JP3553584B2 - Congestion control method in packet transfer device, program for executing the method, and recording medium recording the program - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a quality control function of a packet transfer device constituting an IP network, and more particularly to a congestion control method in a packet transfer device having a closed user group (hereinafter, simply referred to as “CUG”) function and the congestion. The present invention relates to a program for executing a control method, and a computer-readable recording medium on which the program is recorded.
[0002]
[Prior art]
First, an example of a congestion control method in a conventional packet transfer device, which is the basis of the present invention, will be described with reference to the drawings.
FIG. 3 is a functional block diagram of a conventional packet transfer device having a CUG function. As shown in the figure, a conventional packet transfer device having a CUG function is composed of a packet forwarder 32 _{1 to} 32 _m on the input port 31 _{1 to} 31 _m side, and an output route buffer 35 on the output port 38 _{1 to} 38 _p side. _{1 to} 35 _n , a scheduler 37 _{1 to} 37 _p , and a switch unit 34 for connecting a plurality of input / output ports.
[0003]
The packets transmitted from the input ports 31 _{1 to} 31 _{m are} transmitted to the packet forwarders 32 _{1 to} 32 _m . The packet forwarders 32 _{1 to} 32 _m search for an output route and an output port to be transferred from a routing table separated in units of CUG for each packet, and then transmit the packet to the switch unit 34.
[0004]
The switch unit 34 switches the packet for each output port and output route based on the search results in the packet forwarders 32 _{1 to} 32 _m , and sets output route buffers 35 _{1 to} 35 _n installed for each output route to be transmitted. transmitted to and stored in the output route by buffer ₃₅ 1 to 35 _n. Stored in the output path by the buffer ₃₅ 1 to 35 _n packets are sequentially read by the scheduler ₃₇ 1 to 37 _p, is transmitted from the output port ₃₈ 1 _{~38 p.}
[0005]
On the other hand, when packets to a specific output port are concentrated, a congestion state occurs in the switch unit 34. At this time, on the output port side, packets destined for a specific output route of the output port are concentrated, and the amount of packets stored in the buffer for each output route increases. If the output path by the buffer ₃₅ 1 to 35 _n, to set the threshold ₃₆ 1 ~ 36 _n for detecting congestion in advance, the packet accumulated amount exceeds a threshold value, as a congestion notification 39, the output port identifier To the switch unit 34 or the preceding packet forwarders 32 _{1 to} 32 _m . In the packet forwarders 32 _{1 to} 32 _m or the switch unit 34, the transmission of the packet for the output port from the packet forwarder to the switch unit 34 or the transmission from the switch unit 34 to the output port side is stopped. And deter congestion.
[0006]
[Problems to be solved by the invention]
In the conventional congestion control method as described above, when congestion is detected on the output port side, transmission of all packets to be transferred to the output port is stopped. As a result, traffic interference occurred between CUGs and between receiving users in the same CUG. That is, when traffic occurs such that a congestion state occurs in a certain CUG, another CUG is affected by the traffic and packet transmission of the other CUG may be stopped and discarded. Further, even when independent communication is performed between receiving users in the same CUG, packet transmission of another user may be stopped and discarded due to the influence of one user.
[0007]
An object of the present invention is to provide a packet transfer apparatus having a closed user group (CUG) function capable of preventing traffic interference between CUGs and preventing traffic interference between receiving users in the same CUG. An object of the present invention is to provide a congestion control method, a program for executing the congestion control method, and a computer-readable recording medium on which the program is recorded.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, in the invention of claim 1, in output processing in the access link direction, a buffer is set for each CUG and each receiving user on the output port side, and a threshold is provided for each buffer, When the accumulated amount of packets in the buffer exceeds the threshold, the corresponding CUG and the receiving user are notified to the discard control unit provided in the preceding stage. The discard control unit discards a packet for the user in the CUG.
[0009]
According to the second aspect of the present invention, in the output processing in the access link direction, a buffer is set for each CUG and each receiving user on the output port side, and a threshold is provided for each buffer, and the amount of accumulated packets in the buffer is When the threshold value is exceeded, the corresponding CUG is notified to the discard control unit provided in the preceding stage. The discard control unit discards the packet for the CUG.
