JPH1056460A - Communication network and communication method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently use a transmission line and to prevent the device configuration from being complicated by giving the information of the capacity of a virtual path connected to an own equipment to the other communication equipment, managing the capacity, previously storing an alternative virtual path through which ATM cells are transmitted and executing a transmission while selecting the alternative virtual path having sufficient capacity. SOLUTION: Virtual paths 11A-11F having fixed capacity are provided between communication equipment 10 and the other communication equipment and virtual channels 12A1-12F2 are accommodated in these respective paths. In a routing table 10a, direct virtual paths and alternative virtual paths are previously set/registered. A virtual path capacitance table 10b is a table in which the capacities of the virtual paths 11A-11F are stored, and the communication equipment 10 writes its used capacity or idle capacity to the virtual capacity report cell to report the adjacent communication equipment connected through the direct virtual path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication network and a communication method thereof, and more particularly, to a communication technique using an asynchronous transfer mode (ATM) applied to an ISDN (Integrated Services Digital Network) or the like.

[0002]

2. Description of the Related Art As is well known, an ISDN using an ATM is known.
Various technical recommendations concerning ITU-T have been made by ITU-T (International Telecommunication Union, Telecommunication Standardization Sector, formerly CCITT). In a communication network according to this recommendation, when a virtual path for transmitting an ATM cell is set between a plurality of communication apparatuses, a virtual path (CB) having a fixed capacity is set.
R-VP) is used. In this case, one virtual path is usually set between each communication device. Also,
ABR (Available Bit Rate) technology for efficiently using a transmission path by changing the capacity of a virtual path has also been disclosed.

[0003]

However, when a virtual path to a certain communication device is constituted by one CBR-VP, the maximum capacity that can be transmitted to the CBR-VP is prepared. While that is uneconomic,
If the maximum capacity is not prepared, ATM cells may not be transmitted. Further, when the above ABR technology is applied, a communication device related to communication, and A
All devices such as communication nodes (cross-connect devices, subscriber terminating devices, exchanges), and communication terminals in a communication network based on TM require a function to handle ABR technology.
There is a problem that the device configuration is complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a communication network and a communication method capable of efficiently using a transmission line and suppressing the complexity of a device configuration. And

[0005]

In order to achieve the above object, a plurality of communication devices are connected to each other by a virtual path, and each of the communication devices is connected to an asynchronous transfer mode (ATM).
In a communication network that transmits and receives TM cells to and from each other, each communication device notifies a communication device connected to the other of the virtual paths of the capacity of the virtual path connected to the communication device, and performs the communication based on the notification. When the ATM cell is transmitted to another communication device, the notification is sent to the other communication device when one or more bypass virtual paths for bypassing the ATM cell are transmitted and managed. The capacity of the direct virtual path directly connected to the other communication device based on
If it is determined that there is not enough capacity for the transmission of the TM cell, the A is added to the detour virtual path having a sufficient capacity for the transmission of the ATM cell among the detour virtual paths.
Means of transmitting TM cells is employed.

As means for notifying the communication device connected to the other of the virtual paths of the capacity of the virtual path, means for transmitting a virtual path capacity notification cell by each communication device is employed. In this case, the virtual path capacity notification cell is transmitted at predetermined time intervals, when the capacity is changed, or when a request is received from another communication device. The virtual path capacity notification cell notifies either one or both of the used capacity and the free capacity of the virtual path.

[0007] In place of the virtual path, the capacity of a virtual path group consisting of a plurality of virtual paths is notified to a communication device connected to the other of the virtual path groups, and the capacity of the virtual path group is determined based on the notification. Is adopted. Also, each communication device notifies the communication device connected to the other of the transmission paths of the capacity of the entire transmission path instead of the virtual path, and manages the capacity of the transmission path based on the notification. Means is adopted. In addition, ATM
Means of accommodating an IP packet in a cell and transmitting it is adopted.

[0008]

FIG. 2 is a block diagram of a communication network to which the above means are applied. In this figure, reference numerals 1A to 1
D is a communication device, and 2A to 2F are communication devices 1A.
Virtual path with fixed capacity set between ~ 1D, 3A
To 3F are virtual channels included in each of the virtual paths 2A to 2F.

[0009] Here, the virtual channel is a logical line for connecting communication devices to each other and transmitting ATM cells. The virtual path is a bundle of a plurality of the virtual channels to facilitate the management of the virtual channels. Is a logical path provided for
UT technical recommendation). A virtual path group is a logical path that bundles a plurality of virtual paths in order to further facilitate communication management.

