JP2000174794A - Device and method for controlling communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reconstruct a network by automatically canceling a loop configuration by disabling one of ports related to a loop when the duration of a Parent Notify signal is measured and that loop is detected. SOLUTION: At the point of time the loop is detected at respective nodes (nods 1 to 3 and 5) composing of the loop, the timer of certain arbitrary time set for each node is activated at the respective nodes. Since the node 1 is first made into time-out, the port connected with the node 2 is disabled, a route is cut and bus reset is generated. After the bus is completely initialized, the Parent Notify signal from the node 1, which changes from 'Branch' node to 'Leaf' node, and nodes 4 and 6 to 8 of 'Leaf' nodes to the node of a parent candidate is transmitted to the port. The nodes 2, 3 and 5 of 'Branch' nodes transmit Child Notify signals to the node, which receives the Parent Notify signal, for confirming a child node.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication control device and a communication control method using, for example, a serial bus or the like.

[0002]

2. Description of the Related Art In recent years, serial buses have few signal lines, thin cables, small connectors, and IDs.
It has been spotlighted because it has features such as the necessity of setting of a terminal, a terminator and the like, the possibility of hot-swapping, and the possibility of isochronous data transfer.

[0003] In particular, the IEEE 1394 serial bus is capable of transmitting large-capacity data such as moving images at a high speed, is capable of memory access by a bus architecture, and is capable of peer-to-peer connection. Application to not only personal computers but also AV devices at home and other devices is being actively promoted.

[0004] Also, new standards corresponding to higher speeds and longer distances are currently being developed.

FIG. 6 shows an example of the bus structure of IEEE1394.

Reference numerals 1 to 8 denote devices (nodes) connected to each other by a DAISY chain connection or a branch connection by an IEEE 1394 interface. The IEEE 1394 port has two twisted pair cables (one for A and the other for B
) And one set of power supply pair cables. The two sets of twisted pair cables are connected by crossing each other with cables, one A is connected to the other B, and one B is connected to the other. A is connected.

As for the data signal, the data signal is transmitted by the twisted pair A as the differential signal and the strobe signal is transmitted by the twisted pair B, and the strobe signal is transmitted by the twisted pair A and the data signal is received as the operation signal by the twisted pair B in the half pair communication. The arbitration signal is an arbitration signal transmitted from the driver side in front-duplex communication and simultaneously received using the three-phase (0, 1, Z) logic defined by a certain voltage level on the receiver side. Identify.

In order to determine the above three-phase logic, a twisted pair A is provided with "Arb A Rx", and a twisted pair B is provided with "Arb B Rx". Have been. "0" is defined as low voltage at non-inverting input and high voltage at inverting input, "1" is defined as high voltage at non-inverting input and low voltage at inverting input, and "Z" is non-inverting. And low voltage at both inputs.

To establish a bus configuration, initialization of the bus,
Three phases of tree identification and self identification are performed.
During the three phase process, a tree-like topology is built as shown.

[0010] Here, the initialization of the bus occurs when the power supply is discontinuous, when it is generated by a soft command, or when an abnormality in the bus configuration due to a new connection or disconnection of a node in the bus configuration is detected. Causes a bus reset, and is completed when all nodes are in the idle state.

Specifically, first, a logic "1" is transmitted to both the twisted pair A and the twisted pair B to generate a bus reset, and the node receiving this signal recognizes the occurrence of the bus reset. When an arbitrary time elapses after the occurrence of the bus reset, a logic "Z" is transmitted to both the twisted pair A and the twisted pair B to generate an idle signal, and the system waits for the connected node to transmit the idle signal. When the idle signal is received from the node, it recognizes that the bus initialization has been completed.

When the bus initialization is completed, the process proceeds to tree identification.

Here, a node having only one connection node is a "Leaf" node, a node having two or more connection nodes is a "branch" node, and a node having no connection node is "non-connection". There are three types of nodes: nodes.

In tree identification, first, a node transmits a Parent notify signal to a node that is a parent (Root) candidate. In FIG. 6, "Leaf" nodes 4, 6, 7, 8
Sends a Parent notify signal to the port. "Branc
For the `` h '' node, if there are multiple ports,
Since the node cannot be recognized as an oot candidate node, the parent notify signal is not sent first, and "Lea
Wait for the Parentnotify signal from the "f" node.