[0010]
According to the third aspect of the present invention, in the output processing in the relay link direction, a buffer is set for each CUG on the output port side, a threshold is provided for each buffer, and the amount of accumulated packets in the buffer exceeds the threshold. In this case, the corresponding CUG is notified to the discard control unit provided at the preceding stage. The discard control unit discards the packet for the CUG.
[0011]
According to the fourth aspect of the present invention, a congestion notification to be transmitted when a congestion state is detected in the buffer on the output port side is notified to a discard control unit provided in a preceding stage of the switch unit, while following the inventions of the first to third aspects. Then, the discard control unit performs a packet discarding process.
[0012]
According to the fifth aspect of the present invention, when notifying the congestion state from the output port side to the discard control unit, the output port identifier and the output port identifier are used as information for specifying the CUG, while following the inventions of the first to fourth aspects. The CUG identifier is notified, and the output port identifier, the CUG identifier, and the destination address of the receiving user are notified as information for specifying the receiving user in the CUG.
[0013]
According to the sixth aspect of the present invention, when notifying the congestion state from the output port side to the discard control unit while following the first to fourth aspects of the invention, the output port identifier and the output port identifier are used as information for specifying the CUG. A VPI / VCI accommodating the CUG is notified, and an output port identifier and a VPI / VCI accommodating the user in the CUG are notified as information for specifying a receiving user in the CUG.
[0014]
In the invention of claim 7, while following the invention of claims 1 to 6, the discard control unit detects congestion by receiving congestion notification from the output port side, based on the congestion notification received from the output port side, A filtering process for a packet to be discarded is performed, and the corresponding packet is discarded.
[0015]
According to the eighth aspect of the present invention, when the data is temporarily stored in a buffer set individually for each CUG and each receiving user at the output port side and then transmitted at the output port side, the method according to the first and second aspects of the present invention, , And based on the contracted bandwidth, reading is performed from each buffer by using a bandwidth allocation type scheduler.
[0016]
According to the ninth aspect of the present invention, the contract bandwidth is set for each user on the access link and the output bandwidth of the relay link is set for each CUG in the same CUG connected to the link, while following the invention of the third aspect. The sum of the contract bandwidths of the users (that is, the sum of the reception contract bandwidths of the same CUG user accommodated in the packet transfer device) or the same CUG user accommodated in another packet transfer device connected via the link (I.e., the sum of the transmission contract bandwidths of the same CUG user accommodated in other packet transfer devices), whichever is smaller, is set.
[0017]
According to the tenth aspect of the present invention, the contract bandwidth is set for each user on the access link and the scheduler reads out from the CUG-specific buffer on the output port side for each CUG, while following the invention of the third aspect. The sum of the contracted bandwidths of the same CUG user connected to the link (that is, the sum of the received contracted bandwidths of the same CUG user accommodated in the packet transfer apparatus) or the transfer of another packet connected via the link The smaller of the sum of the contracted bandwidths of the same CUG user accommodated in the device (that is, the sum of the transmission contracted bandwidths of the same CUG user accommodated in another packet transfer device) is calculated. Based on this, reading is performed from each buffer using a band allocation type scheduler.
[0018]
In the present invention, when suppressing congestion in the internal switch, by providing a buffer for each receiving user in the CUG on the output port side, congestion is detected for each receiving user, and the detected receiving user and the CUG are detected. By notifying the discard control unit provided in the preceding stage, it becomes possible for the discard control unit to discard the packet causing the congestion in advance for each receiving user, and as a result, in the output direction to the access link side, the receiving user Interference of traffic between them is suppressed.
[0019]
Further, when suppressing congestion in the internal switch, a buffer is provided for each receiving user in the CUG on the output port side to detect congestion on a receiving user basis, and a CUG to which the detected receiving user belongs is provided in the preceding stage. By notifying the discarding control unit, the discarding control unit can discard the packet causing the congestion in CUG units in advance, and as a result, the traffic between the CUGs in the output direction to the access link side can be reduced. Interference is suppressed.
