CA1314337C - Isdn traffic generator adapter - Google Patents
Isdn traffic generator adapterInfo
- Publication number
- CA1314337C CA1314337C CA000599358A CA599358A CA1314337C CA 1314337 C CA1314337 C CA 1314337C CA 000599358 A CA000599358 A CA 000599358A CA 599358 A CA599358 A CA 599358A CA 1314337 C CA1314337 C CA 1314337C
- Authority
- CA
- Canada
- Prior art keywords
- isdn
- circuits
- processor
- channel
- analog
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/14—Monitoring arrangements
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
- H04Q11/0435—Details
Abstract
ABSTRACT OF THE DISCLOSURE
An ISDN traffic generator adapter is provided to couple an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch. The traffic generator adapter includes a plurality of first circuits which couple the analog traffic generator to the ISDN switch. Each of these first circuits includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits. In particular, each of the tip/ring interface circuits can include means for detecting commands from the analog traffic generator and providing a message to the processor upon receipt of these commands. The tip/ring interface circuits further include an arrangement to convert the analog telephone signals from the traffic generator into ISDN B channel signals to be provided to the S interface circuits. The tip/ring interface circuits also include an arrangement to convert B channel signals received from the S
interface circuitry into analog tip/ring signals to be provided to the traffic generator. The processor in each of said first circuits includes means to receive the messages from the tip/ring interface circuit and means for generating D channel signals to be provided to the S interface circuits. The processor also includes an arrangement to receive, act on and store D channel signals received from the ISDN switch through the S interface circuitry. Each of the S interface circuits includes an arrangement to combine the B channel signals received from the tip/ring interface with D channel signals from the processor to provide desired ISDN signals to the ISDN
switch. Correspondingly, the S interface circuitry also includes means to receive ISDN signals from the switch and to provide B channel signals based thereon to the tip/ring interface circuitry and to provide D channel signals based thereon to the processor. In addition to the processor circuitry in the first circuits, a second processor circuit is provided which is coupled to the plurality of first circuits.
The second processor includes an arrangement to selectively address individual ones of the processors of the first circuits. This can be used in conjunction with a D channel monitoring arrangement to control selection of predetermined ones of the processors of the first circuits so that D channel information from the ISDN switch stored in the selected processors can he individually monitored by the D channel monitor.
An ISDN traffic generator adapter is provided to couple an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch. The traffic generator adapter includes a plurality of first circuits which couple the analog traffic generator to the ISDN switch. Each of these first circuits includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits. In particular, each of the tip/ring interface circuits can include means for detecting commands from the analog traffic generator and providing a message to the processor upon receipt of these commands. The tip/ring interface circuits further include an arrangement to convert the analog telephone signals from the traffic generator into ISDN B channel signals to be provided to the S interface circuits. The tip/ring interface circuits also include an arrangement to convert B channel signals received from the S
interface circuitry into analog tip/ring signals to be provided to the traffic generator. The processor in each of said first circuits includes means to receive the messages from the tip/ring interface circuit and means for generating D channel signals to be provided to the S interface circuits. The processor also includes an arrangement to receive, act on and store D channel signals received from the ISDN switch through the S interface circuitry. Each of the S interface circuits includes an arrangement to combine the B channel signals received from the tip/ring interface with D channel signals from the processor to provide desired ISDN signals to the ISDN
switch. Correspondingly, the S interface circuitry also includes means to receive ISDN signals from the switch and to provide B channel signals based thereon to the tip/ring interface circuitry and to provide D channel signals based thereon to the processor. In addition to the processor circuitry in the first circuits, a second processor circuit is provided which is coupled to the plurality of first circuits.
The second processor includes an arrangement to selectively address individual ones of the processors of the first circuits. This can be used in conjunction with a D channel monitoring arrangement to control selection of predetermined ones of the processors of the first circuits so that D channel information from the ISDN switch stored in the selected processors can he individually monitored by the D channel monitor.
Description
BACKGROUND OF THE INVENTION
The present invention is direcked to testing o~ ISDN
(Integrated Services Digital Network~ ~witches ~for example, at an ISDN central office), and, more particularly, to a traffic generator adapter to allow testing such ISDN switc~es using commercially available analog traffic generators.
ISDN is presently being promoted by telephone companies in an effort to improve ~uality, capacity, and Yariety of services..~Preliminary ISDN specifications have been .intro-duced by CCI~T, the international communications standards committee. In the U. S. and Canada~ su~sets and minor variations of these ~tandards are bein~ defined by the major central office equ~pment vendors, ~u¢h a~ ~T&T and No~thern Telecom.
The technical concept o~ ISDN is being accomplished by using the existing copper telephone linPs t~ carry a digital signal instead of the usual analog voice (limited to 3000 Hz).
The digital signal is transmitted at a rate of 160,000 bits per second (bps), offering two S4,000 bps channels ~known as "B"
~ 20 channels) for voice or data calls, and one 16,000 bps channel :~ (identified as the "D" channal~ for establishing and maintaining the call connection to the network (and also used for sending data packets using the X.25 protocol) as a basic service~ Implementation of ISDN requires new central office switching and transmission e~uipment, and sometimesdramatically different terminal equipment (e.~., telephones, modems, data terminals) at the user or subscriber end of the ~, .~
I 3 1 ~337 telephone line. At present, ISDN is starting limited technical ~ield trial6 in ~everal citie~ around the U. S., and is ~lready being widely implemented in Europe.
A method wa3 needed to test the ne~ ISDN cen~ral o~iice switches under simulated load conditions to make sure that they were working and could handle the number of calls expected when placed in operation. With the older style telephone switches, traffic generators were used to place a large number of calls through the switch. They would also monitor the time needed to complete the call, the ~uality of the connection and speed that the switch could handle ~imultaneous request~ for service. Sincs the existing traffic generators were analog and the ISDN switches required a digital input, they could not be used to directly test ISDN switches.
Another method was needed.
Accordingly, most of the ISDN switches now being installed includes self test capability. Thi~ function can t~st a large percentage of the switch hardware for proper operation including controller operation and the integrity ~f internal data paths. However, built-in sel~ test equipment i5 not capable of providing actual 'inputs from external equipment. On the contrary, it only can simulate internal functions. It cannot test the response of the switch to actual of~-hook and dialing signals from the customer's telephone, nor can it test the complete data path ~rom end to end (telephone to telephone). In addition, there is no way ~or the cu~tomer to check that the internal ~elf test provided by the switch 1 3 1 ~337 manufacturer really provides a Gomplate test of the switch.
Accordingly, the present inventlon is directed to an ada~ter permitting the use of commercially available analog tra~fic generators to per~orm extensive testing of ISDN switches.
; 5 In addition, it i5 often necessary to identify the ~ouxce o~ trouble in the event of problems in making or answering a voice or data call. As noked above, in basic ISDN service, the voice or data information is carried ~y one of two B channels on the ISDN circuit. The call transactions to make a connection; or link, are established via the D channel.
~! .
Messages sent to and from the central office on the D channel contain the information defining the status of ~he link. It is very important to know what part of the link acti~ity is failing to determine i~ the trouble is in the loaal equipment or elsewhere. All D channel in~ormation may be ~isplayed in ~, the following formats:
inary.
The present invention is direcked to testing o~ ISDN
(Integrated Services Digital Network~ ~witches ~for example, at an ISDN central office), and, more particularly, to a traffic generator adapter to allow testing such ISDN switc~es using commercially available analog traffic generators.
ISDN is presently being promoted by telephone companies in an effort to improve ~uality, capacity, and Yariety of services..~Preliminary ISDN specifications have been .intro-duced by CCI~T, the international communications standards committee. In the U. S. and Canada~ su~sets and minor variations of these ~tandards are bein~ defined by the major central office equ~pment vendors, ~u¢h a~ ~T&T and No~thern Telecom.
The technical concept o~ ISDN is being accomplished by using the existing copper telephone linPs t~ carry a digital signal instead of the usual analog voice (limited to 3000 Hz).
The digital signal is transmitted at a rate of 160,000 bits per second (bps), offering two S4,000 bps channels ~known as "B"
~ 20 channels) for voice or data calls, and one 16,000 bps channel :~ (identified as the "D" channal~ for establishing and maintaining the call connection to the network (and also used for sending data packets using the X.25 protocol) as a basic service~ Implementation of ISDN requires new central office switching and transmission e~uipment, and sometimesdramatically different terminal equipment (e.~., telephones, modems, data terminals) at the user or subscriber end of the ~, .~
I 3 1 ~337 telephone line. At present, ISDN is starting limited technical ~ield trial6 in ~everal citie~ around the U. S., and is ~lready being widely implemented in Europe.
A method wa3 needed to test the ne~ ISDN cen~ral o~iice switches under simulated load conditions to make sure that they were working and could handle the number of calls expected when placed in operation. With the older style telephone switches, traffic generators were used to place a large number of calls through the switch. They would also monitor the time needed to complete the call, the ~uality of the connection and speed that the switch could handle ~imultaneous request~ for service. Sincs the existing traffic generators were analog and the ISDN switches required a digital input, they could not be used to directly test ISDN switches.
Another method was needed.
Accordingly, most of the ISDN switches now being installed includes self test capability. Thi~ function can t~st a large percentage of the switch hardware for proper operation including controller operation and the integrity ~f internal data paths. However, built-in sel~ test equipment i5 not capable of providing actual 'inputs from external equipment. On the contrary, it only can simulate internal functions. It cannot test the response of the switch to actual of~-hook and dialing signals from the customer's telephone, nor can it test the complete data path ~rom end to end (telephone to telephone). In addition, there is no way ~or the cu~tomer to check that the internal ~elf test provided by the switch 1 3 1 ~337 manufacturer really provides a Gomplate test of the switch.
