JP2002033739A - Communication control system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assign a resource to a node, having reserved a resource prior to re-build-up of a network with priority, even after re-built up of the network has been conducted. SOLUTION: A resource manager stores an isochronous resource map 207, which denotes a resource assigned to a network node. On the occurrence of a bus reset, an item corresponding to a node after bus reset is retrieved from the isochronous resource map before the occurrence of bus reset, and when the item is found, the retrieved resource is assigned as a resource after the bus reset. When a resource request is received from the node after that, the assigned resource is used for the node, and when no resource request is received, the resource is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, IEEE
The present invention relates to a communication control device and method for controlling a communication network or the like using a 1394 serial bus.
The present invention relates to a communication control apparatus and method capable of allocating resources of a communication network to devices on the communication network in the same state as before the reconfiguration of the communication network when the communication network is reconfigured.

[0002]

2. Description of the Related Art In recent years, in computer systems,
IEEE Std 1394-1995 High Performance S
erial Bus (hereinafter referred to as IEEE1394), Universal
New bus standards such as Serial Bus (hereinafter, referred to as USB) are being adopted. These communication methods support a transfer method called isochronous transfer, which guarantees a data transfer amount within a unit time. The isochronous transfer is used for transferring data such as audio and moving images that need to guarantee a transfer amount of data per unit time.

A description will be given by taking IEEE1394 as an example.
FIG. 1 is a diagram of six nodes connected to the IEEE 1394 bus. Node_ID which is an identifier is automatically assigned to each node. In general, node_ID
Is the root node and arbitrates for the bus. Therefore, in FIG. 1, the node 101 with node_ID = 5 is the root node.

A device that has become a root node, if supported, becomes an isochronous resource manager and is called a cycle start packet for performing cycle synchronization on the IEEE 1394 bus.
A packet having a period of μs ± 12.5 ns (8 kHz ± 100 ppm) is transmitted. The nodes of the bus are synchronized by the cycle start packet, and a period of a maximum of 100 μs from the cycle start is called an isochronous period. A node using the isochronous transmission mode can divide and use the isochronous period as needed. In FIG. 1, the node 101 with node_ID = 5 is a root node also serving as an isochronous resource manager.

[0005] The isochronous resource manager has a function of managing an isochronous period in addition to the transmission of the cycle start packet. For this purpose, the isochronous manager uses BANDWIDTH_AVA.
ILABLE register and CHANNEL_AVAILA
The channel and the bandwidth allocated to the node requesting the isochronous transfer are managed by using a value called an isochronous resource that indicates an available resource for the isochronous transfer registered in two registers called a BLE register.

[0006] The nodes connected to IEEE 1394 are:
IEEE1212 Control and Status Register Archit
It is mapped to a 64-bit memory space defined by ecture (CSR). In CSR, the highest 10 bits (63 to 54 bits) of a 64-bit address indicate a bus. The subsequent 6 bits (53 to 48 bits) are nodes, and correspond to node_ID. Then 2
1 bit (47 to 27 bits) is the register space, 27 bits
It (26-0 bits) is defined as a register address.

[0007] BANDWIDTH_AVAILABLE
The register has the address FFFFFFXXFFFFF000 of the node that has become the isochronous resource manager.
0220H (XX changes according to the node_ID of the node, and is C1 when the node_ID is 1, C5 because the node_ID is 5 in FIG. 1, and H is a hexadecimal number). 13b
It is a register of "it", and its initial value is 1333H. One unit of this value corresponds to 20 ns, which is about 100 μs at 1333H. This value indicates the time of the currently valid isochronous period. That is, the initial value of the isochronous period is about 100 μs.

The CHANNEL_AVAILABLE register is a 64-bit register mapped from FFFFFFXXFFFFF0000224H, and the value of each register represents one channel.
Thus, the isochronous period is managed by being divided into a maximum of 64 channels.

A node connected to the IEEE 1394 bus and a node that wishes to perform isochronous transfer is a Lo.
BANDWIDTH_AVAILABLE of the node that is the isochronous resource manager by the packet sequence defined as ok Transaction
It is necessary to access the E register and the CHANNEL_AVAILABLE register to refer to the free bandwidth and the free channel, and to secure the necessary bandwidth and channel, that is, the isochronous resource, from among them. An isochronous resource is a finite resource, and not all nodes can be used.