[0020]
Further, when suppressing congestion in the internal switch, by providing a buffer for each CUG on the output port side, congestion is detected in units of CUG, and the detected CUG is notified to the discard control unit provided in the preceding stage. In addition, the discarding control unit can discard the packet causing the congestion in CUG units in advance, and as a result, the traffic interference between the CUGs is suppressed in the output direction to the relay link side.
[0021]
In addition, a notification of the congestion state is sent from the output port side to a discard control unit provided in a preceding stage of the switch unit, and the discard control unit performs packet discard processing, thereby suppressing congestion in the switch unit in advance.
[0022]
Further, when notifying the congestion state from the output port side to the discard control unit, as information for specifying the CUG, the output port identifier and the CUG identifier are used, and as information for specifying the receiving user in the CUG. By using the output port identifier, the CUG identifier, and the destination address of the receiving user, it is possible to perform a filtering process on a packet to be discarded in the discarding control unit.
[0023]
When the output port notifies the discard control unit of the congestion state, the output port identifier and the VPI / VCI accommodating the CUG are notified as information for specifying the CUG. By notifying the output port identifier and the VPI / VCI accommodating the corresponding closed user group as information for specifying the receiving user, the amount of information to be notified can be reduced, and the packet filtering process in the discard control unit can be performed. .
[0024]
Further, when the accumulated amount of packets in the buffer provided on the output port side exceeds the threshold value, a congestion notification is sent to the discard control unit provided in the preceding stage, thereby setting a trigger for performing the discard process in the discard control unit.
[0025]
In addition, when the data is temporarily stored in a buffer set individually for each receiving user on the output port side and then transmitted, a contracted bandwidth is set for each user, and a bandwidth allocation type scheduler is used based on the contracted bandwidth. By reading from the buffer, a reception band is secured for each user, and band interference between reception users is suppressed.
[0026]
Also, a contract bandwidth is set for each user on the access link, and the output bandwidth of the relay link is set for each CUG by the sum of the contract bandwidths of the same CUG users connected to the link (that is, accommodated in the packet transfer device). Sum of received contract bandwidths of the same CUG user) or the sum of contract bandwidths of the same CUG user accommodated in another packet transfer device connected via the link (that is, accommodated in another packet transfer device). (The sum of the transmission contracted bandwidths of the same CUG user) is not less than the smaller one, so that the reception bandwidth of the contracted bandwidth set for the access link for each CUG is secured, and the band interference between CUGs is reduced. Deter.
[0027]
Also, a contract bandwidth is set for each user on the access link, and when the scheduler reads out from the buffer for each CUG on the output port side connected to the relay link by the scheduler, the same CUG user connected to the link is connected for each CUG. The sum of the contracted bandwidths (that is, the sum of the reception contracted bandwidths of the same CUG user accommodated in the packet transfer apparatus) or the contract of the same CUG user accommodated in another packet transfer apparatus connected via the link A smaller one of the sum of the bands (that is, the sum of the transmission contracted bands of the same CUG user accommodated in another packet transfer device) is calculated, and a band allocation type scheduler is used based on the calculated band. By performing reading from each buffer, band interference between CUGs when reading from the buffer is suppressed.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, an IP-VPN (Internet Protocol-Virtual Private Network) is realized using the congestion control method according to the present invention, and an access link and a relay link connected to a packet transfer apparatus are connected to an ATM (Asynchronous Transfer Mode). ) The protocol shall be used.
[0029]
(Example 1)
First, a first embodiment of the present invention will be described.
FIG. 1 is a functional block diagram in a packet transfer device when outputting to an access link side using the congestion control method according to the present invention.
