JPH08130560A - Inter-network connecting device and its method - Google Patents

Abstract

PURPOSE: To easily receive data by allocating many buffers to a high speed receiving queue and to prevent the generation of convergence in transmitting data by increasing a threshod for a low speed transmitting queue. CONSTITUTION: This inter-network connecting device is provided with plural ports 1 to 4 including transmitting and receiving queues and capable of changing link access speed, a data repeating means 35 for transferring data from the receiving queues to the transmitting queues in the ports 1 to 4, a receiving buffer allocating means 12 for automatically allocating a buffer recorded in a common buffer pool to respective receiving queues in the ports 1 to 4 at the time of changing speed, and a transmitting queue threshold determining means 13 for automatically determining the threshold of each transmitting queue at the time of changing the speed. The device is also provided with a convergence detecting/evading means 38 for detecting the excess of transmitting data from the threshold of the transmitting queue and canceling the excess transmitting data and a link access speed change detecting means 11 for detecting the speed changes of respective ports 1 to 4 and informing the detected results to the means 12, 13.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a LAN, a cell relay,
The present invention relates to an inter-network connection device and method used for frame relay, public data network, etc.

[0002]

2. Description of the Related Art Conventionally, there has been an inter-network connecting device used in a LAN, a cell relay, a frame relay, a public data network, etc., as shown in FIGS. FIG. 3 is a configuration diagram showing a configuration of a conventional inter-network connecting apparatus, and FIG. 4 is a configuration diagram showing details of a buffer allocation function in the conventional inter-network connecting apparatus shown in FIG.

First, in FIG. 3, reference numeral 30 is an inter-network connection device to which the present invention is applied, 31, 32, and 3.
Reference numerals 3 and 34 denote transmission / reception queues of each port, and arrows for the outside indicate transmission / reception of data frames or data (hereinafter, referred to as data) with the outside. Reference numeral 35 is a data relay unit that normally relays data to connect data from one port (data network) to the other port (data network). The data relay unit 35 and the transmission / reception queues 31, 32 of each port, The arrows between 33 and 34 also indicate data transmission and reception.

Further, 37 is a common buffer pool which holds buffers to be distributed to the reception queue of each port, 36 is a reception buffer which is held in the common buffer pool 37 is assigned to the reception queue of each port, and is queued in the transmission queue. Is a buffer amount of a buffer for holding transmission data to be transmitted, that is, a reception buffer allocating means and a transmission queue threshold value determining means for calculating and determining a threshold value. The acquisition and the release are shown, and the transmission / reception queue 3 of each port is determined by the reception buffer allocation means and the transmission queue threshold value determination means 36.
The arrows for 1, 32, 33, 34 indicate the allocation of receive buffers and the determination of transmit queue thresholds.

Further, 38 is a congestion detection / avoidance means for detecting that the amount of transmission data for each transmission queue exceeds a threshold value at each port and discarding the excess transmission data. Port send / receive queue 31,
The arrows between 32, 33 and 34 indicate the detection of the congestion of the transmission data in the transmission queue and the discarding of the data.

FIG. 4 is a block diagram showing the details of the essential parts of the buffer allocation function in the conventional inter-network connecting apparatus, which will be used in the following description of the operation of the conventional inter-network connecting apparatus.

The operation of the conventional inter-network connecting device will be described below with reference to FIGS. 3 and 4. First, when the inter-network connection device is powered on and started up, the reception buffer allocation means and the transmission queue threshold value determination means 36 determine the allocation amount of the reception buffer for each port and the transmission queue threshold value. According to the buffer capacity of the entire network connection device, it is equally determined regardless of the link access speed. Therefore, even when the link access speed is changed, the reception buffer allocation amount and the transmission queue threshold value for each port are not changed.

Even if a large number of data receptions occur and an attempt is made to receive more data than the buffer allocation amount for the reception queue, the data cannot be held in the reception buffer more than the buffer allocation amount, so that more data cannot be received. , The data that is going to be received beyond the buffer allocation amount is discarded.

Further, as a result of the received data being queued in the transmission queue via the data relay means, when the transmission data is about to be accumulated or is received in the transmission buffer above the threshold value designated in the transmission queue, the congestion detection is performed.・ Avoidance means 38
Detects an excessive reception or congestion state of the transmission queue, and discards the transmission data that exceeds the threshold value and tries to accumulate in the transmission buffer.

