services can thus be provided using proprietary peripheral equipment to a proprietary communication control system that can at the same time control standard ISDN peripherals.
Figure 5 illustrates the protocol stacks shown in Figure 4, and in addition that used by the line cards in the PBX. In the latter, it is shown that the physical layer and layer 2 (Q.921) of the PBX
communicate with the physical layers and layers 2 in the proprietary telephone set and in the ISDN terminal. The PBX communicates in layer 3 with the proprietary telephone set using the proprietary MINET protocol, for example, and with the ISDN terminal in the Q.931 protocol.
Thus advanced call features implemented on previous proprietary telephone sets using proprietary protocols now will work identically with those sets that CA 02244~70 1998-08-07 support layers 1 and 2 and the proprietary protocol on layer 3. Because layers 1 and 2 that conform to the BRI
ISDN protocol are used, any stAn~Ard ISDN terminal, such as a digital modem, may be connected to the same circuit and operated normally assuming that the ISDN layer 3 call control has been implemented as described above.
A person understanding this invention may now conceive of alternative structures and embodiments or variations of the above. All those which fall within lo the scope of the claims appended hereto are considered to be part of the present invention.
BRIEF INTRODUCTION TO THE DRAWINGS
A better understanding of the invention will be obtained by considering the detailed description below, with reference to the following drawings, in which:
Figure l is a block diagram of a communication control system in accordance with the prior art, Figure 2 is a block diagram of a communication control system in accordance with an embodiment of the present invention, Figure 3 is an illustration of a data packet used in an ISDN layer 2 protocol, Figure 4 is a block diagram of mixed types of devices that can be used with the present invention, and Figure 5 illustrates an arrangement of protocols in accordance with another embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Figure l is a block diagram of pertinent parts of an example proprietary communication switching system, a type sold as SX2000tm PBX by Mitel CA 02244~70 1998-08-07 Corporation. A description of details of this system may be found in U.S. Patent 4,510,597 issued April 9, 1985 invented by Conrad Lewis, U.S. Patent 4,615,028 issued September 30, 1986, invented by Conrad Lewis and Gino Totti, and in U.S. Patent 4,616,360 issued October 7, 1986, invented by Conrad Lewis and are incorporated herein by reference.
In summary, a main control complex 1 controls a peripheral control complex 3. The main control complex is comprised of a main processor which communicates with and controls a peripheral controller in the peripheral control complex 3 via a message switch, and controls a circuit switch which switches signals between peripherals which signals pass through a peripheral switch system in the peripheral control complex.
Peripherals such as proprietary digital telephone sets 5 generate and receive signals via line circuits 7, which interface the peripheral switch system in the peripheral control complex. Each line circuit is comprised of a microprocessor which communicates with the peripheral switch system, and which interfaces a high level data link controller (HDLC) 11. The HDLC 11 interfaces a multiplexer 13, which interfaces plural digital network interface (DNI) circuits 15 to which the peripherals 5 are connected.
The DNI circuits 15 can be type MT8972B digital subscriber interface circuits sold by Mitel Corporation, specification version MTS23 of which is incorporated herein by reference.
In operation, the peripherals (below referred to as telephone sets, for convenience) generate signals (stimuli) which are received by the associated DNI
circuits. The DNI circuits are scanned via the multiplexer 13 for control messages generated by the telephone sets. These messages are routed, through the CA 02244~70 1998-08-07 HDLC 11 and the microprocessor 9 to the peripheral control complex, and subsequently to the main control complex. Control messages are also routed in the reverse direction.
In addition, the DNI circuits 15 are scanned for the presence of connected telephone sets, and status information is sent to the main control complex.
ScAnn;ng is needed in order to allow sharing of the DHLC
11 between several DNI circuits 15.
In order to provide specialized and advanced services, the DNI circuits 15 communicate with the telephone sets using proprietary protocols. Software or firmware programs to implement these protocols are stored in the DNI circuits, one referred to as MILAP, which corresponds to the ISDN protocol layer 2, and another referred to as MINET, which differs from the ISDN layer 3 protocol in several ways. One of the differences is that the MINET protocol is stimulus in nature, to operate to the design of the proprietary telephone sets 15. The MINET protocol has no relationship to the state of a telephone call, and the network layer concepts associated with call routing, used in layer 3, are not implemented. The DNI circuit does not support ISDN peripherals.
