JPH1084387A - Method for deciding packet transfer route and node equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain better transfer quality by changing the priority of a 1st route whose priority has been placed lower and a 2nd route whose priority has been placed higher in the case that transfer quality of 1st communication information to be transferred with low priority does not meet 1st quality or the like. SOLUTION: A scheduling section 15 conducts cell transmission control in a way that object cells are transmitted immediately when the cells are stored in a CBR container queue 12 and cells stored in a UBR cell container queue 13 are transmitted so long as no cell is stored in the queue 12. Since there is a possibility that a large cell transfer delay is caused from a termination point of the UBR cell container queue 13 to another termination point, a transfer route for cells which are transferred by using a same route and requires the service with high priority is changed different from a transfer route of cells requiring the service with low priority in order to prevent the cell transfer delay requiring the service with low priority from being increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the setting of a virtual connection performed during information communication on an ATM (asynchronous transfer mode) network and the transfer of a packet as an information transfer unit between communication nodes such as routers. The present invention relates to a packet transfer route determination method and a node device for determining a transfer route of a packet performed in information communication via the like.

[0002]

2. Description of the Related Art When performing communication over an ATM network, after a virtual connection is set in advance between a transmitting node and a receiving node, information to be transferred is divided and converted into fixed-length information units called cells. And transfer. When setting up a virtual connection, it is necessary to determine in advance whether the service quality required by the cell traffic accommodated in the virtual connection can be satisfied, and if possible, to provide this service quality. After securing a sufficient amount of resources, this virtual connection is set (connection reception control). Here, the resource amount indicates, for example, a band amount.

[0005] Services provided by the ATM network for cell transfer include, for example, the following. CBR (Constant Bit Rate) service: A service that always provides cell transfer at a constant rate (PCR: Peak Cell Rate). A resource that satisfies the cell transfer at the PCR (possibly the allowable value of the cell delay fluctuation) declared by the user is secured on the virtual connection.

[0004] VBR (Variable Bit Rate) service: Average speed when viewed over a long period of time (SCR: Sustainab)
le Bit Rate), the maximum speed PC
R, a service that provides bursty cell transfer with a burst tolerance (BT: Burst Tolerance). A resource that satisfies the cell transfer in the PCR, SCR, and BT (in some cases, the permissible value of the cell delay fluctuation) declared by the user is secured on the virtual connection. Usually, the resource required for the cell transfer in the SCR is secured. To secure.

ABR (Available Bit Rate) service: Minimum cell rate (MCR)
Service that provides cell transfer by calculating the cell transfer rate that does not cause congestion from time to time based on congestion information in the network fed back from the network within a range not less than. Resources on the virtual connection that satisfy the cell transfer that does not fall below the MCR are secured.

[0006] UBR (Unspecified Bit Rate) service: A service that does not require any quality when transferring cells. No resources are allocated.

[0007] In an ATM node located in an ATM network and configured by an ATM switch or the like, when transferring a cell received from a plurality of different virtual connections, it is based on each service type provided by the virtual connection. , Cell transmission scheduling is performed. As a specific scheduling method, for example, there is a strict priority control method in which cells requesting stricter service quality are preferentially transmitted. In the above service example, if there is a cell received from the CBR connection in the ATM node, this cell (cell requesting the CBR service) is transmitted. If there is no cell received from the CBR connection, It checks whether or not there is a cell received from the VBR connection, and if so, sends the cell. Thereafter, in the order of the ABR service and the UBR service,
The cell requesting the service is transmitted. As a result, the transmission delay in the ATM node of the cell requiring the stricter service quality is reduced.

When the cell transfer scheduling described above is performed, a cell requesting a CBR service is transferred preferentially regardless of the presence or absence of a cell requesting another service in the ATM node. But VBR, AB
The cells requesting the R and UBR services are the cells requesting the services assigned higher priority than the ATM.
Only forwarded if not in the node. In particular, a cell requesting a UBR service is transferred only when no cell requesting the above three types of services having higher priority exists in the ATM node. Therefore, a cell requesting a VBR, ABR, or UBR service is affected by the arrival process of a cell requesting a service to which a higher priority is assigned, and is accumulated in an ATM node until a transfer opportunity is given. As a result, a cell transmission waiting delay occurs. In particular, the cell transmission waiting delay incurred by the cell requesting the UBR service becomes very large, and in some cases, the cell accumulation buffer in the ATM node may overflow. In the case of the VBR service, the resources required for cell transfer in the SCR described above are secured, so that the stored cells are transmitted in the long term, but the cells are transmitted at a speed higher than the SCR ( For example, it becomes impossible to transmit a cell using the PCR, which is the declared value. Similarly, in the case of the ABR service, the cell transfer in the MCR is reliably performed, but whether or not the cell transfer at a speed higher than that is possible depends on the transmission status of the CBR service or another cell requesting the VBR service. . UB
In the case of the R service, since network resources are not secured in the virtual connection, even a minimum cell transfer service guarantee is not given, and a huge cell transfer delay and cell loss are incurred. Can not provide.

[0009] The above problem also occurs when communication other than the communication through the ATM network is performed. For example, IP
(Internet Protocol) Guaranteed service (hereinafter abbreviated as G service) that guarantees an upper limit of end-to-end IP packet delay in an Internet environment in which communication is performed using an IP router that transfers packets. Although there is no delay value to be provided, a controlled load service (hereinafter abbreviated as CL service) that guarantees low-delay, low-discard IP packet transfer that does not depend on the presence or absence of network congestion, and does not guarantee any IP packet transfer Consider a case where three types of services, that is, BestEffort service (hereinafter abbreviated as BE service) are provided.

[0010] In the IP router on the Internet providing the above service, if there is an IP packet requesting the G service, the IP packet is transmitted prior to the IP packet requesting the CL service and the BE service, and the G service is transmitted. If the requested IP packet does not exist, it is checked whether there is an IP packet requesting the CL service next, and scheduling by strict priority control of transmitting the IP packet prior to the IP packet requesting the BE service is performed. In the case of providing, the IP packet requesting the CL service and the BE service can be transferred only when the IP packet requesting the service to which the higher priority is given does not exist in the router. IP packet transfer becomes impossible.

[0011]

As described above, in the conventional packet transfer, there is an overlap between a route through which a packet that can be transferred with low priority can pass and a route through which a packet to be transferred with high priority can pass. If there is, there is a possibility that the service quality of a packet that may be transferred with low priority for priority control may be significantly reduced. This problem is particularly noticeable when the full priority control is performed.

