TRANSMISSION DEVICE AND RESOURCE ALLOCATION METHOD

Abstract

[Problem] To allocate IFs to be used in accordance with buffers such that no packet loss occurs in a case in which the transfer apparatus that performs packet transfer includes as many buffers with grouped interfaces (IFs) mounted in units of groups thereon as the number of groups.

[Solving Means] A packet transfer apparatus 10C has a plurality of buffers 11a to 11n mounting IFs in units of groups and performs, when the traffic amount at the time of packet transfer of the IFs of each of the buffers exceeds maximum transfer capacity of the IFs, buffering packets corresponding to the exceeding traffic amount in the butlers. An IF allocation unit 23 included in the transfer apparatus 10C selects, in a case in which IF groups with no occurrence of any loss indicating packet discarding are present at the time of the packet transfer in the IFs for a unit time from among all the IF groups, an IF group with a longest non-occurrence time of the buffering from among the IF groups with no occurrence of any loss and performs IF allocation of allocating traffic of packets to the IFs in the selected IF groups.

Claims

1. A transfer apparatus comprising a plurality of buffers, the plurality of buffers being an identical number with a number of interface (IF) groups, the IF groups being obtained by grouping a plurality of interfaces (IFs) for packet transfer in units of a number that is smaller than the number of the plurality of IFs, each of the plurality of buffers mounting the number of IFs in units of groups, buffer capacity of each of the plurality of buffers being defined in accordance with the number of mounted IFs in units of groups, the transfer apparatus performing packet transfer to and from a network via the mounted IFs in units of groups of each of the plurality of buffers, the transfer apparatus performing buffering packets corresponding to an exceeding traffic amount in a buffer of the plurality of buffers when a traffic amount at a time of the packet transfer exceeds maximum transfer capacity of the IFs in units of groups, the transfer apparatus comprising: an IF allocation unit, including one or more processors, configured to select, in a case in which, from the IF groups of the transfer apparatus, the IF groups in which a loss indicating packet discarding does not occur during the packet transfer in the IFs in units of groups for a unit time are present, an IF group with a longest non-occurrence time of the buffering from among the IF groups with no occurrence of any loss and perform IF allocation of allocating traffic of packets to IFs in units of groups in the IF group that is selected.

2. The transfer apparatus according to claim 1, wherein the IF allocation unit is configured to allocate the traffic to the IFs in units of groups after preprocessing is executed, the preprocessing being any one of, IF expansion of bringing unused IFs in units of groups mounted on a buffer of the IF group that is selected into a used state, IF connecting destination change of changing the IFs in units of groups connected to the network to the IFs in units of groups of another buffer, and IF expansion or reduction of increasing or reducing the IFs in units of groups in use in the buffer that is selected.

3. The transfer apparatus according to claim 1, further comprising: a management unit, including one or more processors, configured to: detect whether a burst occurs, namely whether burst traffic occurs when the traffic amount at the time of the packet transfer in the IFs in units of groups exceeds the maximum transfer capacity of the IFs in units of groups, store detected information regarding whether the burst occurs in a storage unit in units of the IF groups in association with time information regarding whether the burst occurs, detect whether the loss occurs at the time of the packet transfer in the IFs in units of groups, and store detected information regarding whether the loss occurs in a storage unit in units of the IF groups in association with time information regarding whether the loss occurs, wherein the IF allocation unit regards and selects, when detecting presence of IF groups with no occurrence of any loss based on the information, which is stored in the storage unit, regarding whether the loss occurs, an IF group with a minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as the IF group with a longest non-occurrence time of the buffering, based on the information regarding whether the burst occurs.

4. The transfer apparatus according to claim 1, wherein the IF allocation unit performs, in a case in which, from among all the IF groups in the transfer apparatus, IF groups in which a loss does not occur during the packet transfer in the IFs in units of groups for a unit time are not present, the IF allocation by selecting an IF group with a minimum number of occurrences of the loss from among all the IF groups.

5. The transfer apparatus according to claim 2, further comprising an estimation unit, including one or more processors, configured to estimate information regarding whether the burst occurs, with which time information regarding whether the burst occurs is associated, and information regarding whether the loss occurs, with which time information regarding whether the loss occurs is associated, from traffic characteristics of each of the IF groups after the preprocessing is executed, wherein the IF allocation unit regards and selects, when detecting presence of IF groups with no occurrence of any loss from among the IF groups with the traffic characteristics estimated by the estimation unit, an IF group with a minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as an IF group with a longest non-occurrence time of the buffering.

