JPH1117686A - Atm exchange system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid disable communication due to a fault in a terminal channel and its exchange. SOLUTION: Terminals 11, 12 are contained by two sets of ATM exchanges 15, 16 and 17, 18 respectively by two terminal channels 13, 14. Terminals 19, 29 of a conventional system configuration are contained in an exchange by single lines. In the case that incoming call connection from the terminal 11 to the terminal 12 is terminal 11 -exchanges 15-17 - terminal 12 in a path 1, when the exchange 15 detects a fault of the exchange 17 or a route 21 to be a route fault while setting switched virtual connection(SVC) with the exchange 17, a redundant route path 2 changes the path into exchanges 15-18 - terminal 12 so as to avoid the fault. This is conducted similarly, even in the case of a call reception from the terminals 19, 20 of a conventional configuration to the terminals 11, 12. In the connection of the path 1, when the exchange 17 detects a fault in a terminal line 14, the exchange 17 changes the path 1 into a path 3 which is, exchange 17 - bypass route 25 - exchange 18 - terminal 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM switching system in an ATM network in which a trunk line and a terminal line are redundantly configured.

[0002]

2. Description of the Related Art In an asynchronous transfer mode (ATM) switching system, a user network interface (UNI) specified by an ATM forum is connected via a terminal line, and exchanges are connected between private networks, nodes, and the ATM forum. Connected by an interface (P-NNI), and transmit messages in fixed-length cells. Calling terminal and
A switched virtual connection (SVC) for transmitting and receiving a predetermined signal is performed between the ATM exchange, between the exchanges, and for each transmission section between the exchange and the terminating terminal,
A virtual channel is set between terminals through a virtual path in each section. Ethernet switches and important terminals that join the ATM network have duplicated terminal lines to avoid communication failure due to terminal line failures.

[0003]

However, even if the terminal line is duplicated and a detour route is provided between the exchanges, communication becomes impossible if the exchange accommodating the terminal fails.

[0004] It is an object of the present invention to provide an ATM switching system which solves such disadvantages of the prior art and avoids communication failure due to failure of a terminal line and its exchange.

[0005]

According to the present invention, in order to solve the above-mentioned problems, in an ATM switching system, a communication terminal is provided with a plurality of, for example, two terminal lines.
And a third ATM exchange connected to the second ATM exchange and having a route connected to the first ATM exchange, a redundant route for a communication terminal connected to the second exchange is provided, and the third exchange is connected to the communication terminal. Switch incoming calls to
When setting a virtual connection in the first exchange, if a failure is detected, a redundant route is selected. Also,
A detour route connecting the first exchange and the second exchange is provided. The first exchange receives a switched virtual connection of an incoming call from the third exchange to the communication terminal, and detects a failure in the terminal line. In this case, a switched virtual connection for the terminal-terminated call is set in the second exchange from the bypass route.

[0006] The first, second and third exchanges are provided with line fault detecting means for detecting faults in terminal lines and routes,
Route selection means for selecting a route from the address of the communication terminal, and when the route is faulty, the route selection means selects a redundant route or a detour route.

According to the present invention, a terminal line for connecting a communication terminal to the first and second exchanges, a redundant configuration of connection routes between the third exchange and the first and second exchanges, and a detour route Thereby, it is possible to avoid a communication failure due to a failure of a terminal line and its exchange in the conventional ATM network.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ATM switching system according to the present invention will be described in detail with reference to the accompanying drawings. FIG.
1 shows a configuration example of an ATM switching system according to an embodiment of the present invention. In the ATM network 10, terminals 11 and 12 are connected to two ATM switches 15 and 15 by two terminal lines 13 and 14, respectively.
Housed in 16 and 17, 18. The terminals 19 and 20 having the conventional configuration are accommodated in these exchanges by a single line. Terminals 1 between exchanges 15 and 16 and exchanges 17 and 18
Redundant trunk routes 21, 22, and 2 for 1 and 12
3, 24 and detour routes 25, 26 are provided.

When the incoming connection from one terminal 11 to the other terminal 12 takes route 1: terminal 11-exchange 15-17-terminal 12, exchange 15 switches to virtual 17
During connection (SVC) setup, for example, if a failure of the exchange 17 or a failure of the route 21 is detected as a route failure,
The route 1 is changed to the route 2 of the redundant route: the exchange 15-18-terminal 12 to avoid the failure. This is a conventional terminal 19,
The same applies to incoming calls to terminals 11 and 12 from 20. When the exchange 17 detects, for example, a failure in the terminal line 14 in the connection of the path 1, the exchange 17 changes the path 1 to the path 3: the exchange 18-the detour route 25-the exchange 17-the terminal 12. By such a route change, it is possible to avoid a route failure, a terminal line failure, and a receiving-side exchange failure in the route 1.

FIG. 2 shows a functional configuration of an ATM exchange according to an embodiment of the present invention. The ATM switches 15 to 18 may have the same configuration in this embodiment, and one of them will be described as a representative. switch
15 to 18 have line sections 28 and 29. Line units 28 and 29 are connected to terminals 11, 12, 1 according to a predetermined UNI and P-NNI.
Connected with routes 21, 26 to 9, 20, and other exchanges,
It is a circuit for converting between line signals and signals in the exchange, and has a function of detecting line faults in terminal lines and routes. The line units 28 and 29 are accommodated in a switch unit 30 as shown in the figure. Update the cell to self
This is a switch that transfers data by routing.