The present invention has been made in view of the above circumstances, and a route through which a packet to be transferred with high priority can pass is overlapped with a route through which a packet which can be transferred with low priority can pass. It is an object of the present invention to provide a packet transfer route determination method and a node device capable of avoiding a significant decrease in service quality of a packet which may be transferred with low priority due to the existence of the packet transfer route.

[0013]

Means for Solving the Problems The present invention (claim 1) provides:
A packet transfer route determination method for determining, from among a plurality of routes between node devices, a device to be used for transferring each communication information, between node devices that exchange and transfer packets, which is a transfer unit of communication information. A first route through which a packet for transferring the first communication information that may be transferred with priority may pass, and a second route through which a packet for transferring the second communication information to be transferred with high priority may pass, In a case where at least one physical line is shared, the transfer quality of the first communication information is set to a predetermined first communication information.
When the quality of the second communication information is not satisfied, the second route is changed under a condition that the transfer quality of the second communication information satisfies a predetermined second quality.

According to the present invention (claim 2), a node used for transferring and transmitting each communication information from a plurality of routes between the node devices for exchanging and transferring a packet which is a transfer unit of the communication information. A method for determining a packet transfer route, in which a candidate selected as a first route through which a packet for transferring first communication information that may be transferred with low priority is passed is set to a previously set high priority. In the case where at least one physical line is shared with a second route through which a packet for transferring the second communication information to be transferred can be passed, the candidate is stored in the first route while maintaining the second route.
When the expected transfer quality of the first communication information does not satisfy the first predetermined quality, the transfer quality of the second communication information satisfies the second predetermined quality. The second route is changed under a condition.

According to a third aspect of the present invention, there is provided a method for transmitting and receiving communication information from a plurality of routes between node devices which exchange and transfer a packet which is a transfer unit of communication information. A method for determining a packet transfer route to be determined, wherein when a first route through which a packet for transferring first communication information that may be transferred with a low priority can pass is already set, transfer is performed with a high priority. When determining a second route through which a packet for transferring the second communication information to be transmitted can pass, under the condition that the transfer quality of the second communication information satisfies a predetermined second quality. If the candidate selected as the second route shares at least one physical line with the first route, the first communication information when the candidate is set as the second route The results of examining the relationship between the first quality predetermined and expected transmission quality based on and determines the second route.

For example, if the expected transfer quality of the first communication information satisfies a predetermined first quality for the candidate selected as the second route, the second route is determined as the candidate. . If there is no route that finally causes the expected transfer quality of the first communication information to satisfy the predetermined first quality, a candidate whose expected transfer quality is closest to the first quality is determined. Determine as the second route.

The present invention (Claim 4) provides Claims 1 to 3
In the packet transfer route determination method according to any one of the above, at least one of the node devices is provided with the second
The information of the second route candidate which can satisfy the second quality of the transfer quality of the communication information is stored.

According to a fifth aspect of the present invention, in the packet transfer route determining method according to the first aspect, it is determined whether or not the transfer quality of the first communication information satisfies the first quality. Measuring the time required to transfer the first communication information using the first route between the node device transmitting the first communication information and the node device receiving the first communication information It is characterized by performing by doing.

According to a sixth aspect of the present invention, in the packet transfer route determining method according to the first aspect, the determination as to whether the transfer quality of the first communication information satisfies the first quality is made. (For example, in a router or a communication network located on the first route), the amount of resources (for example, the amount of bandwidth) already reserved for the transfer of the first communication information and the amount of resources on the first route. The process is performed based on a resource amount obtained by summing the remaining resource amount (a resource amount not secured by any communication information) and the arrival process of the first communication information.

According to the present invention (claim 7), in the packet transfer route determination method according to claim 2, it is determined whether or not the expected transfer quality of the first communication information satisfies the first quality. Is an observation value of information (e.g., traffic volume, traffic characteristics) related to traffic of the first communication information transferred on the first route that has been set, and has already been transmitted for the transfer of the first communication information. Performing based on the resource amount obtained by the sum of the secured resource amount (for example, the bandwidth amount) and the remaining resource amount on the first route (the resource amount not secured by any communication information). It is characterized by.

According to the present invention (claim 8), in the packet transfer route determination method according to claim 3, it is determined whether or not the expected transfer quality of the first communication information satisfies the first quality. Is an observed value or a declared value of information (for example, traffic volume, traffic characteristics) related to the traffic of the first communication information transferred on the first route that has been set, and the transfer of the first communication information. Therefore, based on the resource amount obtained by the sum of the resource amount (for example, the bandwidth amount) already reserved and the remaining resource amount (the resource amount not reserved by any communication information) on the first route. It is characterized by performing.

The present invention (claim 9) provides claims 1 to 8
In the packet transfer route determination method according to any one of the above, the route is a route in which a virtual connection is set according to a predetermined routing policy.

According to a tenth aspect of the present invention, there is provided a node device for selecting a route used for transferring a packet, which is a transfer unit of communication information, from a plurality of routes existing between the own node device and another node device. Means for examining the value of the transfer quality of the first communication information or the predicted value thereof which may be transferred with low priority, and a packet for transferring the second communication information to be transferred with high priority based on this value Means for controlling a route that can pass through (setting for an unset route or a necessary change for a preset route).

The present invention (claim 11) is the node device according to claim 10, wherein the route is a route in which a virtual connection is set according to a predetermined routing policy.

According to the present invention, when the service quality of a service having a low priority is not satisfactory, at least one of the physical lines passing through a transfer route of a packet requesting the service is passed. By changing the transfer route of a packet requesting a service with a higher priority, service opportunities given to a service with a lower priority and resources on a physical line are increased, so that it is expected to obtain better service quality. it can.

More specifically, according to the present invention, for example,
When the quality of service that the low priority CL service or BE service receives is not satisfactory, of the physical line on which a low priority VBR connection, ABR connection or UBR connection that accommodates a packet requesting this service is set. A service opportunity given to a low priority service by changing a setting route of a high priority CBR connection accommodating a packet requesting a high priority G service passing through at least one physical line. Since resources on the line increase, it is expected that better service quality will be obtained.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an example of a basic configuration of an IP packet communication network according to an embodiment of the present invention.