6. The transfer apparatus according to claim 5, wherein the IF allocation unit performs, in a case in which the presence of the IF groups with no occurrence of any loss is not detected from among the IF groups with the traffic characteristics estimated by the estimation unit, the IF allocation by selecting an IF group with a minimum number of occurrences of the loss from among all the estimated IF groups.

7. A resource allocation method performed by a transfer apparatus comprising a plurality of buffers, the plurality of buffers being an identical number with a number of interface (IF) groups, the IF groups being obtained by grouping a plurality of IFs for packet transfer in units of a number that is smaller than the number of the plurality of IFs, each of the plurality of buffers mounting the number of IFs in units of groups, buffer capacity of each of the plurality of buffers being defined in accordance with the number of mounted IFs in units of groups, the transfer apparatus performing packet transfer to and from a network via the mounted IFs in units of groups of each of the plurality of buffers, the transfer apparatus performing buffering packets corresponding to an exceeding traffic amount in a buffer of the plurality of buffers when a traffic amount at time of the packet transfer exceeds maximum transfer capacity of the IFs in units of groups, the resource allocation method comprising: detecting, from the IF groups of the transfer apparatus, whether IF groups in which a loss indicating packet discarding does not occur during the packet transfer in the IFs in units of groups for a unit time are present; selecting, in a case in which the IF groups are detected to be present, an IF group with a longest non-occurrence time of the buffering from among the IF groups with no occurrence of any loss; and performing IF allocation of allocating traffic of packets to IFs in units of groups in the IF group that is selected.

8. The resource allocation method according to claim 7, further comprising, allocating by the IF allocation unit, the traffic to the IFs in units of groups after preprocessing is executed, the preprocessing being any one of, IF expansion of bringing unused IFs in units of groups mounted on a buffer of the IF group that is selected into a used state, IF connecting destination change of changing the IFs in units of groups connected to the network to the IFs in units of groups of another buffer, and IF expansion or reduction of increasing or reducing the IFs in units of groups in use in the buffer that is selected.

9. The resource allocation method according to claim 7, further comprising: detecting, by a management unit, whether a burst occurs, namely whether burst traffic occurs when the traffic amount at the time of the packet transfer in the IFs in units of groups exceeds the maximum transfer capacity of the IFs in units of groups, storing detected information regarding whether the burst occurs in a storage unit in units of the IF groups in association with time information regarding whether the burst occurs, detecting whether the loss occurs at the time of the packet transfer in the IFs in units of groups, and storing detected information regarding whether the loss occurs in a storage unit in units of the IF groups in association with time information regarding whether the loss occurs, wherein the IF allocation unit regards and selects, when detecting presence of IF groups with no occurrence of any loss based on the information, which is stored in the storage unit, regarding whether the loss occurs, an IF group with a minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as the IF group with a longest non-occurrence time of the buffering, based on the information regarding whether the burst occurs.

10. The resource allocation method according to claim 7, further comprising, performing, by the IF allocation unit, in a case in which, from among all the IF groups in the transfer apparatus, IF groups in which a loss does not occur during the packet transfer in the IFs in units of groups for a unit time are not present, the IF allocation by selecting an IF group with a minimum number of occurrences of the loss from among all the IF groups.

11. The resource allocation method according to claim 10, further comprising estimating, by an estimation unit information regarding whether the burst occurs, with which time information regarding whether the burst occurs is associated, and information regarding whether the loss occurs, with which time information regarding whether the loss occurs is associated, from traffic characteristics of each of the IF groups after the preprocessing is executed, wherein the IF allocation unit regards and selects, when detecting presence of IF groups with no occurrence of any loss from among the IF groups with the traffic characteristics estimated by the estimation unit, an IF group with a minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as an IF group with a longest non-occurrence time of the buffering.

12. The resource allocation method according to claim 10, further comprising, performing, by the IF allocation unit, in a case in which the presence of the IF groups with no occurrence of any loss is not detected from among the IF groups with the traffic characteristics estimated by the estimation unit, the IF allocation by selecting an IF group with a minimum number of occurrences of the loss from among all the estimated IF groups.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0033] FIG. 1 is a block diagram illustrating a configuration of a transfer apparatus according to an embodiment of the present invention.