As described above, even in the above-mentioned conventional inter-network connecting device, the receiving buffer is allocated and the transmission queue threshold value is determined, and the data reception exceeding the allotted amount of the receiving buffer in the inter-network connecting device is avoided. When,
It is possible to detect a congestion state of transmission data that is equal to or more than the threshold of the transmission queue and discard the data. The calculation formulas for the reception buffer allocation amount and the transmission queue threshold value described above may be summarized in Table 1 below.

Table 1 [Link access speed ratio] Port 1: Port 2: Port 3: Port 4 = x0: x
1: x2: x3 [Total buffer amount] Bx [Minimum buffer reservation amount of buffer pool] Ba [Reception buffer allocation amount] [For port 1] (Bx-Ba) / 8 [For port 2] (Bx-Ba) ÷ 8 [for port 3] (Bx-Ba) ÷ 8 [for port 4] (Bx-Ba) / 8 [threshold of transmission queue] [for port 1] (Bx-Ba) ÷ 8 [ For port 2] (Bx-Ba) / 8 [For port 3] (Bx-Ba) / 8 [For port 4] (Bx-Ba) / 8

[0012]

However, in the conventional inter-network connecting device as shown in FIGS. 3 and 4, the receiving buffer allocation amount and the transmission queue are irrespective of the difference in the link access speed of each port. Since the threshold value of is fixed to the value, the data arrival rate is higher in the port with the faster link access speed than in the port with the slower link access speed. When transmitting from a port with a high link access speed to a port with a slow link access speed, the link access speed is However, there was a problem that congestion was likely to occur on the slow port side.

As described above, there are cases where the buffer allocation amount is less than the necessary amount for the reception queue of a port where reception failure is likely to occur. On the other hand, for the reception queues of other ports, There is a problem in that the common buffer cannot be effectively used, because unnecessary buffer allocation is performed more than necessary, or buffer allocation is performed for unused buffers.

The present invention has been made in order to solve the above-mentioned conventional problem, and recalculates the allocation amount of the reception buffer and the threshold value of the transmission queue every time the link access speed changes. In the receiving port, a large amount of receiving buffer is allocated to the port with high link access speed so that the common buffer can be used without waste.
In the transmission port, a large amount of the transmission buffer that can be used is allocated to the port with the slow link access speed, that is, by increasing the threshold value of the transmission queue, the occurrence of the congestion state of the transmission data is prevented. Therefore, the object is to provide an efficient inter-network connection device.

[0015]

In order to achieve the above object, an inter-network connecting device according to the present invention comprises a plurality of ports including a reception queue and a transmission queue and having a variable link access speed, and a reception queue of each port. Data relay means for transferring data to the transmission queue; reception buffer allocation means for automatically allocating the reception buffer held in the common buffer pool to each reception queue of the port when the link access speed is changed; When the access speed is changed, the transmission queue threshold value determining means for automatically determining the threshold value of the transmission queue for each transmission queue of each port, and the usage amount of the transmission buffer by the transmission data in each transmission queue Detecting that the threshold has been exceeded, and discarding transmission data that exceeds the threshold, congestion detection and avoidance And the change of the link access speed in each of the ports is notified to the receiving buffer allocating means and the transmitting queue threshold value determining means to allocate the receiving buffer to each of the ports and determine the transmitting queue threshold value. And a link access speed change detection means adapted to be changed.

Further, in order to achieve the above-mentioned object, the inter-network connecting device according to the present invention determines the allocation amount of the reception buffer for each port by the reception buffer allocation means based on the ratio of the link access speed for each port. It is characterized by having done.

Further, in order to achieve the above-mentioned object, the inter-network connecting device according to the present invention sets the threshold of the transmission queue at each port by the transmission queue threshold determining means to the transmission queue at the port having the lowest link access speed. It is characterized in that the determination is made based on the inverse ratio to the threshold value of.