Accordingly, the present inventlon is directed to an ada~ter permitting the use of commercially available analog tra~fic generators to per~orm extensive testing of ISDN switches.
; 5 In addition, it i5 often necessary to identify the ~ouxce o~ trouble in the event of problems in making or answering a voice or data call. As noked above, in basic ISDN service, the voice or data information is carried ~y one of two B channels on the ISDN circuit. The call transactions to make a connection; or link, are established via the D channel.
~! .
Messages sent to and from the central office on the D channel contain the information defining the status of ~he link. It is very important to know what part of the link acti~ity is failing to determine i~ the trouble is in the loaal equipment or elsewhere. All D channel in~ormation may be ~isplayed in ~, the following formats:
inary.
2. H~x.
3. Bus activation state.
4. OSI layer l HDLC ~ramesO
5. OSI layer 2 L~PD/LAPD de~oder fxames.
6. OSI layer 3 Q.931 and decoder X.25 frames.
The present invention also includes a D channel monitor feature to help i~olate the location of any problems quickly and accurately.
Figure 1 shows a basic ISDN terminal which the present invention can be used in aon~unction with. The terminal is divided into functional groupings. By separating ~unctions conceptually in this way, it is possible to identify and .~
specify the inter~aces between them. A description o~ the 131~337 functional groups is as follows, noting that this description is conXined to th~ ~unctions of ~asic access.
N~l Nekwork Termination l~ ~his is the group of functions which terminate the transmission line. As such, it is seen in the CCITT recommendations as belonging to the networ~ pr~vided, i.e., the owner of the transmission line. The functions of the NTl are described as:
~ine transmission termination.
.~ Line maintenance and performance monitoring.
Timing.
Power trans~er, extracting power from the line to drive at least the "wake-up" portion of the terminal.
: 15 Parts of the multiplexing functions.
Termination o the T interface which may include multi-drop termination and associated contention : resolution functions.
NT~ - Network Te~mination:2. This is the group of functions which give the terminal its particular "character". An NT2 could be a PABX if acce~s is primary, a LAN or a terminal controllerO The functions of the NT2 are described as:
Protocol handling or handling that part of the protocol associated with information transfer across a network.
:.J
The higher-level parts of the multiplexing function.
Switching and concentration functi~ns.
Ma.intenance functions.
Inter~ace ~unctions to thls S and T interfaces.
The NT2 functional group may be more or less complex depending on the application. The range extends fxom the quite complex function of a PABX clown to relatively simple functions required for a time ~ivision multiplexer. In specific, simple cases all .. ..
the functions may be adequately performed by NTl, .~ and NT2 becomes merely physical connections.
TE - Terminal Equipment. Thi~ iB the device itself. It : could be a digital telephone, a CADCAM workstation, a computer terminal, etc.
El - Terminal Equipment Type 1~ Such terminal squipment complies with ISDN user-network interface recommendations and therefore supports interface 5.
TE2 - Terminal Equipment Type 2. Such a terminal supports the same functions but does not comply with the ISDN
user-network lnterface recommendations. It must therefore interface with the ISDN ~ccess via a TA Terminal Adapter which con~erts the non-ISDN
- interface functions into ISDN acceptable foxm at ; reference points S or ~.
. .
131~337 This description has largely revealed the nature of the interfaces. A further description is as ~ollows:
Reference point T tT for Terminal) Separates the network provider's equipment from the user equipment. Provides a standardized intarface between equipment, sending and receiving, validating and timing information to the network and to terminal eguipment devoted to the u~e of ~ this ln~ormation.
Reference point S (S for System) Separates the user terminal equipment from the network functions of the terminal.
Reference point R (R ~or Rate) Provides a non-ISDN
interfac~ between non-ISD~ compatible user eguipment and adapter equipment.
:. Such an interface may well comply with : one o~ the ~CITT X series interfaca ~: recommendations.
Reference point U (U for User) Interface between NTl and the transmis~ion line.
The terminology from Figure l will be used throughout the rest of the specification. This terminology is presently well accepted standard terminology, as discussed, for example, in the textbook, ~The Integrated Services Digital Network: from Concept to Application", by ~ohn Ronayne, publi~hed by " ~
I!
-` 1 31 ~,337 John Wile & Sons, Inc., 1988, to which the reader is .eE-e~red..-OBJECTS OF THE INVENTION
It is an object of the present invention to provide a testing arrangement for ISDN switchesO
It is a further object of the present invention to provide a traffic generator adapter that can allow testing such ISDN
switche~ using commercially available analog traffic generators.
Another object of the present invention is to provide a traffic generator adapter which can monitor D channel operation of the central office switches.
SUMMARY OF THE INVENTION
To achieve these and other objects, the present invention provides an ISDN traffic generator adaptar to couple an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch. The traffic generator adapter includes a plurality of first circuits which couple the an~log traffic generator to the ISDN switch. Each of these first circuite includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuit6. In particular, each of the tip/ring interface circuits can include means for detecting commands from the 1 31 ~337 analog traffic generator and providing a message to the processor upon rec~ipt of these commands. The tip/ring interface circuits further include an arrangement to convert the analog telephone signals from the traf~i~ generator into ISDN B channel signals to be provided to the S interface circuit6. The tip/ring interface circuits also include an arrangement to convert B channel signals received from the S
interface circuitry înto analog tip/ring signals to be provided to the traffic generator~ The processor in each ~f said first circuits includes means to receive ~he messages from the , tip/ring interface circuit and means for generating D channel signals to be provided to the s interface circuits. The ~ pr~cessor also includes an arrangement to receive, act on and ; 6tore D channel ~i.gnals received from the ISDN switch through the S interface circuitry. Each of the S interface circuits includes an arrangement to combine the B channel signals recei~ed from the tip/ring interface with D channel signals ~: from the processor to provide desired ISDN signals to the ISDN
switch. Correspondingly, the S interface circuitry also .~ 20 includes means to ~eceive ISDN signals ~rom the switch and to provide B channel signals based thereon to the tip/ring interface circuitry and to provide ~ channel si~nals ~ased thereon to the processor.
; In addition to the pxocessor circuitry in the first circuits, a second processor circuit is provided which is coupled to the plurality of first circuits. The ~econd processor includes an arrangement to selectively address .~
1 31 ~337 individual ones of the processors of the first circuits.
This can be used in conjunction with a D channel monitoring arrangement to control selection of predetermined ones of the processors of the first circuits so that D channel information from the IS~N switch stored in the selected processors can be individually monitored by the D channel monitor.
In accordance with an embodiment: of the invention, an integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch is comprised of a plurality of first circuits for providin~ a plurality of two-way communication links between the analog traffic generator and the ISDN switch, wherein each of the first circuits includes apparatus for converting the analog telephone signals from the analog traffic generator into a plurality of ISDN signals, including B channel information and D channel information, for the ISDN switch, and apparatus for converting a plurality of ISDN signals from the ISDN switch, including B channel information and D
channel information, into analog telephone signals for the analog traffic generator, so that each two-way communication link provides a particular ISDN signal to : 25 the ISDN switch in response to a particular analog signal from the analog traffic generator and a particular analog telephone signal for the analog traffic g~narator in :, 1 3 1 ~337 response to a particular ISDN signal from the ISDN switch;
a processor coupled to the plurality of first circuits, including apparatus for selectively addressing individual ~nes of the plurality of irst circuits; and D channel monitor apparatus coupled to the processo:r for monitoring D channel communication between the first circuits and the ISDN switch, including apparatus for selecti.vely monitoring D channel communication between the first circuits and the ISDN switch for individual two-way communication links between the analog traffic generator and the ISDN switch in accordance with the selection of one of the first circuits by the processor.
In accordance with another embodiment of the invention, an apparatus for generating a plurality of ISDN
traffic signals for testing an ISDN switch is comprised of a plurality of first circuits coupled to the ISDN switch including apparatus for generating a plurality of two-way communication links between the ISDN switch and the first circuits, wherein each two-way communication link includes a first ISDN signal including B channel information and D
channeI information from a first circuit to the ISDN
switch and a second ISD~ signal including B channel information and D channel information from the ISDN switch to the first circuit; a processor coupled to the plurality of first circuits including apparatus for selectively addressing individual ones of the first circuits; and D
channel monitoring apparatus cvupled to the processor for 9a 131~337 monitoring D channel communication between the first circuits and the ISDN switch including apparatus for selectively monitoring individual two-way communication links between the first circuits and the ISDN switch in accordanc.e with the selection of the first circuit by the processor.
