JP2002261803A - Method of setting label switching path - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a band effectively utilizable through out a network by making the band sharable between a current path and a spare path or between spare paths. SOLUTION: In some case, sum of a required band C of newly set path LSP3 in a label requirement message LR 1 and a total D is a band containing an existing path LSP1 on the set channel of the path LSP3 exceeds a threshold value Th of the channel. At that time, a path which is commonly usable within the band, whose usable number in combination with other paths lowers a predetermined upper limit, and whose combination with the path LSP3 has a mode of connecting preparative path to preparative path or connecting working path to preparative path, is selected on the condition that the newly set path LSP3 is commonly usable within the band. The extracted existing path LSP1 is selected as the commonly usable path within the band, when the total B of the band assigned to these extracted existing path LSP1 exceeds the total C of the required band B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for setting a label switching path (LSP) which becomes a path for transferring data in a network to which a plurality of nodes are connected.

[0002]

2. Description of the Related Art As this kind of prior art, for example, a document "Constraint-Based LSP Setup using LDP" (draft
t-ietf-mpls-cr-ldp-04.txt, July 2000 Bilel Jamouss
i, et.al.). FIG. 19 is an MPLS showing an arrangement of label switching routers and a setting state of a label switching path used for explaining the label switching path setting method shown in the prior art.
It is a network configuration diagram of a (MultiProtocol LabelSwitching) domain. In FIG. 19, R1 to R6
Denotes label switching routers that become nodes, and LSP1 to LSP3 denote label switching paths, respectively. 20 and 21 show LSPs respectively.
3 is a control sequence for setting the label switching path No. 3, in which FIG. 20 shows an example of successful setting, and FIG. 21 shows an example of unsuccessful setting. 20 and 21
, LR indicates a label request message, LM indicates a label message, and Notify indicates a notification message.

[0003] Now, in FIG. 19, as a starting point the label switching router R5, LSP1 to endpoint label switching router R6 via a label switching router R2 and label switching routers R3 is set, also label switching router R6 It is assumed that an LSP2 starting from is set up and ending at the label switching router R4 via the label switching router R3. From this state, the label switching router R1 and the label switching router R3 are connected to the network starting from the label switching router R1.
The procedure for setting the LSP3 having the label switching router R4 as the end point via the LSP3 will be described.

As shown in FIG. 20, first, the label switching router R1 which is the starting point of the LSP3 transmits a label request message LR1 to the relay label switching router R2. Upon receiving the label request message LR1, the relay label switching router R2 compares the required bandwidth and the required QoS class information included in the message LR1 with the available bandwidth on the path from the label switching router R2 to the label switching router R3, It is determined whether LSP3 can be set.

[0005] If the available bandwidth is insufficient, the path setting priority included in the label request message LR1 and the path maintenance priority of the LSP1 already existing on the path from the label switching router R2 to the label switching router R3. Compare with

If the path maintenance priority of the LSP1 is lower than the path setting priority of the label request message LR1, the sum of the bandwidth allocated to the LSP1 and the free bandwidth is calculated, and the sum is calculated with the label request message LR1. And the required bandwidth. If the sum of the bandwidth allocated to LSP1 and the available bandwidth is larger than the required bandwidth of the label request message LR1, determine the LSP1 bandwidth stealing, determine that LSP3 can be set, and send the label switching router R3 On the other hand, the label request message L
R2 (message content is required bandwidth, required QoS
(Same for the class information), and further sends a notify A-1 for notifying the bandwidth stealing to the label switching router R5 serving as the starting point of the LSP1.

[0007] Similarly, the label switching router R3 also
When the label request message LR2 is received from the label switching router R2, the requested bandwidth and the required QoS class information included in the message LR2, and the label switching router R3 sends the label request message
Is compared with the free bandwidth on the route toward the router, and if the free bandwidth is insufficient, the path setting priority included in the label request message LR2 and the label switching router R3
From the LSP2 that already exists on the path from the LSP2 to the label switching router R4. L for the path setting priority of the label request message LR2
If the path maintenance priority of SP2 is low, the sum of the bandwidth allocated to LSP2 and the free bandwidth is calculated, and this is compared with the required bandwidth of label request message LR2.
LSP for the requested bandwidth of label request message LR2
If the sum of the band allocated to the LSP2 and the vacant band is large, LSP2 band preemption is determined and LS
Judging that P3 can be set, the label switching router R
4 transmits a label request message LR3.
Further, the label switching router R3 transmits a notify A-2 for notifying the preemption of the band to the label switching router R6 serving as the starting point of the LSP1.