Further, in order to achieve the above object, the inter-network connection method according to the present invention transmits / receives data via the reception queue and the transmission queue of a plurality of ports having variable link access speeds, and via the data relay means. In the inter-network connection method that transfers data from the receive queue of a port to the send queue, a change in the link access speed of each port is detected, and in the common buffer pool in response to the detection of the change in the link access speed The assigned receive buffer to the receive queue of each port automatically, and in response to the detection of the change in the link access speed, the threshold value of the transmit buffer is automatically determined for each receive queue of each port. To the use of the transmit buffer for the transmit data for each transmit queue at each port. By detecting that the amount exceeds the threshold value, it is characterized in that comprises the steps of discarding the transmission data exceeds the threshold.

Further, in order to achieve the above-mentioned object, the inter-network connection method according to the present invention automatically changes the allocation of the reception buffer so that the allocation amount of the reception buffer becomes a ratio of the link access speed of each port. It is characterized in that it is decided based on the above.

Further, in order to achieve the above-mentioned object, the inter-network connecting method according to the present invention automatically changes the threshold value of the queue of the transmission buffer to change the threshold value of the transmission queue at each port. It is characterized in that the link access speed is determined based on the inverse ratio to the lowest port.

In summary, the inter-network connection apparatus and method according to the present invention, in order to achieve the above object, detect a change in the link access speed of a port and, in response thereto, receive buffer quota and transmission queue threshold. And a link access speed change detecting means for recalculating and updating

In summary, the inter-network connecting apparatus and method according to the present invention, in order to achieve the above-mentioned object, expands the function of the conventional receiving buffer allocating means for the receiving buffer allocation in the receiving queue of each port. Each time the access speed is changed, the receiving buffer allocation amount is recalculated based on the ratio of the link access speed of each port, and the receiving buffer is allocated to each corresponding port.

In short, the inter-network connecting apparatus and method according to the present invention expands the function of the conventional transmission queue threshold value determining means for the threshold value of the transmission queue of each port in order to achieve the above object. Each time the link access speed changes, the threshold of the transmission queue of the port with the minimum link access speed is first determined from the total buffer capacity and the link access speed of each port, and the minimum threshold of the link access speed is set. And the inverse ratio of the minimum link access speed and the link access speed of each port.

[0024]

The inter-network connecting apparatus and method according to the present invention is configured as described above, and the allocated amount of the reception buffer and the transmission queue corresponding to the actual link access speed at each port are changed every time the link access speed is changed. By making the decision to change the threshold value of, the useless resources are not allocated to unused ports, the buffer can be used without waste, and the congestion state of the transmitted data is prevented. be able to.

Further, the inter-network connecting apparatus and method according to the present invention are configured as described above, and in the reception queue of each port, the port with the higher link access speed stores the data of the port with the lower link access speed. Since the arrival rate is high and data cannot be received easily, by allocating buffers according to the ratio of link access speeds, it is possible to allocate more buffers to ports with faster link access speeds. A buffer amount suitable for the actual link access speed is allocated, and the common buffer can be used efficiently.

The inter-network connecting apparatus and method according to the present invention is configured as described above, and in the transmission port or transmission queue, data is physically transmitted from a port having a high link access speed to a port having a slow link access speed. In this case, the buffer overflows and the congestion of transmitted data is likely to occur. Therefore, the threshold is determined by the inverse ratio of the link access speed, and the threshold for the port with a slow link access speed is increased. By increasing the buffer amount of the slow port, the threshold corresponding to the link access speed is determined rather than the fixed threshold, and the congestion of the transmission data that discards the transmission data is prevented from occurring. Then, it is possible to transmit and receive with a good balance.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings and FIGS. FIG. 1 is a schematic block diagram showing the configuration of an inter-network connecting device in an embodiment of the present invention, and FIG. 2 is a configuration diagram showing details of a buffer allocation function in the inter-network connecting device of FIG.
First, with reference to FIG. 1, a configuration of an inter-network connection device in one embodiment of the present invention will be described. In FIGS. 1 and 2, the same reference numerals as those used in FIGS. 3 and 4 indicate the same functions, and thus detailed description thereof will be omitted in the following description.

In FIG. 1, 10 is an inter-network connecting device to which this embodiment is applied, 11 is each port (1, 2, 3, 4) used in the inter-network connecting device 10 or other means (not shown). For example, it is a link access speed change detecting means for detecting the link access speed of each port (1, 2, 3, 4) from the control device, and a dotted arrow to the link access speed change detecting means 11 detects the link access speed. The arrow from the link access speed change detecting means 11 indicates that the detected change in the link access speed is notified.