In accordance with another embodim~nt of the invention, an integrated services digital network ~ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch is comprised of a plurality of first circuits for coupling the analog traffic generator to the ISDN switch, for two-way communication therebetween, wherein each of the first circuits includes a plurality of tip/ring interface ; circuits, a processor and a plurality of S interface :~: circuits, wherein each of the tip/ring inter~ace circuits includes apparatus for detecting commands from the analog traffic generator and providing a message to the processor upon receiving the commands, each of the tip/ring interface circuits further including apparatus for converting analog telephone signals from the analog traffic g~nerator into ISDN B channel signals to be provided to one of the S interface circuits and apparatus ~ 25 for ~onverting B channel signals received from one of the - S interface circuits into analog tip/ring signals to be provided to the analog traffic generator, wherein the : 9b ~., 1 3 1 ~337 processor includes apparatus for receiving the messages from the tip/ring interface circuits and generating D
channel signals to be provided to one the 5 in~erface circuits, the processor further including apparatus for receiving and storing D channel signals f:rom the ISDN
switch through the S interfaca, and wherein each of the S
interface circuits includes apparatus for combining B
channel signals received from a tip/ring interface with D
channel signals received from the prOCe~SQr to provide an ISDN signal to the ISDN switch and apparatus for receiving ISDN signals from the switch and providing B channel signals based thereon to on~ of the tiptring interface circuits and apparatus for providing D channel signals based thereon to the processor; a second processor circuit coupled to the plurality of first circuits, wherein the ; second processor circuit includes apparatus for selectively addressing individual ones of the processors of the plurality of first circuits; and apparatus coupled to the D channel monitor for monitoring predetermined operation characteristics of a selected processor of the first circuits in accordance with the selection of the processor of the first circuits by the second proce~sor.
In accordance with another embodiment of the invention an integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch, is comprised 9c of a first circuit for coupling the analog traffic generator to the ISDN switch, for two-way communication therebetween, wherein the first circuit includes a plurality of tip/ring interface circuits, a processor and S a plurality of S interface circuits, wherein each of the tip/ring interface circuits includes apparatus for detecting commands from the analog traffic generator and providing a message to the processor upon receiving the commands, each of the tip/ring interface circuits further including apparatus for converting analog telephone signals from analog traffic generator into ISDN B channel signals to be provided to one of the S interface circuits and apparatus for converting B channel signals received from one of the S interface circuits into analog tip/ring signals to be provided to the analog traffic generator, wherein the processor includes apparatus for receiving the messages from the tip/ring interface circuits and generating D channel signals to be provided to the S
interface circuits, the processor further including apparatus for receiving and storing D channel signals from the ISDN switch through the S interface, and wherein each of the S interface circuits includes apparatus for combining B channel signals received from a tip/ring interface with D channel signals received from the processor to provide an ISDN signal to the ISDN switch and apparatus for receiving ISDN signals from the switch and 9d 1 31 ~337 providing B channel signals based thereon to one of the tip/ring interface circuits and apparatus for providing D
channel signals based thereon to the processor; and a D
channel monitor coupled to the processor for æelecting and monitoring D channel information on predetermined ~wo-way ISDN communication links between the first circuit and the ISDN switch.
R_F DE CRIPTION OF THE DRAWINGS
Figure l shows a block diagram of a basic ISDN
terminal which the present invention can be used in conjunction with;
Figure 2 is a block diagram showing an embodiment of a traffic generator adapter in accordance with the present invention;
Figure 3 is a block diagram showing an individual daughter board of the traffic generator adapter o~ Figure 2;
Figure 4 is a block diagram of a tip/ring interface of the traffic generator adapter of Figure 2;
Figure 5 is a block diagram showing a single D
channel monitor for a plurality of trafic generator adapters; and Figures 6 to 24 show d~tailed schematic circuitry for the block diagrams of Figures 2 to 5.
DETAILED DESCRIPTION
Figure 2 illustrates an embodiment of a traffic generator adapter (hereinafter TGA) in accordance with the present 9e 1 31 ~337 invention. As can be seen therel the TGA is formed to include a processor board 10, a plurality o~ daughter boards 12 and a bac~ plane board 14 for interfacing the TGA to ~n ISDN central ; o~ice on the one hand and to an analo~ traffic generator on the other. The TGA is also coupled via the processor board lO
to a D channel monitor 16, preferably through an RS232 port~
If desired, the TGA can also be coupled, again through the processor board 10, to other TGAs. Figure 5 ~hows an example o~ coupling a plurality of TGAs to a ~ingle D channel monitor, - 10 with each of the TGAs belng coupled to one anokher through their respective processor boards 10.
In Figure 2, the ISDN central office and the traffic generator are not shown since they do not form a direct part of the present invention. It is envisioned that the present invantion could be used with a large number of comm~rcially available traf~ic generators. Solely for purposes of example, it i~ noted that suitable traffic generators for khis purpose are manufactured by Ameritec Corporation in its bulk call generat~r line. A number of models are put out by Ameritec ; 20 Corporation as "Model AMlPlus" whiGh can be used in con~unction with the present invention.
Similarly, at the present time, a number of ISDN central offices have been developed which the pre~ent invention can be used in conjunction with. For example, Northcom Corporation has developed an ISDN cenkral o~fice called the DMS-lOO, while AT&T has developed the 5ESSTM syste~. The present invention can be used in conjunction with either of khese ISDN cankral TM - Trade Mark "J
o~fice switching arrangements, although, of course, it is not intended to be limited to either of these~
~ ommunication bekween the daughter boards 12 and the processor board is accomplished by way of a bac~ plane generator board 14. This back plane board 14 is ~ormed o~
connectors and wiring designed to interconnect the various boards shown in Figure 2 and to interconnect the TGA to the traffic generator and the ISDN central of~ice switches.
Although it is not shown in Figure 2, the connection betwPen the back plane 14 and the ISDN central office would normally be made either through a NTl or both through a NTland NT2 such-as shown in Figure 1. In other words, the TGA of Figure 2 would normally be loaated at either an S interface or a T interface of an ISDN terminal. The traffic generator would then 6~rve ~5 effectively as terminal equipment o~ the T~ type ~hown in Figure 1, while the TGA of Figure 2 ef~ectively serves as the terminal adapter ~A (noting, however, that it could also be located at the T interface rather tha~ being limited to the S
interface).
The six daughter boards 12 contain circuitry to simulate an analog central office switch to the analog traffic generator. The daughter boards al60 contain B channel encoding/decoding processars in a Codec ~hich changes the analog voice signal from the traffic generator into digital data to be transmitted on the B channel~ (e.g. ~ee Figure 3 ) .
In addition, the daughter boards 12 contain hardwara for transmitting and receiving on the "S~T" inter~ace. The 1 3 1 ~337 processor board 10 contains the necessary equipment for interrogating the D channels of any of the daughter boards, as well as equipment to ~ormat it and send it to the D channel monitor 16. The processor board 10 al80 handles the interaonnecti~n protoc~l b~tween the respective circuit elements.
As can be seen in Figure 2, the TGA is designed to handle 48 tip/ring lines ~rom the traffic generator and to provide 2 S interfaces into the ISDN central o~fice. This number, of 10 Gourse~ is for purposes of example only since the invention is not intended to be limited to this. Similarly, although each daughter board is shown as operating with eight tip/ring pairs and four S interface pairs, this is also solely for purposes of example. It is, however, noted that the example of 48 tip/ring lines was chosen since this is a suitable number ~or testing many I~DN central office switchesO For example, up to 4 telephone calls can be placed into the central office simultaneously to study how well the ISD~ central o~fice ; replie~. Essentially, the testing operator can try to overload the ISDN system to see at what point it stop5 making connections. At the same time, using the present in~e~tion, the D channel operation can also be studied under these conditions.
More specifically, an important aspect of the present invention is the D channel capability of the arrangemellt. As can be seen in Figure 2, each of the daughter boards 12 has D
channel data lines and D channel monitor enable lines. The ,,, 1 3 1 ~337 daughter boards 12 operate to provide D channel information from their internal processors to the ISDN central office in a manner which will be described in more detail with regard to Figure 3. The daughter boards also operate to recei~e, act on and store D channel information from the ISDN central office which can be used for ~elective D ~hannel monitoring. This selective D channel monitoring is achieved by virtue of the enable lines shown from the processor board 10 to the back plane board 14 and the D monitor enable lines from the back plane boar~ 14 to the individual daughter boards. A command signal from the processor board 10 serves to elect indi~idual ones of the daughter boards 12 for readout of the stored D
channel information. This selected D channel information can then be provided from the selecked daughter board 12 to the D
channel monitor 16 through the pr~c2ssor board 10, as will be discussed in further detail hereinafter.
Figure 3 shows an individual daughter board 12 o~
Figure 2. As can be seen there, each daughter board 12 includes a pluraIity of tip/ring interfaces ~hereinafter T~R
interface) 18, a processor 20 and a plurality of S
inter~aces 22. The ~&R inter~aces 18 receive tip and ring signals from the traffic generator, and also provide return tip and ring ~ignals to the traffic ~enerator (from the ISDN
central office through the TGA).
;i 25 Basically, the T&R interface 18 handles the analog data and signalling to and from the traffic generator. In order to do this, it is capable of detecting conditions such as off 1~
.~
1 31 ~337 hook, on hook, and dialing from the traffic generator and translatlng these into 5~ gnals to the processor 20. In return it receives signals from the processor 20 and translates them into signals for the traffic generator such as ringing. More speclfically,as shown in Figure 4, the T~R inter~ace 18 contains several sensing circuits to detect co~mands from the tra~ic generator. These signals can include on hoo~, off hook, and DTMF dialing. Whenever these ~ignals are detected, a message is sent to the processor 20 through an I/0 port. The processor.20 passes this message on to t~e switch through the S
interface. Subsequently, one of the processors 20 can respond '' to a command from the switch to command a T~R interface through an I/0 port to start ringing to signal the traffic generator that it should answer the call.
~hen the processor 20 receives these signals from the T&R
interface 18, it generates equivalent D channel messages to the central office switch through the S interface 22 and handles all the handshakes needed to establish the proper central office action. It also will translate commands from the central office into action to be produced by the T&R
- interface 18. In addition to handling the messaging back and forth between the analog traffic generator and the digital ISDN
switch, the processor 20 fo~mats the D channel traffic and stores it to be a~ailable to be sent to the proce~sor board 10 when the processor board 10 requests it.