[0034] FIG. 2 is a diagram illustrating whether a burst occurs.

[0035] FIG. 3 is a diagram illustrating whether a packet loss occurs.

[0036] FIG. 4 is a flowchart for explaining IF allocation processing performed by the transfer apparatus according to the embodiment.

[0037] FIG. 5 is a block diagram illustrating a configuration of a shared buffer in the related art.

[0038] FIG. 6 is a block diagram illustrating a plurality of buffers in each IF group in the related art.

DESCRIPTION OF EMBODIMENTS

[0039] Hereinafter, an embodiment of the present invention will be described swim reference to the drawings.

Configuration of Embodiment

[0040] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, in all the drawings of the present specification, components having corresponding functions are denoted by the same reference signs and description will be appropriately omitted.

[0041] FIG. 1 is a block diagram illustrating a configuration of a transfer apparatus according to an embodiment of the present invention.

[0042] A transfer apparatus 10C illustrated in FIG. 1 is different from the transfer apparatus 10B (FIG. 6) in that a resource allocation control unit (also referred to as a control unit) 20 is provided in addition to the configuration of the transfer apparatus 10B. The control unit 20 performs control for allocating IFs to be used in accordance with the buffers 11a to 11n in response to a resource allocation command from a higher-order apparatus, which is not illustrated. The control unit 20 is configured to include a resource management unit 21, a resource estimation unit 22, and an IF allocation unit 23.

[0043] However, the buffers 11a to 11n are divided into a number of groups (n groups) such that the number is obtained by dividing all the IFs into a plurality of groups in accordance with dependence on connecting destinations, and the buffers 11a to 11n individually mount IFs in units of groups in advance. In other words, the buffer 11a mounts four IFs that are represented with the reference signs a1, a2, a3, and a4 and form one group a. The buffer 11b mounts four IFs that are represented with the reference signs b1, b2, b3, and b4 and form one group b. The buffer 11n mounts four IFs that are represented with the reference signs n1, n2, n3, and n4 and form one group n.

[0044] The IFs a1 to a4, b1 to b4, . . . n1 to n4 (also expressed as IF a1 to n4) in the groups a to n include unused IFs, and in a case in which the unused IFs are used, IF expansion of manually coupling wiring to an optical fiber or a metal cable of the network is performed. Also, IF connecting destination change of changing network connection of IFs to IFs of other buffers is also manually performed. Further, in a buffer (11a, for example), IF expansion/reduction of changing four IFs a1 to a4 in use, which belong to one group a, to three IFs a1 to a3 and changing the three IFs a1 to a3 in use to the four IFs a1 to a4 is also manually performed. Note that the IF expansion, the IF connecting destination change, and the IF expansion/reduction indicate the preprocessing described in the aspects.

[0045] However, the number of buffers 11a to 11n and the number of IFs a1 to n4 in each of the groups mounted in advance on each of the buffers 11a to 11n are fixed in advance and cannot be changed.

[0046] Next, the resource management unit (also referred to as a management unit) 21 performs management of detecting the traffic amount at the time of packet transfer in the IFs mounted on each of the buffers 11a to 11n to detect a use rate of the buffer capacity of each of the buffers 11a to 11n. However, the detection is performed as will be described below because the use rate cannot be detected directly. Also, the detection of the traffic amount is performed by a method of counting packets input to the IFs or the like.

[0047] Each of the buffers 11a to 11n is used such that, when the traffic amount of the IFs exceeds the maximum transfer capacity of the IFs, the packets corresponding to the exceeding traffic amount are buffered. Because the buffer capacity can be converted into the traffic amount, it is possible to detect the use rate of the buffer capacity by accumulating the exceeding traffic amount and comparing the accumulated value with the buffer capacity of one buffer.

[0048] When the traffic amount of the IFs becomes equal to or less than a predetermined value, the buffered packets are transferred via the IFs. It is thus possible to detect the use rate of the buffer capacity by detecting the traffic amount of the transferred packets, subtracting the traffic amount from the accumulated value, and comparing the accumulated value after the subtraction with the buffer capacity. The management unit 21 adapted to detect the use rate in this manner detects burst occurrence and packet loss occurrence as will be described below.