However, even if the "Branch" node has a plurality of ports, if only one port is connected to the node and all other ports are not connected, "Leaf"
Become a node.

Next, FIG. 7 shows that “Branch” nodes 3 and 5
Send a Child notify signal to the node that received the Parent notify signal to recognize that it is a child node,
The “f” node receives the Child notify signal and recognizes that the connection of the port has been completed.

As described above, the “Branch” node
After the child notify signal is sent in response to the rent notify signal and the port that has not received the parent notify signal becomes one after the connection is completed, Pare is sent to that port.
When the nt notify signal is transmitted and the Childnotify signal is received, the connection of the bus configuration of this port is completed.
Anch "indicates that nodes 3 and 5 have completed the connection.

FIG. 8 shows that “Branch” node 1
Send "ify" signal and "Branch" node 2
The "Root" node transmitting the y signal is determined to be node 2, indicating that tree identification has been completed.

When the tree identification is completed, a node number is assigned to each node, and each node enters a self-identification for enabling data communication.

[0020]

However, in the above-mentioned prior art, since the connectors are all the same, when the nodes 3 and 5 are connected as shown in FIG. An unacceptable loop connection other than the branch connection is established between the nodes 3 and 5 of the nodes 1 and 2.

In this loop connection, a plurality of ports of the "Branch" node wait for receiving a parent notify signal from another node.
Since the tree identification cannot be completed without transmitting the nt notify signal, there is a problem that a state in which subsequent self-identification and data communication cannot be performed.

The present invention has been made in view of the above conventional example, and has as its object to provide a communication control apparatus and method for detecting a loop, automatically resolving the loop configuration, and reconstructing a network.

[0023]

To achieve the above object, the present invention measures a wait time of a Parent Notify signal to detect a loop, and if a loop is detected, detects at least one of the ports connected to the loop. Re-establish the network with one disabled to eliminate the loop.

Alternatively, it has the following configuration. In other words, a communication control device that configures a connection relationship between devices by notifying each other of a subordination relationship.
Connecting means for connecting to another device via one port, and loop detecting means for detecting that the connected device forms a loop in the connecting means while forming a connection relationship with the other device; and When a loop is detected by the loop detecting unit, at least one of the ports in which the loop is detected is disabled after a predetermined time, and a reset notification for reconfiguring a connection relationship between the devices is transmitted to another device. And disable means for notifying the user.

Preferably, the predetermined time is set longer for a device having a larger number of ports forming a loop.

Preferably, the predetermined time is a first value proportional to the number of ports forming a loop, and a second value which is unique to the device and shorter than the time of one port forming a loop. Is set as a time obtained by adding

Preferably, the loop detecting means comprises:
When the reset notification is received or when the reset notification is output, if the number of ports is plural, a device connected via another port may leave any one of the ports. The device waits for a predetermined time to receive a notification that the device is a child node, and detects the presence of a loop when the predetermined time has elapsed.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, nodes 1 to 8
Devices (nodes) connected by the IEEE 1394 interface. In the present invention, each node has a loop detection function, has a function of independently disabling each IEEE 1394 port of each node, and each node has an arbitrary time timer function.

FIG. 5 is a block diagram of a computer which is an example of a node. IEEE 1394 interface 5
01 is connected to another device via a cable. The interface of FIG. 5 has three ports. The HDD 502 stores data and program files, and is loaded into the RAM 505 and stored in the CPU 5.
04 for processing or execution. A medium storing data or a program is set in a file device 503 using a removable medium such as a CDROM, a floppy disk, or a magneto-optical disk.
02 or loaded into the RAM 505. The programs and data include those for performing processing such as transmission / reception of data according to IEEE 1394, bus reset, and loop detection, which will be described later. ROM50
6 also stores programs and data. The timers 1, 2, and 3 are used for detecting and canceling a loop at the time of a bus reset described later. Although FIG. 5 shows the configuration of the computer, an input / output device such as a printer can be connected to the IEEE 1394. In such a device, a mechanism for input / output is provided in addition to the configuration shown in FIG.

Next, the operation of the node will be described. Each node uses the above function to start a timer for an arbitrary time when the node detects a loop, and when one of the nodes detects a loop, deactivates any one of the plurality of ports that have detected the loop of the node. Disable, generate a bus reset and restart from bus initialization. If the bus initialization is started before the timer is out, the timer is stopped and restarted from the bus initialization.