Reference numerals 12 and 13 correspond to the conventional reception buffer allocating means and transmission queue threshold value determining means 36, and 12 is each port (1, 2, 3, 4).
When a change in the link access speed is detected in, the allocation amount of the reception buffer for each port (1, 2, 3, 4) is determined based on the ratio of the link access speed for each port, and Receiving buffer allocation means for automatically allocating the receiving buffers held in the common buffer pool to the respective receiving queues of the ports for the ports (3, 4), and 13 when each port (1 2, 3, 4) based on the inverse ratio to the threshold of the transmission queue at the port with the lowest link access speed,
It is a transmission queue threshold value determining means for automatically determining the threshold value of the queue of the transmission buffer for each port.

Next, the operation of the inter-network connecting apparatus according to this embodiment will be described with reference to FIG.
First, when starting up the system, each port (1,
2, 3, 4) calculating the receive buffer quota and the transmit queue threshold for each port (1, 2, 3, 4) and the appropriate receive buffer quota and transmit queue threshold for each. Assign Then, when the link access speed is changed while the inter-network connecting device 10 is operating, the link access speed change detection means 11 detects it and notifies the reception buffer allocation means 12 and the transmission queue threshold value determination means 13. .

The reception buffer allocation means 12 and the transmission queue threshold value determination means 13 which have received the notification recalculate the reception buffer allocation amount and the transmission queue threshold value, and receive the reception queue of each port from the common buffer pool 37. Receive buffers are allocated and supplied to the buffers, and the transmission queue threshold value determining means 13 determines the ports (1, 2,
For 3, 4) a threshold is provided for the receive buffer of the transmit queue. The method of recalculating the reception buffer allocation amount and the transmission queue threshold value according to the present invention will be described later with reference to FIG. Moreover, even when this embodiment is used,
In the case where unreceivable data due to overflow of received data or congestion due to excessive transmitted data occurs, unreceivable data is not received, and transmitted data equal to or more than a threshold value is detected by congestion means as in the conventional case. It would be detected by 38 and discarded, but by the present invention it seems to be little or very few.

As described above, according to the present embodiment, the reception buffer allocation amount and the transmission queue threshold value are recalculated each time the link access speed is changed, so that the port is calculated for each port from the total buffer amount. Appropriate amount of buffer can be allocated, transmission queue threshold can determine transmission queue threshold suitable for link access speed, and link access speed can not be detected. Therefore, it is possible to use the buffer without wasting resources by allocating no resources to unused ports.

Next, with reference to FIG. 2, a method of calculating the reception buffer allocation amount and the transmission queue threshold value will be described. Figure 2
FIG. 2 is a configuration diagram showing details of a buffer allocation function in the inter-network connection device of FIG. 1. Note that the functions shown in FIG. 2 are the same as those in FIG. The calculation for the allocation of the reception buffer and the determination of the transmission queue threshold value performed there is performed by the reception buffer allocation means 12 and the transmission queue threshold value determination means 13 as follows.

In this calculation, the number of ports allocated to the inter-network connecting device 10 is set to 4 and the total amount Bx is stored in the common buffer pool 37 before buffer allocation.
Buffers are stored in each port (1, 2,
It is assumed that the link access speeds of 3 and 4) are assigned to each port at a ratio of x0: x1: x2: x3, respectively.

First, it is assumed that at least "Ba"(Bx> Ba) of the remaining amount of the common buffer pool 37 is secured,
"Bu = Bx-Ba" buffers are used for each transmission / reception port. In addition, the minimum allocated amount of each port shall be "Bs" secured as a standard buffer amount.
With the remaining buffer amount as a variable buffer amount, “Bv = B
u-Bs × (number of ports) × 2 ”is distributed according to each link access speed. In reception,“ Br = Bv ÷
2 "pieces, and" Bt = Bv / 2 "pieces are used for transmission.