Reference is now made to Figure 2, which is a block diagram of an embodiment of the present invention.
The proprietary communication system including the main control complex 1 and the peripheral control complex, as in the prior art, is maintained. However, the DNI
circuits 7 are replaced with basic rate interface (BRI) line circuits 17.
The BRI line circuits 17 are comprised of a microprocessor 9, but instead of an HDLC 11, plural HDLCs 19 interface the microprocessor 9. Instead of DNI
circuits 15, BRI circuits 21 compatible with ISDN
CA 02244~70 1998-10-29 standards are used, each interfacing a corresponding HDLC circuit 19. Scanning is not used. Having one HDLC
circuit 19 for each BRI circuit 21, and no scanning, conforms to the ISDN standard.
S The proprietary system manufacturer's telephone sets have their internal physical interfaces changed to be compatible with the ISDN basic rate interface standards (S interface). Now either or both the proprietary telephone sets 5A and ISDN telephone sets 23 can be connected to corresponding BRI circuits 21.
The MILAP protocol used to correspond between the line circuit and the telephone set, which corresponds to layer 2 of the ISDN standard, is changed to comply with the aforenoted Q.921 standard for layer 2, except in one regard, to be described below. In addition, the BRI line circuit stores both the proprietary MINET protocol as well as the ISDN Q.931 for layer 3.
Figure 3 illustrates an example of a format of a frame of data 24 transmitted in accordance with layer 2 protocol. The frame is comprised of first and last flag fields each comprised of beginning and end 0 bits with six 1 bits between, at least one address field, at least 1 control field, and frame check sequences (FCS). Part of the address field is a service access point identifier (SAPI) subfield 25.
In accordance with the ISDN standard, the SAPI
value identifies a point at which data link layer services are provided by data link layer entity type to a layer 3 of management entity. Thus the SAPI specifies a data link layer entity type that should process a datalink layer frame and also a layer 3 or management entity which is to receive information carried by the data link layer frame. The following SAPI values were allocated by Q.921:
CA 02244~70 1998-08-07 SAPI VALUE Related Layer 3 or Management Entity 0 Call control procedures 1 - 15 Reserved for future standardization 16 Packet communication in X.25 level 3 procedures 17 - 31 Reserved for future standardization 63 Layer 2 management procedures All others Not available for level 2 procedures In accordance with an embodiment of the present invention, one of the SAPI values in this layer 2 protocol identifies conformance with the ISDN Q.931 S protocol at layer 3, and value of the same bit or group of bits identifies conformance with the proprietary MINET protocol at layer 3. These bits in the layer 2 protocol can be established at the time of installation of whichever sets 5A or 23, by the installer programming the data stored in the BRI line circuits 21, or in the factory, with the correct line circuit being plugged into the line card 17 at a connector which corresponds to the correct telephone set 5A, 23 at the time of installation of the telephone sets.
The control messages supported by the above should include both the stimulus oriented messages used with the proprietary telephone sets 5A, and the functionally oriented messages as required in layer 3 and described in the Q.931 standard. Some examples of the latter type of message are call setup messages, disconnect messages, etc.
CA 02244~70 1998-10-29 Figure 4 illustrates peripherals connected via a single ISDN circuit terminating at a PBX, in accordance with the present invention. A computer 26, requiring a wide bandwidth e.g. to communicate video and/or data, operates using the ISDN protocol. The protocol stack used to communicate via the communication control system is shown adjacent the computer, and is comprised of the physical layer, layer 2 conforming to ISDN Q.921, and layer 3 conforming to ISDN Q.931.
The communication control system can also communicate with proprietary telephone set 5A, using the protocol stack shown next to the telephone set 5A, comprised of the physical layer, layer 2 conforming to ISDN Q.921, and layer 3 conforming to the proprietary protocol MINET.