In IEEE 1394, when a new node is connected or a connected node is disconnected and the network configuration is changed, the bus is reset by a bus reset request from the node that detects the change. Then, reconfiguration of the network such as reassignment of the node_ID is performed.

After the reconfiguration of the network, the node that has previously become the root node cannot always become the root node again. In that case, the node that was previously the root declares itself to be the root again and reconstructs the network again. Similarly, the node that becomes the isochronous resource manager (generally, the root node) controls the reconfiguration of the network so that the node itself becomes the isochronous resource manager again.

A node that has secured an isochronous resource before the reconfiguration of the network is to be preferentially assigned the isochronous resource. The control method is that the interval from the reconfiguration of the network to the issue of the Look Transaction to secure the isochronous resources is different between the node that previously secured the isochronous resource and the node that did not secure the isochronous resource. It is recommended by the standard to achieve this. Specifically, the node that previously secured the isochronous resource is
It is said that a request for securing resources can be made after 5 ms, and that a node that has not previously secured isochronous resources can request resources after 1000 ms after network reconfiguration.

[0013]

However, in practice, the node that has secured the isochronous resource before the reconfiguration of the network cannot always preferentially secure the resource. This is because each node connected to the IEEE 1394 bus, after reconstructing the network,
First, in order to recognize the configuration of the operation bus, the CS of another node is used.
This is to read R. After the reconfiguration of the network, there is a high possibility that a value different from that before the reconfiguration of the network is assigned as the value of the node identifier node_ID of the node. Therefore, each node transmits a read request to the memory space defined as the Configuration ROM in the CSR information of all the nodes connected to the bus again in order to resume data transfer between the nodes, and from the response, Identify the node and resume data transfer.

According to this procedure, as the number of nodes increases, the number of read request and response packet transfers increases, and the operation of re-securing isochronous resources is performed within the time recommended by the standard after the reconfiguration of the network. It becomes difficult. Therefore, especially in a large-scale network, even if the node has previously secured the isochronous resource, it may take 625 ms after reconstructing the network.
It may not be possible to request the securing of the resource later, and a situation may arise in which the node that has not secured the isochronous resource previously competes for the resource.

The present invention has been made in view of the above conventional example, and even if a network is reconfigured, a node which has secured resources prior to the network reconfiguration is given priority over the previous resource. It is an object of the present invention to provide a communication control device and method capable of assigning a communication control.
In particular, even in a large-scale network having a large number of nodes, a communication control apparatus and method capable of preferentially allocating previous resources to a node that has secured resources before restructuring the network. provide.

[0016]

In order to achieve the above object, the present invention has the following arrangement.

Storage means for storing resource information indicating a use state of resources of a communication network formed by connecting a plurality of nodes; and, when the communication network is reconstructed, reconstructing based on the resource information before reconstructing. A communication control device comprising: resource information generating means for generating later resource information; and allocating means for reallocating resources based on the resource information generated by the resource information generating means.

Preferably, if the node to which the resource has been assigned before the rebuilding is connected after the rebuilding, the resource information generating means preferably uses the resource information before the rebuilding based on the resource information before the rebuilding. Allocate resources that have been allocated to.

Preferably, when a resource request is sent from a node to which a resource is assigned in the resource information generated by the resource information generating means, the allocating means permits the resource request according to the resource information. .

Preferably, when the resource requested by the resource request is different from the resource included in the resource information and allocated to the node, the allocating means preferably transmits the requested resource. Is assigned with priority.

[0021] Preferably, when no resource request is sent from a node to which a resource is assigned in the resource information generated by the resource information generating means, the allocating means includes a resource for the node in the resource information. Unassign.

Preferably, one of the resources is communication channel information.

[0023] Also preferably, one of said resources is a communication bandwidth.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] The details of a network according to an embodiment of the present invention will be described below with reference to the drawings. IEEE1 as the interface to be used
394 is used.