The S interface 22 combines the digitized analog data ~rom two T&R sections with the D channel data produced by the 1~
.~
processor into the ISDM standard 2B+D S or T interface to be sant to the central of~ice. It al~o xeceives such ISDN 6ignals from the central of~ice and provid~s B c~annel information to the T~R interfac;:e~ and D channel ~ignals to the S proce~sor 2 0 .
A typical se~uence of operation for the TGA of Figure ~3 would be as ~ollows. The tr~t~lc generator would go o~f hook.
This would be detected by the ~R inter~aces 18 of a daughter board and a signal would be sent to th2 proces~or 2 0 that a 10 connectio~ is desired. By means o~ D chann~l messages, the TGA
r would reque~ ~ sonnection ~rom the ISDN central office switch. The ISDN switch would then respond with 21 cormect message and dial tone which would be sent to the traffic : generator through the TGA. Upon receipt of dial tone, the traffic generator would begin dialing. The DTMF tones would be detected by a T&R interface, sent to a processor 20 and then to the central office ISDN switch on the D channel. The ISDN
switch would complete the call an~ send a message to another T~R interface 18 to start ringing. The tra~fic generator would detect ring~ng and go off hook to answer the call. The secon~
T~R interface would detect the o~f hook and signal the switch to complete the call. Once this is done, the tra~fic generator would send tones end-to-end to t~st the quality of the connection and then hang up. The T&R interface 18 would detect the on hook condition and signal the switch to tear down the call.
,.~
13~337 As noted previously, an important aspect of the present invention is the ~act that it permits selective monitoring of individual D channel information within the TGA using, i~
desired, a single D channel monitor 16. This can even be the case if a plurality o~ TG~s are coupl~d together in the manner shown in Figure 5. In othex words, even though there may be hundreds of S interface lines between the TGA system of Figure 5 and ISDN central offioe, the prPsent invention allows a testing operator to isolate on a single D channel line within a particular daughter boaxd 12 of one o~ the individual TGAs.
In effect, the present invention allows addressing particular D
channel lines. The reason for the importance o~ this is that although an analog tra~ic generator coupled to the TG~ o~ the present invention is capable of determining if an ISDN switch is operating up to specifications, it has no way of assisting troubleshooting if a problem is found without the D channel ~;
~ monitoring feature. The D channel monitor 16 analyzeæ the ;~ signalling traffic between the adapter and the ISDN s~itch to assist in determining why the proper connections are not taking place. It does this by displaying messages being passed between the two devices as the call progresses. By interpreting these messages, a trained operator can determine the cause of faiiure. Since there are many D channels in the TGA, the arrangement of permitting the processor boards 10 to selectively enable processors 20 of the daughter board~ 12 is .
; included to select which D channel is to be monitored.
131~337 As noted previously, the selection of the desired D
c~annel line is controlled through the processor bGards 10 o~
each ~f the TGAs. More specifically, by controlling an enable line to each of the six daughter boards 12, an RS232 port is enabled on a particular dau~hter board. When this i~ ena~led, D channel data is placed on a bus to ~e received and translated by the processor board 10. For c~mmunication with another box, the D channe~ monitor 16 precedes the re~uest for the data with.
a box num~er. If this is anything other than zero, the box number i5 decremented by one and relayed dir~ctly to the next box in the cnain. This decrementing and relaying is continued by each box until the address reaches æero and that box responds w.ith data from the requested D channel.
As described above, the pxesent invention provides an arrangement which allows both exercising both ISDN centraI
office switches with commercially available analog tra~fis ~enerators and selective D channel m~nitorin~ of individual D
channel lines within the TGA. With regard to this, it is noted that the present invention is not intended to be limited to a particular D channel monitor 16 since a varieky o~ D channel testing equipment could be u6ed. In other words, the present invention is not intended to be limited to a particular D
channel test pro~ram. However, one example of a D channel monitor that could be used with the present invention is 25 described in Canadian Patent Application Serial No. 599,357 filed May 10~ 1989 by the same inventors as the present application, and entitled "D Channel Monitor", to which the .
reader i.s referred. It is noted that this related application includes an example of software speci~ications that ; could be used ~or such D channel monitoring.
Also, it is to be noted that the processor boards 10 and the processors 20 described above can be any suitable processors for carrying out the functions described. For example, Intel 801~8 microprocessors could be used throughout, alth~ugh the invention is not limited to this. Regarding the softw~re for these operations, essentially the TGA of the present invention operates in a manner similar to a terminal adapter for converting a plurality of anal~g signals from an analog traf~ic generator into ISDN signals for an ISDN central office. As such, the processors 10 and 20 can operate using known terminal adapter software programs modified to permit the selective accessing by the D channel monitor 16 to individual D
channel lines through the processor boards 10 and the processor 20, as described above.
-~ Although the invention has been described with regard to use in permitting testing of ISDN central office switches using analog trafflc generators, it is to be noted that the present -~ invention could also be useful for other purposes. For exampler the present invention could be used, if desired, as an adapter to permit the connection of a large number o~ analog telephones ~or other analog equipment) to an ISDN central office in plaae of using a large number of individual t~rminal adapters. The advantage o~ this over using commercially available terminal adapters would be that the present invention , ~
....
t 3 1 ~337 permits the isolation of individual D channel lines ~or testing using a single D channel monitor, a~ discussed above.
Flgures 6 to 24 provide detailed schematic drawings for the elements illustrated in Figures 2 to 6. These figures are labelled to identify the particular circuit elPments o~
Figures 2 to 6 in the specification which are illustrated.
Figuras 6 to 24 identify integrated circuits and other electrical and el~ctronic elements with convention~lly utilized industrial identification.
It is~to be understood that the above-described arrangements are simply illustrative o~ the application of the `' principles of this invention. Numerous other arrangements may be readily devised by those skilled in the art which embody the principles of the invention and fall within its spirit and scope.
, .~
.... ... .
The present invention also includes a D channel monitor feature to help i~olate the location of any problems quickly and accurately.
Figure 1 shows a basic ISDN terminal which the present invention can be used in aon~unction with. The terminal is divided into functional groupings. By separating ~unctions conceptually in this way, it is possible to identify and .~
specify the inter~aces between them. A description o~ the 131~337 functional groups is as follows, noting that this description is conXined to th~ ~unctions of ~asic access.
N~l Nekwork Termination l~ ~his is the group of functions which terminate the transmission line. As such, it is seen in the CCITT recommendations as belonging to the networ~ pr~vided, i.e., the owner of the transmission line. The functions of the NTl are described as:
~ine transmission termination.
.~ Line maintenance and performance monitoring.
Timing.
Power trans~er, extracting power from the line to drive at least the "wake-up" portion of the terminal.
: 15 Parts of the multiplexing functions.
Termination o the T interface which may include multi-drop termination and associated contention : resolution functions.
NT~ - Network Te~mination:2. This is the group of functions which give the terminal its particular "character". An NT2 could be a PABX if acce~s is primary, a LAN or a terminal controllerO The functions of the NT2 are described as:
Protocol handling or handling that part of the protocol associated with information transfer across a network.
:.J
The higher-level parts of the multiplexing function.
Switching and concentration functi~ns.
Ma.intenance functions.
Inter~ace ~unctions to thls S and T interfaces.
The NT2 functional group may be more or less complex depending on the application. The range extends fxom the quite complex function of a PABX clown to relatively simple functions required for a time ~ivision multiplexer. In specific, simple cases all .. ..
the functions may be adequately performed by NTl, .~ and NT2 becomes merely physical connections.
TE - Terminal Equipment. Thi~ iB the device itself. It : could be a digital telephone, a CADCAM workstation, a computer terminal, etc.
El - Terminal Equipment Type 1~ Such terminal squipment complies with ISDN user-network interface recommendations and therefore supports interface 5.
TE2 - Terminal Equipment Type 2. Such a terminal supports the same functions but does not comply with the ISDN
user-network lnterface recommendations. It must therefore interface with the ISDN ~ccess via a TA Terminal Adapter which con~erts the non-ISDN
- interface functions into ISDN acceptable foxm at ; reference points S or ~.
. .
131~337 This description has largely revealed the nature of the interfaces. A further description is as ~ollows:
Reference point T tT for Terminal) Separates the network provider's equipment from the user equipment. Provides a standardized intarface between equipment, sending and receiving, validating and timing information to the network and to terminal eguipment devoted to the u~e of ~ this ln~ormation.
Reference point S (S for System) Separates the user terminal equipment from the network functions of the terminal.
Reference point R (R ~or Rate) Provides a non-ISDN
interfac~ between non-ISD~ compatible user eguipment and adapter equipment.
:. Such an interface may well comply with : one o~ the ~CITT X series interfaca ~: recommendations.
Reference point U (U for User) Interface between NTl and the transmis~ion line.
The terminology from Figure l will be used throughout the rest of the specification. This terminology is presently well accepted standard terminology, as discussed, for example, in the textbook, ~The Integrated Services Digital Network: from Concept to Application", by ~ohn Ronayne, publi~hed by " ~
I!
-` 1 31 ~,337 John Wile & Sons, Inc., 1988, to which the reader is .eE-e~red..-OBJECTS OF THE INVENTION
It is an object of the present invention to provide a testing arrangement for ISDN switchesO
It is a further object of the present invention to provide a traffic generator adapter that can allow testing such ISDN
switche~ using commercially available analog traffic generators.