[0008] Upon receiving the label request message LR3, the label switching router R4 sets a valid label value LA between the label switching router R3 and the label switching router R4 in the label message LM1, and transmits the label message LM1 to the label switching router R3. I do. Upon receiving the label message LM1, the label switching router R3 sets a valid label value LB instead of the label value LA between the label switching router R2 and the label switching router R3, and sends the label message LM2 to the label switching router R2. Send. The label switching router R2 similarly sets a valid label value LC between the label switching router R1 and the label switching router R2 instead of the label value LB, and transmits a label message LM3 to the label switching router R1.

As a result, the setting of LSP3 is completed, the label value LC between the label switching router R1 and the label switching router R2, the label value LB between the label switching router R2 and the label switching router R3, and the label value LB. Data can be transferred between the switching router R3 and the label switching router R4 using the label value LA.

[0010] The label switching router R5 is, notif
When y A-1 is received, LSP1 is released once, and when label A-2 receives notify A-2, LSP2 is released once, which is not shown in the figure.
Reconfigure the label switching path via each of the transit label switching routers.

[0011] As shown in FIG. 21, the relay label switching router R2 transmits a label request message LR1.
Is received, the available bandwidth on the path from the label switching router R2 to the label switching router R3 is insufficient, and the sum of the bandwidth allocated to the LSP1 and the available bandwidth is the sum of the label request message LR1 If the bandwidth is smaller than the requested bandwidth, the path setting priority included in the label request message LR1 and the label switching router R2
It determines that LSP3 cannot be set due to lack of bandwidth regardless of the result of comparison with the path maintenance priority of LSP1 existing on the route toward No.3, and sends Notify2 for notifying the label switching router R1 of path setting failure.

[0012]

As described above, according to the conventional label switching path setting method, when there is not enough free bandwidth on the path for which a new path is to be set, the priority is set higher than the setting priority of the new path. the bandwidth of the existing path on the lower same route path maintains priority is intended to be allocated transferred to the new path. For this reason, even if the new path is a backup path that does not flow traffic during normal times,
Alternatively, even if the existing path on the same route is a protection path and the new path is a working path, the bandwidth cannot be shared, that is, the bandwidth cannot be shared between the working path and the protection path or between the protection path and the protection path. However, there is a problem that the bandwidth cannot be effectively used in the entire network because it cannot be shared.

The present invention has been made in view of the above-mentioned circumstances, and makes it possible to share a band between a working path and a protection path or between a protection path and a protection path, thereby enabling effective use of the band throughout the network. It is an object of the present invention to obtain a label switching path setting method which can be set as follows. Also,
When setting a new label switching path, the number of bandwidth sharing paths must be equal to or greater than a predetermined threshold, or a relay route whose ratio of the unshared bandwidth to the maximum available bandwidth of the target path is less than a predetermined threshold should be settable. Accordingly, it is an object of the present invention to obtain a label switching path setting method capable of selecting a path in consideration of the intensity of band sharing.

[0014]

In order to achieve the above object, a label switching path setting method according to the present invention provides a method for setting a label switching path according to an information element included in a label request message transmitted from an upstream node to a downstream node. The upstream node secures the bandwidth, allocates a label to be used for data transfer, and returns a label message containing the allocated label information to the upstream node, so that a label can be placed between the upstream node and the downstream node. In the method for setting a switching path, the sum of the requested bandwidth of the newly set path indicated in the label request message and the total bandwidth of the existing paths already existing on the set path of the newly set path is determined for the path. When a predetermined threshold value set in advance is exceeded, on the condition that the newly set path can share a band. Among the existing paths, the bandwidth can be shared, and the number of bandwidth sharing with other paths is less than a predetermined upper limit, and the combination with the newly set path is a protection path and a protection path or a working path and a protection path. Extracting a path that is to be a path, and selecting the extracted existing path as a shared bandwidth path when the total allocated bandwidth allocated to the extracted existing paths is equal to or greater than the required bandwidth of the newly set path. And