FIG. 1 shows a specific example of the above operation. Each node constituting the loop (nodes 1, 2 and 3
When 5) and 5) detect a loop, each node starts a timer for an arbitrary time set for each node. First, since the timer of the node 1 is out, the port connected to the node 2 is disabled, the loop path is cut off, and a bus reset is generated. After the initialization of the bus is completed, the node 1 that has been changed from the “Branch” node to the “Leaf” node and the parent node (Root) from the nodes 4, 6, 7, and 8 that are the “Leaf” nodes are Parent. A notify signal is sent to the port. "Branch" node 2,
The nodes 3 and 5 transmit a child notify signal to the node that has received the parent notify signal to recognize that the node is a child node, and the “Leaf” node receives the child notify signal and recognizes that the connection of the port has been completed. I do. Furthermore, "Branc
h "In the node 2, since the port connected to the node 1 has been disabled, the only port that has not received the Parent notify signal is the port connected to the node 5, and the Parent notify signal is sent to that port. Is being transmitted.

FIG. 2 shows a state in which the node 5 has been determined as the “Root” node and tree identification has been completed. To reach this state, first, "Branch" nodes 3 and 5
The child notify signal is transmitted from the port that has received the ify signal, and the respective connections are completed. After that, a Parent notify signal is transmitted from the node 3 to the node 5, a Child notify signal is transmitted from the node 5 to the node 3, and the node 5 is determined to be the “Root” node and the connection is completed.

FIG. 3 is a diagram showing a case where a node 5 has timed out instead of the node 1 in FIG. 1 and a loop has been detected, a port connected to the node 2 has been disabled, and a bus reset has occurred. It is. After the bus initialization is completed, the connection of the “Leaf” node to the parent node is completed in the same manner as in FIG. 1, and the “Branch” node 5 becomes a port in which the port connected to the node 2 is disabled. Therefore, the only port that does not receive the Parent notify signal is the port connected to the node 3, and the parent notify signal is transmitted to that port, and the node 3 is the root. Similarly, in the “Branch” node 2, since the port connected to the node 5 has been disabled, the only port that has not received the Parent notify signal is the port connected to the node 1. Indicates that a Parent notify signal is being transmitted.

FIG. 4 shows that the connection of all the nodes in FIG. 3 has been completed, the node 3 has been determined as the “Root” node, and the tree identification has been completed.

That is, although the bus configuration changes depending on the location of the disconnection, any one of the nodes forming the loop automatically disconnects and reconfigures the loop. A normal bus configuration can be formed by avoiding loops.

When the tree identification is completed, a node number is assigned to each node, and each node enters a self-identification for enabling data communication.

<Tree Identification Procedure> The operation flow of the present invention is shown in FIG.

This operation flow shows a flowchart for executing the tree identification process. This procedure starts when a bus reset is detected from a port to which a device is connected or when a bus reset is generated by itself, and ends when tree identification is completed.

First, when started by a bus reset, it is determined whether or not there is an active port (S10).
1) If there is no active port, it recognizes that there is no device to be connected, starts a standalone operation (S111), and ends.

When there is an active port,
It is determined whether or not the request is a transmission request for generating a bus reset (S102). If the request is a transmission request, a bus reset is transmitted to all active ports (S103). An idle signal is transmitted (S104), and it is determined whether or not idle signals have been received from all active ports (S10).
5) When an idle signal is received, the process proceeds to S201.

If the bus reset is not a transmission request in step S102, a bus reset is received (S10).
6), it is determined whether or not there is an active port (S1).
07), if not, the process proceeds to S201, and if there is, a bus reset is transmitted to all other active ports (S10).
8) An idle signal is transmitted to all active ports that have transmitted the bus reset (S109), it is determined whether or not idle signals are received from all other active ports (S110), and idle signals are transmitted from all active ports. If it has been received, the process proceeds to S201.

Here, the bus reset is completed as described above, and the tree identification is started from step S201.

In step S201, the timer 1 is started. Timer 1 is sufficient time to complete tree identification, and timer 1 out means that there is a loop connection and the tree configuration cannot be configured.

Next, it is determined whether or not the active port is one port (S203). If not, the process proceeds to step S301. If the active port is one, a Parent notify signal is transmitted to the port (S203), and it is determined whether or not the timer 1 is out (S204). If the timer is out, the device does not respond. And recognizes that communication is not possible (S21).
6) Perform error processing such as not adding the device connected to the port to the tree configuration (S217), and end.