This communication network provides communication of IP packets between routers. A router A (121 in the figure) and a router B (122 in the figure) are connected via the ATM network 11, and After the IP packet is divided into cells and converted, the communication is performed using the ATM network. The ATM network 11 is composed of a plurality of ATM switches, and the router A-router B
There can be multiple routes between. Here, the ATM network 1
1 denotes ATM exchanges SWa to SWe (131 to 13 in the figure)
5). Router A is S
Wa and the router B are physically connected via an interface defined by the ATM layer, and the router B is physically connected via an interface defined by the ATM layer.

Here, the router A-SWa-SWb-SW
In the route of e-router B, 2 between router A and router B
It is assumed that one virtual connection (141 and 142 in the figure) is set. U in virtual connection 141
The BR service is provided.
BR services shall be provided. In the following,
A virtual connection that provides a UBR service is described as a UBR connection, and a virtual connection that provides a CBR service is described as a CBR connection.

The router A transmits an IP packet requesting the G service and an IP packet requesting the BE service to the router B. I requesting G service
The P packet is transferred to the router B by the CBR connection 142 after being converted into a cell by the router A, and
It is assumed that the IP packet requesting the service is transferred to the router B by the UBR connection 141 after being converted into a cell by the router A. The router B reassembles each cell transmitted through the CBR connection and the UBR connection into an IP packet, and transmits the packet to the destination address described in the IP packet.

In FIG. 1, router A (121), SW
a to SWe (131 to 135) are equipped with a scheduling function for controlling the transfer order of cells transmitted by the CBR connection (142) and cells transmitted by the UBR connection (141).

As a scheduling function, as shown in FIG. 2, it is general to realize strict priority control for assigning a high priority to cells belonging to a CBR connection. In this case, if there is a cell stored in the CBR cell accommodation queue 12, the cell is immediately transmitted and the CBR is transmitted.
Only when no cells are stored in the cell accommodation queue 12, the scheduling unit 15 performs cell transmission control so as to transmit the cells accumulated in the UBR cell accommodation queue 13. In general, the present scheduling function can be summarized as follows. "N types (n ≧
When the priority order is assigned to the different services in 2), the service given the i-th highest priority (1 ≦ i
≦ n) is allowed to be transferred only if there is no cell requesting the service with the j-th highest priority that satisfies j <i. When the strict priority control as shown in FIG.
Since the chances of transferring a cell requesting a service having a lower priority than other services, such as a BR service, are reduced, a cell transfer waiting delay in an ATM switch where scheduling based on strict priority control is performed. As a result, the cell transfer delay (the IP packet transfer delay from the router A to the router B in FIG. 1) from the terminal point of the UBR connection to the terminal point may become very large.

Therefore, in the present embodiment, in order to prevent a transfer delay of a cell requesting a service to which a low priority is given, a higher priority is given to a cell transferred using the same route. The transfer route of the cell requesting the service is changed so as to be different from the transfer route of the cell requesting the service given the lower priority.

An example of such a control procedure is shown in the flowchart of FIG. Appropriate when the transfer route of a cell requesting a service with a lower priority and the transfer route of a cell requesting a service with a higher priority are set by sharing at least one physical line. At a certain time interval, for example, a predetermined period, it is checked whether or not the transfer quality of a cell (or the transfer quality of an IP packet transferred by the cell) requesting a service given a low priority satisfies the required quality. (Step S11). And
If it is determined that they are not satisfied (step S1
2) Change the transfer route of the cell requesting the service with the higher priority (step S13).

However, a different route is a condition that a satisfactory transfer quality can be provided to a cell with a high priority, and when there is no other such route,
Do not change the route.

FIG. 4 shows a CBR connection 142 (router AS) established from router A to router B.
Wa-SWb-SWe-Router B) is connected to the CBR connection 1 through a route different from the UBR connection 141.
43 (router A-SWa-SWc-SWd-SWe-router B). 4 is performed when the cells transferred on the UBR connection 141 are SWa (131) and SWb (13).
In 2), it is possible to reduce a cell transfer waiting delay that is affected by a cell transferred on the CBR connection 142 to which a higher priority is assigned than the present cell. As a result, the end-to-end cell transfer delay value between the router A and the router B becomes smaller.

In the CBR connection reassignment example shown here, the IP packet transferred by using the UBR connection 141 between the router A and the router B (here, the IP packet requesting the BE service) is transferred. Router A finds quality unsatisfactory
If the router (or the router B) determines, the router A (or the router B) issues an instruction to change the CBR connection in the ATM network 11, and does not change the interface unit for transmitting and receiving data. That is, the route change of the IP packet transferred using the CBR connection is performed only at the ATM network level (that is, performed by resetting the CBR connection), and the routing change at the IP level is unnecessary.

As shown in the example of FIG. 4, the router A (or the router B) that determines that the IP packet requesting the BE service cannot obtain a satisfactory transfer quality receives the currently set CBR connection. Release 142,
AT to set up a new CBR connection 143
Notify the M network 11. At this time, the route for setting the new CBR connection is set to be a route determined in advance by router A (or router B).
A method for notifying the M network 11 or the router A (or router B) does not instruct the ATM network 11 of a new CBR connection setting route,
A method of determining a route based on the determination of the M network 11 is conceivable.

FIG. 5 is another example of the basic configuration of the IP packet communication network according to one embodiment of the present invention. The difference between the IP packet communication network of FIG. 5 and the IP packet communication network of FIG. 1 is that there are a plurality of ATM network candidates connecting the router A (421) and the router B (422). Here, it is assumed that two ATM networks a and b exist as a plurality of ATM network candidates. ATM network a (41
1) are ATM exchanges SWa to SWe (431 to 43)
5), and the ATM network b (412)
It is assumed that the switches SWf to SWi (436 to 439) are configured. The router A is connected to the SW in the ATM network a.
a, physically connected to the SWf in the ATM network b via an interface defined by the ATM layer,
Is SWe in ATM network a, SWi in ATM network b and AT
It is assumed that they are physically connected via an interface defined by the M layer.

Router A for performing IP packet transfer,
The operations of the router B and each exchange are basically the same as described above. Here, it is also assumed that the full priority control as shown in FIG. 2 is being performed.

Here, the router A-SWa-SWb-SW
In the route of the e-router B, a UBR connection 441 and a CBR connection 4
It is assumed that 42 has been set.

In the IP packet communication network shown in FIG. 5, when reassigning a virtual connection to which a high priority is assigned, a method for reassigning a virtual connection by closing the ATM network which is already set, A new method of setting a virtual connection in an ATM network different from the ATM network is considered.

