JP3445471B2 - ATM communication network - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ATM (Asynchronou).
s Transfer Mode: Used for communication.
In particular, it relates to a technique for setting a backup route used when the working route fails.

[0002]

2. Description of the Related Art With respect to a failure of a node or a transmission line in an ATM communication network, a reroute is set in advance or by searching for a backup route when the failure occurs. For example,
THWu "Fiber Network Service Survivability", Artech
House, (1992).

Setting of the working and protection routes of the conventional ATM communication network will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram for explaining a conventional detouring process for a failure point in which a backup route for the working route is always set. FIG. 11 is a diagram for explaining a conventional detouring process for a failure location in which a backup route is set after a failure occurs.

In the detouring process for the faulty part shown in FIG. 10, when the working route is set, the spare route (the detouring route) is set. This spare route is fixed and secures the same bandwidth as the working route. In the example shown in FIG. 10, 10Mb / s is also used for the working route of 10Mb / s.
The backup route 2 of b / s is set in advance, and the transmitting node N1 has the table T thereof. However, in order to effectively use the band, the spare route 2 is designed to be shared with other spare routes. The operation system (OpS system and illustrated) 10 grasps the band information of the route passing through each node and comprehensively sets the working route and the backup route.

In the detouring process of the fault location shown in FIG. 11, a cell called a flatting cell is sent from the receiving node N4 to all the connected nodes N6, N3 and N8. Each node N6, N3, N8 copies its flooding cell, and each node N6, N3, N8
To the node connected to. By repeating such a transfer process, the route in which the flatting cell first arrives at the transmitting node N1 and the free capacity is 10 Mb / s or more is set as the spare route.

A technique for setting a preliminary route according to the arriving flooding cell in the transmitting node N1 is a known technique, so a detailed description thereof will be omitted, but the flooding cell transmitted from the receiving node N4 is on the route. Each time it passes through a node, it is transferred while the identification code of that node is written in the cell. The transmitting node N1 that has received this flatting cell recognizes the route that the flattening cell has passed by referring to the identification code, and sets that route as a backup route.

According to the conventional example shown in FIG. 11, each node can autonomously set a working route and a spare route without providing the operation system 10 unlike the conventional example shown in FIG. Furthermore, since the route is selected and set by actually transferring the flatting cell, the shortest optimum route can be easily selected and set.

By adopting the detouring processing of the failure point shown in FIGS. 10 and 11, a highly reliable ATM communication network which can use a spare route when a failure occurs in the working route is realized. be able to.

[0009]

However, in the detouring processing of the failure point shown in FIG. 10, the backup route is fixedly set in advance when the working route is set. Therefore, for example, the amount of traffic and the state of the ATM communication network. This reserve route cannot be changed even if the is changed. For this reason, there may be a case where a traffic route is partially biased or the current route cannot be used because of this backup route. Further, in the detouring process of the failure point shown in FIG. 11, it takes a long time to recover because the backup route is selected and set after the failure occurs, and the communication is interrupted.

The present invention has been made against such a background, and provides an ATM communication network in which a backup route can be flexibly set in response to changes in traffic and changes in network conditions. With the goal. An object of the present invention is to provide an ATM communication network in which communication interruption time is short when a failure occurs.

[0011]

The main feature of the present invention is to set a spare route in advance, but periodically re-search for bandwidth information of the spare route and / or reset the spare route.

This is different from the conventional technique in that the working route may be used by the working route, and the bandwidth information of the working route is periodically searched and / or the working route is reset.

That is, the present invention is an ATM communication network in which a spare cell transfer route used between a transmitting node and a receiving node is used when the current cell transfer route cannot be transferred. AT with means to set
M communication network. A feature of the present invention is that the setting means includes means for setting a preliminary route on a trial basis at regular intervals.

In other words, according to the present invention, the route set as a backup route for a certain working route is allowed to be used by another working route, so that the band of this backup route is occupied by another working route. It may be cut off. Therefore, by setting a spare route on a trial basis at regular intervals, it is possible to cancel the setting of such a spare route whose band is occupied by another working route and set a new spare route. Furthermore, by setting the preliminary route on a trial basis at regular intervals, it is possible to realize the setting of the preliminary route that is adapted to the situation of the network, which changes every moment.

The trial setting means may include means for selectively setting another route as a spare route when the scheduled spare route is not available. That is, as described above, the spare route may be periodically reset regardless of the bandwidth of the spare route that has already been set, but the bandwidth information of the spare route that has already been set is detected. Alternatively, another route may be newly selected and set as a backup route only when the band of the backup route is insufficient.