[0049] The management unit 21 detects, at a preset cycle, the traffic amount at the time of packet transfer for each of the IF groups a to n in the transfer apparatus 10C to detect whether a burst occurs and to detect whether a packet loss (loss) occurs, as will be described below. Furthermore, the management unit 21 stores each of the determined information regarding whether the burst occurs and information regarding whether the loss occurs in a storage unit (not illustrated), such as various memory devices or hard disk devices, in units of the IF groups. A packet loss can be detected by IFs because it occurs in the IFs in a case in which the buffers are full.

[0050] The detection of whether the burst occurs will be described with reference to FIG. 2. The vertical axis in FIG. 2 represents a burst occurrence amount b.sub.i(t) while the horizontal axis represents time t. i in b.sub.i(t) represents the consecutive numbers a1 to a4, b1 to b4, and n1 to n4 (see FIG. 1) of the IFs. A line th1 of a predetermined level represents a threshold value corresponding to the maximum transfer capacity of the IFs.

[0051] The management unit 21 detects the traffic amounts k1 and k2 of the packets of one IF for each of the IF groups a to n, detects that a burst occurs in a case in which the detected traffic amounts k1 and k2 exceed the threshold value th1, and stores the detected burst occurrence information “1” in the storage unit. Because a burst occurrence time t of k2 out of the traffic amounts k1 and k2 is as long as twice the burst occurrence time of the other, k1=“1” and k2=“1, 1” may be stored in accordance with the occurrence time t.

[0052] Also, the management unit 21 detects that no burst occurs (non-occurrence) in a case in which the detected traffic amounts are equal to or less than the threshold value th1 and stores the detected burst non-occurrence information “0” in the storage unit.

[0053] The detection of whether the packet loss occurs will be described with reference to FIG. 3. The vertical axis in FIG. 3 represents a packet loss occurrence amount 1.sub.i(t) while the horizontal axis represents time t. i in 1.sub.i(t) is the consecutive numbers a1 to a4, b1 to b4, and n1 to n4 of the IFs. A line th2 of a predetermined level is a threshold value for determining packet loss occurrence of the IFs.

[0054] When a packet loss k3 in which the count value of packet loss exceeds the threshold value th2 is detected in one IF of each of the IF groups a to n, the management unit 21 stores the detected packet loss occurrence information “1” in the storage unit. Also, the management unit 21 determines that no loss occurs in a case in which the aforementioned count value is equal to or less than the threshold value th2 and stores the determined packet loss non-occurrence information “0” in the storage unit.

[0055] However, any one of or both the burst occurrence amount b.sub.i(t) and the packet loss occurrence amount 1.sub.i(t) will be referred to as traffic characteristics of IF.sub.i.

[0056] A total value of the burst occurrence amount b.sub.i(t) of each of the IFs n1 to n4 of an IF group (IF group n, for example) will be defined as total traffic characteristics b.sub.n(t). The total traffic characteristics b.sub.n(t) in a case in which each of the IFs n1 to n4 of the IF group n is defined as i are represented by Equation (1) below.

[00001]$\begin{array}{cc}\left[\mathrm{Math}.1\right]& \\ b_{n}t=\underset{i}{.Math.}{b}_i\left(t\right)& \left(1\right)\end{array}$

[0057] A total value of the packet loss occurrence amounts 1.sub.i(t) of each of the IFs n1 to n4 of the IF group (IF group n, for example) will be defined as total traffic characteristics l.sub.n(t). Total traffic characteristics l.sub.n(t) in a case in which each of the IFs n1 to n4 of the IF group n is defined as i are represented by Equation (2) below.

[00002]$\begin{array}{cc}\left[\mathrm{Math}.2\right]& \\ l_n\left(t\right)=\underset{i}{.Math.}{l}_i\left(t\right)& \left(2\right)\end{array}$

[0058] Next, the resource estimation unit (also referred to as an estimation unit) 22 estimates how the traffic characteristics of each of the IF groups a to n will change in a case in which IFs are expanded in the existing buffers 11a to 11n, for example, in a case in which the unused IF a4 of the buffer 11a is expanded in a used state, or an IF connecting destination is changed, for example, in a case in which a connecting destination is changed from the IF a1 of the buffer 11b to the IF b1 of the buffer 11b. Note that the estimation may also include estimation in a case in which the aforementioned IF expansion/reduction is performed. However, it is assumed that traffic characteristics of the IFs as targets of performing the IF expansion and the IF connecting destination change are known.