If the timer 1 has not expired in step S204, it is determined whether or not a Child Notify signal has been received (S205). It recognizes that it has been determined to be "Leaf" in the middle (S215), and ends.

If not received, Parent not
It is determined whether or not a ify signal has been received (S206). If it has not been received, the process proceeds to step S204. If it has been received, a root conflict for determining “Root” is started, After stopping the timer 1, the timer 2 is started (S207).

The timer 2 is a random timer for determining the time until only two devices competing in the timer for root conflict transmit the next parent notify signal.

Next, it is determined whether or not the timer 2 has timed out (S208). If the timer has expired, it is determined whether or not a Parent notify signal has been received (S209). In this case, a Child notify signal is transmitted (S213), and it is recognized that the own device has been determined to be "Root" in the bus configuration, and the process ends.

If the parent notify signal has not been received in step S209, the parent notify signal is transmitted, and then it is determined whether or not the child notify signal has been received from the port (S211). Recognizes that the own device has been set to “Leaf” in the bus configuration, and becomes an end. Next, when there are a plurality of active ports in step S202, the number of active ports is set to N (S301), and it is determined whether or not the timer 1 has timed out (S302). If no out has occurred, it is determined whether a Parent notify signal has been received from any of the ports N (S303), and if not received, the process proceeds to S302, and if a Parent notify signal has been received, the process proceeds to S302. If so, a child notify is transmitted to the port that received the Parent notify (S304), N is reduced by one port (S305), and it is determined whether or not N has become one port (S306). The process proceeds to S302 (i.e., two or more ports). If the number of ports becomes one, the process proceeds to S501.

Next, when the time-out of the timer 1 has occurred in step S302, it is recognized that a loop has occurred because there is a port in which no response continues.
Normally, the loop detection ends here. However, the node according to the present invention next enters a process of avoiding a loop. First, the timer 3 is started (S401).

The timer 3 covers all devices forming a loop, but each device needs to have a unique timer value. The timer value is determined by the number of ports forming the loop. The device with the most devices should have a longer timer value, and each of the devices with the least number of ports forming a loop should execute a loop release and generate a bus reset so that only one device performs a loop reset. Set the timer value of the device.

For example, this can be realized by setting the following timer values.

T3 = Tα + Tβ × N + Tγ Tα: arbitrary fixed timer value Tβ: fixed timer value applied when there is a non-responding port (this timer value is multiplied by the number N of non-responding ports) Tγ: device (For example, a device-specific timer value is calculated using a device-specific value such as a company ID or a unique ID). Here, Tβ> Tγ.

Next, it is determined whether or not the timer 3 times out (S402).
It is determined whether a Parent notify signal has been received from any of the ports N (S403). If it has not been received, the process proceeds to S406. If it has been received, the Parent notify signal has been received. Receive to port and not Child
A ify signal is transmitted (S404), N is decreased by one port (S405), and it is determined whether an inactive port is detected from any of the N ports (S40).
6) If not detected, the process proceeds to S408.
If detected, N is reduced by one port (S40).
7) Then, it is determined whether or not N has become one port (S4).
08) If not one port (that is, two or more ports), the flow shifts to S402. If the number of ports becomes one, the flow shifts to S501.

Next, when the timeout of the timer 3 has occurred in step S402, it is recognized that the own device is the device for executing the loop release processing, and any one of the N ports is set. Disabled (S409), and request generation of a bus reset (S41).
0), transit to step S101.

In step S501, Pa is sent to the remaining ports.
A rent notify signal is transmitted to determine whether or not the timer 1 is out (S504).
Recognizing that the device is not responding and is in a communication disabled state (S514), and performs error processing such as not adding the device connected to the port to the tree configuration (S5).
15) End.

If the timer 1 has not expired in step S502, it is determined whether or not a child notify signal has been received (S503). It recognizes that it has been determined to be "Branch" (S513), and ends.

If not received, Parent not
It is determined whether or not a ify signal has been received (S504). If it has not been received, the process proceeds to S502. If it has been received, a root conflict for determining “Root” is started and a timer is started. After stopping the timer 1, the timer 2 is started (S5).
05).