In the former case, the virtual connection is switched as shown in FIG. 4, for example. In the following, in the latter case, switching of a CBR connection which is a virtual connection to which a higher priority is assigned will be described with reference to a specific example of FIG.

In FIG. 6, a CBR connection 442 (router A-
SWa-SWb-SWe-router B) is replaced by a CBR connection 443 (router A-SWf-SWg-SWi-router B) that passes through a route different from the UBR connection 441.

In this example, an IP packet transferred between the router A and the router B by using the UBE connection 441 (here, an IP packet requesting a BE service)
If router A (or router B) determines that the transfer quality experienced by the P packet) is unsatisfactory, the AT
CBR connection 442 set in M network a
Router A (or router B) issues an instruction to perform the reassignment to pass through the ATM network b. The above CBR
By performing connection reassignment, the IP packet transferred using the CBR connection is transmitted through A
Since the TM network is changed (ATM network a → ATM network b),
The router A and the router B change the interface for transmitting and receiving the IP packet. That is, the above CB
The route change of the IP packet transferred using the R connection is performed at each of the ATM network level (resetting of the CBR connection) and the IP level (change of the interface unit).

As shown in the example of FIG. 6, the router A (or router B) that has determined that the IP packet requesting the BE service cannot obtain a satisfactory transfer quality receives the currently set CBR connection. Notify ATM network a (411) to release 442,
ATM network b to set up a new CBR connection
Notify (412). At this time, the setting route of the new CBR connection is set to be the route determined in advance by the router A (or)
A method for notifying the M-network b (412) and the router A
In the (or router B), a method of determining the route based on the judgment of the ATM network (412) without instructing the setting route of the new CBR connection to the ATM network b (412) can be considered. Note that the router A (421), which is the transmitting side of the IP packet, sets the destination interface of the IP packet for requesting the G service transferred using the above CBR connection to the ATM.
The interface connected to the network a is changed to the interface connected to the ATM network b. Also, IP
In the router B (422), which is the packet receiving side, if necessary, the interface for receiving the IP packet is changed from the interface connected to the ATM network a to the interface connected to the ATM network b. Recognize that it has become.

As shown in FIG. 5, in an IP packet communication network in which there are a plurality of candidates for an ATM network connecting between routers, when a virtual connection to which a high priority is assigned is to be replaced, if possible, Closes the already set ATM network and replaces the virtual connection. If this is not possible, the currently set AT
It is preferable to control so as to newly set a virtual connection in an ATM network different from the M network.

Next, a CBR accommodating a cell with a high priority
An example of a method of selecting / determining a connection route will be described.
FIG. 7 is an example of a table showing route candidates for which a CBR connection can be set. This table can be held by the router A or the router B in FIG. 5, but FIG. 7 shows an example of a table held by the router A which is a source router of the IP packet.

In this table, "destination router", "route for which CBR connection can be set to destination router", "output port to be selected when performing transfer using each route", "minimum value when each route is adopted" Guaranteed Quality "(in the example of FIG. 7,
Information such as a maximum delay value required for IP packet transfer) is held in association with each other. In the example of FIG. 7, the minimum guaranteed quality is the maximum delay value required for IP packet transfer. The information stored in this table is, for example, the ATM Forum's PNNI (Private Network N
ode Interface).

When setting or resetting the CBR connection between the router A and the router B, the router A recognizes the candidate of the route of the CBR connection connecting the routers by using a table as shown in FIG. Then, a route that satisfies the packet transfer quality required in advance for the IP packet flow to be transferred using this CBR connection is selected / determined by referring to the minimum guaranteed quality information in this table, and the route is selected. CBR on top
Set up a new connection.

Since the setting of a new CBR connection reduces the remaining resources on the route where the present CBR connection is set, the minimum guaranteed quality information in this table is recalculated and updated. In addition, the already set CB
When releasing the R connection, the amount of remaining resources on the route where this connection is set is increased accordingly, so the minimum guaranteed quality information in this table is recalculated,
Update.

Next, several examples of a method of checking, at the transmitting router A, the transfer quality of an IP packet requesting a BE service, which is being transferred using a UBR connection, will be described. In the present embodiment, a case where the transfer quality is a packet transfer delay value will be described as an example.

As one of the methods for checking the transfer quality, a method is conceivable in which a control packet is generated by the router A, and the transfer quality received by the control packet is recognized by the router A via the router B. That is, as shown in FIG.
“Information indicating that it is a control packet” (751),
A control packet 7 at least including "address of transfer destination router" (752), "identifier of flow into which control packet is inserted" (753), and "transfer time ta" (754)
5 is periodically generated by the router A (721),
(722). At the router B that has received the control packet, the transfer time t
The required time (tb-ta) required for packet transfer is calculated from a and the current time tb, and the required time is notified to the router A (76 in the figure). The router A that has received the required time determines whether or not the required time is a satisfactory value as the transfer delay value to be provided for the IP packet requesting the BE service. If this book U
C set on the same route as the BR connection
It operates to change the route of the BR connection. When executing this method, it is necessary to match the times measured by the router A and the router B.

As one of the transfer quality checking methods different from the method described above, a judgment is made based on the available bandwidth on the route where the UBR connection accommodating the IP packet requesting the BE service is set. There is a way to do it. In this method, the router A sends information on the free bandwidth (the bandwidth not secured by any virtual connection) in each link in the ATM network to which this route is connected via the physical interface, for example, PN
The information is periodically acquired using a routing protocol defined by the NI, and based on this information, the amount of free bandwidth on the route where the UBR connection is set is calculated. This is performed by determining whether or not the amount is appropriate for high-speed transfer of the IP packet accommodated therein.

Some examples of specific criteria are shown below. (1) If the average transfer rate of the IP packet requesting the BE service exceeds the bandwidth, the route of the CBR connection is changed. (2) If (100 × α)% value of the maximum transfer rate of the IP packet requesting the BE service exceeds the present bandwidth amount,
Change the route of CBR connection (however, 0 <
α <1, and α × (maximum transfer speed)> (average transfer speed)). (3) If the maximum transfer rate of the IP packet requesting the BE service exceeds the bandwidth, the route of the CBR connection is changed.