As shown in FIG. 1, the packet transfer apparatus, the input port ₁₁ 1 to 11 and the packet forwarder ₁₂ 1 to 12 _m and discarding control section ₁₃ 1 to 13 _m provided on the _m-side, the output port ₁₈ 1 ~ 18 _p-side And the user-specific buffers 15 ₁ to 15 _n and schedulers 17 _{1 to} 17 _p, and a switch unit 14 for connecting a plurality of input / output ports. In the present embodiment, when the user-specific buffer belongs to a plurality of CUGs, a user-specific buffer is set for each of them. Such a buffer for each user in the first embodiment is referred to as "each closed user group and each receiving user" (refer to claims 1 and 2).
[0030]
Hereinafter, the operation of the first embodiment will be described in detail with reference to FIG.
Packet transmitted from the input port ₁₁ 1 to 11 _m is transmitted to the packet forwarder ₁₂ 1 to 12 _m. In the packet forwarder ₁₂ 1 to 12 _m, the packet forwarding process in the IP layer is performed for each CUG, after the output port and the output VPI / VCI to be transmitted on the basis of this result is searched, the packet discard controller ₁₃ 1 - _13m, and transmitted to the switch unit 14.
[0031]
In the discard controller ₁₃ 1 to 13 _m, when the packet accumulated amount of user-specific buffer ₁₅ 1 to 15 _n to be described later during the previous packet transfer has exceeded the threshold value ₁₆ 1 ~ 16 _n, the user-specific buffer performs a process of discarding packets based on congestion notification sent from 15 ₁ to 15 _n (described in detail later).
[0032]
In the switch unit 14, and switching the packet to the output port and the output VPI / VCI for, and sends the user-specific buffer ₁₅ 1 to 15 _n that are set for each receiving user in CUG accumulates.
[0033]
Packets stored in the user-specific buffer ₁₅ 1 _~15n is transmitted to the access link from the read sequentially output ports ₁₈ 1 ~ 18 _p by the scheduler ₁₇ 1 to 17 _p. Here, a contract band is set for an access link for each user in the CUG, scheduling is performed based on the contract band, and transmission is performed from an output port in ATM cell units. The scheduling algorithm in the scheduler ₁₇ 1 to 17 _p, for example, a WRR (Weighted Round Robin).
[0034]
When packets to a specific output port are concentrated, a congestion state occurs in the switch unit 14. In this case, packets destined for a specific user of the output port are concentrated on the output port side, and the amount of packets stored in the buffer for each user increases. Therefore, previously setting a predetermined threshold ₁₆ 1 ~ 16 _n for user-specific buffer ₁₅ 1 to 15 _n.
[0035]
When the threshold is exceeded the accumulated amount of packets in a user-specific buffer is set in advance, detects the presence of the congestion state, the congestion to discard controller 13 ₁ to 13 _m provided on the front as the notification 19, after notifying the CUG identifiers and destination IP address / netmask output port identifier and the user applicable, the packet stored in the user-specific buffer ₁₅ 1 to 15 _n, the scheduler ₁₇ 1 to 17 _p It is transmitted to the access link from the read sequentially output ports ₁₈ 1 ~ 18 _p.
[0036]
When discard control is performed on a CUG basis, the corresponding output port identifier and the CUG identifier of the user are notified as the congestion notification 19.
[0037]
Further, in order to reduce the information to be notified to the discard control section ₁₃ 1 to 13 _m, the VPI / VCI to accommodate the user instead of the CUG identifiers and destination IP address / netmask of the user, discard control in CUG units In this case, it is also possible to notify the VPI / VCI accommodating the CUG user instead of the CUG identifier of the user.
[0038]
Upon receiving the congestion notification 19 from the output port side, the discard control units 13 _{1 to} 13 _m detect a congestion state, use this as a trigger to perform filtering processing on the packet to be discarded based on the congestion notification 19, and satisfy the filtering condition. Perform discard processing on the packet.
[0039]
In the filtering process, it maintains a list of packets to be discarded based on congestion notification 19, the lookup table the list (not shown), the packet from the input port side to the discard control unit 13 ₁ to 13 _m is transferred Each time, a search table is used to search for a corresponding packet. If the packet is a relevant packet, the packet is discarded.