In the receive queue, each port (1,
The ratio of velocity to 2, 3, 4) is x0: x1: x2: x
Therefore, the variable buffer amount "Br" is distributed according to this ratio, and the standard buffer amount "Bs" is added to determine the allocation amount. For example, at port 1, it is calculated and determined by the following equation. (Reception buffer amount of port 1) = Br × x0 ÷ (x0 +
x1 + x2 + x3) + Bs

Similarly, port 2, port 3 and port 4 are calculated and determined by the following equations. (Reception buffer amount of port 2) = Br × x1 ÷ (x0 +
x1 + x2 + x3) + Bs (reception buffer amount of port 3) = Br × x2 ÷ (x0 +
x1 + x2 + x3) + Bs (reception buffer amount of port 4) = Br × x3 ÷ (x0 +
x1 + x2 + x3) + Bs

On the other hand, regarding the threshold value of the transmission queue,
The minimum value "xmin" (for example, xmin = x0) of the link access speed of all ports (1, 2, 3, 4) is searched for, the threshold value of the transmission queue of that port is calculated, and the value is calculated. Set to "Bmin". The thresholds of the other ports are calculated and determined by the inverse ratio of the link access speed of the minimum port and the link access speed of each port.
It is determined by adding "Bs" of standard buffer amount to the value of each port. Therefore, the threshold of the transmission queue of port 1 is calculated by the following formula. (Threshold value of transmission queue of port 1) = Bmin × xm
in ÷ x0 + Bs

The threshold values of port 2, port 3 and port 4 are also given by the following equation. (Threshold value of transmission queue of port 2) = Bmin × xm
in ÷ x1 + Bs (transmission queue threshold of port 3) = Bmin × xm
in ÷ x2 + Bs (threshold of transmission queue of port 4) = Bmin × xm
in ÷ x3 + Bs Here, Bt = Bmin × xmin (1 ÷ x0 + 1 ÷ x1 + 1 ÷
Since x2 + 1 ÷ x3) holds, “Bmin” is determined using this formula.

As described above, according to this embodiment,
When the link access speed is determined, the buffer allocation for the reception queue of the reception port is determined according to the link access speed, and the threshold for the transmission queue of the transmission port is determined. You can increase the amount of data received by increasing the buffer quota for the port with the faster link access speed than the port with the slower speed. For the send queue, for the send queue of the port with the slower link access speed, Since the amount of discarded transmission can be reduced by increasing the threshold value, the transmission / reception buffer can be used efficiently.

Further, according to this embodiment, since the link access speed is variable, the buffer amount can be assigned and the threshold value can be determined every time the link access speed changes, and the link access speed can be changed. It can be seen that the buffer can be efficiently used without supplying the buffer to the boat that is not given.

Although four ports are used in this embodiment described above, any number of ports may be used. In this case, the number of ports is n, the link access speed ratio is x0: x1: x2: ...: xn, and k
.., n, the receiving buffer amount can be determined by the following equation. (Reception buffer amount of port k) = Br × xk ÷ (x0 +
x1 + ... + xn) + Bs

The threshold value of the transmission queue can be determined by the following equation. (Threshold of transmission queue of port k) = Bmin × xm
in ÷ xk + Bs In order to make it easy to see the calculation method of the reception buffer allocation amount and the transmission queue threshold value described above, they are collectively shown in Table 2 below.

Table 2 [Link access speed ratio] Port 1: Port 2: Port 3: Port 4 = x0: x1: x2: x3 [Total buffer amount] Bx [Minimum buffer reservation amount of buffer pool] Ba [Standard of each port] Buffer amount] Bs [Variable buffer amount for reception] Br = ((Bx-Ba) -Bs x 4 x 2) / 2 [Variable buffer amount for transmission] Bt = ((Bx-Ba) -Bs x 4 x 2) ÷ 2 [Receive buffer allocation amount] [For port 1] Br × x0 ÷ (x0 + x1 + x2 + x3) + Bs [For port 2] Br × x1 ÷ (x0 + x1 + x2 + x3) + Bs [For port 3] Br × x2 ÷ (x0 + x1 + x2 + x3) + Bs [For port 4] Br × x3 ÷ (x0 + x1 + x2 + x3) + Bs [Transmission queue threshold] [Minimum link access speed] xmin [ Is calculated from the small link access transmission speed port queue threshold] Bmin Bt = Bmin × xmin (1 ÷ x0 + 1 ÷ x1 + 1 ÷ x2 + 1 ÷ x3). [For Port 1] Bmin × xmin ÷ x0 + Bs [For Port 2] Bmin × xmin ÷ x1 + Bs [For Port 3] Bmin × xmin ÷ x2 + Bs [For Port 4] Bmin × xmin ÷ x3 + Bs

[0045]

The inter-network connecting apparatus and method according to the present invention resets the allocation amount of the reception buffer and the threshold value of the transmission queue in correspondence with the actual link access speed at each port every time the link access speed is changed. By calculating and making the change decision, it is possible to prevent unreceivability of received data, prevent congestion of transmitted data, and avoid unnecessary resource allocation to unused ports. You can use the buffer.