As shown in FIG. 1, devices connected to a bus constructed by the IEEE 1394 interface include three types of nodes: root, branch, and leaf. The root node is a node 10 that performs arbitration and management of the bus.
It is one. The branch nodes are nodes 102a and 102b that are connected to a plurality of nodes and are not root nodes.
It is. The leaf nodes are nodes 103a, 103b, and 103c that are connected to only one node.

IEEE 1394 supports a transfer method called isochronous transfer, which guarantees a data transfer amount per unit time. The isochronous transfer is to be performed in accordance with the management of a management node called an isochronous resource manager. Generally, the root node 101 provides the function of the isochronous resource manager. However, if the root node 101 does not support the function of the isochronous resource manager, the root node 101 sets the isochronous resource manager among other nodes on the IEEE 1394. Is selected to provide the function of the isochronous resource manager.
Here, description will be made on the assumption that the root node has the function of the isochronous resource manager.

The root node 101 having the function of the isochronous resource manager sends a special packet called a cycle start packet for 125 μs ± for the cycle synchronization of all the nodes connected to the bus.
Transmission is performed at a period of 25 ns.

In the IEEE 1394 bus, a period of 125 μs separated by a cycle start packet is called a frame, and a period from the beginning of the frame to a maximum of 100 μs is called an isochronous period. The length of the isochronous period is determined by the sum of the time required by the nodes performing the isochronous transfer among the nodes connected to the IEEE 1394 bus. The sum of the times is managed by the isochronous resource manager so as not to exceed 100 μs. A node that performs isochronous transfer must acquire a period of use within the range of an unused isochronous period from the isochronous resource manager. In addition, a maximum of 64 channels can be set in the isochronous period, and a node performing isochronous transfer must acquire an unused channel from the isochronous resource manager.

That is, the isochronous transfer on the IEEE 1394 bus is realized by the node sharing two resources of an isochronous period of up to 100 μs and 64 channels by the isochronous resource manager. In the IEEE1394 bus standard, the former is BANDWIDTH_AVAILABLE.
E register, CHANNEL_AVAILABLE for the latter
It is defined to be managed by the E register.

<Node Configuration> FIG. 2 shows the basic configuration of a node. The CPU 201 is a control unit that controls the entire node. An OS (operating system) and application programs that control the CPU 201 are stored in the memory unit 202. The memory unit 202 is a ROM,
It is composed of a semiconductor memory such as a RAM and a large-capacity memory device such as an HDD. RAM in the memory 202
And the like, a later-described isochronous resource map 207 is stored.

The PHY 203 is a physical layer that controls transmission and reception of packets, bus arbitration, and encoding / decoding of packet data, as defined by IEEE 1394. Also, P
The HY 203 performs a bus configuration operation when the bus is initialized, and at that time, a unique n
It has a function of automatically transmitting a SelfID packet for assigning a mode_ID. Link 204 is C
The function of supplying a packet data transmission request by the application program stored in the PU 201 and the memory unit 202 to the PHY 203, and conversely, the notification of packet data reception and the received data from the externally connected node Has the function of passing to

The display unit 205 comprises a CRT monitor for displaying messages and images according to the requests of the application programs in the CPU 201 and the memory unit 202.

The input unit 206 comprises an input device such as a keyboard and a mouse for a user to give an instruction to the system. The instructions from the input unit 206
The application program 201 and the application program in the memory unit 202 are notified, and control is performed according to the instruction.

The above configuration is an example of a general computer system, and is different from the configuration with peripheral devices such as a printer and a scanner. In peripheral devices such as printers and scanners, the display unit 205 is not a CRT monitor but an LED.
And small liquid crystal display devices are used. Input unit 206
For example, a switch is used. Although not shown in the figure, a functional block having a configuration necessary to realize a function unique to the peripheral device is provided.

<Structure of Isochronous Resource Map>
The node having the isochronous resource manager function according to the present invention has a program operating as an isochronous resource manager and an area of an isochronous resource map 207 for managing the isochronous resources in the memory unit 202. The isochronous resource map 207 includes a BANDWID as shown in FIG.
TH_AVAILABLE register, CHANNEL_
Memory area ba corresponding to AVAILABLE register
nd_ava, Chan_ava, an identifier node_ID defined at the time of bus reset for each node using the isochronous resource, an identifier unique_ID unique to the node and unchanged, a bandwidth used_band in the used isochronous period, and a used channel used_chan. , Next_ptr to the next node are stored.

