JP3877463B2 - Bandwidth change method of PVC channel in ATM communication network - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for dynamically changing channel communication information in an ATM communication network using a PVC channel.
[0002]
[Prior art]
Conventionally, in the communication on the PVC channel in the ATM communication network, VPI / VCI, ATM address, communication speed and communication speed control method, and communication information for each channel such as AAL information cannot change preset values. It was. The means for changing the communication information is not performed by the PVC channel, but is realized by the SVC channel capable of changing the communication information.
The operation of the PVC channel and the SVC channel will be described using the example of the ATM communication network in FIG.
In the figure, T11, T12 and T13 indicate ATM communication devices, Sw11, Sw12 and Sw13 indicate relay devices, N01 indicates a plurality of relay devices Sw11, Sw12 and Sw13, and a plurality of ATM communication devices T11, T12 and T13. An ATM network consisting of
A solid line arrow from the ATM communication device T11 to the ATM communication device T12 via the relay device Swll indicates communication on the PVC channel, and the channel is always used based on communication information such as fixed VPI / VCI and communication speed. . Instead, the bandwidth is always secured and communication is possible at any time.
On the other hand, in FIG. 1, the SVC channel is indicated by a dashed arrow. A method in which VPI / VCI is not specified in connection of a line through an SVC channel, VPI / VCI assignment is requested to the ATM network N01 by an ATM address, and the ATM network N01 resolves the route and VPI / VCI assignment. It is.
[0003]
When the ATM communication device T13 communicates with the ATM communication device Tll, prior to the communication, the ATM communication device T13 requests connection to the relay device in the ATM network N01, for example, Sw11. The relay device Sw11 confirms that the route to the ATM communication device Tll can be secured with the requested communication information (communication speed, quality, etc.), and connects the channel when the ATM communication device Tll is receivable. The same procedure is used for releasing the channel after the communication is completed.
Therefore, both the transmission side and the reception side ATM communication devices and the ATM network N01 are required to have a function for realizing communication using the SVC channel. In addition, in order to resolve the path and VPI / VCI assignment every time a connection request occurs, time is required from the PVC channel to the start of communication.
Therefore, when the SVC channel is used in communication applications such as image transfer accompanied by band change, there is a problem that image transfer stops every time communication information is switched.
[0004]
[Problems to be solved by the invention]
As described above, when the communication information is changed by the original SVC channel, arbitration is performed between the communication apparatuses, so that the change process requires a considerable time. Changing the communication speed on the SVC channel during communication in a system that does not allow communication delay such as VOD has a problem that the image is disturbed due to the above time.
Therefore, the present invention uses a PVC channel and immediately reflects the change in communication information only on the ATM communication device on the transmission side, thereby allowing the PVC in an ATM communication network to change the communication information during communication in a system in which no delay is allowed. An object of the present invention is to provide a channel band changing method.
[0005]
[Means for Solving the Problems]
The bandwidth change method of the PVC channel in the ATM communication network according to the present invention is as follows:
In an ATM communication network in which a plurality of ATM communication devices communicate with each other via a PVC channel,
A processor for controlling the ATM communication device;
ATM communication control means that can be controlled from this processor;
A shared memory accessible by both the processor and the ATM communication control means;
A first table managed by the ATM communication control means, holding channel information, and arranged in the shared memory;
A second table managed by the processor and holding channel information;
Means for performing pseudo-channel release based on information in the second table;
Means for updating the information in the first and second tables based on the information in the first and second tables and reconnecting the channels in a pseudo manner.
With such a configuration, in a PVC channel for which communication information such as VPI / VCI and communication speed is determined in advance, information that can be changed such as communication speed within the range of the communication information (communication capacity) is transmitted. It can be changed quickly by changing only on the side.
Therefore, even in a communication application such as image transmission involving a change in communication information, communication information can be changed and communication can be continued without causing image disturbance.
[0006]
Here, the first table may be a table that holds at least predetermined channel information including information indicating whether each channel is communicating.
Further, the second table may be a table that holds predetermined channel information including at least information indicating whether each channel is unused, connected, or released.