When requesting a higher-speed transfer of an IP packet requesting a BE service, one of the above-mentioned criteria may be used.
It is desirable to adopt (2) or (3). Also,
As the average transfer rate and the maximum transfer rate of the IP packet, a method using a value observed by the router A for a certain period of time, or a method using a value previously declared by the source of the IP packet may be used.

Next, FIG. 9 shows an example of a basic configuration of a router according to an embodiment of the present invention. This router (m-input n-output router) includes input ports 811 to 81m, an IP packet switching unit 82, output ports 831 to 83n, an output port selection unit 84, a CL / BE quality monitor unit 85, a G service /
It has a CBR connection route control unit 86 and a CBR connection output port / route candidate table 87. Each input port includes a cell receiving unit 8111 and a packet assembling unit 8112, and each output port includes a packet accumulation buffer 8311, a packet cellization unit 8312, a cell accumulation buffer 8313, a cell transmission server 8314, an ATM layer control unit. 8315.

The IP packet arriving at the router is sent to the IP packet switching unit 8 based on the flow to which the packet belongs.
At 2, the data is sent to the corresponding output port. When an IP packet arrives at the router in the form of an ATM cell, it is first received by the cell receiving section 8111 in the arriving input port, and after being converted from a plurality of ATM cells into an IP packet by the packet assembling section 8112. , And the same processing as described above is performed and sent to the output port.

At the output port, based on the service (G / CL / BE service) requested by the received IP packet, the packet is stored in a packet storage buffer 8311 that is physically and logically independent for each service. Insert packets,
The packet celling unit 8312 converts the data into a plurality of ATM cells again.

The converted ATM cell is used for a service (CBR / VBR (ABR) / UBR) at the ATM layer level.
Each service is inserted into a cell storage buffer 8313 which is physically / logically independent for each service, and is transmitted to the cell transmission server 8314.
Is sent according to the instruction. In this cell transmission server, CBR service, VBR (ABR) service, UB
Full priority control for transmitting cells in the order of the R service is realized.

The CL / BE quality monitor 85 monitors the service quality of an IP packet flow requesting a CL service or a BE service, determines whether or not a predetermined quality is obtained. G service / C
It requests the BR connection route control unit 86 to change the transfer route of the G service to which higher priority is given.

The following methods can be considered as the quality monitoring method. (1) Generate and transfer a control packet, measure the time required for transfer to the destination router, and determine whether or not a predetermined quality is satisfied based on this value. Specifically, the control packet 75 shown in FIG.
Inserted in the L buffer or BE buffer (at this time, the time of insertion into the buffer is described in this control packet), transferred to the destination router, and returned to the destination router. Is received by the CL / BE quality monitor unit 85, and a determination is made based on this value. (2) The amount of available bandwidth on the route in the ATM network to which the CL or BE service is transferred is calculated, and based on this value, it is determined whether or not a predetermined quality can be satisfied.
Specifically, the CL / BE quality monitor unit 85 periodically acquires information on the amount of available bandwidth in each physical link on the ATM network (executes a routing protocol defined by PNNI), and Based on the information, the amount of free bandwidth on the route where the virtual connection (VBR (ABR) connection or UBR connection) accommodating the service is set is calculated, and the determination is made based on this value.

The G service / CBR connection route control unit 86 determines whether the service quality provided for the CL service or the BE service notified from the CL / BE quality monitor unit 85 satisfies a predetermined quality. And if not satisfied, the IP requesting the G service
The setting route of the CBR connection accommodating the packet flow is changed. Specifically, P at each output port
FIG. 7 describes a plurality of route candidates created based on topology information in the ATM network to which each output port is connected, obtained by previously executing a routing protocol defined by the NNI. CBR as shown
Using the connection output port / route candidate table, the ATM selects a route different from the currently used route, and sets a CBR connection according to the selected route.
Make a request to the network. At that time, the newly selected CBR
If the connection setting route uses a port different from the current output port, this is notified to the output port control unit 84, and the routing information of the IP packet requesting the G service is changed.

In the following, under the condition that a CBR connection accommodating an IP flow requesting a G service to which a high priority has been given, an IP requesting a BE service to which a low priority has been given under the condition that the CBR connection has already been set. A method of determining a routing when a UBR connection accommodating a flow is newly set will be described with reference to FIGS.

An example of the control procedure in this case is shown in the flowchart of FIG. A transfer route of a cell requesting a service with a low priority to be newly used and a transfer route of a cell requesting a service with a preset high priority share at least one physical line. Is set, it is checked whether or not the predicted value of the transfer quality of the cell requesting the service given the low priority (or the transfer quality of the IP packet transferred by the cell) can satisfy the requested quality (step). S21). If it is determined that the service cannot be satisfied (step S22), the transfer route of the cell requesting the service with the preset high priority is changed (step S23). However, as a different route, it is a condition that satisfactory transfer quality can be provided to a cell with a high priority. If there is no other such route, the route is not changed.

In FIG. 10, an IP packet communication network similar to that of FIG. 1 is configured, and the router A-SWa-SW
The CBR connection 142 has already been set on the route of the b-SWe-router B. Here, when a new UBR connection is set, a CBR connection accommodating an IP flow requesting a G service has already been established on at least one of the physical lines through which the route for which this connection is to be set passes. If present, the UB
It is necessary to predict the service quality experienced by the IP flow requesting the BE service transferred on the R connection and determine whether or not the quality is satisfactory.

For example, in router A (121), this UB
The declared value of the transfer quality notified by the user for the IP flow to be transferred on the R connection, and each ATM exchange (SWa) to be passed through this UBR connection
(131), SWb (132), SWe (135)), the amount of bandwidth that can be used by this UBR connection is grasped, and each AT through which this UBR connection passes
Between M exchanges or between a router and an ATM exchange,
The bandwidth available for the UBR connection is compared with the declared value. If the bandwidth exceeds the declared value between all the ATM exchanges and between the router and the ATM exchange, the IP transferred by the newly set UBR connection. The flow judges that a satisfactory service can be obtained. And an IP requesting a G service with a higher priority.
The CBR connection accommodating the flow is maintained as it is.

On the other hand, between ATM exchanges and between routers and ATs
If there is a portion of the M exchanges where the above-mentioned bandwidth amount is lower than the declared value, it is determined that a satisfactory service cannot be obtained for the IP flow transferred by the newly set UBR connection, and a high priority is given. The CBR connection accommodating the IP flow requesting the G service is changed to a different route (however, it can provide a satisfactory service quality) by referring to the table shown in FIG.