Another object of the present invention is to provide a traffic generator adapter which can monitor D channel operation of the central office switches.
SUMMARY OF THE INVENTION
To achieve these and other objects, the present invention provides an ISDN traffic generator adaptar to couple an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch. The traffic generator adapter includes a plurality of first circuits which couple the an~log traffic generator to the ISDN switch. Each of these first circuite includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuit6. In particular, each of the tip/ring interface circuits can include means for detecting commands from the 1 31 ~337 analog traffic generator and providing a message to the processor upon rec~ipt of these commands. The tip/ring interface circuits further include an arrangement to convert the analog telephone signals from the traf~i~ generator into ISDN B channel signals to be provided to the S interface circuit6. The tip/ring interface circuits also include an arrangement to convert B channel signals received from the S
interface circuitry înto analog tip/ring signals to be provided to the traffic generator~ The processor in each ~f said first circuits includes means to receive ~he messages from the , tip/ring interface circuit and means for generating D channel signals to be provided to the s interface circuits. The ~ pr~cessor also includes an arrangement to receive, act on and ; 6tore D channel ~i.gnals received from the ISDN switch through the S interface circuitry. Each of the S interface circuits includes an arrangement to combine the B channel signals recei~ed from the tip/ring interface with D channel signals ~: from the processor to provide desired ISDN signals to the ISDN
switch. Correspondingly, the S interface circuitry also .~ 20 includes means to ~eceive ISDN signals ~rom the switch and to provide B channel signals based thereon to the tip/ring interface circuitry and to provide ~ channel si~nals ~ased thereon to the processor.
; In addition to the pxocessor circuitry in the first circuits, a second processor circuit is provided which is coupled to the plurality of first circuits. The ~econd processor includes an arrangement to selectively address .~
1 31 ~337 individual ones of the processors of the first circuits.
This can be used in conjunction with a D channel monitoring arrangement to control selection of predetermined ones of the processors of the first circuits so that D channel information from the IS~N switch stored in the selected processors can be individually monitored by the D channel monitor.
In accordance with an embodiment: of the invention, an integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch is comprised of a plurality of first circuits for providin~ a plurality of two-way communication links between the analog traffic generator and the ISDN switch, wherein each of the first circuits includes apparatus for converting the analog telephone signals from the analog traffic generator into a plurality of ISDN signals, including B channel information and D channel information, for the ISDN switch, and apparatus for converting a plurality of ISDN signals from the ISDN switch, including B channel information and D
channel information, into analog telephone signals for the analog traffic generator, so that each two-way communication link provides a particular ISDN signal to : 25 the ISDN switch in response to a particular analog signal from the analog traffic generator and a particular analog telephone signal for the analog traffic g~narator in :, 1 3 1 ~337 response to a particular ISDN signal from the ISDN switch;
a processor coupled to the plurality of first circuits, including apparatus for selectively addressing individual ~nes of the plurality of irst circuits; and D channel monitor apparatus coupled to the processo:r for monitoring D channel communication between the first circuits and the ISDN switch, including apparatus for selecti.vely monitoring D channel communication between the first circuits and the ISDN switch for individual two-way communication links between the analog traffic generator and the ISDN switch in accordance with the selection of one of the first circuits by the processor.
In accordance with another embodiment of the invention, an apparatus for generating a plurality of ISDN
traffic signals for testing an ISDN switch is comprised of a plurality of first circuits coupled to the ISDN switch including apparatus for generating a plurality of two-way communication links between the ISDN switch and the first circuits, wherein each two-way communication link includes a first ISDN signal including B channel information and D
channeI information from a first circuit to the ISDN
switch and a second ISD~ signal including B channel information and D channel information from the ISDN switch to the first circuit; a processor coupled to the plurality of first circuits including apparatus for selectively addressing individual ones of the first circuits; and D
channel monitoring apparatus cvupled to the processor for 9a 131~337 monitoring D channel communication between the first circuits and the ISDN switch including apparatus for selectively monitoring individual two-way communication links between the first circuits and the ISDN switch in accordanc.e with the selection of the first circuit by the processor.
In accordance with another embodim~nt of the invention, an integrated services digital network ~ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch is comprised of a plurality of first circuits for coupling the analog traffic generator to the ISDN switch, for two-way communication therebetween, wherein each of the first circuits includes a plurality of tip/ring interface ; circuits, a processor and a plurality of S interface :~: circuits, wherein each of the tip/ring inter~ace circuits includes apparatus for detecting commands from the analog traffic generator and providing a message to the processor upon receiving the commands, each of the tip/ring interface circuits further including apparatus for converting analog telephone signals from the analog traffic g~nerator into ISDN B channel signals to be provided to one of the S interface circuits and apparatus ~ 25 for ~onverting B channel signals received from one of the - S interface circuits into analog tip/ring signals to be provided to the analog traffic generator, wherein the : 9b ~., 1 3 1 ~337 processor includes apparatus for receiving the messages from the tip/ring interface circuits and generating D
channel signals to be provided to one the 5 in~erface circuits, the processor further including apparatus for receiving and storing D channel signals f:rom the ISDN
switch through the S interfaca, and wherein each of the S
interface circuits includes apparatus for combining B
channel signals received from a tip/ring interface with D
channel signals received from the prOCe~SQr to provide an ISDN signal to the ISDN switch and apparatus for receiving ISDN signals from the switch and providing B channel signals based thereon to on~ of the tiptring interface circuits and apparatus for providing D channel signals based thereon to the processor; a second processor circuit coupled to the plurality of first circuits, wherein the ; second processor circuit includes apparatus for selectively addressing individual ones of the processors of the plurality of first circuits; and apparatus coupled to the D channel monitor for monitoring predetermined operation characteristics of a selected processor of the first circuits in accordance with the selection of the processor of the first circuits by the second proce~sor.
In accordance with another embodiment of the invention an integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch, is comprised 9c of a first circuit for coupling the analog traffic generator to the ISDN switch, for two-way communication therebetween, wherein the first circuit includes a plurality of tip/ring interface circuits, a processor and S a plurality of S interface circuits, wherein each of the tip/ring interface circuits includes apparatus for detecting commands from the analog traffic generator and providing a message to the processor upon receiving the commands, each of the tip/ring interface circuits further including apparatus for converting analog telephone signals from analog traffic generator into ISDN B channel signals to be provided to one of the S interface circuits and apparatus for converting B channel signals received from one of the S interface circuits into analog tip/ring signals to be provided to the analog traffic generator, wherein the processor includes apparatus for receiving the messages from the tip/ring interface circuits and generating D channel signals to be provided to the S
interface circuits, the processor further including apparatus for receiving and storing D channel signals from the ISDN switch through the S interface, and wherein each of the S interface circuits includes apparatus for combining B channel signals received from a tip/ring interface with D channel signals received from the processor to provide an ISDN signal to the ISDN switch and apparatus for receiving ISDN signals from the switch and 9d 1 31 ~337 providing B channel signals based thereon to one of the tip/ring interface circuits and apparatus for providing D
channel signals based thereon to the processor; and a D
channel monitor coupled to the processor for æelecting and monitoring D channel information on predetermined ~wo-way ISDN communication links between the first circuit and the ISDN switch.
R_F DE CRIPTION OF THE DRAWINGS
Figure l shows a block diagram of a basic ISDN
terminal which the present invention can be used in conjunction with;
Figure 2 is a block diagram showing an embodiment of a traffic generator adapter in accordance with the present invention;
Figure 3 is a block diagram showing an individual daughter board of the traffic generator adapter o~ Figure 2;
Figure 4 is a block diagram of a tip/ring interface of the traffic generator adapter of Figure 2;
Figure 5 is a block diagram showing a single D
channel monitor for a plurality of trafic generator adapters; and Figures 6 to 24 show d~tailed schematic circuitry for the block diagrams of Figures 2 to 5.
DETAILED DESCRIPTION
Figure 2 illustrates an embodiment of a traffic generator adapter (hereinafter TGA) in accordance with the present 9e 1 31 ~337 invention. As can be seen therel the TGA is formed to include a processor board 10, a plurality o~ daughter boards 12 and a bac~ plane board 14 for interfacing the TGA to ~n ISDN central ; o~ice on the one hand and to an analo~ traffic generator on the other. The TGA is also coupled via the processor board lO
to a D channel monitor 16, preferably through an RS232 port~
If desired, the TGA can also be coupled, again through the processor board 10, to other TGAs. Figure 5 ~hows an example o~ coupling a plurality of TGAs to a ~ingle D channel monitor, - 10 with each of the TGAs belng coupled to one anokher through their respective processor boards 10.
In Figure 2, the ISDN central office and the traffic generator are not shown since they do not form a direct part of the present invention. It is envisioned that the present invantion could be used with a large number of comm~rcially available traf~ic generators. Solely for purposes of example, it i~ noted that suitable traffic generators for khis purpose are manufactured by Ameritec Corporation in its bulk call generat~r line. A number of models are put out by Ameritec ; 20 Corporation as "Model AMlPlus" whiGh can be used in con~unction with the present invention.
Similarly, at the present time, a number of ISDN central offices have been developed which the pre~ent invention can be used in conjunction with. For example, Northcom Corporation has developed an ISDN cenkral o~fice called the DMS-lOO, while AT&T has developed the 5ESSTM syste~. The present invention can be used in conjunction with either of khese ISDN cankral TM - Trade Mark "J
o~fice switching arrangements, although, of course, it is not intended to be limited to either of these~
~ ommunication bekween the daughter boards 12 and the processor board is accomplished by way of a bac~ plane generator board 14. This back plane board 14 is ~ormed o~
connectors and wiring designed to interconnect the various boards shown in Figure 2 and to interconnect the TGA to the traffic generator and the ISDN central of~ice switches.