More specifically, the bandwidth change method of the PVC channel in the ATM communication network according to the present invention is:
In an ATM communication network in which a plurality of ATM communication devices communicate with each other via a PVC channel,
A processor for controlling the ATM communication device;
ATM communication control means that can be controlled from this processor;
A shared memory accessible by both the processor and the ATM communication control means;
A first table managed by the ATM communication control means, holding channel information, and arranged in the shared memory;
A second table managed by the processor and holding channel information;
Means for accepting a request to change channel information;
Based on the request received by this means, the corresponding channel is searched from the second table, and if detected, the channel is released in a pseudo manner by setting the use state of the corresponding channel in the second table to release. When,
When the first table is searched and the use state of the channel information detected in the second table is confirmed, if communication is not in progress, the information is rewritten to new information and the channel use state of the second table is connected. And a means for artificially reconnecting channels by setting the inside.
[0007]
In addition to this configuration, when the first table is searched and the use state of the channel information detected in the second table is confirmed, if communication is in progress, a request for changing the channel information is failed or rejected. It may be further provided with a means for responding,
When the first table is searched and the use state of the channel information detected in the second table is confirmed, if communication is in progress, no response is made to the request to change the channel information, and a retry is made after a predetermined time. In addition, it may be further provided with means for notifying success when succeeding.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In this embodiment, the ATM communication network is the already described ATM communication network of FIG. 1, and an example of the configuration of the ATM communication devices T11, T12, and T13 is shown in FIG.
In FIG. 2, reference numeral 21 denotes an ATM physical layer interface, which converts an optical signal from the ATM network N01 into an electrical signal, synchronizes the processing for extracting the clock and data and the data to be transmitted with the clock from the ATM network N01. A process of converting a signal into an optical signal and a process of generating an alternative clock when the clock cannot be extracted are performed.
Reference numeral 22 denotes an ATM communication control circuit, for example, an ATM communication LSI, which performs packet generation / decomposition. That is, the ATM communication LSI 22 detects a cell from information input from the ATM network N01, assembles it into a packet and receives it in the buffer, or discards the cell, and disassembles the packet in the buffer into a cell to separate the ATM network N01. Is output.
A shared memory 24 holds a first table used by the ATM communication LSI 22 for communication control. A processor 27 controls the ATM communication apparatus, and executes not only a program for controlling the ATM communication apparatus but also a higher-level application program. A host memory 28 holds a second table used for control by the processor 27 and a packet buffer used by the ATM communication LSI 22.
[0009]
A bus 25 connects the ATM communication LSI 22 and the processor 27. Reference numeral 23 denotes a control circuit for the bus 25 for connecting the processor 27 and the ATM communication LSI 22. A control circuit 26 of the bus 25 for connecting the processor 27 and the ATM communication LSI 22 also manages access to the host memory 28 that holds the packet buffer.
FIG. 3 is a configuration example of a second table that holds channel information managed by the processor 27 that controls the ATM communication devices T11, T12, and T13. FIG. 4 holds channel information managed by the ATM communication LSI 22. It is a structural example of a 1st table.
In the second table shown in FIG. 3, the following items are provided for each channel. The “channel usage status” item holds information indicating whether it is unused, connected, or released.
Here, “unused” indicates that the channel has never been used after the ATM communication devices T11, T12, and T13 are activated. “Connected” means that data is currently being transmitted using the channel and communication is in progress. “Released” indicates that the channel has been used once, but no data is currently flowing through the channel, that is, communication is not in progress.
[0010]
The item “VPI / VCI or ATM address” holds the value of the VPI / VCI or ATM address used by the channel. The item “pointer to the table managed by the LSI” holds an address to the corresponding item in the table managed by the ATM communication LSI 22 or a search number. In the “channel information” item, different information is stored for each channel such as the AAL type used by the packet, the address of the buffer holding the packet data, the communication speed, and the speed management method. Note that the second table has a plurality of pieces of information for each channel.
In the first table shown in FIG. 4, the following items are provided for each channel. Information indicating whether the ATM communication LSI 22 is communicating with the VPI / VCI packet or not is reflected in the item “current usage”. Since the ATM communication LSI 22 may still be communicating even after the processor 27 has instructed to open the channel, even if the second table has already been released, the first time is required until a predetermined time elapses. One table may be in communication.