The register band_ava is internally b
It is mapped to the address indicated by “andwidth_ptr”, but is transmitted from other nodes to the BA in the CSR space.
Address FFF of NDWIDTH_AVAILABLE
FFFXXFFFFFF0000220H (XX changes according to the node_ID of the node, and node_ID is 1
, C1 when node_ID is 5
5). Data size is 13
bit, and the initial value is 1333H. This value indicates that the isochronous period is not used. 0000H indicates that there is no vacancy in the isochronous period.

Similarly, the register chan_ava is:
Channel_ptr is mapped to the address indicated by channel_ptr, but from other nodes CHANNEL_A
VAILABLE address FFFFFFXXFFFF
Appears to be at F0000240H. The data size is 64 bits, and the initial value is FFFFFFFFH. Each bit corresponds to a channel, and 1 indicates unused and 0 indicates used.

The node_ID is an identifier of a node using the isochronous resource.
There is 0001H is 0 node, 0005H is is stored as the value of ID _n when node_ID is 5. The unique_ID stores an identifier of a node which is a value unique to each node. UNIQUE_ID is CSR
48-bit information in the space FFFFFFXXFFFFF000008H, which is read from each node when the bus is reconstructed.

Used_band is the time of the isochronous period used by the node, the time that one node can secure at a time is about 40 μs, and the value is 95 BH.

Used_chan indicates the channel used by the node. For example, FFFFFFFE
H indicates that channel 0 is used.

Next_ptr stores a pointer for storing a resource use status of a node using the next isochronous resource. This next_ptr
Is NULL, it indicates that there is no more node using the isochronous resource.

FIG. 3 shows a state of a general address space in which N nodes use isochronous resources. value of band_ava total_band
Is calculated as follows: total_band = 1333H-bandwidth ₀ -bandwidth ₁ -... -bandwidth _N ... (1) The value of Band_ava indicates an unused isochronous period.

The value of Chan_ava used_C
han is calculated as used_chan = Channel ₀ {channel ₁ } ... ^ channel _N ... (2) (where ＾ represents an exclusive OR). Each bit corresponds to a channel, and 0 indicates that the bit is used and 1 indicates that the bit is not used.

The isochronous resource map has the above configuration. The node having the function of the isochronous resource manager in the present embodiment stores the previous isochronous resource map and creates a new isochronous resource map based on the previous isochronous resource map when the network is reconfigured by the bus reset. That is, two isochronous resource maps are stored. The former is a pointer Previous_Iso_res
source, the latter being the pointer Curre
Referenced by nt_Iso_resource.

<Procedure at Bus Reset> IEEE 139
In the 4-bus system, when a node is newly connected to the bus, when the node is disconnected from the bus, or when a bus reset request is issued from the connected node, the network is reconstructed. At this time, the node that provided the function of the isochronous resource manager before the bus reset controls the bus so as to provide the function of the isochronous resource manager again. Here, the description is continued on the assumption that the function of the isochronous resource manager can be provided again after the bus reset.

This node functioning as an isochronous resource manager (hereinafter, also simply referred to as a manager node) resets the isochronous resource according to the flow shown in FIG. After the bus reset, step 60
1, the Current_Iso_resource that has been used to refer to the isochronous resource map until now
e_pointer value is set to Previous_Iso_reso
source pointer value. Thus, the isochronous resource map before the bus reset indicates the pointer P
The value can be referred to by the "revision_Iso_resource".

At step 602, as a bus configuration operation, the value of the configuration ROM stored in the CSR of each node is read, and an identifier unique_ID unique to each node is obtained.

At step 603, a correspondence table is created between the identifier node_ID reassigned to each node after the bus reset and the unique_ID read at step 602. The node_ID is an identification number on the IEEE 1394 bus that is automatically assigned after a bus reset, and is assigned in order from 0, with the root node having the largest number. The unique_ID is a value unique to the node, and does not change even when the bus is reset.

At step 604, a management area for a new isochronous resource is secured, and
Retake the Iso_resource pointer.