Further, the inter-network connecting apparatus and method according to the present invention determines the allocated amount of the receiving buffer based on the ratio of the link access speeds, so that a port having a higher link access speed can have more buffers. Allocation can be made, and a buffer amount suitable for the actual link access speed is allocated rather than fixed allocation, and the common buffer can be used efficiently.

Further, the inter-network connecting apparatus and method according to the present invention, in the transmission port or the transmission queue,
Fixed threshold value is set by increasing the threshold value for ports with slow link access speed and increasing the buffer amount for ports with slow link access speed by determining the threshold value by the inverse ratio of link access speed. A threshold corresponding to the link access speed is determined more effectively, preventing the occurrence of congestion in the system that discards transmission data,
You can send and receive in good balance.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of an inter-network connection device according to an embodiment of the present invention,

FIG. 2 is a configuration diagram showing details of a buffer allocation function in the inter-network connection device of FIG.

FIG. 3 is a configuration diagram showing a configuration of a conventional inter-network connection device.

FIG. 4 is a configuration diagram showing details of a buffer allocation function in the conventional inter-network connection device shown in FIG.

[Explanation of symbols]

10 inter-network connection device 11 link access speed change detection means 12 reception buffer allocation means 13 transmission queue threshold determination means 30 inter-network connection device 31 port 1 transmission / reception queue 32 port 2 transmission / reception queue 33 port 3 transmission / reception queue 34 port 4 transmission / reception queue 35 data relay means 36 reception buffer allocation means and transmission queue threshold value determination means 37 common buffer pool 38 width congestion detection / avoidance means

Claims (6)

[Claims] 1. A plurality of ports including a reception queue and a transmission queue and having a variable link access speed, data relay means for transferring data from a reception queue of the port to a transmission queue, and a case of changing the link access speed. A receive buffer allocation unit that automatically allocates a receive buffer held in a common buffer pool to each receive queue of the port, and a send queue queue for each send queue of the port when the link access speed is changed. A transmission queue threshold value determining means for automatically determining the threshold value, and in each of the transmission queue, detecting that the amount of use of the transmission buffer by the transmission data exceeds the threshold value,
Congestion detection / avoidance means for discarding transmission data exceeding the threshold value, the reception buffer allocation means and the transmission queue threshold value determination by detecting a change in link access speed in each of the ports Link access speed change detecting means for notifying the means and changing the allocation of the receiving buffer to each of the ports and the determination of the transmission queue threshold value. 2. The network according to claim 1, wherein the receiving buffer allocating means determines the amount of receiving buffer allocated to each of the ports based on a ratio of link access speeds of the ports. Inter-connection device. 3. The transmission queue threshold value determining means determines the threshold value of the transmission queue at each port based on the inverse ratio to the threshold value of the transmission queue at the port having the lowest link access speed. The inter-network connecting device according to claim 1 or 2. 4. A network which transmits / receives data via a reception queue and a transmission queue of a plurality of ports having variable link access speeds and transfers the data from the reception queue of the port to a transmission queue via a data relay means. In the connection method, a change in the link access speed at each of the ports is detected, and in response to the detection of the change in the link access speed, the reception buffer held in the common buffer pool is allocated to the reception queue of each port. Automatically change, in response to the detection of the change in the link access speed, automatically change the determination of the threshold of the transmission buffer for each reception queue of each port, in each of the ports, Detecting that the send buffer usage for send data for each send queue exceeds the threshold And a step of discarding transmission data that has exceeded the threshold value. 5. The step of automatically changing the allocation of the reception buffer is such that the allocation amount of the reception buffer is determined based on the ratio of the link access speed of each port. How to connect between networks. 6. The step of automatically modifying the queue threshold determination of the transmit buffer is such that the transmit queue threshold at each port is determined based on an inverse ratio to the port with the lowest link access rate. The inter-network connection method according to claim 4 or 5, wherein