In this figure, when ATM cells are transmitted from the communication device 1A to the communication device 1D, the virtual path 2A is a direct virtual path directly connecting the communication device 1A and the communication device 1D, and the virtual path 2B , 2
C is a bypass virtual path that transmits an ATM cell while bypassing the virtual path 2A. Each communication device 1A-
In 1D, a direct virtual path and a bypass virtual path to another communication device are registered in the routing table in advance.

Each of the communication devices 1A to 1D is configured to notify either or both of the used capacity and the free space of the virtual path to the communication device connected thereto by using a virtual path capacity notification cell. Then, based on the notification by the virtual path capacity notification cell, the used capacity is stored in the virtual path capacity table for all the virtual paths connected thereto.

FIG. 3 is a frame configuration diagram showing a configuration example of a virtual path capacity notification cell. As shown in this figure, the virtual path capacity notification cell is composed of a header (part) indicating the communication device of the transmission destination and a payload (part). The payload portion includes a communication device identification number portion indicating the identification number of the transmission source communication device, a virtual path capacity portion indicating the capacity of the corresponding virtual path, a virtual path used capacity portion indicating the used capacity of the virtual path, and the virtual path used capacity portion. And a virtual path free capacity section indicating the free capacity of the virtual path. When each of the communication devices 1A to 1D receives the virtual path capacity notification cell configured as described above from another communication device, the corresponding portion of the virtual path capacity table is updated.

For example, when an ATM cell arrives at the communication device 1A, the communication device 1A should read the header portion describing the destination of the ATM cell and transmit the ATM cell by comparing the header with the routing table. Search for virtual paths. Here, the capacity of the direct virtual path to the target communication device is checked in a virtual path capacity table, and if the available capacity is sufficient for transmitting the arrived ATM cell, the ATM cell is transmitted to the direct virtual path.

On the other hand, when there is not enough free space in the direct virtual path, each of the communication devices 1A to 1D uses a preset detour virtual path whose free space is sufficient to transmit the ATM cell. And sends an ATM cell. When a plurality of detour virtual paths are applicable, the detour virtual path is selected according to a predetermined order. In this case, for example, a bypass virtual path with the largest free space or a bypass virtual path with the shortest transmission distance is selected.

In the communication device connected to the bypass virtual path of the ATM cell, the virtual path is set in advance, and the AT is transferred to the next communication device according to its own routing table.
Transfer M cells. Then, the final arrival communication device of the ATM cell transmits the arrived ATM cell to a predetermined virtual path according to the contents of the routing table.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a communication network and a communication method according to the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a block diagram showing a functional configuration of a communication apparatus according to this embodiment. In this figure, reference numeral 10 denotes a communication device, 11A to 11F denote virtual paths having a fixed capacity provided between the communication device 10 and another communication device, and 12A1 to 12F2 denote respective virtual paths 11A to 11F. , The communication device 1
0 is a virtual channel connecting to another communication device.

The virtual paths 11A to 11F
It is assumed that another communication device is connected to the destination of the virtual paths 11D to 11F. Also, in this figure, each virtual path 11A to 11F is described as including two virtual channels, respectively, but the present invention is not limited to this.

The communication device 10 has a routing table 10
a, virtual path capacity table 10b, and ATM processing unit 10c
To 10h and the virtual path capacity notification cell processing unit 10i to
10k, and a switch unit 10m.

The routing table 10a stores not only a direct virtual path directly connected from the communication apparatus 10 to another communication apparatus (more precisely, a direct virtual channel included in the direct virtual path) but also a direct communication path to the other communication apparatus. A bypass virtual path that is not connected and passes through the third communication device is set and registered in advance.

The virtual path capacity table 10b is a table in which the capacities of the virtual paths 11A to 11F are stored. The communication device 10 is connected to the virtual path 1 as described above.
One or both of the used capacity and the free capacity of 1A to 11F are written in the virtual path capacity notification cell, and the adjacent communication devices connected by the direct virtual path are notified. This is the same for all the communication devices constituting the communication network.

Virtual path capacity notification cell processing unit 10i
10 to 10k are provided corresponding to the virtual paths 11D to 11F to which the communication devices are connected earlier, and each of the virtual paths 11D written in the virtual path capacity notification cell.
Read the capacity of D-11F. This capacity is stored in the virtual path capacity table 10b for each of the virtual paths 11A to 11F.
Is stored.