[0059] After an IF of an existing buffer (buffer 11n, for example) is expanded, or after the IF connecting destination is changed, the total traffic characteristics b'.sub.n(t) that are a total value of the burst occurrence amounts b.sub.i(t) of the IF group n are represented by Equation (3) below.

b'.sub.n(t)=b.sub.n(t)+b.sub.target(t)   (3)

[0060] However, “'” represents after the expansion of an IF or after the change of the IF connecting destination, “target” represents the IF that has been expanded or the IF of which the connecting target has been changed.

[0061] After an IF is expanded in an existing buffer (buffer 11n, for example), or after the IF connecting destination is changed, the total traffic characteristics 1'.sub.n(t) that are a total value of the loss occurrence amounts 1.sub.i(t) of the IF group n are represented by Equation (4) below.

1'.sub.n(t)=1.sub.n(t)+1.sub.target(t)   (4)

[0062] Next, the IF allocation unit 23 allocates the IFs to be used in accordance with the buffers such that no packet loss occurs, in response to a resource allocation request from a higher-order apparatus or the like. This IF allocation processing will be described with reference to the flowchart illustrated in FIG. 4.

[0063] It is assumed that in Step S1 in FIG. 4, a resource allocation request (IF allocation request) from a higher-order apparatus or the like has been input to the IF allocation unit 23.

[0064] In Step S2, the IF allocation unit 23 determines whether b.sub.target(t) {see Equation (3)} and 1.sub.target(t) {see Equation (4)} of the IF expansion or IF connecting destination change are unknown (known), in the total traffic characteristics b'.sub.n(t) of the IF group in accordance with the resource allocation request.

[0065] In a case in which the determination result is unknown (Yes), the IF allocation unit 23 determines whether IF groups with no occurrence of any packet loss are present in a unit time from among all the IF groups a to n in the transfer apparatus 10C in Step S3.

[0066] In a case in which the IF groups with no occurrence of any packet loss are present as the determination result (Yes), the IF allocation unit 23 selects an IF group n with the longest non-occurrence time of the buffering B.sub.n from among the IF groups with no occurrence of any loss in Step S4. In other words, the IF allocation unit 23 selects an IF group with the smallest total traffic characteristics b.sub.n(t) that are the total value of the burst occurrence amounts b.sub.i(t) of Equation (1) above. The selection is made by the IF allocation unit 23 comparing the information regarding whether the burst occurs stored in units of the IF groups in the storage unit.

[0067] A calculation equation of the buffering non-occurrence time B.sub.n in the aforementioned selected IF group n is represented by Equation (6) below when a function f(x) that is Equation (5) below is defined.

[00003]$\begin{array}{cc}\left[\mathrm{Math}.3\right]& \\ f\left(x\right)=\{\begin{array}{cc}1& \left(x=0\right)\\ 0& \left(x\ne 0\right)\end{array}& \left(5\right)\\ \left[\mathrm{Math}.4\right]& \\ B_n=\int f\left(b_n^{\prime }\left(t\right)\right)\mathrm{dt}& \left(6\right)\end{array}$

[0068] Next, in Step S5, the IF allocation unit 23 performs IF allocation designated through the resource allocation request on the IF group selected in Step S4.

[0069] On the other hand, it is assumed that no IF groups with no occurrence of any loss are present in the unit time (No) as the determination result in Step S3, in other words, it is assumed that losses have occurred in all the IF groups a to n. In the case in which the determination is No. the IF allocation unit 23 selects an IF group (assumed to be the IF group n) with a minimum number of occurrences of the loss, in other words, the IF group n with the longest loss non-occurrence time L.sub.n, from among all the IF groups a to n in Step S6. The IF allocation unit 23 performs the IF allocation on the selected IF group n in Step S5.

[0070] A calculation equation of the loss non-occurrence time L.sub.n in the aforementioned selected IF group n is represented by Equation (7) below when a function f(x) that is Equation (5) above is defined.