It may be seen that devices that conform to ISDN
layers 1 and 2 can be mixed, since the SAPI field identifies what protocol to use for layer 3. Services such as enhanced telephone services can thus be provided using proprietary peripheral equipment to a proprietary communication control system that can at the same time control standard ISDN peripherals.
Figure 5 illustrates the protocol stacks shown in Figure 4, and in addition that used by the line cards in the PBX. In the latter, it is shown that the physical layer and layer 2 (Q.921) of the PBX
communicate with the physical layers and layers 2 in the proprietary telephone set and in the ISDN terminal. The PBX communicates in layer 3 with the proprietary telephone set using the proprietary MINET protocol, for example, and with the ISDN terminal in the Q.931 protocol.
Thus advanced call features implemented on previous proprietary telephone sets using proprietary protocols now will work identically with those sets that CA 02244~70 1998-08-07 support layers 1 and 2 and the proprietary protocol on layer 3. Because layers 1 and 2 that conform to the BRI
ISDN protocol are used, any stAn~Ard ISDN terminal, such as a digital modem, may be connected to the same circuit and operated normally assuming that the ISDN layer 3 call control has been implemented as described above.
A person understanding this invention may now conceive of alternative structures and embodiments or variations of the above. All those which fall within lo the scope of the claims appended hereto are considered to be part of the present invention.
Claims (4)
1. A communication control system comprising:
(a) a switching system peripheral controller, (b) plural high level data link controllers (HDLCs) communicating with the peripheral controller, (c) plural basic rate interface (BRI) line cards each communicating with a respective HDLC, (d) at least one proprietary peripheral connected to a first BRI line card, (e) at least one integrated services digital network (ISDN) peripheral connected to a second BRI line card, and (f) communication channels between the peripherals and the BRI line cards, comprising data channels carrying data conforming to (i) a physical layer, (ii) a second layer conforming to an operating system interface (OSI) layer 2 ISDN standard protocol, and (iii) which selectably conforms to a layer 3 ISDN
standard protocol for operating an ISDN peripheral and a proprietary protocol for operating a proprietary peripheral.
(a) a switching system peripheral controller, (b) plural high level data link controllers (HDLCs) communicating with the peripheral controller, (c) plural basic rate interface (BRI) line cards each communicating with a respective HDLC, (d) at least one proprietary peripheral connected to a first BRI line card, (e) at least one integrated services digital network (ISDN) peripheral connected to a second BRI line card, and (f) communication channels between the peripherals and the BRI line cards, comprising data channels carrying data conforming to (i) a physical layer, (ii) a second layer conforming to an operating system interface (OSI) layer 2 ISDN standard protocol, and (iii) which selectably conforms to a layer 3 ISDN
standard protocol for operating an ISDN peripheral and a proprietary protocol for operating a proprietary peripheral.
2. A communication control system as defined in claim 1 in which the second layer includes a frame structure having at least one character defining whether the ISDN peripheral protocol or the proprietary peripheral protocol in the third layer should be used by an associated line card to communicate with a peripheral connected therewith.
3. A communication control system as defined in claim 2 in which the frame structure of the second layer includes an address field and a control field, the address field including a service access point identifier (SAPI) subfield, the SAPI subfield including the at least one character.
4. A communication control system as defined in claim 3 in which the control field contains functionally oriented messages in the event the SAPI field defines the ISDN peripheral protocol, and the control field contains stimulus oriented messages in the event the SAPI subfield defines the proprietary peripheral protocol.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90762597A | 1997-08-08 | 1997-08-08 | |
| US08/907,625 | 1997-08-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2244570A1 true CA2244570A1 (en) | 1999-02-08 |
Family
ID=25424398
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2244570 Abandoned CA2244570A1 (en) | 1997-08-08 | 1998-08-07 | Implementing minet on layers 1 and 2 of the isdn protocol stack |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2244570A1 (en) |
| GB (1) | GB9817181D0 (en) |
-
1998
- 1998-08-06 GB GBGB9817181.2A patent/GB9817181D0/en not_active Ceased
- 1998-08-07 CA CA 2244570 patent/CA2244570A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| GB9817181D0 (en) | 1998-10-07 |
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| FZDE | Dead |