For example, the method of transmitting the virtual path capacity notification cell includes a method of transmitting the virtual path capacity notification cell at a predetermined time interval, a method of transmitting when the capacity is changed, and a method of transmitting the virtual path capacity notification cell when a request is received from another communication device. May be applied. When the communication device 10 receives the virtual path capacity notification cell from a certain communication device, the communication device 10 updates the recorded content of the corresponding portion of the virtual path capacity table 10b.

Each of the ATM cell processing units 10c to 10h is provided corresponding to each of the virtual paths 11A to 11F, and reads a header portion of an ATM cell received from another communication device to check its destination. The communication device 10 has sufficient free space on the direct virtual path to the communication device to which the ATM cell is to be sent based on the routing table 10a and the virtual path capacity table 10b for this destination to transmit the ATM cell. It is determined whether or not there is enough free space, and if it is determined that the free space is not sufficient, all free space of the bypass virtual path is checked to search for a virtual path that can transmit the ATM cell.

The switch unit 10m is connected to each virtual path 1
The connection relation of 1A to 11F is switched. The communication device 10 switches the switch unit 10 when there is a corresponding detour virtual path by the search for the virtual path.
m and activates the ATM to the corresponding detour virtual path.
Send the cell. The communication device ahead of the bypass virtual path transfers the ATM cell as set in the routing table, and the communication device that is the final destination of the ATM cell transfers the ATM cell to the target virtual path according to the routing table. Send out.

Here, instead of the capacity of the virtual path,
For a virtual path group including a plurality of virtual paths or the entire transmission path including all virtual paths, one or both of the used capacity and the free capacity may be notified. By controlling the transmission of the ATM cells based on the capacity of the virtual path group having a larger capacity than the virtual path or the capacity of the transmission path having a larger capacity, the transmission efficiency can be improved.

[Second Embodiment] Next, a second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. In the present embodiment, instead of setting and registering the detour virtual path in the routing table, a detour control cell processing for adding a detour control cell to the beginning and end of the ATM cell and reading the detour control cell is performed. It is characterized by having parts 10p to 10r. The other configuration is the same as the first configuration.
This is the same as the control device 10 described in the embodiment.

When a virtual path to be detoured is written in the detour control cell, and the ATM cell to which the detour control cell is added is received, the communication device 10 'causes the detour control cell processing unit 10p to At 10r, the bypass control cell is read. Then, by searching the routing table 10a, a communication device to which the ATM cell is to be transmitted is determined and transmitted. Upon receiving the ATM cell, the communication device, which is the final purpose of the ATM cell, reads the header of the ATM cell in the ATM cell processing units 10p to 10r and sends out the ATM cell according to the routing table.

In the present embodiment, for example, by writing the number of cells of an ATM cell group for dividing and transmitting one data into the detour control cell, the first A of the ATM cell group is written.
It is sufficient to add a detour control cell in which the number of cells is written only to the TM cell.

[Third Embodiment] Next, a third embodiment of the present invention will be described.
An embodiment will be described. In this embodiment, instead of setting and registering the bypass virtual path in the routing table, a virtual path provided between all other communication devices is set and registered in the routing table, and the respective virtual paths are searched. It is characterized by having a function to perform. When each communication device receives an ATM cell that needs to be bypassed, the communication device searches the routing table for a communication device to be transmitted, and
The ATM cell is transmitted to the selected virtual path.
When the communication device, which is the final purpose of the ATM cell, receives the ATM cell, the ATM processing unit detects the ATM cell header and sends it to the virtual path set in the routing table.

[Fourth Embodiment] FIG. 5 is a block diagram showing the configuration of a communication apparatus according to a fourth embodiment. This embodiment is characterized in that an IP packet is accommodated in an information area of an ATM cell. That is, in this figure, reference numerals 10s to 10u and 10w to 10y denote IP processing units, which read the header part of the IP packet contained in the information area of the ATM cell. Then, the communication device 10 ″ sends the ATM cell to the communication terminal specified by the header section.

[0032]

As described above, according to the communication network and the communication method according to the present invention, the following effects can be obtained. (1) In a communication network in which a plurality of communication devices are mutually connected by a virtual path, and each of the communication devices mutually transmits and receives ATM cells in an asynchronous transfer mode (ATM), each communication device is connected to itself. Notifying the communication device connected to the other of the virtual paths of the capacity of the virtual path, managing the capacity of the virtual path connected to itself based on the notification, and transmitting the ATM cell by bypassing the ATM cell. One or more bypass virtual paths are stored in advance, and when sending an ATM cell to another communication device, the capacity of the direct virtual path directly connected to the other communication device based on the notification is reduced. Said A
If it is determined that there is not enough capacity for the transmission of the TM cell, the A is added to the detour virtual path having a sufficient capacity for the transmission of the ATM cell among the detour virtual paths.
Since the TM cell is transmitted, the transmission path can be used efficiently by using the bypass virtual path, and data loss and the like can be prevented. (2) Since there is no need to apply the ABR technology, it is possible to suppress the complexity of the devices constituting the communication network.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a functional configuration of a communication device in a communication network and a communication method according to a first embodiment of the present invention;