According to the present invention, the sum of the required bandwidth of the newly set path and the total bandwidth of the existing paths already existing on the set path of the newly set path is determined by the predetermined bandwidth set for the path. Even if the threshold value is exceeded, the bandwidth can be shared among the existing paths, and the number of bandwidth sharing with other paths is set to a predetermined value, provided that the newly set path can share the bandwidth. If the combination with the newly set path is below the upper limit value and the combination of the newly set path becomes the backup path and the backup path or the working path and the backup path, the total of the bandwidths allocated to the extracted existing paths is calculated by the new setting path. When the bandwidth exceeds the required bandwidth of the path, the extracted existing path can be selected as the bandwidth sharing path.

[0016] In the label switching path setting method according to the next invention, in the above invention, before the upstream node transmits the label request message, the path in which the bandwidth sharing number becomes equal to or more than a predetermined upper limit value is set. It is characterized in that a path relay route is set by excluding a route including the route in advance.

According to the present invention, a relay route can be set by excluding in advance a route including a path which is highly likely to be unable to set a path.

[0018] A label switching path setting method according to the next invention is characterized in that, in the above invention, information relating to the number of shared bandwidths of each node is included in the label request message or the label message and transmitted.

According to the present invention, it is possible to obtain information relating to the number of shared bandwidths of each node through a label request message or a label message required when setting a path.

[0020] A label switching path setting method according to the next invention is characterized in that, in the above invention, information relating to the bandwidth sharing number is notified at a predetermined cycle between the respective nodes for which the label switching path is set. I do.

According to the present invention, information relating to the number of shared bandwidths can be shared by all nodes for which a label switching path is set.

The label switching path setting method according to the next invention secures a band at the downstream node in accordance with an information element included in a label request message transmitted from the upstream node to the downstream node, and performs data transfer. By assigning a label to be used and returning a label message including the assigned label information to the upstream node, a method of setting up a label switching path between the upstream node and the downstream node,
The sum of the requested bandwidth of the newly set path indicated in the label request message and the total bandwidth of the existing paths already existing on the set path of the new set path is equal to a predetermined threshold value preset for the path. If it exceeds, on the condition that the newly set path can share the bandwidth, the bandwidth of the existing path can be shared, and the ratio of the unshared bandwidth to the maximum available bandwidth on the path is a predetermined predetermined value. A threshold value or more, and a combination of the newly set path and a backup path and a backup path or a working path and a backup path are extracted, and the sum of the allocated bandwidths assigned to the extracted existing paths is calculated by the newly set path. When the bandwidth exceeds the required bandwidth, the extracted existing path is selected as a shared bandwidth path.

According to the present invention, the sum of the required bandwidth of the newly set path and the total bandwidth of the existing paths already existing on the set path of the newly set path is determined by a predetermined value set in advance for the path. Even if the threshold value is exceeded, the bandwidth of the existing path can be shared, and the ratio of the unshared bandwidth to the maximum available bandwidth on the path can be determined on the condition that the newly set path can share the bandwidth. A combination of a backup path and a backup path or a working path and a backup path in which the combination with the newly set path becomes equal to or more than a predetermined threshold value set in advance is extracted, and the total of the allocated bandwidths allocated to the extracted existing paths is extracted. When the bandwidth exceeds the required bandwidth of the newly set path, the extracted existing path can be selected as the bandwidth sharing path.

[0024] In the label switching path setting method according to the next invention, in the above invention, the ratio of the unshared bandwidth to the maximum available bandwidth is set to a predetermined threshold value before the upstream node transmits the label request message. The method is characterized in that a route that is less than the predetermined route is excluded in advance and a relay route of the path is set.

According to the present invention, it is possible to set a relay route by excluding in advance a route having a high possibility that a path cannot be set.

In the label switching path setting method according to the next invention, in the above-mentioned invention, the information relating to the ratio of the unshared band to the maximum usable band on the path between the nodes to which the label switching path is set is predetermined. The notification is performed in a cycle of

According to the present invention, information relating to the ratio of the unshared bandwidth to the maximum available bandwidth on the path can be shared by all nodes for which the label switching path is set.