[0040]
Thus, by discarding in advance in the previous paragraph of the discard control section 13 ₁ to 13 _m to the packet causing the congestion in the switch section 14 is congested state occurs, the output processing to the access link direction, between the received user Can be suppressed, and the reception band of the user can be secured. When discard control is performed on a CUG basis, it is possible to suppress traffic interference between CUGs and secure a band for each CUG.
[0041]
(Example 2)
Next, a second embodiment of the present invention will be described.
FIG. 2 is a functional block diagram at the time of outputting to the relay link side in the same packet transfer device.
As shown in FIG. 2, the packet transfer apparatus, the input port ₂₁ 1 to 21 and the packet forwarder ₂₂ 1 through 22 _m and discarding control section ₂₃ 1 ~ 23 _m provided on the _m-side, the output port ₂₈ 1 ~ 28 _p-side And the CUG-specific buffers 25 _{1 to} 25 _n and the schedulers 27 _{1 to} 27 _p provided in the CPU and the switch unit 24 for connecting a plurality of input / output ports.
[0042]
Hereinafter, the operation of the second embodiment will be described in detail with reference to FIG.
The packets transmitted from the input ports 21 _{1 to} 21 _{m are} transmitted to the packet forwarders 22 _{1 to} 22 _m . In the packet forwarder ₂₂ 1 through 22 _m, the packet forwarding process in the IP layer is performed for each CUG, after the output port and the output VPI / VCI to be transmitted on the basis of this result is searched, the packet discard controller ₂₃ 1 - through 23 _m, it is transmitted to the switch unit 24.
[0043]
In the discard controller ₂₃ 1 ~ 23 _m, when the packet accumulated amount of CUG-graded buffer ₂₅ 1 to 25 _n to be described later during the previous packet transfer has exceeded the threshold value ₂₆ 1 ~ 26 _n, the CUG by buffer performs a process of discarding packets based on congestion notification sent from 25 ₁ to 25 _n (described in detail later).
[0044]
The switch unit 24 switches the packet for the output port and the output VPI / VCI, and transmits and stores the packets to the CUG-specific buffers 25 _{1 to} 25 _n set for each CUG.
[0045]
The packets stored in the CUG-based buffers 25 _{1 to} 25 _n are sequentially read out by the schedulers 27 _{1 to} 27 _p and transmitted from the output ports 28 _{1 to} 28 _p to the relay link.
[0046]
As the output bandwidth of the relay link, for each CUG, the sum of the contract bandwidths of the same CUG user accommodated in the link (that is, the sum of the reception contract bandwidths of the same CUG user accommodated in the packet transfer device), or Either the sum of the contracted bandwidth of the same CUG user accommodated in another packet transfer device connected via the link (that is, the sum of the transmission contracted bandwidth of the same CUG user accommodated in another packet transfer device) The value is set so as not to be smaller than the smaller one, WRR scheduling is performed by weighting the band for each CUG, and the data is transmitted from the output port in ATM cell units.
[0047]
When packets to a specific output port are concentrated, a congestion state occurs in the switch unit 24. In this case, on the output port side, packets for a specific CUG of the output port are concentrated, and the amount of packets stored in the buffer for each CUG increases. Predetermined thresholds 26 _{1 to} 26 _n are set in advance in the CUG-specific buffers 25 _{1 to} 25 _n .
[0048]
When it exceeds the threshold amount of accumulated packets in a certain CUG another buffer is set to detect that it is in the congestion state, the congestion notification to the discard control section 23 ₁ ~ 23 _m provided on the front 29 , The corresponding output port identifier and the CUG identifier of the CUG are notified.
[0049]
At this time, in order to reduce the information to be notified to the discard control section ₂₃ 1 ~ 23 _m, it is also possible to notify the VPI / VCI to accommodate the CUG instead of CUG identifier of the user.
[0050]
The discard control section 23 ₁ ~ 23 _m, by receiving the congestion notification 29 from the output port side, detects the congestion state, which a packet should be discarded based on congestion notification 29 to filter processing as a trigger, corresponding to the filtering criteria The discard processing is performed on the packet that has been set.