In step 605, the current IEEE 139
The number of nodes connected on the four buses is set in a variable n. The number n of nodes can be obtained by setting node_ID + 1 of the root node or by counting the number of self_ID packets broadcast from all nodes after the bus reset.

In step 606, it is determined whether the number n of nodes is not zero. If n is not 0, step 607
Proceed to.

In step 607, node_ID is set to n
Of the node prior to the bus reset using the isochronous resource.
A search is made from an isochronous resource map that can be referenced by _Iso_resource. At this time, node
Since the value of _ID may be different before and after the bus reset, the unique_ID of each node is set to Pre
The search is sequentially performed from the information of the isochronous resources stored in the "view_Iso_resource". u
In step 608, it is determined whether there is resource information having the same unique_ID.

If there is an isochronous resource used before the bus reset in step 608, the process proceeds to step 609, where node_I in the resource information is set.
D is changed to the value of the current node_ID of the node and added to the isochronous resource map referenced by Current_Iso_resource. In step 610, an area for storing information on the isochronous resource is secured next.

Next, at step 611, the value of the variable n is decremented by 1, and the routine proceeds to step 606, where the same operation is repeated.

A node that did not use the isochronous resource before the bus reset or a node that was not connected before the bus reset did not use the isochronous resource, and therefore, step 608. Then match unique_I
D is not found. Therefore, Current_Iso
No resource information is added to _resource.

When the search of the usage status of the isochronous resources before the reconfiguration of the bus is completed for all the nodes, it is determined in step 606 that n is 0. In that case, in step 612, Current_Is
next of the storage area of the last node of o_resource
A NULL pointer is inserted into t_ptr, and step 6
At 10, the area reserved for the next node is released, and the process ends.

When the processing of FIG. 6 is completed, the values of the BANDWIDTH_AVAILABLE register and the CHANNEL_AVAILABLE register are calculated again and stored based on the resource information allocated to each node by the processing.

When this series of flows is completed, Curr
In ent_Iso_resource, an isochronous resource map in which an isochronous resource is allocated to a node that has used the isochronous resource before the network reconfiguration can be created.

In this flow, since the isochronous resources used by the node removed from the bus after the reconfiguration of the network are not secured, the isochronous resources can be effectively used.

<Assignment of Isochronous Transfer Channel> Next, the operation when a channel is requested will be described. I
In order for a node connected to the IEEE 1394 bus to perform isochronous transfer, an isochronous resource must be secured for a node providing the function of an isochronous resource manager. To do this, the node specifies the required channel number and bandwidth value
Requests resources from the node that is the isochronous resource manager by the Look transaction. The isochronous resource manager that has requested the resource performs a channel assignment operation along the flow shown in FIG.

Step 401 is to look up the channel request Look tra.
The nsaction is waiting to be received. Look for a channel request from a node requesting a channel (hereinafter referred to as node i)
When a transaction is received, the process proceeds to step 402.

In step 402, the node i that has requested the channel has already performed Curre by the procedure shown in FIG.
A search is made as to whether an isochronous resource is secured in nt_Iso_resource. As a result, Cur
If the channel resource is assigned to the rent_Iso_resource, the process proceeds to step 404.

In step 404, the request channel number specified by the Look transaction and the Current_Is
channel stored in o_resource
_i , that is, the channel number assigned to the node i, to determine whether the channel has changed. Equation (2) is used as the comparison equation. As a result, if they are the same, that is, if there is no change, the process proceeds to step 407 to return a response for notifying that the reservation of the requested channel has been accepted. If not, step 405
To check whether the requested channel is being used by another node and whether it is free. If it has not been used, the process proceeds to step 406, and if it has been used, the process proceeds to step 408.

At step 406, a new channel is secured.
And the value of the CHANNEL_AVAILABLE register
Is updated, and Current_Iso_resource is further updated.
ch of the resource information of the node i currently requesting ce
value of an_ava channel_iLook transaction
Change to the value corresponding to the channel number specified in
Proceed to step 407. At this time, the value of used_band
bandwidth _iValue is left as it is. Sand
That is, the requested resource over the allocated resource
Is assigned to the requesting node with priority.

At step 408, a response for notifying that the channel reservation has failed because the requested channel is being used by another node is returned.