FIG. 4 shows a CBR connection 142 (router A) already set up from router A to router B.
CBR connection 143 (router A-SWa-) passing through different routes through -SWa-SWb-SWe-router B
Switch to SWc-SWd-SWe-Router B) and create a new UBR connection 141 (Router A-SWa-SW)
b-SWe-router B) is shown.

When the virtual connection is switched, the method is described with reference to FIGS. 5 and 6 in addition to the method of switching the virtual connection by closing the ATM network which is already set as described above. As described above, a method of newly setting a virtual connection in an ATM network different from the currently set ATM network is also conceivable. Also in this case, if possible, the virtual connection is reconnected by closing the currently set ATM network, and if not possible, a new virtual connection is newly set in an ATM network different from the currently set ATM network. It is preferable to set.

The configuration of the router in this case is as follows.
Basically, it is the same as that shown in FIG. However, since a UBR connection accommodating an IP flow requesting a BE service to which a low priority is given is not set, the CL / BE quality monitor unit 85 compares the declared value with the bandwidth amount as described above. It is determined whether to change the transfer route of the G service to which a higher priority is given.

In the following, under the condition that a UBR connection accommodating an IP flow requesting a BE service with a low priority has been set, an IP requesting a G service with a high priority has been established. A method of determining a routing when a CBR connection accommodating a flow is newly set will be described with reference to FIG.

An example of the control procedure in this case is shown in the flowchart of FIG. At least one physical line is a candidate for a transfer route of a cell requesting a service with a preset low priority and a transfer route of a cell requesting a service with a high priority to be newly set. Is shared, it is checked whether or not the predicted value of the transfer quality of the cell requesting the service given the low priority (or the transfer quality of the IP packet transferred by the cell) satisfies the required quality (step). S31). If it is determined that the priority is not satisfied (step S32), the transfer route of the cell requesting the service with the higher priority is selected from other candidates (step S33).

In FIG. 12, an IP packet communication network similar to that of FIG. 1 is configured, and the router A-SWa-SW
The UBR connection 151 has already been set in the route of the b-SWe-router B. Here, when a new CBR connection is set, the setting route of this connection is determined by referring to a table as shown in FIG. 7, for example. It is necessary to estimate in advance how the quality of service suffered by the IP flow being transferred will be changed by newly setting this CBR connection, and determine whether or not the quality is satisfactory. There is.

For example, in the router A (121), first,
The current observation value of the traffic characteristic of the IP flow transferred on the UBR connection or the declared value notified by the user before the transfer of the IP flow, and each ATM exchange (SWa (13)
1), SWb (132), and SWe (135)) grasp the amount of bandwidth that can be currently used by this UBR connection. The UBR connection 15 is set on at least one of the physical lines through which the setting candidate route 152 of the CBR connection to be newly set passes.
1 exists, when the CBR connection is set on this setting candidate route, the bandwidth amount obtained by removing the bandwidth amount secured by the CBR connection is set to the corresponding A
It is calculated by the TM exchange (SWb, SWe in the example of FIG. 12). Based on the newly calculated bandwidth amount and the traffic characteristics, a predicted value of the service quality to be affected by the IP flow transferred by the UBR connection when the CBR connection is set on the setting candidate route is calculated. As a method of determining the predicted value of the quality, for example, between each ATM exchange or between the router and the ATM exchange, the amount of bandwidth that the UBR connection can use,
The transfer rate (for example, average transfer rate, maximum transfer rate, etc.) of the IP packet obtained as the traffic characteristic is compared, and the bandwidth exceeds the transfer rate between all ATM exchanges and between the router and the ATM exchange. If you have, UB
The IP flow transferred by the R connection determines that a satisfactory service can be continuously obtained. Then, this setting candidate route is determined as a route used for setting the CBR connection.

On the other hand, if there is a portion where the amount of bandwidth is lower than the transfer rate, it is determined that the IP flow transferred by the UBR connection cannot provide a satisfactory service, and the setting candidate of the CBR connection different from the above route is determined. A similar determination is made for the route.

Needless to say, if there is no UBR connection to be newly set in any of the physical lines passing through the setting candidate route of the CBR connection to be newly set, the above judgment is unnecessary.

If there is not finally a route whose bandwidth exceeds the transfer speed, a route whose bandwidth is closest to the transfer speed is selected. The configuration of the router in this case is basically the same as that shown in FIG. However, an IP requesting a G service with high priority
Since the CBR connection accommodating the flow is not set, the G service / CBR connection route control unit 86 does not perform the process related to the change of the route setting, but performs the process related to the new route setting.

As described above, (1) the transfer route of the cell requesting the service given the low priority and the transfer route of the cell requesting the service given the high priority share at least one physical line. (2) Transfer route of a cell requesting a service given a low priority to be newly used and transfer of a cell requesting a service given a preset high priority to be used Control in the case where a route is set by sharing at least one physical line; (3) a transfer route of a cell requesting a service given a low priority that has been set and a high priority that is to be newly set Although the control in the case where the transfer route candidates of the cell requesting the granted service share at least one physical line has been described,
The router may perform only one of the above three controls (1) to (3), or may perform any two or all three controls.

In the above, the embodiment in which the present invention is applied to an IP packet communication network environment in which routers are connected via an ATM network has been described.
The present invention is also applicable to an IP packet communication network environment in which routers are connected by a communication network different from an ATM network, such as a DI network.

FIG. 14 is an example of a basic configuration of an IP packet communication network different from those in FIGS. 1 and 5 according to an embodiment of the present invention. In this communication network, router A (921) and router 1 (923), router 2 (924), and router 3 communicate with each other via router 1, router 2 and router B (922) via communication network 1 (911). ) Via the communication network 2 (912) and between the router 3 and the router B via the communication network 3 (91).
3). Each router has a function of converting an IP packet to conform to a data format specified by a communication network to which the router is connected, and then transmitting the IP packet to the communication network, and a function of receiving from the communication network to which the router is connected. It has a function of converting data into an IP packet.

In FIG. 14, communication of the G service flow and the BE service flow between the router A and the router B is performed through the route of the router A-the communication network 1-the router 1-the communication network 2-the router B. Have been done. The route of the G service flow is indicated by 932, and the route of the BE service flow is indicated by 931. Also, it is assumed that each router performs packet transfer scheduling based on complete priority control, and assigns priorities in the order of G service, CL service, and BE service.