Although it is not shown in Figure 2, the connection betwPen the back plane 14 and the ISDN central office would normally be made either through a NTl or both through a NTland NT2 such-as shown in Figure 1. In other words, the TGA of Figure 2 would normally be loaated at either an S interface or a T interface of an ISDN terminal. The traffic generator would then 6~rve ~5 effectively as terminal equipment o~ the T~ type ~hown in Figure 1, while the TGA of Figure 2 ef~ectively serves as the terminal adapter ~A (noting, however, that it could also be located at the T interface rather tha~ being limited to the S
interface).
The six daughter boards 12 contain circuitry to simulate an analog central office switch to the analog traffic generator. The daughter boards al60 contain B channel encoding/decoding processars in a Codec ~hich changes the analog voice signal from the traffic generator into digital data to be transmitted on the B channel~ (e.g. ~ee Figure 3 ) .
In addition, the daughter boards 12 contain hardwara for transmitting and receiving on the "S~T" inter~ace. The 1 3 1 ~337 processor board 10 contains the necessary equipment for interrogating the D channels of any of the daughter boards, as well as equipment to ~ormat it and send it to the D channel monitor 16. The processor board 10 al80 handles the interaonnecti~n protoc~l b~tween the respective circuit elements.
As can be seen in Figure 2, the TGA is designed to handle 48 tip/ring lines ~rom the traffic generator and to provide 2 S interfaces into the ISDN central o~fice. This number, of 10 Gourse~ is for purposes of example only since the invention is not intended to be limited to this. Similarly, although each daughter board is shown as operating with eight tip/ring pairs and four S interface pairs, this is also solely for purposes of example. It is, however, noted that the example of 48 tip/ring lines was chosen since this is a suitable number ~or testing many I~DN central office switchesO For example, up to 4 telephone calls can be placed into the central office simultaneously to study how well the ISD~ central o~fice ; replie~. Essentially, the testing operator can try to overload the ISDN system to see at what point it stop5 making connections. At the same time, using the present in~e~tion, the D channel operation can also be studied under these conditions.
More specifically, an important aspect of the present invention is the D channel capability of the arrangemellt. As can be seen in Figure 2, each of the daughter boards 12 has D
channel data lines and D channel monitor enable lines. The ,,, 1 3 1 ~337 daughter boards 12 operate to provide D channel information from their internal processors to the ISDN central office in a manner which will be described in more detail with regard to Figure 3. The daughter boards also operate to recei~e, act on and store D channel information from the ISDN central office which can be used for ~elective D ~hannel monitoring. This selective D channel monitoring is achieved by virtue of the enable lines shown from the processor board 10 to the back plane board 14 and the D monitor enable lines from the back plane boar~ 14 to the individual daughter boards. A command signal from the processor board 10 serves to elect indi~idual ones of the daughter boards 12 for readout of the stored D
channel information. This selected D channel information can then be provided from the selecked daughter board 12 to the D
channel monitor 16 through the pr~c2ssor board 10, as will be discussed in further detail hereinafter.
Figure 3 shows an individual daughter board 12 o~
Figure 2. As can be seen there, each daughter board 12 includes a pluraIity of tip/ring interfaces ~hereinafter T~R
interface) 18, a processor 20 and a plurality of S
inter~aces 22. The ~&R inter~aces 18 receive tip and ring signals from the traffic generator, and also provide return tip and ring ~ignals to the traffic ~enerator (from the ISDN
central office through the TGA).
;i 25 Basically, the T&R interface 18 handles the analog data and signalling to and from the traffic generator. In order to do this, it is capable of detecting conditions such as off 1~
.~
1 31 ~337 hook, on hook, and dialing from the traffic generator and translatlng these into 5~ gnals to the processor 20. In return it receives signals from the processor 20 and translates them into signals for the traffic generator such as ringing. More speclfically,as shown in Figure 4, the T~R inter~ace 18 contains several sensing circuits to detect co~mands from the tra~ic generator. These signals can include on hoo~, off hook, and DTMF dialing. Whenever these ~ignals are detected, a message is sent to the processor 20 through an I/0 port. The processor.20 passes this message on to t~e switch through the S
interface. Subsequently, one of the processors 20 can respond '' to a command from the switch to command a T~R interface through an I/0 port to start ringing to signal the traffic generator that it should answer the call.
~hen the processor 20 receives these signals from the T&R
interface 18, it generates equivalent D channel messages to the central office switch through the S interface 22 and handles all the handshakes needed to establish the proper central office action. It also will translate commands from the central office into action to be produced by the T&R
- interface 18. In addition to handling the messaging back and forth between the analog traffic generator and the digital ISDN
switch, the processor 20 fo~mats the D channel traffic and stores it to be a~ailable to be sent to the proce~sor board 10 when the processor board 10 requests it.
The S interface 22 combines the digitized analog data ~rom two T&R sections with the D channel data produced by the 1~
.~
processor into the ISDM standard 2B+D S or T interface to be sant to the central of~ice. It al~o xeceives such ISDN 6ignals from the central of~ice and provid~s B c~annel information to the T~R interfac;:e~ and D channel ~ignals to the S proce~sor 2 0 .
A typical se~uence of operation for the TGA of Figure ~3 would be as ~ollows. The tr~t~lc generator would go o~f hook.
This would be detected by the ~R inter~aces 18 of a daughter board and a signal would be sent to th2 proces~or 2 0 that a 10 connectio~ is desired. By means o~ D chann~l messages, the TGA
r would reque~ ~ sonnection ~rom the ISDN central office switch. The ISDN switch would then respond with 21 cormect message and dial tone which would be sent to the traffic : generator through the TGA. Upon receipt of dial tone, the traffic generator would begin dialing. The DTMF tones would be detected by a T&R interface, sent to a processor 20 and then to the central office ISDN switch on the D channel. The ISDN
switch would complete the call an~ send a message to another T~R interface 18 to start ringing. The tra~fic generator would detect ring~ng and go off hook to answer the call. The secon~
T~R interface would detect the o~f hook and signal the switch to complete the call. Once this is done, the tra~fic generator would send tones end-to-end to t~st the quality of the connection and then hang up. The T&R interface 18 would detect the on hook condition and signal the switch to tear down the call.
,.~
13~337 As noted previously, an important aspect of the present invention is the ~act that it permits selective monitoring of individual D channel information within the TGA using, i~
desired, a single D channel monitor 16. This can even be the case if a plurality o~ TG~s are coupl~d together in the manner shown in Figure 5. In othex words, even though there may be hundreds of S interface lines between the TGA system of Figure 5 and ISDN central offioe, the prPsent invention allows a testing operator to isolate on a single D channel line within a particular daughter boaxd 12 of one o~ the individual TGAs.
In effect, the present invention allows addressing particular D
channel lines. The reason for the importance o~ this is that although an analog tra~ic generator coupled to the TG~ o~ the present invention is capable of determining if an ISDN switch is operating up to specifications, it has no way of assisting troubleshooting if a problem is found without the D channel ~;
~ monitoring feature. The D channel monitor 16 analyzeæ the ;~ signalling traffic between the adapter and the ISDN s~itch to assist in determining why the proper connections are not taking place. It does this by displaying messages being passed between the two devices as the call progresses. By interpreting these messages, a trained operator can determine the cause of faiiure. Since there are many D channels in the TGA, the arrangement of permitting the processor boards 10 to selectively enable processors 20 of the daughter board~ 12 is .
; included to select which D channel is to be monitored.
131~337 As noted previously, the selection of the desired D
c~annel line is controlled through the processor bGards 10 o~
each ~f the TGAs. More specifically, by controlling an enable line to each of the six daughter boards 12, an RS232 port is enabled on a particular dau~hter board. When this i~ ena~led, D channel data is placed on a bus to ~e received and translated by the processor board 10. For c~mmunication with another box, the D channe~ monitor 16 precedes the re~uest for the data with.
a box num~er. If this is anything other than zero, the box number i5 decremented by one and relayed dir~ctly to the next box in the cnain. This decrementing and relaying is continued by each box until the address reaches æero and that box responds w.ith data from the requested D channel.
As described above, the pxesent invention provides an arrangement which allows both exercising both ISDN centraI
office switches with commercially available analog tra~fis ~enerators and selective D channel m~nitorin~ of individual D
channel lines within the TGA. With regard to this, it is noted that the present invention is not intended to be limited to a particular D channel monitor 16 since a varieky o~ D channel testing equipment could be u6ed. In other words, the present invention is not intended to be limited to a particular D
channel test pro~ram. However, one example of a D channel monitor that could be used with the present invention is 25 described in Canadian Patent Application Serial No. 599,357 filed May 10~ 1989 by the same inventors as the present application, and entitled "D Channel Monitor", to which the .
reader i.s referred. It is noted that this related application includes an example of software speci~ications that ; could be used ~or such D channel monitoring.
Also, it is to be noted that the processor boards 10 and the processors 20 described above can be any suitable processors for carrying out the functions described. For example, Intel 801~8 microprocessors could be used throughout, alth~ugh the invention is not limited to this. Regarding the softw~re for these operations, essentially the TGA of the present invention operates in a manner similar to a terminal adapter for converting a plurality of anal~g signals from an analog traf~ic generator into ISDN signals for an ISDN central office. As such, the processors 10 and 20 can operate using known terminal adapter software programs modified to permit the selective accessing by the D channel monitor 16 to individual D
channel lines through the processor boards 10 and the processor 20, as described above.