The means for setting sets a cell for periodically setting a spare route to a plurality of routes from the receiving node side, and sets a route where the cell arrives at the transmitting node as a spare route. It may be configured to include means.

That is, the receiving node side causes a plurality of routes to transmit a spare route setting cell. Since this cell first arrives at the transmitting node via the shortest route at that point, the passage route of the cell that first arrives at the transmitting node is set as a backup route, and In this situation, it is possible to easily select and set the optimum route that is the shortest.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram for explaining a detouring process for a fault location according to the first embodiment of the present invention.

The present invention is an ATM communication network, and as a means for setting a spare route 2 to be used between the transmitting node N1 and the receiving node N4 for the working route 1 when the route becomes untransferable. It is an ATM communication network provided with an operation system (shown as OpS system) 10 of.

Here, the feature of the present invention resides in that the operation system 10 sets a preliminary route on a trial basis at regular intervals.

[0021]

【Example】

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 to 3 are diagrams for explaining the detouring process for a fault location according to the first embodiment of the present invention. FIG. 4 is a flow chart showing the detouring process of the failure point according to the first embodiment of the present invention. As shown in FIG. 1, a backup route 2 is secured for the working route 1. However, since the spare route 2 is not fixed and may be used by another working route or the like, the band information of the spare route is periodically searched and reset.

As shown in FIG. 2, when the backup route 2 is used by another working route, the band is occupied by the other working route, and thus the band for the backup route 2 is insufficient. , Or disappear. Since the bandwidth information of the route passing through each node is collected in the database of the operation system 10 shown in FIG. 1, it is not necessary to actually transfer the cells, and the database is searched to determine the bandwidth status. Can be detected. Therefore, in the first embodiment of the present invention, the bandwidth information of the spare route 2 is periodically searched, and if a shortage of the bandwidth of the spare route 2 is detected at that time, a new spare route is reset. It should be noted that the operation system 10 grasps all the used routes and the band information thereof in each node in the network and comprehensively sets the working route and the backup route.

The search and resetting of the bandwidth information of the spare route is an event within the time Pt. When the time Pt has elapsed, it is searched whether or not the virtually planned backup route 2 is already used by another working route, and if it is being used, as shown in FIG. Resets the other spare route 3.

As described above, the backup route is not fixed, and the other working routes can use the virtual backup route as if they were empty routes, so that the entire network can be flexibly used. Do not create a backup route that could cause a bottleneck.

That is, as shown in FIG. 4, the operation system 10 monitors the timing (S1),
When the time Pt has passed since the last time the bandwidth information of the spare route was searched or reset and the search time has come (S2), the database of the operation system 10 is searched to detect the bandwidth of the currently set spare route ( S3). If the band is not secured in the spare route (S4), a new spare route is reset (S5). Where time Pt
May be set to an optimum value according to the network condition. In the first embodiment of the present invention, the time Pt is set to 10 seconds.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram for explaining a detouring process for a fault location according to the second embodiment of the present invention. The second embodiment of the present invention is an embodiment in which, in addition to the setting of the preliminary route of the first embodiment of the present invention, the setting of the preliminary route by the flatting cell described in FIG. 11 of the conventional example is performed.

That is, the second embodiment of the present invention includes the operation system 10 as in the first embodiment of the present invention, and performs the processing according to the flowchart shown in FIG. In the resetting of a new spare route (S5), the spare route is reset using the flatting cell described in FIG. 11 of the conventional example. The operation system 10 sends out a flatting cell from the receiving node N4, detects arrival of a flatting cell at the transmitting node N1, and sets a backup route according to the route information written in the flatting cell.

According to the second embodiment of the present invention, as described in the first embodiment of the present invention, the result of actually transferring the flatting cell is obtained regardless of the band information collected in the operation system 10. Therefore, since the backup route is set, it is possible to easily select and set the optimum backup route that is the shortest in the situation of the network at that time.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flow chart showing the detouring process of the failure point according to the third embodiment of the present invention. The third embodiment of the present invention is an embodiment in which band detection of the spare route performed in the first and second embodiments of the present invention is not performed. That is, the spare route is periodically reset regardless of the band of the spare route that has already been set. As a result, even if the bandwidth of the backup route is not occupied by other working routes, it is possible to set a new backup route that adapts to the changing network conditions, so the current network conditions can be set. It is possible to set the optimum spare route that is the shortest in.

As shown in FIG. 6, the operation system 10 monitors the timing (S7), and when the time Pt has elapsed from the previous resetting of the preliminary route and the resetting time has come (S8), it is already set. Regardless of the bandwidth of the existing backup route, a new backup route is reset (S9).