Next, it is determined whether or not the timer 2 has timed out (S506).
It is determined whether a Parent notify signal has been received (S50).
7) If it has been received, a Child notify signal is transmitted (S511), and it is recognized that the own device has been determined to be "Root" in the bus configuration, and the process ends.

In step S507, if the parent notify signal has not been received, a parent notify signal is transmitted, and it is determined whether a child notify signal has been received from the port (S211). Recognizes that the own device has been set to "Branch" in the bus configuration, and becomes an end.

FIGS. 15 to 17 show an example of a loop avoiding procedure in a bus configuration having a plurality of loop connections based on the above operation flow.

FIG. 15A shows nodes 10, 11, 1
This shows a state where all ports 2 and 13 are connected in a loop. In this case, since all ports are connected in a loop at each node, Pare is connected from all ports.
nt notify signal is not sent, and P
Since the arent notify signal is not received and the connection is not completed, a loop is detected. Therefore, when each node detects a loop, each node starts an arbitrary timer. Here, since all the nodes have detected a loop with three ports, the number of ports at which all the nodes have detected a loop is three, and
Since the timer value Tβ based on the number of ports becomes the same timer value, one of the nodes first times out due to the timer value Tγ unique to each node.

FIG. 15B shows a case where the node 10 or the node 13
If either of the timers goes out first and the node 10 goes out of timer, the port connected to the node 13 is disabled, a bus reset is generated, and the node 13 goes out of timer. In such a case, the port connected to the node 10 is disabled to generate a bus reset. Therefore, after the initialization of the bus is completed, a loop is detected again at the remaining two ports of the node 10 and the node 13 and at the three ports of the node 11 and the node 12, and each node starts an arbitrary timer value again.

Here, the number of ports at which a loop is detected is 2 ports for nodes 10 and 13, and 3 ports for nodes 11 and 12, so that the timer value Tβ based on the number of ports is And the node 13 has a shorter timer value for the smaller number of ports,
Although the timer goes out earlier, which of the nodes 10 and 13 goes out first due to the node-specific timer value Tγ.

In FIG. 16 (a), the node 13 first goes out of timer, disables the port connected to the node 11, and generates a bus reset. Therefore,
After the initialization of the bus is completed, the port of the node 13 becomes one port and becomes a “Leaf” node, and the connection of the port connected to the node 12 is completed, but the remaining two ports of the node 10, the node 11, and the node 12 A loop is detected again, and the node detecting this loop starts an arbitrary timer value again.

Here, since all the nodes that have detected the loop are detected at two ports, the number of ports that have detected the loop is two, and the timer value Tβ based on the number of ports is the same timer value. By the timer value Tγ,
Any one node times out first.

FIG. 16B shows an example in which the timer of the node 12 first goes out, in which the port connected to the node 10 is disabled to generate a bus reset. Therefore, after the initialization of the bus is completed, the tree identification is completed by forming a normal bus configuration in which the node 10, the node 11, the node 12, and the node 13 are connected in a data chain, and thereafter, the self identification is performed. Data communication becomes possible.

FIG. 17A shows an example in which the timer of the node 12 first goes out. The port connected to the node 11 which is different from that of FIG. Generate a reset. Therefore, after the initialization of the bus is completed, the node 11, the node 10, and the node 1
When a normal bus configuration in which the node 2 and the node 13 are connected in a daisy chain is formed, tree identification is completed. Thereafter, self-identification is performed, and data communication becomes possible.

FIG. 17B shows an example in which the timer of the node 10 first goes out, in which the port connected to the node 11 is disabled and a bus reset is generated. Then, after the initialization of the bus is completed, the tree identification is completed when a normal bus configuration in which the node 12 is connected to the node 11, the node 10, and the node 13 in a branch is completed. Communication becomes possible.

As described above, even when a plurality of loops exist, the loops can be avoided and a normal bus configuration can be formed.

As described above, the IEEE according to the present invention
A node with a 1394 interface can detect a loop and release it. When releasing the loop, the time from the detection of the loop to the disabling of the port is changed for each node according to the number of ports of each node and the time unique to each node. By doing so, the link that is disabled by one loop release process is limited to one location, and it is possible to prevent a situation in which the network is disconnected.

[0072]

[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 provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
Or MPU) reads and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) Performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, The case where the CPU of the function expansion board or the function expansion unit performs part or all of the actual processing, and the function of the above-described embodiment is realized by the processing.

