JPH1093567A - Atm network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the use of a new optimum communication path by making a path setting request from an ATM end system again while occurrence of a state change in an ATM exchange network is used for a trigger. SOLUTION: ATM exchanges 11, 12 are connected by a line 12, ATM exchanges 12, 13 are connected by a line 22, and ATM exchanges 11, 13 are connected by a line 23. An ATM end system 14 and the ATM exchange 11 are connected by a line 24 and an ATM end system 15 and the ATM exchange 13 are connected by a line 25. The ATM exchanges 11-13 detect network information reception from the adjacent ATM exchange or restoration of a line containing by its own equipment and starts it operation by using the detection. In the case of line restoration, a database in its own equipment is updated and network information is sent to the adjacent ATM exchange and ATM end system. Upon the receipt of it, the database is updated and when a more proper path than the existing path is in existence, the path is set up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM network system and, more particularly, to an ATM network system suitable for dynamically setting an optimal communication path between ATM end systems when the topology of the ATM network changes.

[0002]

2. Description of the Related Art In the case of setting a path between ATM end systems in an ATM network, an ATM for ATM is used.
As shown in um UNI 3.0 / 3.1,
A path setting request is made from the ATM end system where the transmission request has occurred. When a path setting request is issued from an ATM end system, the ATM switching device that has received the request selects an optimum path in the ATM switching device based on the network information in its own device. The ATM switching device is
As shown in TM Forum PNNI ph1, network information is automatically exchanged between adjacent ATM exchanges to collect network topology and QOS information. Thus, when a path setting request is issued from the ATM end system, path setting using an optimal path can be performed.

[0003] However, in the above-mentioned prior art, line restoration,
There has been a problem that a network topology change due to the start-up of an ATM switching device or the like occurs and a new optimum path cannot be changed even if a new optimum path can be set. These will be specifically described with reference to FIG.

In FIG. 1, reference numerals 14 and 15 denote ATM end systems for transmitting and receiving information.
Is an ATM switching device for relaying information, 21, 22, 23 are relay lines connecting the ATM switching devices, and 24, 25 are A
This line connects between the TM end system and the ATM switching device. If the path is set up from the ATM end system 14 to the ATM end system 15 when the line 23 is in the trouble, the path via the lines 21 and 22 is set. However, even if the failed line 23 is restored, the ATM end system 14 cannot recognize the restoration of the line 23. Therefore, even though a more optimal path can be set, the ATM end system 14 and the ATM end system 14 cannot communicate with each other. Path remains via the lines 21 and 22, and as a result, communication is continued using the long path. Therefore, the recovery from the failure of the line 23, that is, the change in the topology of the network is represented by A
It is necessary to notify the ATM end system from the TM switching device and allow the ATM end system which has recognized the change in the topology to issue a request for resetting the optimum path so that the optimum communication path corresponding to the network topology can be set.

[0005]

The UNI (User Network) is connected between the ATM end system and the ATM switching device.
k Interface) and NNI (Network Network Int) between ATM exchanges.
interface) protocol is used, and the selection of a route in the ATM switching device network is performed by the ATM switching device which has received a path setting request from the ATM end system. At this time, AT
The ATM end system is not informed of which route in the M-switch network. Further, the information of the restoration of the line failure is not notified to the ATM end system side, and there is a problem that it is not possible to automatically change the path to the optimum path with the restoration of the line.

An object of the present invention is to automatically generate a new optimal communication path when a new optimal communication path becomes available by issuing a path setting request again from the ATM end system, triggered by the occurrence of a state change of the ATM switching network. To provide an ATM network system for switching to a new communication path.

[0007]

A protocol is provided between the ATM end system and the ATM switching equipment for notifying a change in the topology to the ATM end system upon detecting a change in the topology of the ATM switching equipment network. By issuing a path setting request again from the ATM end system, it is possible to automatically switch to a new optimal communication path.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a network configuration diagram showing a connection form of an ATM switching device and an ATM end system to which a path setting method between ATM end systems using an ATM according to the present invention is applied. In the network of this embodiment, as shown in FIG. 1, the ATM switching device 11 and the ATM switching device 12 are connected by a line 21, and the ATM switching device 12 and the ATM switching device 13
Is a line 22, the ATM switching device 11 and the ATM switching device 1
The ATM end system 14 and the ATM switching device 11 are connected via a line 24, and the ATM end system 15 and the ATM switching device 13 are connected via a line 25.