[0028] In the label switching path setting method according to the next invention, in the above-mentioned invention, when the total allocated bandwidth allocated to the extracted existing path is less than the required bandwidth of the newly set path, the label allocation path is allocated. When the sum of the total bandwidth and the free bandwidth existing on the setting path of the newly set path exceeds the required band of the newly set path, and when the following conditions are satisfied, the extracted existing path is selected as the shared bandwidth path. It is characterized by doing. D + CB−Th, where D is the total bandwidth of the existing paths already existing on the setting path of the newly set path, C is the requested bandwidth of the newly set path, B is the total allocated bandwidth assigned to the extracted existing path, T
h is a preset threshold value for the set route of the newly set path

According to the present invention, even when the total allocated bandwidth allocated to the extracted existing path is less than the required bandwidth of the newly set path, the total of the allocated bandwidth and the newly set path When the sum of the available bandwidth existing on the set route exceeds the required bandwidth of the newly set path and satisfies the above-described predetermined condition, the extracted existing path can be selected as the shared bandwidth path.

[0030] In the label switching path setting method according to the next invention, in the above invention, the node that has selected the bandwidth sharing path adds identification information of the selected bandwidth sharing path and sends a label request message to the downstream node. On the other hand, the downstream node receiving the label request message determines the origin node of the bandwidth sharing path from the identification information, and notifies the origin node that the bandwidth sharing state has been reached. .

According to the present invention, it is possible to grasp whether or not the bandwidth sharing setting and the shared bandwidth are actually used at the originating node.

In the label switching path setting method according to the next invention, in the above invention, when the working / standby state of the path changes, a node on the path of the path is notified of the switching of the working / standby state. It is characterized by doing.

According to the present invention, since a change in the state of the path is notified, it is possible to control each node in accordance with the change in the state of the path.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a label switching path setting method according to the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a sequence diagram showing a control message flow of the label switching path setting method according to the first embodiment of the present invention. In FIG. 1, LR is a label request message, LM is a label message, shared-notify is a bandwidth sharing setting notification message, s
tate-notify is a path status notification message, and PR is a bandwidth sharing status notification message.

FIG. 2 is a diagram showing a format of the label request message LR shown in FIG. In FIG.
4 is a message header, and 41 is a header indicating that it is a label request message. 5 is a message ID field used to identify messages of the same type, 6 is a traffic parameter field that sets the required bandwidth of the path to be set, and 7 is L that identifies the path to be set.
SPID field. The LSPID field 7 includes an IP address 71 of the source edge router of the message and an ID 72 unique to the source edge router. Reference numeral 8 denotes a preemption field indicating a setting / maintenance priority of a path, and includes a setting priority field 81 and a maintenance priority field 82. 9
Is a Diffserv PHBscheduling class for displaying the QoS class conforming to the diffserv model to be attached to the path
Field 10 is explicit rout that describes route information
An e field, 11 is a path bandwidth sharing attribute field indicating whether or not the path can share the bandwidth, 12 is a path type field indicating whether the path at the time of initial setting is working or spare, and 13 is an existing path sharing the bandwidth. This is a shared LSPID field that stores the LSPID.

FIG. 3 shows the label message L shown in FIG.
It is a figure showing the format of M. In FIG. 3, 15
Is a label field for storing a label value. FIG.
Is the bandwidth sharing setting notification message shared-
It is a figure showing the format of notify. Reference numeral 17 denotes a shared indication field indicating a bandwidth sharing status, and a shared status field 1 indicating a bandwidth sharing status for each path.
71 and LSPI indicating the LSPID of the band sharing target path
D field 172.

FIG. 5 is a diagram showing the format of the bandwidth sharing status notification message PR shown in FIG. 19 is a band common display field indicating band shared state, shared preemption status indicating the bandwidth shared state of each path
A field 191 and an LSPID field 192 indicating the ID of the path corresponding to the sharedpreemption status field 191 are included. FIG. 6 is a diagram showing a format of the path state notification message state-notify shown in FIG. Reference numeral 21 denotes a state notification field indicating whether the path is active or standby, and includes a path status display field 211 and an LSPI indicating the LSPID of the target path in the path status display field 211.
D field 212.

FIG. 7 is a diagram showing an algorithm for selecting whether or not a path can be set and selecting a shared bandwidth path when the relay label switching node receives the new label request message LR. Figure 8 is a sequence diagram showing a modification of the control message flow shown in FIG.

