Network system and communication device

Details Network system and communication device Network system and communication device

1998-10-28

2002-02-05

Olms, Douglas (Department: 2732)

Multiplex communications

Pathfinding or routing

Combined circuit switching and packet switching

C370S217000, C370S356000, C370S386000, C370S281000

Reexamination Certificate

active

06345049

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a network system constructed of a narrow-band network such as a TDM (Time Division Multiplex) network and of a broad-band network (integrated network) such as an ATM (asynchronous transfer mode) network, and to communication devices constituting the broad-band network.
In recent years, a technology of an asynchronous transfer mode (ATM) has increasingly advanced and spread. As a relay network of data between terminal devices, there appears an integrated network based on one of technologies using an ATM network, wherein conventional time division multiplex (TDM) lines are relayed to ATM lines. The integrated network, for example, is accommodated a plurality of TDM networks (a plurality of TDM-SWs), The integrated network relays data transmitted between the TDM networks.
In the case of constructing the integrated network, it is desired that a detour function be actualized by the integrated network. The detour function is a function that a transmission route of data is charged another route so as to avoidance of a fault occured in a network and the data is transmitted a destination of the data.
Herein, the detour function is explained.
FIGS. 16 and 17
are explanatory diagrams each showing the detour function in the TDM network. As shown in
FIG. 16
, when the TDM network is normal (no fault), it is assumed that, for example, the data transferred from a terminal device
114
to a terminal device
115
be transferred on a route such as the terminal device
114
→a TDM-SW (TDM switch)→a DMIX (multiplexer)
501
→a DMIX
502
→a TDM-SW
112
→a DMIX
502
→a DMIX
503
→a TDM-SW
113
→the terminal device
115
.
Herein as shown in
FIG. 17
, for instance, if a fault occurs in the TDM line (a relay line) for connecting the DMIX
503
to the TDM-SW
113
, the data transferred from the terminal device
114
to the terminal device
115
can not be transferred on the route described above. Therefore, the TDM-SW
112
changes the route such as the TDM-SW
112
→a public network
116
→the TDM-SW
113
→the terminal device
115
, thus detouring around the line in which the fault occurs.
Incidentally, a plurality of TDM-SWs (e.g., PBXs (Private Branch Exchanges)) constituting the TDM network set a path in a link-by-link manner by terms of a characteristic of the TDM. If the relay line in which a link should be set can not be connected, the TDM-SW accommodating this relay line sets the link in other relay line by executing a detour function.
In contrast with this, as shown in
FIG. 18
, when the TDM networks are bridged by the ATM network, each of ATM-WAN (Wide Area Network) nodes (hereinafter abbreviated to “AWNS”
600
-
603
constituting the ATM network, is capable of directly setting a VC (Virtual Channel) from a transmitting side AWN to a receiving side AWN.
For example, as shown in
FIG. 18
, when data communications are carried out between the terminal device
114
and the terminal device
115
, the terminal device
114
transmits to the TDM-SW
111
call-out information (such as dial information) etc) containing call-in address information (a destination address). The call-in address information includes an intra TDM network node address number “730” for specifying the TDM-SW
113
and an intra TDM-SW
113
terminal device address number “2000” for specifying the terminal device
115
.
The TDM-SW
111
transmits, to an AWN
601
, call setting signaling (a call setting message) containing the call-in address information requesting the terminal device
115
to receive. The AWN
601
, when receiving the call setting signaling from the TDM-SW
111
, controls a transmission of the call setting signaling in accordance with a procedure of “STR-VTOA-LLT-01.12” based on recommendations of ATM-Forum.
Namely, the AWN
601
detects an intra broad-band network ATM address “awn3” corresponding to the call-in address information “730” contained in the call setting signaling, and edits a broad-band call setting message. Next, the AWN
601
transmits the broad-band call setting signaling toward the AWN
603
in order to set a narrow-band signaling transmission VC. As a result, the narrow-band signaling transmission VC is directly set between the AWN
601
and the AWN
603
.
Incidentally, as shown in
FIGS. 19 and 20
, a fault or a line busy etc occurs in the TDM line through which the AWN
601
is connected to the TDM-SW
111
, the AWN
601
is unable to receive the call setting signaling from the TDM-SW
111
. Therefore, the narrow-band signaling transmission VC can not be set between the AWN
601
and the AWN
603
. In this case, for example, the TDM-SW
111
makes route such as the public network
116
→the TDM-SW
112
→the AWN
602
→the AWN
603
→the TDM-SW
113
, whereby the call setting signaling can be received by the TDM-SW
113
.
In the conventional ATM network (each of the AWNs
601
-
603
) has not detour function descrived above. Hence, if the transmitting side TDM-SW (which is herein the TDM-SW
111
) actualizes the detour function described above, the transmitting side TDM-SW holds all pieces of detour information in the ATM network, and must control the detour (routing) in the ATM network.
On the other hand, in terms of a promotion of utilizing the ATM network as a relay network for bridging the TDM networks, it is desirable that the ATM network be constructed so that the ATM network accommodates the TDM network without changing the configuration of the existing TDM network (a PBX network). That is, if the narrow-band signaling transmission VC ca not be set, the transmitting side AWN (the AWM
601
in FIG.
19
), it is desirable, actualizes the detour function.
SUMMARY OF THE INVENTION
It is a primary object of the present invention, which was devised to overcome the problems described above, to provide a network system and a communication device that are capable of actualizing a detour function without changing a configuration of an existing TDM network.
To accomplish the above object, the present invention adopts the following construction.
According to a first aspect of the present invention, A network system of the present invention comprises a TDM network including a plurality of TDM switches connected to each other via TDM lines and an ATM network including a plurality of communication devices connected via the TDM lines in such a state as to be paired with the TDM switches. Each of the communication devices in this network system comprises a first call setting unit for setting, when receiving a call setting request message from the transmitting side TDM switch, a call between this communication device and a receiving side communication device paired with the receiving side TDM switch indicated by the call setting request message, a specifying unit for specifying, if the first call setting unit is unable to set the call, any one of TDM switches excluding the receiving side TDM switch as a detour TDM switch, a storing unit stored with detour information for setting the call between the detour TDM switch specified by the specifying unit and the receiving side TDM switch, a reading unit for reading the detour information when the specifying unit specifies the detour TDM switch, a second call setting unit for setting a call between the communication device and a detour communication device defined as a communication device paired with the detour TDM switch specified by the specifying unit, and a unit for making, when the second call setting unit sets the call, the detour communication device transmit a call setting request message containing the detour information read by the reading unit to the detour TDM switch. The detour TDM switch sets the call between the detour TDM switch and the receiving side TDM switch on the basis of the detour information contained in the call setting request message received from the detour communication device.
According to the first aspect of the present invention, when each communication device receives the call setting request m

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