-~ Although the invention has been described with regard to use in permitting testing of ISDN central office switches using analog trafflc generators, it is to be noted that the present -~ invention could also be useful for other purposes. For exampler the present invention could be used, if desired, as an adapter to permit the connection of a large number o~ analog telephones ~or other analog equipment) to an ISDN central office in plaae of using a large number of individual t~rminal adapters. The advantage o~ this over using commercially available terminal adapters would be that the present invention , ~
....
t 3 1 ~337 permits the isolation of individual D channel lines ~or testing using a single D channel monitor, a~ discussed above.
Flgures 6 to 24 provide detailed schematic drawings for the elements illustrated in Figures 2 to 6. These figures are labelled to identify the particular circuit elPments o~
Figures 2 to 6 in the specification which are illustrated.
Figuras 6 to 24 identify integrated circuits and other electrical and el~ctronic elements with convention~lly utilized industrial identification.
It is~to be understood that the above-described arrangements are simply illustrative o~ the application of the `' principles of this invention. Numerous other arrangements may be readily devised by those skilled in the art which embody the principles of the invention and fall within its spirit and scope.
, .~
.... ... .
Claims (5)
1. An integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch, comprising:
a plurality of first circuits for coupling said analog traffic generator to said ISDN switch, for two-way communication therebetween, wherein each of said first circuits includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits, wherein each of said tip/ring interface circuits includes means for detecting commands from said analog traffic generator and providing a message to said processor upon receiving said commands, each of said tip/ring interface circuits further including means for converting analog telephone signals from said analog traffic generator into ISDN B channel signals to be provided to one of said S interface circuits and means for converting B channel signals received from one of said S
interface circuits into analog tip/ring signals to be provided to said analog traffic generator, wherein said processor includes means for receiving said messages from said tip/ring interface circuits and generating D channel signals to be provided to one of said S interface circuits, said processor further including means for receiving and storing D channel signals from said ISDN switch through said S interface, and wherein each of said S interface circuits includes means for combining B channel signals received from a tip/ring interface with D channel signals received from said processor to provide an ISDN signal to said ISDN switch and means for receiving ISDN
signals from said switch and providing B channel signals based thereon to one of said tip/ring interface circuits and means for providing D channel signals based thereon to said processor;
a second processor circuit coupled to said plurality of first circuits, wherein said second processor circuit includes means for selectively addressing individual ones of said processors of said plurality of first circuits; and D channel monitoring means coupled to said second processor to control said second processor to select predetermined ones of said processors of said first circuit so that predetermined D channel information from said ISDN switch stored in said selected processors of said first circuits can be individually monitored by said D channel monitor through said second processor circuit.
a plurality of first circuits for coupling said analog traffic generator to said ISDN switch, for two-way communication therebetween, wherein each of said first circuits includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits, wherein each of said tip/ring interface circuits includes means for detecting commands from said analog traffic generator and providing a message to said processor upon receiving said commands, each of said tip/ring interface circuits further including means for converting analog telephone signals from said analog traffic generator into ISDN B channel signals to be provided to one of said S interface circuits and means for converting B channel signals received from one of said S
interface circuits into analog tip/ring signals to be provided to said analog traffic generator, wherein said processor includes means for receiving said messages from said tip/ring interface circuits and generating D channel signals to be provided to one of said S interface circuits, said processor further including means for receiving and storing D channel signals from said ISDN switch through said S interface, and wherein each of said S interface circuits includes means for combining B channel signals received from a tip/ring interface with D channel signals received from said processor to provide an ISDN signal to said ISDN switch and means for receiving ISDN
signals from said switch and providing B channel signals based thereon to one of said tip/ring interface circuits and means for providing D channel signals based thereon to said processor;
a second processor circuit coupled to said plurality of first circuits, wherein said second processor circuit includes means for selectively addressing individual ones of said processors of said plurality of first circuits; and D channel monitoring means coupled to said second processor to control said second processor to select predetermined ones of said processors of said first circuit so that predetermined D channel information from said ISDN switch stored in said selected processors of said first circuits can be individually monitored by said D channel monitor through said second processor circuit.
2. An integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch, comprising:
a plurality of first circuits for providing a plurality of two-way communication links between the analog traffic generator and the ISDN switch, wherein each of said first circuits includes means for converting the analog telephone signals from the analog traffic generator into a plurality of ISDN signals, including B channel information and D channel information, for said ISDN switch, and means for converting a plurality of ISDN signals from the ISDN switch, including channel information and D channel information, into analog telephone signals for said analog traffic generator, so that each two-way communication link provides a particular ISDN
signal to the ISDN switch in response to a particular analog signal from the analog traffic generator and a particular analog telephone signal for the analog traffic generator in response to a particular ISDN signal from the ISDN switch:
a processor coupled to said plurality of first circuits, including means for selectively addressing individual ones of said plurality of first circuits; and D channel monitor means coupled to said processor for monitoring D channel communication between the first circuits and the ISDN switch, including means for selectively monitoring D channel communication between the first circuits and the ISDN
switch for individual two-way communication links between the analog traffic generator and the ISDN switch in accordance with the selection of one of the first circuits by the processor.
a plurality of first circuits for providing a plurality of two-way communication links between the analog traffic generator and the ISDN switch, wherein each of said first circuits includes means for converting the analog telephone signals from the analog traffic generator into a plurality of ISDN signals, including B channel information and D channel information, for said ISDN switch, and means for converting a plurality of ISDN signals from the ISDN switch, including channel information and D channel information, into analog telephone signals for said analog traffic generator, so that each two-way communication link provides a particular ISDN
signal to the ISDN switch in response to a particular analog signal from the analog traffic generator and a particular analog telephone signal for the analog traffic generator in response to a particular ISDN signal from the ISDN switch:
a processor coupled to said plurality of first circuits, including means for selectively addressing individual ones of said plurality of first circuits; and D channel monitor means coupled to said processor for monitoring D channel communication between the first circuits and the ISDN switch, including means for selectively monitoring D channel communication between the first circuits and the ISDN
switch for individual two-way communication links between the analog traffic generator and the ISDN switch in accordance with the selection of one of the first circuits by the processor.
3. An apparatus for generating a plurality of ISDN
traffic signals for testing an ISDN switch comprising:
a plurality of first circuits coupled to said ISDN switch including means for generating a plurality of two-way communication links between the ISDN switch and the first circuits, wherein each two-way communication link includes a first ISDN signal including B channel information and D channel information from a first circuit to the ISDN switch and a second ISDN signal including B channel information and D
channel information from the ISDN switch to the first circuit:
a processor coupled to said plurality of first circuits including means for selectively addressing individual ones of said first circuits; and D channel monitoring means coupled to said processor for monitoring D channel communication between said first circuits and said ISDN switch including means for selectively monitoring individual two-way communication links between the first circuits and said ISDN switch in accordance with the selection of said first circuit by the processor.
traffic signals for testing an ISDN switch comprising:
a plurality of first circuits coupled to said ISDN switch including means for generating a plurality of two-way communication links between the ISDN switch and the first circuits, wherein each two-way communication link includes a first ISDN signal including B channel information and D channel information from a first circuit to the ISDN switch and a second ISDN signal including B channel information and D
channel information from the ISDN switch to the first circuit:
a processor coupled to said plurality of first circuits including means for selectively addressing individual ones of said first circuits; and D channel monitoring means coupled to said processor for monitoring D channel communication between said first circuits and said ISDN switch including means for selectively monitoring individual two-way communication links between the first circuits and said ISDN switch in accordance with the selection of said first circuit by the processor.
4. An integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch, comprising:
a plurality of first circuits for coupling said analog traffic generator to said ISDN switch, for two-way communication therebetween, wherein each of said first circuits includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits, wherein each of said tip/ring interface circuits includes means for detecting commands from said analog traffic generator and.
providing a message to said processor upon receiving said commands, each of said tip/ring interface circuits further including means for converting analog telephone signals from said analog traffic generator into ISDN B channel signals to be provided to one of said S interface circuits and means for converting B channel signals received from one of said S
interface circuits into analog tip/ring signals to be provided to said analog traffic generator, wherein said processor includes means for receiving said messages from said tip/ring interface circuits and generating D channel signals to be provided to one of said S interface circuits, said processor further including means for receiving and storing D channel signals from said ISDN witch through said S interface, and wherein each of said S interface circuits includes means for combining B channel signals received from a tip/ring interface with D channel signals received from said processor to provide an ISDN signal to said ISDN switch and means for receiving ISDN
signals from said switch and providing B channel signals based thereon to one of said tip/ring interface circuits and means for providing D channel signals based thereon to said processor;
a second processor circuit coupled to said plurality of.
first circuits, wherein said second processor circuit includes means for selectively addressing individual ones of said processors of said plurality of first circuits; and means coupled to said D channel monitor for monitoring predetermined operation characteristics of a selected processor of said first circuits in accordance with the selection of said processor of said first circuits by said second processor.
a plurality of first circuits for coupling said analog traffic generator to said ISDN switch, for two-way communication therebetween, wherein each of said first circuits includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits, wherein each of said tip/ring interface circuits includes means for detecting commands from said analog traffic generator and.
providing a message to said processor upon receiving said commands, each of said tip/ring interface circuits further including means for converting analog telephone signals from said analog traffic generator into ISDN B channel signals to be provided to one of said S interface circuits and means for converting B channel signals received from one of said S
interface circuits into analog tip/ring signals to be provided to said analog traffic generator, wherein said processor includes means for receiving said messages from said tip/ring interface circuits and generating D channel signals to be provided to one of said S interface circuits, said processor further including means for receiving and storing D channel signals from said ISDN witch through said S interface, and wherein each of said S interface circuits includes means for combining B channel signals received from a tip/ring interface with D channel signals received from said processor to provide an ISDN signal to said ISDN switch and means for receiving ISDN
signals from said switch and providing B channel signals based thereon to one of said tip/ring interface circuits and means for providing D channel signals based thereon to said processor;
a second processor circuit coupled to said plurality of.
first circuits, wherein said second processor circuit includes means for selectively addressing individual ones of said processors of said plurality of first circuits; and means coupled to said D channel monitor for monitoring predetermined operation characteristics of a selected processor of said first circuits in accordance with the selection of said processor of said first circuits by said second processor.