[0078]

As described above, when a loop in which a bus configuration cannot be formed is detected, a normal bus configuration can be formed by automatically avoiding the loop and normal data communication becomes possible. There is an effect that the reliability at the time of forming the bus configuration is dramatically improved.

Further, since the operation of disconnecting the cable forming the loop by the operator becomes unnecessary, there is an effect that the convenience for the operator is dramatically improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a loop disconnection by a node A;

FIG. 2 is a diagram showing completion of a tree after a loop is cut by a node A;

FIG. 3 is a diagram showing loop disconnection by a node E;

FIG. 4 is a diagram showing completion of a tree after a loop is cut by a node E;

FIG. 5 is a diagram illustrating a configuration example of each node.

FIG. 6 is a diagram showing a conventional example (1).

FIG. 7 is a diagram showing a conventional example (2).

FIG. 8 is a diagram showing a conventional example (3).

FIG. 9 is a diagram showing a conventional example (4).

FIG. 10 is a diagram showing an operation flow (1) of a node according to the present invention.

FIG. 11 is a diagram showing an operation flow (2) of the node according to the present invention.

FIG. 12 is a diagram showing an operation flow (3) of the node according to the present invention.

FIG. 13 is a diagram showing an operation flow (4) of the node according to the present invention.

FIG. 14 is a diagram showing an operation flow (5) of the node according to the present invention.

FIG. 15 is another diagram showing a state of loop cutting according to the present invention.

FIG. 16 is another view showing a state of loop cutting according to the present invention.

FIG. 17 is another diagram showing a state of loop cutting according to the present invention.

[Explanation of symbols]

1,2,3,4,5,6,7,8,10,11,12,
13 nodes

Claims (9)

[Claims] 1. A communication control device configured to notify a subordinate relationship to each other to form a connection relationship between devices, comprising: a connection unit configured to connect to another device via at least one port; During the construction of the connection relationship,
Loop detection means for detecting that a connected device forms a loop, and when a loop is detected by the loop detection means, disables at least one of the ports where the loop is detected after a predetermined time. And a disabling means for notifying another device of a reset notification for reconfiguring a connection relationship between the devices. 2. The communication control device according to claim 1, wherein the predetermined time is set longer for a device having a larger number of ports forming a loop. 3. The predetermined time is a first value proportional to the number of ports forming a loop, and a second value unique to the device and shorter than the time of one port forming a loop. The communication control device according to claim 1, wherein the communication control device is set as an added time. 4. When the reset notification is received or the reset notification is output, if the number of ports is plural, the loop detection unit leaves one of the ports, 2. The system according to claim 1, wherein the control unit waits for a predetermined time from a device connected via another port that the device is a child node, and detects a loop when the predetermined time has elapsed. 4. The communication control device according to any one of claims 1 to 3. 5. A communication control method for devices that are connected to another device via at least one port and notify each other of a dependency relationship to form a connection relationship with each other, the communication control method comprising: During the construction of the connection relationship,
A loop detection step of detecting that a connected device forms a loop, and, if a loop is detected by the loop detection step, disabling at least one of the ports where the loop is detected after a predetermined time. And a disabling step of notifying another device of a reset notification for reconfiguring a connection relationship between the devices. 6. The communication control method according to claim 5, wherein the predetermined time is set longer for a device having a larger number of ports forming a loop. 7. The predetermined time is a first value proportional to the number of ports forming a loop, and a second value unique to the device and shorter than the time of one port forming a loop. The communication control method according to claim 5, wherein the time is set as an added time. 8. The loop detecting step, when the reset notification is received or the reset notification is output, if the number of ports is plural, leaving any one of the ports, 6. The method according to claim 5, further comprising: waiting for a predetermined time from a device connected via another port, the notification indicating that the device is a child node, and detecting the presence of a loop when the predetermined time has elapsed. The communication control method according to any one of claims 1 to 7. 9. A storage medium which is connected via at least one port and which stores a program which can be executed by a computer which forms a connection relationship by notifying a dependency relationship to each other, wherein the program is: In the connection means during the configuration of the connection relationship with the device,
A loop detection step of detecting that a connected device forms a loop, and, if a loop is detected by the loop detection step, disabling at least one of the ports where the loop is detected after a predetermined time. And a disabling step of notifying another device of a reset notification for reconfiguring a connection relationship between the devices.