If it is determined in step 403 that the source node of the channel request is a node for which the isochronous resource has not been secured before the reconfiguration of the network, the process proceeds to step 409, in which the requested channel is determined. Whether it is used is Current_Iso_
Check with the information of resource. As a result, if the requested channel has not been used, the process proceeds to step 406. If the requested channel has been used, the process proceeds to step 40.
Proceed to 8.

According to the above procedure, the same channel as the previous one can be preferentially allocated to the node that has secured the isochronous resource before the bus reset. When a certain node requests a channel different from the channel allocated in the procedure shown in FIG. 6 to the node, and the manager node fails to secure the channel, a predetermined number of retries are allowed. , The reserved channel may be released.

<Assignment of Isochronous Transfer Bandwidth> The node that has secured the channel continuously transmits a Look transaction to secure the bandwidth. The operation of allocating the bandwidth in this case will be described. At that time, the isochronous resource manager performs a channel assignment operation along the flow shown in FIG.

In step 501, the bandwidth request Look
Waiting for transaction. Lo for bandwidth request
If an ok transaction is received, the process proceeds to step 502.

In step 502, the node i which has requested the bandwidth already has the Current_Iso_resource
A search is made as to whether an isochronous resource is secured in ce. As a result, Current_Iso_reso
If the resource of the bandwidth is allocated to the resource, the process proceeds to step 504.

[0071] To notify willing to accepted to secure request bandwidth to step 507 if the same is compared with the bandwidth _i stored in the value and Current_Iso_resource request bandwidth specified in the Look transaction Is returned. If they are not the same, it is checked in step 505 whether the updated bandwidth has exceeded the maximum value of 100 μs of the isochronous period when updated to the required bandwidth. The equation is: 0 ≦ total-band + bandwidth _N −the required value ... (3) If this expression is satisfied, the process proceeds to step 506; otherwise, the process proceeds to step 508.

In step 506, the value on the right side of the equation (3) is set to BAND as the remaining time of the new isochronous period.
WIDTH_AVAILABLE is written to the value of the register. Further, the value of the bandwidthwidth _N of the resource information of the Current_Iso_resource in which the previously secured channel information is stored is changed to the requested value, and the process proceeds to step 507.

In step 507, a response for notifying that the requested channel width has been secured is transmitted.

In step 508, since the requested bandwidth exceeds the remaining isochronous period, a response for notifying that the securing of the bandwidth has failed is returned.

If it is determined in step 503 that the node has not secured the isochronous resource before the reconfiguration of the network, the flow advances to step 509 to determine the isochronous period in which the requested bandwidth remains. Current_Iso_ is not exceeded
Check with the information of resource. As a result, if the required bandwidth has not been exceeded, step 5
The process proceeds to step 06, and if it has exceeded, the process proceeds to step 508.

According to the above procedure, it is possible to preferentially allocate the same bandwidth to the node that has secured the isochronous resource before the bus reset.

As described above, IEEE 139
Isochronous resource information before the bus reset after the network has been reconfigured because a new node has been connected or disconnected on the 4 bus, or a bus reset request has been issued from the connected node. , It is possible to preferentially allocate the isochronous resource to the node that has secured the isochronous resource before the bus reset.

In the description of the present embodiment, the I bus
Although EEE1394 has been described as an example, the present invention is not particularly limited to this, and is applicable to a communication network that manages resources and performs communication control.

[Second Embodiment] In the first embodiment, it is possible to preferentially allocate the isochronous resources of the channel and the bandwidth to the node which has secured the isochronous resources before the bus reset.
If there is a node that no longer requires the isochronous resource as before the bus reset, the resource is secured even though the node does not use it.

Therefore, if there is no request for an isochronous resource from a node to which a resource is allocated according to the procedure of FIG. 6 after a predetermined time, for example, 10 s after the bus reset, it is determined that the node does not use the isochronous resource. And Current_Iso_
The isochronous resource information of the node in the resource is deleted, and the result of updating the isochronous resource after the deletion is set to BANDWIDTH_AVAILABLE.
This is reflected in the register and the CHANNEL_AVAILABLE register.

Thus, the isochronous resources can be used effectively.

[0082]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Further, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and a computer (a computer) of the system or apparatus Alternatively, this can be achieved by a CPU or an MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. By executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. This also includes a case where some or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.