[0051]
In this way, by discarding the packet causing the congestion in the switch unit before the congestion occurs, the traffic interference between the CUGs is suppressed in the output processing toward the relay link, and the bandwidth for each CUG is reduced. Can be secured.
[0052]
Note that a program created by converting each process in the first embodiment and each process in the second embodiment into a program code is recorded on a computer-readable recording medium such as a CD-ROM or a DVD and distributed. Can be distributed over a network. A person who intends to implement the present invention can easily implement the congestion control method according to the present invention by obtaining the program according to the present invention from a recording medium or a network and loading the program into the system.
[0053]
【The invention's effect】
As described above, according to the present invention, since packet discard control can be performed for each receiving user in the CUG, when implementing IP-VPN, band interference between receiving users in the VPN is realized. , And a receiving band can be secured for each receiving user in the VPN.
In addition, since packet discard control can be performed in CUG units, band interference between VPNs can be suppressed, and traffic independence can be ensured in VPN units.
[Brief description of the drawings]
FIG. 1 is a functional block diagram in a packet transfer device when outputting to an access link side using a congestion control method according to the present invention (first embodiment).
FIG. 2 is a functional block diagram in a packet transfer device when outputting to a relay link side using the congestion control method according to the present invention (second embodiment).
FIG. 3 is a functional block diagram of a conventional packet transfer device having a CUG function.
[Description of symbols],
_{11 1 ~11 m, 21 1 ~21} m, 31 1 ~31 m: input ports _{12 1 ~12 m, 22 1 ~22} m, 32 1 ~32 m: packet forwarder ₁₃ 1 _{~13 m,} 23 1 _{~23 m:} discard controller 14, 24 and 34: the switch unit ₁₅ 1 to 15 _n: user-specific buffer ₂₅ 1 _{to 25} n: CUG-graded buffer ₃₅ 1 to 35 _n: output path by the buffer _{16 1 ~16} n, 26 1 ~26 _{n, 36} 1 ~36 _n: threshold _{17 1 ~17 p, 27 1 ~27} p, 37 1 ~37 p: scheduler _{18 1 ~18 p, 28 1 ~28} p, 38 1 ~38 p: output port 19, 29, 39: Congestion notification

Claims (12)

A plurality of user hosts are accommodated via an access link, and a plurality of input ports and a plurality of output ports are connected to a relay packet transfer device or a packet transfer device which also accommodates a user host via a relay link. The internal configuration is such that a packet forwarder and a discarding control unit are arranged on the input port side and an output buffer is arranged on the output port side. A congestion control method in a packet transfer device having a function of configuring a closed user group by separating each group into different groups,
When routing a packet transmitted from a plurality of input ports connected to an access link or a relay link and transmitting the packet to an output port connected to the access link, the output port side individually separates each closed user group and each receiving user. A means for temporarily storing the data in the set buffer and then transmitting the data is provided. Each buffer is provided with a threshold value, and when the accumulated amount of packets in the buffer exceeds the threshold value, the buffer is set for the receiving user in the closed user group. Detects that the traffic is in a congested state, notifies the detected receiving user and the closed user group to which the receiving user belongs to the discard control unit provided in the previous stage, and discards the packet for the user in the closed user group. A congestion control method characterized by discarding in a control unit. A plurality of user hosts are accommodated via an access link, and a plurality of input ports and a plurality of output ports are connected to a relay packet transfer device or a packet transfer device which also accommodates a user host via a relay link. The internal configuration is such that a packet forwarder and a discarding control unit are arranged on the input port side and an output buffer is arranged on the output port side. A congestion control method in a packet transfer device having a function of configuring a closed user group by separating each group into different groups,
When routing a packet transmitted from a plurality of input ports connected to an access link or a relay link and transmitting the packet to an output port connected to the access link, the output port side individually separates each closed user group and each receiving user. A means for transmitting data once stored in the set buffer is provided, and a threshold is provided for each buffer. When the amount of accumulated packets in the buffer exceeds the threshold, traffic for the closed user group is in a congested state. A congestion control method comprising: detecting that a closed user group has been detected; and reporting the detected closed user group to a discard control unit provided in a preceding stage, and discarding a packet for the closed user group in the discard control unit. Accommodates multiple user hosts via access links,