In the item “channel communication speed”, the communication speed of the channel or a parameter obtained from the communication speed and information indicating the control method of the communication speed are held. In the “channel information other than communication speed” item, channel-specific information such as AAL type and ATM header information is held. The item “buffer information etc.” holds information such as the address and length of the buffer where the packet data exists and the length of the packet to be communicated. Note that the first table has a plurality of pieces of information for each channel.
[0011]
Next, this operation will be described.
FIG. 5 shows an example of a procedure for connecting a channel, and FIG. 6 shows an example of a procedure for releasing a channel.
First, when connecting channels, as shown in FIG. 5, channel connection processing is started by a command from a higher-level application or by generation of a connection request by self-detection of the device (step S51). The processor 27 searches the second table based on the obtained VPI / VCI (step S52). Then, it is determined whether or not there is an item that matches the VPI / VCI in the item “VPI / VCI or ATM address” of the second table (step S53). If there is no match with the VPI / VCI, whether or not there is a vacancy in the table, that is, an unused channel, is searched by searching for “channel usage status” in the second table. It is determined whether or not there is (step S54). If there is an unused item in the “channel usage status” item of the second table, each item of the unused channel portion of the second table and the first table is set to the given information. Thus, it is newly created (set) (step S55). If it is started by a request from the host application, the completion of connection is notified as a termination process (step S56). If it is determined whether there is an unused channel (step S54), if there is no unused channel, a connection failure (or rejection) is notified as an end process (step S57).
[0012]
On the other hand, in the determination of whether there is a match with the VPI / VCI (step S53), if there is a match, the VPI is checked by looking at the item “channel usage status” in the second table. It is determined whether the / VCI channel has been released (step S58). If released, the current usage status of the first table managed by the LSI of the same channel is confirmed (step S59). Then, it is determined whether or not the current usage status of the item is in communication (step S60). If the communication is in progress, if the request is started from a higher-level application, connection failure ( (Or rejection) is notified (step S61). Alternatively, processing is performed so as to try again after a predetermined time. That is, a retry is made at the next event by a timer or the like, and if successful, the success is notified.
If the current usage status is not in communication, only the information that is different from the set information is set again in the given information (step S62). If it is started by a request from a higher-level application, connection completion is notified as termination processing (step S63).
If it is determined whether the VPI / VCI channel has been released (step S58), if it has not been released, that is, if it has been connected, if it is started by a request from a higher-level application, it is connected as an end process. The failure is notified (step S64).
[0013]
When releasing a channel, as shown in FIG. 6, the release processing of the channel is started by the generation of a release request such as a command from a higher-order application (step S65). In the release process, only the channel usage status in the second table is rewritten to released, and other information is not changed (step S66). Then, the release completion is notified as an end process (step S67).
With this procedure, channel information can be reused and release processing can be performed without interrupting the communication even during communication.
Now, in the ATM communication apparatus operating in this way, when changing the bandwidth of the PVC channel being communicated, that is, when changing communication information such as a change in communication speed, the communication is performed according to the procedure shown in FIG. The corresponding channel is released in a pseudo manner, and then the channel is reconnected in a pseudo manner by the procedure shown in FIG.
For example, when a request for changing communication information such as a transmission speed of transmission data or a management method thereof is received in communication using a PVC channel, channel information managed by the processor 27 for the corresponding channel based on this request is held. If the second table is searched and detected, the channel usage state of the table is set to release, and the channel is released in a pseudo manner.
[0014]
Next, the first table holding the channel information managed by the ATM communication LSI 22 is searched, the channel usage status is confirmed, rewritten with new information when not in communication, and the channel usage status in the second table. The channel is reconnected in a pseudo manner by setting to.
If the channel usage status detected in the first table is in communication, a failure (or rejection) response is made.
If the channel usage status detected in the first table is in communication, the response to the request to change the communication information is not responded, and a retry is made with the next event by a timer or the like, and it succeeds. It is good also as notifying that it succeeded.
As described above, according to this embodiment, in a PVC channel for which communication information such as VPI / VCI and communication speed is determined in advance, information that can be changed such as communication speed within the range of the communication information is transmitted. It can be changed quickly by changing only the ATM communication device on the side.