In the present embodiment, in order to prevent the quality of service suffered by an IP packet flow requesting a service to which a lower priority is assigned from being significantly degraded, a higher priority transferred using the same route is assigned. Transfer route of the IP packet flow requesting the requested service,
The route is changed to be different from the transfer route of the IP packet flow requesting the service to which the low priority is assigned.

An example of the control procedure in this case is as shown in the flowchart of FIG. It is low based on the current service quality obtained by actually transmitting the control packet, or the current service quality estimated from the available resources (available network bandwidth and buffer capacity) in the relay communication network and the relay router. IP requesting a service to which priority is assigned (BE service in FIG. 14)
It is determined whether or not the service quality of the packet flow satisfies a predetermined quality (for example, a current observed value of the traffic characteristics of the IP flow or a declared value notified by the user before the transfer of the IP flow) (step S1).
1) If the quality is not satisfactory (step S12), the service to which a high priority is assigned (FIG. 1)
In step 4, the route of the IP packet flow requesting the G service is changed under conditions that do not violate the service quality required by the present service (step S13).

For example, as shown in FIG. 15, in order to change the route 932 of the packet requesting the G service to the route 933 of the router A—the communication network 1—the router 3—the communication network 3—the router B, the router A Then, the transfer destination of the packet is changed from the router 1 to the router 3, and the router A instructs the router 3 to transfer the packet to the router B.

FIG. 16 shows an example of a basic configuration of a router different from FIG. 9 according to an embodiment of the present invention. Unlike the configuration of FIG. 9 in which transmission and reception of data in the router is performed only through the ATM layer, FIG. 16 illustrates a configuration example of the router when transmitting and receiving data from a communication network not limited to the ATM network.

The present router has basically the same configuration as the router shown in FIG.
The packet is received by the packet receiving / assembling unit 8113,
IP to output port specified by output port selection unit 84
A packet storage buffer 8 transferred by the packet switching unit 82 and logically or physically divided for each service.
After being accumulated at 316, the packet transmission server 831
At 7, the packet in the buffer is extracted based on the complete priority control, and output from the packet transmission unit 8318.
If data transmission / reception by IP packet is not possible in the communication network to which the router is connected, the received data packet is converted into an IP packet by the packet reception / assembly unit 8113, and the packet transmission unit 8318. , The IP packets to be transmitted are respectively converted into data packet formats defined by the communication network. The output port selection unit 84 determines the transfer destination output port of the G service according to the instruction from the G service transfer route control unit 861. The G service transfer route control unit 861 in the router A also notifies the relay router of the G service transfer route to the routers (routers 1 to 3 in FIG. 15) (8319 in the figure). The G service transfer route control unit lists the G service output port / route candidate table 871 based on the service quality of the IP packet flow requesting the CL service or the BE service notified from the CL / BE quality monitor unit 85. The transfer route of the IP packet flow requesting the G service is changed as necessary from the route candidates that have been set.

In FIG. 14, when the transfer route is changed, there is no change in the communication network connected on the router A side as described above, but as described above with reference to FIGS. 5 and 6. Alternatively, a method of reconnecting to a communication network different from the currently connected communication network can be considered. In this case, the router A changes the interface for transmitting and receiving the packet.

Also in the present embodiment, a request for a BE service to which a low priority is given is requested under the condition that an IP packet flow route for requesting a G service to which a high priority is given is already set. Also, when a route of an IP packet flow to be set is set, the route can be controlled by the same method as that described in the above embodiment in a similar case.

An example of the control procedure in this case is as shown in the flowchart of FIG. That is, the route of a packet requesting a service with a newly assigned lower priority and a route of a packet requesting a service with a preset higher priority share at least one physical line. If it is set, it is checked whether or not the predicted value of the transfer quality of the packet requesting the service given the low priority can satisfy the required quality (step S2).
1). Then, when it is determined that the priority cannot be satisfied (step S22), the route of the packet requesting the service with the preset high priority is changed (step S2).
3). However, as a different route, it is a condition that a satisfactory transfer quality can be provided to a packet with a high priority. If there is no other such route, the route is not changed.

The configuration of the router in this case is as follows.
Basically, it is the same as that shown in FIG. However,
Since the route of the IP packet flow requesting the BE service with low priority is not set, CL /
The BE quality monitor unit 85 compares the declared value of the transfer quality notified by the user with the amount of bandwidth available for the packet transfer of the lower priority, as described in the previous embodiment, so that the higher priority is determined. It is determined whether to change the transfer route of the given G service.

Also in the present embodiment, a request for a G service to which a higher priority has been given is requested under the condition that the route of an IP packet flow requesting a BE service to which a lower priority is given is already set. Also, when a route of an IP packet flow to be set is set, the route can be controlled by the same method as that described in the above embodiment in a similar case.

An example of the control procedure in this case is as shown in the flowchart of FIG. In other words, at least one physical line is a candidate for a route for a packet requesting a service with a preset low priority and a route for a packet requesting a service with a high priority to be newly set. Is shared, it is checked whether or not the predicted value of the transfer quality of the packet requesting the service given the low priority satisfies the required quality (step S).
31). If it is determined that the priority is not satisfied (step S32), the route of the packet requesting the service with the higher priority is selected from other candidates (step S33).

Of course, if there is no overlapping part in the physical line of the quantity route, the above judgment is unnecessary. If there is not finally a route for which the predicted transfer quality value satisfies the required quality, a route whose predicted transfer quality value is closest to the required quality is selected.

The configuration of the router in this case is as follows.
Basically, it is the same as that shown in FIG. However,
Since the route of the IP packet flow requesting the G service to which the high priority is given is not set, the G service transfer route control unit 861 does not perform the process related to the change of the route setting, but performs the process related to the new route setting. Perform processing.

Of course, in the present embodiment as well, only one of the above three types of control may be performed, or any two or all three controls may be performed. The present invention is not limited to the above-described embodiment, and can be implemented with various modifications within the technical scope.

[0097]

According to the present invention, when the transfer quality of the first communication information, which may be transferred at a low priority, does not satisfy or is predicted not to satisfy the predetermined first quality. A packet for transferring second communication information to be transferred with high priority that shares at least one physical line with a first route through which a packet for transferring first communication information that may be transferred with low priority may pass By changing the second route that can be passed through, the service opportunities provided for the packet transfer of the first communication information, which may be transferred with low priority, and the resources on the physical line increase, It can be avoided that the transfer quality of the packet transfer of the first communication information, which may be transferred, is greatly reduced, and it can be expected to provide better transfer quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of an IP packet communication network according to an embodiment of the present invention.