In setting the backup route, the backup route may be set based on the band information which the operation system 10 grasps as described in the first embodiment of the present invention, or the second embodiment of the present invention. As described in the example, the preliminary route may be set by using a flatting cell.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIGS. 7 to 9. FIG. 7 is a diagram for explaining the detouring process of the failure point according to the fourth embodiment of the present invention. Figure 8
11 is a flow chart showing a detouring process of a faulty part in the receiving node of the fourth embodiment of the present invention. FIG. 9 is a flow chart showing the detouring process of a fault location in the transmitting node of the fourth embodiment of the present invention. Similar to the third embodiment of the present invention, the fourth embodiment of the present invention is an embodiment in which the spare route is periodically re-set regardless of the bandwidth of the already set spare route. However, in the fourth embodiment of the present invention, FIG.
As shown in, each node can perform processing autonomously without installing the operation system 10 in the network.

As shown in FIG. 8, the receiving node N4 monitors the timing (S10), and when the time Pt has elapsed from the previous resetting of the spare route and the resetting time comes (S1).
1), nodes N6, N connected to receiving node N4
3. Send the flatting cell to N8 (S1
2). Each node N6, N3, N8 copies the flooding cell and sends it out to the nodes connected to each node N6, N3, N8. While repeating such transfer processing, the flatting cell eventually arrives at the transmitting node N1.

As shown in FIG. 9, the transmission node N1 monitors the arrival of a flatting cell (S13), and if there is a arriving flatting cell, a new backup route is obtained according to the passage route information recorded in the cell. Is reset (S15). When a plurality of flatting cells arrive at the transmission note N1, a new preliminary route is reset according to the passage route information recorded in the first flatting cell that arrived.

As described above, in the fourth embodiment of the present invention, the backup route is periodically reset regardless of the bandwidth of the backup route that has already been set. At that point, an optimal spare route can be set. In particular, by using the flatting cell, the shortest backup route at that time can be easily selected and set.

[0036]

As described above, according to the present invention,
A backup route can be set flexibly in response to changes in traffic and changes in network conditions. In addition, it is possible to shorten the communication interruption time when a failure occurs.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a detouring process for a failure point according to the first embodiment of this invention.

FIG. 2 is a diagram for explaining a detouring process for a failure point according to the first embodiment of this invention.

FIG. 3 is a diagram for explaining a detouring process of a failure point according to the first embodiment of this invention.

FIG. 4 is a flowchart showing a detouring process for a fault location according to the first embodiment of this invention.

FIG. 5 is a diagram for explaining a detouring process for a fault location according to the second embodiment of the present invention.

FIG. 6 is a flow chart showing a detouring process for a fault location according to the third embodiment of the present invention.

FIG. 7 is a diagram for explaining a detouring process for a fault location according to the fourth embodiment of the present invention.

FIG. 8 is a flowchart showing a detouring process of a failure point in the receiving node according to the fourth embodiment of the present invention.

FIG. 9 is a flowchart showing a detouring process for a faulty part in the transmitting node according to the fourth embodiment of the present invention.

FIG. 10 is a diagram for explaining a conventional detouring process for a failure point in which a backup route for the working route is always set.

FIG. 11 is a diagram for explaining a conventional detouring process for a failure location in which a backup route is set after a failure occurs.

[Explanation of symbols]

1 working route A few reserve routes 10 Operation system N1 to N8 nodes T table

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-9-18492 (JP, A) JP-A-9-55751 (JP, A) JP-A-2-277354 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04L 12/56

Claims (2)

(57) [Claims] 1. Existence between a transmitting node and a receiving node
Receiving cell transfer route of the active is a spare cell transfer route to use when it becomes transfer impossible and the transmitting node Bruno
In the ATM communication network having means for setting a spare cell transfer route,
This is set as a trial for each T and this preliminary set as a backup
The available bandwidth of the cell transfer route of every predetermined period Pt
(However, Pt ≦ T), and measure the spare cell transfer route.
The available bandwidth of the network is higher than the bandwidth of the working cell transfer route.
If it is smaller, the other cell transfer route is changed to the spare cell transfer route.
A including means for selecting as a transmission route
TM communication network. 2. The setting means is the receiving node side.
To multiple cell transfer routes from
A means for transmitting a regular cell every predetermined period Pt,
From the cell transfer route where the cell arrived at the transmitting node,
The shortest cell transfer route is the spare cell transfer route
ATM communication according to claim 1, including means for setting as
network.