[00004]$\begin{array}{cc}\left[\mathrm{Math}.5\right]& \\ L_n=\int f\left(l_n^{\prime }\left(t\right)\right)\mathrm{dt}& \left(7\right)\end{array}$

[0071] Here, integral intervals of Equations (6) and (7) above, that is, times as targets of the calculation may be set to any values. The reasons for setting the times B.sub.n and L.sub.n in Equations (6) and (7) will be described. Commonly, a case in which burst has occurred and buffering has been performed can be regarded as a symptom of a loss even if no packet loss has occurred. The present invention is thus designed such that, in a case in which an IF group with the most excellent traffic characteristics is selected from IF groups with no occurrence of any loss, an IF group on which buffering has not been performed that much, that is, an IF group that still has enough time until a loss occurs is selected.

[0072] Next, in a case in Which the determination result is “known” rather than “unknown” (No) in Step S2 described above, the estimation unit 22 performs resource estimation processing on all the known IF groups a to n Step S7.

[0073] The resource estimation unit is adapted to estimate how the traffic characteristics of each of the IF groups a to n will change in a case in which IFs are expanded in the existing buffers 11a to 11n in or IF connecting destination change is performed. For example, after the IF n4 of the buffer 11n is expanded, or after the connecting destination of the IF n4 is changed, the total traffic characteristics b'.sub.n(t) that are a total value of the burst occurrence amount b.sub.i(t) of each of the IF groups a to n are represented by Equation (3) above. Further, the total traffic characteristics l'.sub.n(t) that are a total value of the loss occurrence amounts 1.sub.i(t) of each of the IF groups a to n are represented by Equation (4) above.

[0074] After such resource estimation processing, the IF allocation unit 23 determines whether IF groups with no occurrence of any packet loss are present or whether IF groups with no occurrence of any loss are present among the groups after the IFs are expanded or the IF connecting destination change is performed, in a unit time from among the IF groups a to n of the estimated traffic characteristics in Step S8.

[0075] In a case in which the IF groups with no occurrence of any packet loss or the IF groups with no occurrence of any loss among the groups after the IFs are expanded or the IF connecting destination change is performed are present as a determination result (Yes), the IF allocation unit 23 selects the IF group n with the longest buffering non-occurrence time B.sub.n from among the IF groups with no occurrence of any loss in Step S9. The IF allocation unit 23 performs the IF allocation on the selected IF group n in Step S5.

[0076] On the other hand in a case in which no IF groups with no occurrence of any loss are present, in other words, in a case in which losses have occurred in all the IF groups a to n (No) in the unit time as the determination result in Step S8 above, the IF allocation unit 23 selects the IF group n with a minimum number of occurrences of the loss, in other words, the IF group n with the longest loss non-occurrence time L.sub.n from among all the IF groups a to n in Step S10. The IF allocation unit 23 performs the IF allocation on the selected IF group n in Step S5.

Effects of Embodiment

[0077] Effects of the resource allocation processing performed by the transfer apparatus 10C according to this embodiment will be described.
The transfer apparatus 10C has the plurality of buffers 11a to 11n that are an identical number with the number groups a to n in which the plurality of packet transfer IFs a1 to n4 are divided into a smaller number of groups than the number of IFs, that mount the IFs a1 to 4, b1 to b4, . . . , n1 to n4 in units of groups, and that have buffer capacity defined in accordance with the number of mounted IFs. Packet transfer is performed to and from a network via the IFs of each of the buffers 11a to 11n, and when the traffic amount at the time of the packet transfer exceeds the maximum transfer capacity of the IFs, packets corresponding to the exceeding traffic amount are buffered in the buffers. Such a transfer apparatus 10C is configured to have features as described below.

[0078] (1) The transfer apparatus 10C includes the IF allocation unit 23. The IF allocation unit 23 is configured to select, in a case in which, from among all the IF groups in the transfer apparatus 10C, the IF groups in which any loss indicating packet discarding does not occur during the packet transfer in the IFs for a unit time are present, an IF group with the longest non-occurrence time of the buffering from among the IF groups with no occurrence of any loss and perform IF allocation of allocating the traffic of the packets to the IFs in the selected IF group.

[0079] With this configuration, it is possible to allocate IFs to be used in accordance with the buffers such that no packet loss occurs, in a case in which the transfer apparatus 10C that performs the packet transfer includes as many buffers with the grouped IFs mounted in units of groups thereon as the number of groups.