The ATM exchanges 15-18 are a central control unit (CPU) 31
Having. The central control unit 31 is connected to the switch unit 30 and the line units 28 and 29 via the data bus 32,
Is a control circuit for program-controlling an exchange based on call processing data such as network configuration information, routing information, and address information stored in the switch. In particular, with respect to the present invention, when the central control unit 31 detects line fault information of the line units 28 and 29 from the data bus 32, or when there is no return of a predetermined response signal from the partner exchange in the SVC signal setting process. In the case of a route failure such as, for example, the switching unit 30 is instructed to change the cell route.

FIG. 3 shows an example of an address table stored in the memory 33. When selecting a route for an input cell, the central controller 31 obtains an outgoing route in the address table 311 from the destination address of the header of the call setup message (SETUP). For example, in the network 10 shown in FIG.
It is assumed that the address “123” is assigned to 15. In this address "123", "1" is a network prefix and "23" is a terminal address. For example, if a cell addressed to the terminal 12 having the address "123" arrives at the ATM exchange 15 and a failure is detected in the SVC with the exchange 17, the central controller 31 sends the address table 3 shown in FIG.
31 is indexed by the network prefix "1" of the address "123", and the selection of the normal route 21 is changed to an index to which a substitute counter α at the time of failure is added as indicated by a dotted line 333 in FIG. In this example, the redundant route 22 is selected. Then, the cell goes to route 2, ie, route 22-
The transfer is performed on the path between the ATM switch 18 and the terminal 12.

FIG. 4 shows an example of the SVC signal sequence of the above-mentioned path 1. In the sequence 332, the originating side sets up a call (SET) for each section of the terminal 11, the exchange 15, the 17 and the terminal 12.
UP), and the receiving side returns a call setting acceptance (CALLPROC). In the next sequence 333, a response (CON
N) is sent, and when the calling terminal receives this,
(CONNACK) is returned.

FIG. 5 shows an example of an SVC for changing the route 1 to the route 2 due to the failure of the exchange 17. In this example, in response to a call setup SETUP from the exchange 15 to the exchange 17, a response CALLPR
OC is not returned from switch 17. Accordingly, the central control unit 31 of the exchange 15 determines that a route failure has occurred, and selects the redundant route 22 according to the address table 331 shown in FIG. In this manner, the exchanges 15-18-terminal 12
SVC setting is performed through. If the exchange 18 detects the failure of the terminal line 14, the route change in the address memory for setting the route as the bypass route 25 is performed in the same manner.

The method of the present invention can also be applied to LAN-connected devices such as Ethernet switches and routers that join the ATM network as terminals, and uses other switching methods such as circuit switching and packet switching other than ATM switching. It is, of course, applicable to communication networks such as integrated service digital networks (ISDN).

[0016]

As described above, if the ATM exchange communication system according to the present invention is applied to the local network and important terminals connected to the ATM network, it is possible to avoid the communication failure due to the failure of the terminal line and the exchange, and to improve the communication. Reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of an ATM network switching system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a functional configuration of an ATM exchange according to the embodiment;

FIG. 3 is an explanatory diagram showing an example of an address table of the embodiment shown in FIG. 2;

FIG. 4 is a sequence diagram showing an example of a normal SVC signal sequence in the system configuration shown in FIG. 1;

FIG. 5 is a diagram similar to FIG. 4, showing an example of a signal sequence of the exchange in FIG. 1;

[Explanation of symbols]

 10 ATM network 11, 12, 19, 20 Terminal 15-18 ATM switch 28, 29 Line section 31 Central controller 33 Memory

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI H04L 11/20 C

Claims (3)

[Claims] 1. A plurality of asynchronous transfer mode (ATM) switches for setting a virtual channel between communication terminals by a switched virtual connection, and a plurality of ATM switches in first and second switches among the plurality of ATM switches. And a communication terminal connected by a terminal line of the plurality of ATM exchanges, wherein a third one of the plurality of ATM exchanges has a first route connected to the first exchange, A second route is provided as a redundant route for the communication terminal connected to the second switch, and the third switch sets a switched virtual connection to the first switch for an incoming call to the communication terminal. An ATM switching system for selecting a second route when a failure is detected. 2. The system according to claim 1, wherein the system further includes a third route as a bypass route connecting the first switch and the second switch, wherein the first switch comprises a third switch. Upon receiving a switched virtual connection of an incoming call to the communication terminal from an exchange and detecting a failure of the terminal line, the switched virtual connection of the incoming call is sent from a third route to a second exchange. ATM switching system characterized by setting. 3. The system according to claim 1, wherein each of the first, second, and third exchanges includes: a line failure detection unit that detects a failure of the terminal line or the first route; Route selection means for selecting any one of the first to third routes according to the address of the terminal, wherein when the line failure detection means detects a failure in the terminal line or the first route, the route selection means: An ATM switching system for selecting a second or third route.