5. An integrated services digital network (ISDN) traffic generator adapter for coupling an analog traffic generator which produces a plurality of commands and analog telephone signals to an ISDN switch, comprising:
a first circuit for coupling said analog traffic generator to said ISDN switch, for two-way communication therebetween, wherein said first circuit includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits, wherein each of said tip/ring interface circuits includes means for detecting commands from said analog traffic generator and providing a message to said processor upon receiving said commands, each of said tip/ring interface circuits further including means for converting analog telephone signals from analog traffic generator into ISDN B
channel signals to be provided to one of said S interface circuits and means for converting B channel signals received from one of said S interface circuits into analog tip/ring signals to be provided to said analog traffic generator, wherein said processor includes means for receiving said messages from said tip/ring interface circuit and generating D
channel signals to be provided to said S interfasce circuits, said processor further including means for receiving and storing D channel signals from the ISDN switch through said S
interface, and wherein each of said S interface circuits includes means for combining B channel signals received from a tip/ring interface with D channel signals received from said processor to provide an ISDN signal to said ISDN switch and means for receiving ISDN signals from said switch and providing channel signals based thereon to one of said tip/ring interface circuits and means for providing D channel signals based thereon to said processor; and a D channel monitor coupled to said processor for selecting and monitoring D channel information on predetermined two-way ISDN communication links between said first circuit and said ISDN switch.
a first circuit for coupling said analog traffic generator to said ISDN switch, for two-way communication therebetween, wherein said first circuit includes a plurality of tip/ring interface circuits, a processor and a plurality of S interface circuits, wherein each of said tip/ring interface circuits includes means for detecting commands from said analog traffic generator and providing a message to said processor upon receiving said commands, each of said tip/ring interface circuits further including means for converting analog telephone signals from analog traffic generator into ISDN B
channel signals to be provided to one of said S interface circuits and means for converting B channel signals received from one of said S interface circuits into analog tip/ring signals to be provided to said analog traffic generator, wherein said processor includes means for receiving said messages from said tip/ring interface circuit and generating D
channel signals to be provided to said S interfasce circuits, said processor further including means for receiving and storing D channel signals from the ISDN switch through said S
interface, and wherein each of said S interface circuits includes means for combining B channel signals received from a tip/ring interface with D channel signals received from said processor to provide an ISDN signal to said ISDN switch and means for receiving ISDN signals from said switch and providing channel signals based thereon to one of said tip/ring interface circuits and means for providing D channel signals based thereon to said processor; and a D channel monitor coupled to said processor for selecting and monitoring D channel information on predetermined two-way ISDN communication links between said first circuit and said ISDN switch.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/192,175 US4910729A (en) | 1988-05-10 | 1988-05-10 | ISDN traffic generator adapter |
| US192,175 | 1988-05-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1314337C true CA1314337C (en) | 1993-03-09 |
Family
ID=22708569
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000599358A Expired - Fee Related CA1314337C (en) | 1988-05-10 | 1989-05-10 | Isdn traffic generator adapter |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4910729A (en) |
| EP (1) | EP0374231A4 (en) |
| CA (1) | CA1314337C (en) |
| GB (1) | GB2231466B (en) |
| WO (1) | WO1989011190A1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1335832C (en) * | 1989-04-21 | 1995-06-06 | Wing-Man Chan | Remote test access system for isdn testing |
| US4998240A (en) * | 1989-08-15 | 1991-03-05 | C & P Of Virginia | Method of and system for remote testing of integrated services digital networks |
| US5157665A (en) * | 1990-06-06 | 1992-10-20 | Fakhraie Fard Mostafa | Integrated services digital network (ISDN) test device |
| JP2763421B2 (en) * | 1991-07-01 | 1998-06-11 | 三菱電機株式会社 | Method of manufacturing display device using test pattern signal generator |
| WO1993023809A1 (en) * | 1992-05-15 | 1993-11-25 | Connective Strategies, Inc. | Isdn-based high speed communication system |
| US6851042B1 (en) * | 1993-07-19 | 2005-02-01 | Hewlett-Packard Development Company, L.P. | Audio, fax and modem capabilities with a digital signal processor of a sound card of a computer system |
| US5748628A (en) * | 1996-11-05 | 1998-05-05 | Interack Communications, Inc. | ISDN D-channel signaling discriminator |
| GB2329297A (en) * | 1997-09-11 | 1999-03-17 | Optima Telecommunications Ltd | An ISDN Communication System |
| US6320883B1 (en) | 1997-10-21 | 2001-11-20 | 3Com Corporation | Method and apparatus for automatic selection of an unknown ISDN reference |
| US6272450B1 (en) | 1998-06-16 | 2001-08-07 | Telefonaktiebolaget L M Ericsson (Publ) | Cellular network traffic simulator (cents) |
| US6823051B1 (en) * | 2001-04-10 | 2004-11-23 | Cisco Technology, Inc. | Traffic distribution generator |
Family Cites Families (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4096354A (en) * | 1977-03-11 | 1978-06-20 | Bell Telephone Laboratories, Incorporated | Apparatus for distinguishing between failures in a digital transmission network |
| US4383312A (en) * | 1980-11-28 | 1983-05-10 | The United States Of America As Represented By The Secretary Of The Navy | Multiplex system tester |
| JPS5866448A (en) * | 1981-10-16 | 1983-04-20 | Hitachi Ltd | Error detecting system for exchange of packet |
| JPS58134554A (en) * | 1982-02-03 | 1983-08-10 | Nec Corp | Transmission line monitoring device |
| FR2524231A1 (en) * | 1982-03-29 | 1983-09-30 | Telecommunications Sa | METHOD FOR TRANSMITTING A SIGNAL IN HDBN CODE WITH AN AUXILIARY BINARY SIGNAL, ENCODER AND DECODER ACCORDING TO THE METHOD AND SYSTEM FOR REMOTE MONITORING OF REPEATERS OF A DIGITAL LINK USING SUCH AUXILIARY SIGNALS |
| US4488289A (en) * | 1982-06-25 | 1984-12-11 | At&T Bell Laboratories | Interface facility for a packet switching system |
| US4584680A (en) * | 1982-11-30 | 1986-04-22 | Itt Corporation | Use of a tone bus to provide polling and data distribution apparatus for communication system terminal groups |
| US4663776A (en) * | 1982-12-08 | 1987-05-05 | Wiltron Company | System for accessing electrical circuits and relay switch thereof |
| DE3317116A1 (en) * | 1983-05-10 | 1984-11-15 | Siemens AG, 1000 Berlin und 8000 München | DIGITAL SIGNAL MULTIPLEX DEVICE |
| CH655822A5 (en) * | 1983-07-14 | 1986-05-15 | Siemens Ag Albis | Device for testing exchanges |
| US4602364A (en) * | 1984-04-23 | 1986-07-22 | Codex Corporation | Local area data communication network |
| US4589106A (en) * | 1984-08-20 | 1986-05-13 | Itt Corporation | Data line card printed board assembly |
| CA1253940A (en) * | 1985-06-12 | 1989-05-09 | Yoshinori Yoshida | Digital local switching system |
| US4682347A (en) * | 1986-02-10 | 1987-07-21 | Keptel, Inc. | Telephone line selection and isolation method and apparatus |
| GB2189890B (en) * | 1986-04-30 | 1990-02-14 | Plessey Co Plc | A unit for testing digital telecommunications exchange equipment |
| US4730313A (en) * | 1986-08-18 | 1988-03-08 | Racal Data Communications Inc. | Access circuit diagnostics for integrated services digital network |
-
1988
- 1988-05-10 US US07/192,175 patent/US4910729A/en not_active Expired - Lifetime
-
1989
- 1989-05-10 WO PCT/US1989/001999 patent/WO1989011190A1/en not_active Application Discontinuation
- 1989-05-10 EP EP19890906216 patent/EP0374231A4/en not_active Withdrawn
- 1989-05-10 CA CA000599358A patent/CA1314337C/en not_active Expired - Fee Related
-
1990
- 1990-01-05 GB GB9000207A patent/GB2231466B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0374231A4 (en) | 1990-10-24 |
| GB2231466B (en) | 1992-09-23 |
| GB9000207D0 (en) | 1990-07-25 |
| US4910729A (en) | 1990-03-20 |
| GB2231466A (en) | 1990-11-14 |
| EP0374231A1 (en) | 1990-06-27 |
| WO1989011190A1 (en) | 1989-11-16 |
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