FIG. 2 is a view showing an example of a scheduling function according to the embodiment;

FIG. 3 is a flowchart illustrating an example of a packet transfer route determination process;

FIG. 4 is a diagram for explaining an example of a change in a setting route of a CBR connection;

FIG. 5 is a diagram showing another basic configuration of the IP packet communication network according to the embodiment of the present invention;

FIG. 6 is a diagram for explaining an example of a change in a setting route of a CBR connection;

FIG. 7 is a diagram showing an example of a CBR connection configurable route candidate table;

FIG. 8 is a view for explaining an example of a transfer quality checking method using a control packet;

FIG. 9 is a diagram showing a basic configuration of a router according to an embodiment of the present invention.

FIG. 10 is a diagram for explaining an example of a change in a setting route of a CBR connection;

FIG. 11 is a flowchart illustrating another example of the packet transfer route determination process.

FIG. 12 is a diagram for explaining an example of a change in a set route of a CBR connection;

FIG. 13 is a flowchart showing still another example of the packet transfer route determination process.

FIG. 14 is a diagram showing still another basic configuration of the IP packet communication network according to one embodiment of the present invention.

FIG. 15 is a diagram for explaining an example of a transfer route change of the G service.

FIG. 16 is a diagram showing another basic configuration of the router according to the embodiment of the present invention.

[Explanation of symbols]

11,71,411,412,911-913 ... ATM
Network 12: CBR cell accommodation queue 13: UBR cell accommodation queue 14: Scheduling unit 15: Sending units 121, 122, 421, 422, 721, 722, 9
21-925 ... Routers 131-135, 431-43
5,436-439,731,732,735 ... ATM
Exchanges 811-81m input port 82 IP packet switching section 831-83n output port 84 output port selection section 85 CL / BE quality monitor section 86 G service / CBR connection route control section 87 CBR connection output port / Route candidate table 8111 Cell receiving unit 8112 Packet assembling unit 8311 Packet storage buffer 8312 Packet cellizing unit 8313 Cell storage buffer 8314 Cell transmission server 8315 ATM layer control unit 861 G service transfer route control unit 871 G service output port / route candidate table 8113: packet reception / assembly unit 8316: packet storage buffer 8317: packet transmission server 8318: packet transmission unit

Claims (11)

[Claims] A packet transfer route determining method for determining, from among a plurality of routes between node devices, a device to be used for transferring each communication information between node devices that exchange and transfer packets, which is a unit of transfer of communication information. A first route through which a packet for transferring the first communication information which may be transferred at a low priority may pass, and a first route at which a packet for transferring the second communication information to be transferred at a high priority may pass. 2 is set by sharing at least one physical line. If the transfer quality of the first communication information does not satisfy a predetermined first quality, the second communication information Wherein the second route is changed under a condition that the transfer quality of the second route satisfies a predetermined second quality. 2. A packet transfer route determining method for determining, from among a plurality of routes between node devices, a device to be used for transferring each communication information, between node devices that exchange and transfer packets, which is a transfer unit of communication information. The candidate selected as the first route through which the packet for transferring the first communication information that may be transferred with low priority is passed is the second route to be transferred with high priority already set. A second route through which a packet transferring communication information can pass;
When at least one physical line is shared, when the candidate is set as the first route while maintaining the second route, the expected transfer quality of the first communication information is set to a predetermined first quality. When not satisfied,
A method for determining a packet transfer route, wherein the second route is changed under a condition that the transfer quality of the second communication information satisfies a predetermined second quality. 3. A packet transfer route determining method for determining, from among a plurality of routes between node devices, a device to be used for transferring each communication information, between node devices that exchange and transfer packets as a unit of transfer of communication information. When a first route through which a packet for transferring the first communication information that may be transferred with low priority has been set has already been set, the second communication information to be transferred with high priority is set. When determining a second route through which a packet to be transferred can pass, the transfer quality of the second communication information is selected as the second route under a condition that satisfies a predetermined second quality. In the case where the candidate shares at least one physical line with the first route, the expected transfer quality of the first communication information when the candidate is set as the second route is determined. The first packet transfer route determination method characterized by the results of examining the relationship between the quality based on determining the second route defined troduction. 4. A method according to claim 1, wherein at least one of said node devices holds information on said second route candidate which can satisfy said second quality in transfer quality of said second communication information. The method for determining a packet transfer route according to claim 1. 5. The transmission quality of the first communication information is the first communication information.
The determination as to whether or not the quality of the first communication information is satisfied is based on the first route using the first route between the node device transmitting the first communication information and the node device receiving the first communication information. 2. The packet transfer route determination method according to claim 1, wherein the method is performed by measuring a time required for transferring one communication information. 6. The transfer quality of the first communication information is the first communication information.
The determination as to whether or not the quality of the first communication information is satisfied is based on the resource amount obtained by the sum of the resource amount already reserved for the transfer of the first communication information and the remaining resource amount on the first route. 2. The method according to claim 1, wherein the method is performed based on an arrival process of the first communication information. 7. A determination as to whether or not the expected transfer quality of the first communication information satisfies the first quality is performed by the first communication information transferred on the first route that has been set. And the amount of resources obtained from the sum of the amount of resources already reserved for the transfer of the first communication information and the amount of residual resources on the first route. 3. The packet transfer route determination method according to claim 2, wherein 8. A determination as to whether or not the expected transfer quality of the first communication information satisfies the first quality, includes determining whether the expected transfer quality of the first communication information is the first communication information transferred on the first route that has been set. An observed value or a declared value of information related to the traffic of the first communication information, and a resource amount obtained by a sum of a resource amount already secured for transfer of the first communication information and a remaining resource amount on the first route. 4. The method according to claim 3, wherein the determination is performed based on the packet transfer route. 9. The packet transfer route determination method according to claim 1, wherein the route is a route in which a virtual connection is set according to a predetermined routing policy. 10. A node device for selecting, from a plurality of routes existing between its own node device and another node device, a route to be used for transferring a packet which is a unit of transfer of communication information, Means for examining the value of the transfer quality of the first communication information or its predicted value, and controlling a route through which a packet for transferring the second communication information to be transferred with high priority can pass based on the value. A node device comprising: 11. The node device according to claim 10, wherein the route is a route in which a virtual connection is set according to a predetermined routing policy.