FIG. 2 is a block diagram illustrating a functional configuration of a communication network to which a communication network and a communication method according to the present invention are applied;

FIG. 3 is a frame configuration diagram showing a configuration example of a virtual path capacity notification cell in the communication network and the communication method according to the present invention;

FIG. 4 is a block diagram illustrating a functional configuration of a communication device in a communication network and a communication method according to a second embodiment of the present invention;

FIG. 5 is a block diagram showing a functional configuration of a communication device in a communication network and a communication method according to a fourth embodiment of the present invention.

[Explanation of symbols]

1A to 1D, 10, 10 ', 10 "... communication device, 2A
~ 2F, 11A ~ 11F ... virtual path, 3A ~ 3
F, 12A1-12F2 ... virtual channel, 10a
... routing table, 10b ... virtual path capacity table, 10c-10h ... ATM cell processing unit, 10i-1
0k ... virtual path capacity notification cell processing unit, 10p ~
10r: detour control cell processing unit, 10s to 10u, 10
w-10y IP processing unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideyuki Tsuboi 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Hiroyuki Fujiwara 3- 192-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Japan Telegraph and Telephone Corporation

Claims (10)

[Claims] A plurality of communication devices are interconnected by a virtual path, and each of the communication devices is connected to an asynchronous transfer mode (A).
In a communication network for mutually transmitting and receiving ATM cells by TM), each communication device notifies the communication device connected to the other of the virtual paths of the capacity of the virtual path connected to itself, and When managing the capacity of the virtual path connected to itself and storing one or more bypass virtual paths for bypassing the ATM cell and transmitting the ATM cell to other communication devices, , When it is determined based on the notification that the capacity of the direct virtual path directly connected to the other communication device is not sufficient for the transmission of the ATM cell, A communication network for transmitting an ATM cell to a bypass virtual path having a sufficient capacity for transmitting the ATM cell. 2. The communication network according to claim 1, wherein each communication device notifies the communication device connected to the other of the virtual paths of the capacity of the virtual path by transmitting a virtual path capacity notification cell. A communication network, characterized in that: 3. The communication network according to claim 1, wherein each of the communication devices has a capacity of a virtual path group including a plurality of virtual paths connected to the other of the virtual path groups instead of the virtual paths. A communication device for notifying the communication device which has made the communication, and managing the capacity of the virtual path group based on the notification. 4. The communication network according to claim 1, wherein each communication device notifies the communication device connected to the other of the transmission paths of the capacity of the entire transmission path instead of the virtual path. A communication network for managing the capacity of the transmission path based on the notification. 5. The communication network according to claim 1, wherein an IP packet is accommodated in an ATM cell and transmitted. 6. A plurality of communication devices are interconnected by a virtual path, and each of the communication devices is connected to an asynchronous transfer mode (A).
TM) is a communication method of a communication network for mutually transmitting and receiving ATM cells, wherein each communication device is directly connected to another communication device when transmitting the ATM cell to the other communication device. The capacity of the direct virtual path
If the transmission capacity of the TM cell is not provided, the relevant virtual path having a sufficient capacity for the transmission of the ATM cell among the preset detour virtual paths is assigned to the AT.
A communication method for a communication network, comprising transmitting an M cell. 7. The communication method for a communication network according to claim 6, wherein each communication device notifies a virtual path capacity of a virtual path connected to itself to a communication device connected to the other of the virtual paths. A communication method for a communication network, comprising: notifying by transmitting a cell; and managing the capacity of a virtual path connected to itself based on the virtual path capacity notification cell. 8. The communication method according to claim 5, wherein each of the communication devices connects a capacity of a virtual path group including a plurality of virtual paths to another of the virtual path groups instead of the virtual path. A communication method for a communication network, comprising: notifying a communication device that has made a request and managing the capacity of the virtual path group based on the notification. 9. The communication method according to claim 5, wherein each communication device notifies the communication device connected to the other of the transmission paths of the capacity of the entire transmission path instead of the virtual path. And a method of managing the capacity of the transmission path based on the notification. 10. The communication method according to claim 5, wherein an IP packet is accommodated in an ATM cell and transmitted.