Further, after the program code read from the storage medium is written into the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. This also includes the case where the CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium includes the storage medium described above (shown in FIGS. 4 to 6).
The program code corresponding to the flowchart is stored.

[0086]

As described above, according to the present invention,
Even after the network is reconfigured, the resources can be preferentially allocated to the nodes that have secured the resources before the network is reconfigured. In particular,
Even in a large-scale network having a large number of nodes, it is possible to preferentially allocate the previous resources to the nodes that have secured the resources before reconstructing the network.

[Brief description of the drawings]

FIG. 1 is a diagram of an IEEE 1394 bus topology.

FIG. 2 is a schematic block diagram of an IEEE 1394 node.

FIG. 3 is a diagram of an isochronous resource map.

FIG. 4 is a flowchart of a channel assignment flow.

FIG. 5 is a flowchart of a bandwidth allocation flow.

FIG. 6 is a flowchart of an isochronous resource reconstruction flow.

[Explanation of symbols]

 201 CPU 202 Memory unit 203 IEEE 1394 PHY 204 IEEE 1394 Link 205 Display unit 206 Input unit 207 Isochronous resource map

Claims (15)

[Claims] 1. A storage means for storing resource information indicating a use state of a resource of a communication network formed by connecting a plurality of nodes, and when the communication network is reconstructed, based on the resource information before the reconstruction. A communication control device comprising: resource information generating means for generating reconstructed resource information; and allocating means for reallocating resources based on the resource information generated by the resource information generating means. 2. The method according to claim 1, wherein the resource information generating unit allocates the resource before the reconstruction based on the resource information before the reconstruction if the node to which the resource was allocated before the reconstruction is connected after the reconstruction. The communication control device according to claim 1, wherein the allocated resources are allocated. 3. When the resource request is transmitted from a node to which a resource is allocated in the resource information generated by the resource information generating means, the allocating means permits the resource request according to the resource information. The communication control device according to claim 1 or 2, wherein: 4. When the resource requested by the resource request is different from the resource included in the resource information and allocated to the node, the allocating unit gives priority to the requested resource. The communication control device according to claim 3, wherein the communication control device allocates the communication control information. 5. The resource allocating unit according to claim 2, wherein the resource information generated by the resource information generating unit does not receive a resource request from a node to which the resource has been allocated. 3. The communication control device according to claim 1, wherein 6. The communication control device according to claim 1, wherein one of the resources is communication channel information. 7. The communication control device according to claim 1, wherein one of the resources is a communication bandwidth. 8. A resource information generating step of, when a communication network is reconfigured, generating resource information after reconfiguration based on resource information indicating a use state of resources of the communication network before reconfiguration; An allocation step of re-allocating resources based on the resource information generated by the information generating means. 9. The resource information generating step, if the node to which the resource has been allocated before the reconfiguration is connected after the reconfiguration, allocates the resource before the reconfiguration based on the resource information before the reconfiguration. The communication control method according to claim 8, wherein the allocated resources are allocated. 10. The allocating step, when a resource request is transmitted from a node to which a resource is allocated in the resource information generated in the resource information generating step, permitting the resource request according to the resource information. The communication control method according to claim 8 or 9, wherein: 11. The assigning step, when the resource requested by the resource request and the resource included in the resource information and assigned to the node are different, gives priority to the requested resource. The communication control method according to claim 10, wherein the assignment is performed. 12. The allocating step includes allocating a resource to the node in the resource information when no resource request is sent from a node to which the resource is allocated in the resource information generated in the resource information generating step. 10. The communication control method according to claim 8, wherein the communication control method is canceled. 13. The communication control method according to claim 8, wherein one of the resources is communication channel information. 14. The communication control method according to claim 8, wherein one of the resources is a communication bandwidth. 15. A computer-readable storage medium for storing a program for controlling a communication network by a computer, wherein the program stores, when the communication network is reconstructed, resources of the communication network before the reconstruction. A code of a resource information generating step of generating resource information after restructuring based on resource information indicating a use state, and a code of an allocating step of reallocating resources based on the resource information generated by the resource information generating means. And a computer-readable storage medium.