[0080] (2) The aforementioned IF allocation is the processing of allocating the traffic to the IFs after the preprocessing is executed. The preprocessing is any one of the IF expansion of bringing the unused IFs mounted on the buffer of the selected IF group into a used state, IF connecting destination change of changing the IFs connected to the network to the IFs of another buffer, and IF expansion/reduction of increasing or reducing the IFs in use in the selected buffer.

[0081] With this configuration, it is possible to allocate IFs to be used in accordance with the buffers, which are targets of the IF allocation on which the preprocessing that is any of the IF expansion, the IF connecting destination change, and the IF expansion/reduction has been performed.

[0082] (3) The transfer apparatus 10C further includes the management unit 21. The management unit 21 detects whether a burst occur, which is occurrence of burst traffic when the traffic amount at the time of the packet transfer in the IFs exceeds the maximum transfer capacity of the IFs and stores the detected information regarding whether the burst occurs in a storage unit in units of the IF groups in association with the time information regarding whether the burst occurs. Also, the management unit 21 performs the processing of detecting whether the loss occurs at the time of the packet transfer in the IFs and storing the detected information regarding whether the loss occurs in the storage unit in units of the IF groups in association with the time information regarding whether the loss occurs. At this time, the IF allocation unit 23 is configured to regard and select, when detecting the presence of the IF groups with no occurrence of any loss based on the information, which is stored in the storage unit, regarding whether the loss occurs, an IF group with the minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as the IF group with the longest non-occurrence time of the buffering, based on the information regarding whether the burst occurs.

[0083] With this configuration, it is possible to regard and select the IF group with the minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as the IF group with the longest non-occurrence time of the buffering, based on the information regarding whether the loss occurs and the information regarding whether the burst occurs, with which the time information acquired by the management unit 21 is associated. Calculation for the selection can be achieved with a simple calculation equation because an algorithm for the selection is simple. It is thus possible to perform the IF allocation such that a loss can be prevented in advance with the simple calculation when the IF allocation is performed.

[0084] (4) The IF allocation unit 23 is configured to perform, in a case in which, from among all the IF groups in the transfer apparatus 10C, the IF groups in which a loss does not occur during the packet transfer in the IFs for a unit time are not present, the IF allocation by selecting an IF group with the minimum number of occurrences of the loss from among all the IF groups.

[0085] With this configuration, it is possible to allocate IFs to be used in accordance with the buffers such that a packet loss is minimized.

[0086] (5) The transfer apparatus 10C further includes the estimation unit 22. The estimation unit 22 estimates the information regarding whether the burst occurs and the information whether the loss occurs, with which the aforementioned time information is associated, from the traffic characteristics of each of the IF groups after the preprocessing is executed. At this time, the IF allocation unit 23 is configured to regard and select, when detecting the presence of the IF groups with no occurrence of any loss from among the IF groups with the traffic characteristics estimated by the estimation unit 22, the IF group with the minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as the IF group with the longest non-occurrence time of the buffering.

[0087] With this configuration, it is possible to regard and select the IF group with the minimum number of occurrences of the burst from among the IF groups with no occurrence of any loss as the IF group with the longest non-occurrence time of the buffering when the presence of the IF groups with no occurrence of any loss is detected from among the IF groups with the traffic characteristics estimated by the estimation unit 22. Calculation for the selection can be achieved with a simple calculation equation because an algorithm for the selection is simple. It is thus possible to perform the IF allocation such that a loss can be prevented in advance with simple estimation calculation when the IF allocation is performed.

[0088] (6) The IF allocation unit 23 is configured to perform, in a case in which the presence of the IF groups with no occurrence of any loss is not detected from among the IF groups with the traffic characteristics estimated by the estimation unit 22, the IF allocation by selecting the IF group with the minimwn number of occurrences of the loss from among all the estimated IF groups.

[0089] With this configuration, it is possible to allocate IFs to be used in accordance with the buffers such that a packet loss is minimized from among the IF groups with the traffic characteristics estimated by the estimation unit 22.

[0090] In addition, a specific configuration can he appropriately changed without departing from the gist of the present invention.

REFERENCE SIGNS LIST

[0091] 10C Transfer apparatus [0092] 11a to 11n Buffer [0093] a1 to a4, b1 to b4, n1 to n4 IF (interface) [0094] 12B Transfer control unit [0095] 20 Resource allocation control unit [0096] 21 Resource management unit [0097] 22 Resource estimation unit [0098] 23 IF allocation unit