Connected via a relay link to a relay packet transfer device or a packet transfer device that also accommodates a user host, a plurality of input ports and a plurality of output ports are connected by a switch unit, and a packet forwarder is connected to the input port side. A discarding control unit is arranged, and an output buffer is arranged on the output port side. A closed user group is formed by physically separating path information into logical groups in one device. Congestion control method in a packet transfer device having a function to perform,
When routing packets transmitted from multiple input ports connected to an access link or relay link and transmitting them to an output port connected to a relay link, the output port side stores the packets individually set for each closed user group. Taking the means of once storing and transmitting, providing a threshold for each buffer, when the amount of packets stored in the buffer exceeds the threshold, detects that traffic for the closed user group is in a congestion state, A congestion control method, wherein the detected closed user group is notified to a discard control unit provided at a preceding stage, and a packet for the closed user group is discarded by the discard control unit. In the congestion control method according to any one of claims 1 to 3,
A congestion control method comprising: notifying a congestion notification transmitted when a congestion state is detected on an output port side to a discard control unit provided in a preceding stage of a switch unit, and performing a packet discarding process in the discard control unit; . In the congestion control method according to any one of claims 1 to 4,
When the output port notifies the discard control unit of the congestion state, the output port identifier and the closed user group identifier are notified as information for specifying the closed user group, and the receiving user in the closed user group is specified. A congestion control method comprising: notifying an output port identifier, a closed user group identifier, and a destination address for a receiving user as information for performing the operation. In the congestion control method according to any one of claims 1 to 4,
Using an ATM line as an access link or a relay link, assigning a specific VPI / VCI to each user of each closed user group, and specifying the closed user group when the output port notifies the discard control unit of the congestion state As information to perform, the output port identifier and the VPI / VCI accommodating the closed user group are notified, and as information for specifying the receiving user in the closed user group, the output port identifier and the corresponding user in the closed user group are notified. A congestion control method, wherein a VPI / VCI accommodating a user is notified. In the congestion control method according to any one of claims 1 to 6,
The discarding control unit detects congestion in response to the congestion notification from the output port side, performs filtering processing of a packet to be discarded based on the congestion notification received from the output port side, and discards the corresponding packet. Congestion control method. In the congestion control method according to claim 1 or 2,
On the output port side, when a packet is temporarily stored in a buffer individually set for each closed user group and for each receiving user and then read out and transmitted by the scheduler, a contract bandwidth is set for each user on the access link, and the A congestion control method, wherein a buffer is read from each buffer using a bandwidth allocation type scheduler based on a contract bandwidth. In the congestion control method according to claim 3,
A contract band is set for each user on the access link, and the output band of the relay link is set to the sum of the contract bands of the same closed user group user connected to the link for each closed user group (that is, Or the sum of the contracted bandwidths of the same closed user group users accommodated in other packet transfer devices connected via the link (that is, other Congestion control method characterized in that the setting is made so as not to fall below the smaller one of the transmission contract bandwidths of the same closed user group user accommodated in the packet transfer device of the above. In the congestion control method according to claim 3,
A contract bandwidth is set for each user on the access link, and at the output port side, when packets are temporarily stored in a buffer for each closed user group and then read out and transmitted by the scheduler, the packet is connected to the link for each closed user group. Sum of the contracted bandwidths of the same closed user group user (that is, the sum of the received contracted bandwidths of the same closed user group user accommodated in the packet transfer apparatus) or other packets connected via the link. Calculate the smaller of the sum of the contracted bandwidths of the same closed user group users accommodated in the transfer device (that is, the sum of the transmission contracted bandwidths of the same closed user group users accommodated in other packet transfer devices). Applying a bandwidth allocation type scheduling algorithm based on the bandwidth, Congestion control method characterized by reading from §. A program for realizing each processing procedure in the congestion control method according to claim 1. A computer-readable recording medium storing the program according to claim 11.

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