FIG. 2 is an operation flowchart when the ATM switching apparatus updates its own database. AT
Each of the M switching devices 11, 12, and 13 detects the reception of network information from an adjacent ATM switching device or the restoration of a line accommodated by the M switching device, and starts operation by using this as a trigger. When a change in network information is detected (step 102) or the line is restored, the database in the own device is updated (step 1).
03), and transmits network information to the adjacent ATM switching equipment and ATM end system (step 10).
4, 105).

FIG. 3 shows a format of network information transmitted and received between ATM switching devices. The network information includes a plurality of entries 204 corresponding to one physical line. In the entry 204, the physical line indicates which ATM
Node ID (port I
D) 200, a partner node ID (port ID) 201, a cell loss rate 202 indicating a characteristic of a corresponding line, and a cell delay 203. The connectivity of the path can be evaluated based on the set of node IDs (port IDs), and the optimal communication path can be selected based on the cell loss rate and cell delay.

FIG. 4 shows an ATM for receiving network information.
6 is an operation flowchart of the end systems 14 and 15; The ATM end system sets up a path according to this flow, triggered by the start of path setup (data generation) and reception of network information from an adjacent ATM switching device. When network information is received, the database is updated (step 113), and it is checked whether there is a path that is more optimal than the current path (step 116). If there is a path that is more optimal than the current path, the path is set up (step 117).

FIG. 5 is a sequence diagram summarizing this situation. In other words, this is a sequence diagram in the case where the ATM end system 14 shown in FIG. 1 sends a path setting request to the ATM end system 15 and the optimum communication path is the path (of the ATM switching device 11-13) passing through the line 23. .
If the line 23 is communicable without a line failure, the above-mentioned optimal path is selected. In the case of this sequence diagram, the line 23 is a line failure at the initial stage, and the path between the ATM end systems is the line 24. , 21, 22, 25. The path between the ATM switching units 11-13 is shown in the figure (of the ATM switching units 11-12-13).
It will be a path. After the restoration of the line 23, the ATM switching apparatus 11 sets the A in step 105 according to the flowchart of FIG.
When the network information is transmitted to the TM end system 14, the ATM end system 14 finds a new optimal communication path (the path of the ATM switching device 11-13) according to step 116 shown in FIG.
And sends a path setting request again. The ATM switching device 11 that has received this path setting request sets the route again using the optimum communication path (the path of the ATM switching device 11-13) corresponding to the network topology since the line 23 has already been restored. Becomes possible.

[0014]

According to the present invention, when the topology of the ATM network changes and a new transmission path becomes communicable, the optimum path between the ATM end systems is automatically searched and switched to the new optimum communication path. It is possible to communicate.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a network configuration according to an embodiment of the present invention.

FIG. 2 is an operation flowchart when the ATM switching apparatus updates its own database.

FIG. 3 is a format diagram of network information transmitted and received between ATM switching devices.

FIG. 4 is an operation flowchart of the ATM end system.

FIG. 5 shows an ATM end system sending a path setting request to an ATM.
It is a sequence diagram in the case of putting out to an exchange device.

[Explanation of symbols]

11, 12, 13 ... ATM switching equipment, 14, 15 ... AT
M end system, 21, 22, 23 ... line (NNI connection), 24, 25 ... line (UNI connection).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norihiro Niwa 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Prefecture Hitachi, Ltd. Office Systems Division (72) Inventor Tomohisa Nishijima 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Hitachi, Ltd. (72) Inventor Ryoji Sasaki 6-81 Onoe-cho, Naka-ku, Yokohama-shi, Kanagawa Prefecture In-house Hitachi Software Engineering Co., Ltd. (72) Inventor Kenji Ishida 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Prefecture Hitachi, Ltd. Office Systems Division

Claims (1)

[Claims] 1. A plurality of ATM switching devices for performing communication by ATM, a plurality of ATM end systems for transmitting and receiving information, and a plurality of ATM switching devices for connecting the plurality of ATM switching devices and the plurality of ATM end systems. An ATM network system having a transmission line, wherein the ATM switching device exchanges network information including connection information and characteristic information of the transmission line between the ATM switching devices,
Means for selecting an optimum communication path from the exchanged network information, and means for notifying the network information to the ATM end system when the optimum communication path changes, the ATM end system comprising: Means for setting a path to the other party's ATM end system via a network, and means for selecting an optimum communication path based on network information notified from the ATM switching device,
The ATM exchange device recognizes the network information collected at the time of recognizing a change in the topology of the network.
The ATM end system notified to the end system and notified of the network information from the ATM switching device selects an optimum communication path based on the received network information, and selects an optimal communication path over the path currently set as the partner ATM end system. An ATM network system characterized by setting an optimum communication path according to the topology of a network by resetting a communication path again when it is found that there is a path having a high communication capability.