Therefore, even in a communication application such as image transmission involving a change in communication information, communication information can be changed and communication can be continued without causing image disturbance.
[0015]
Note that it is also possible to use an ATM communication LSI in which the functions of the ATM communication LSI 22 and the control circuit 23 are combined in the configuration of FIG.
Further, in the case of a communication control unit in a large system, the processor 27 and the bus 25 may be configured to have a communication function with a higher-order control device outside the ATM communication device having this configuration. However, a bus different from the bus 25 may be used. Further, the processor 27 itself may generate a connection request or a change request.
[0016]
【The invention's effect】
As described above, according to the bandwidth change method of the PVC channel in the ATM communication network of the present invention, the communication information can be changed without causing image disturbance even in communication applications such as image transmission that involves changing the communication information. Communication can be continued.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of an ATM communication network.
FIG. 2 is a block diagram showing a configuration of a main part of the ATM communication apparatus in the embodiment of the present invention.
FIG. 3 is a diagram showing a configuration example of a second table holding channel information managed by a processor in the embodiment.
FIG. 4 is a diagram showing a configuration example of a first table that holds channel information managed by the ATM communication LSI in the embodiment.
FIG. 5 is a flowchart showing a procedure for connecting channels in the embodiment.
FIG. 6 is a flowchart showing a procedure for releasing a channel in the embodiment;
[Explanation of symbols]
T11, T12, T13 ... ATM communication devices Sw11, Sw12, Sw13 ... Relay device N01 ... ATM network 21 ... ATM physical layer interface 22 ... ATM communication LSI
23 ... Control circuit 24 ... Shared memory 25 ... Bus 26 ... Control circuit 27 ... Processor 28 ... Host memory

Claims (6)

In an ATM communication network in which a plurality of ATM communication devices communicate with each other via a PVC channel,
A processor for controlling the ATM communication device;
ATM communication control means that can be controlled from this processor;
A shared memory accessible by both the processor and the ATM communication control means;
A first table managed by the ATM communication control means, holding channel information, and arranged in a shared memory;
A second table managed by the processor and holding channel information;
Means for releasing a channel in a pseudo manner based on the information in the second table;
A PVC channel in an ATM communication network comprising means for updating the information in the first and second tables based on the information in the first and second tables and reconnecting the channels in a pseudo manner Bandwidth change method. 2. The PVC channel in the ATM communication network according to claim 1, wherein the first table is a table holding at least predetermined channel information including information indicating whether or not each channel is communicating. Bandwidth change method. 2. The table according to claim 1, wherein the second table is a table that holds predetermined channel information including at least information indicating whether each channel is unused, connected, or released. For changing the bandwidth of a PVC channel in an ATM communication network. In an ATM communication network in which a plurality of ATM communication devices communicate with each other via a PVC channel,
A processor for controlling the ATM communication device;
ATM communication control means that can be controlled from this processor;
A shared memory accessible by both the processor and the ATM communication control means;
A first table managed by the ATM communication control means, holding channel information, and arranged in a shared memory;
A second table managed by the processor and holding channel information;
Means for accepting a request to change channel information;
Based on the request received by this means, the corresponding channel is searched from the second table, and if detected, the channel usage state of the second table is set to release to release the channel in a pseudo manner. Means to do,
When the use state of the channel information detected in the second table is confirmed by searching the first table, if it is not in communication, it is rewritten with new information, and the channel use state of the second table. Means for changing the bandwidth of a PVC channel in an ATM communication network, characterized by comprising: means for performing a reconnection of a channel in a pseudo manner by setting the connection to the connected state. Means for performing a response of failure or refusal to a request to change channel information when communication is in progress when searching the first table and confirming the use state of the channel information detected in the second table 5. The method for changing the bandwidth of a PVC channel in an ATM communication network according to claim 4, further comprising: When the first table is searched and the use state of the channel information detected in the second table is confirmed, if communication is in progress, no response is made to the request to change the channel information, and a predetermined time later 5. The method for changing the bandwidth of a PVC channel in an ATM communication network according to claim 4, further comprising means for retrying and notifying success if successful.

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