The label switching path setting method according to the first embodiment will be described below in accordance with the control message flow shown in FIG. 1 and the algorithm shown in FIG. In addition,
Placement of label switching routers, and setting the state of the label switched path is the same as FIG. 19. That is, the LSP1 is set starting from the label switching router R5 and ending at the label switching router R6 via the label switching router R2 and the label switching router R3.
It is assumed that an LSP2 having the label switching router R4 as an end point is set via the router. A procedure for setting an LSP3 having the label switching router R1 as a starting point and the label switching router R4 as an end point via the label switching router R2 and the label switching router R3 from this state will be described.

First, in order to set LSP3 in a state where LSP1 and LSP2 have already been set, the originating label switching router R1 sets the label switching router R2.
Sends a label request message LR1 to the Upon receiving the label request message LR1, the label switching router R2 sends the traffic parameter field 6
Requested bandwidth shown in explicit route field 10
Of the next-stage label switching router, the bandwidth sharing attribute shown in the path bandwidth sharing attribute field 11, and the path type at the time of initial setting shown in the path type field 12 (discrimination of working / standby).

Next, the label switching router R2
Is an explicit name included in the label request message LR1.
The setting route of LSP3 is determined from the next-stage label switching router address in the route field 10 and this LS
The path already existing on the set path of P3 (LS in FIG. 19)
It is checked whether or not the sum of the allocated bandwidth total D of P1) and the required bandwidth C included in the label request message LR1 exceeds a predetermined threshold Th preset for the route (step). S101). If the sum of the allocated bandwidth D and the required bandwidth C of the existing path does not exceed the threshold Th, the path setting is accepted and the path is set on the LSP3 (in FIG. 19, the label switching router R3 and the label switching router R2 communicate with each other). (The path between the two), and allocates a bandwidth corresponding to the required bandwidth C, and transmits a label request message LR2 to the label switching router R3 (step S10).
2).

On the other hand, when the sum of the allocated bandwidth total D of the existing path and the required bandwidth C exceeds the threshold Th, the bandwidth sharing attribute of the path bandwidth sharing attribute field 11 included in the label request message LR1 is set to “ It is checked whether or not sharing is possible (step S103). If sharing is not possible, it is determined that the path cannot be set, and the process proceeds to step S105. In step S105, a Notify message is transmitted to the label switching router R1 that is the transmission source of the label request message LR1 due to lack of resources as a rejection factor (not shown in FIG. 1).

On the other hand, if the bandwidth sharing attribute is "shared", it is further checked whether or not the path type in the path type field 12 included in the label request message LR1 is a protection path (step S104). If it is a pass, the process proceeds to step S106, and if it is not a backup path, that is, if it is a working path, the process proceeds to step S112.

In step S106, the bandwidth sharing attribute is the bandwidth sharing attribute among the existing paths on the setting path of the LSP3 (the path between the label switching router R3 and the label switching router R2 in FIG. 19). A path whose bandwidth sharing setting number with the path is less than a predetermined upper limit value is extracted. On the other hand, in step S112, LS
On the set path of P3 (the path between label switching router R3 and label switching router R2 in FIG. 19)
Out of the existing paths, the path whose path status is spare, the bandwidth sharing attribute is bandwidth sharing, and the number of bandwidth sharing settings with other paths is less than a predetermined upper limit value is extracted. For example, in the configuration of FIG. 19, assuming that LSP3 is set as a backup path, LSP1 can share a band, and does not share a band with another path, the condition of step S104 becomes true (yes), Step S10
In step 6, this LSP1 is extracted.

Next, a combination of existing paths where the sum B of the bands assigned to the existing paths extracted in step S106 or step S112 (hereinafter simply referred to as extracted existing paths) is equal to or greater than the required band C of the label request message LR1. It is checked whether or not exists (step S107),
If not, the process proceeds to step S108. Step S1
08, the sum B of the bands assigned to the extracted existing path
There is a combination of existing paths in which the sum of the value and the value of an arbitrary free band on the set path of the LSP3 is equal to or more than the requested band C of the label request message LR1.
Check whether or not.

D + CB ≦ Th (1)

Here, in the above equation (1), CB is a value obtained by subtracting the shared band from the required band C, and represents a newly allocated band. The sum with the total D (D + CB), that is, the left side is
This indicates a new bandwidth used on the set path of LSP3. Therefore, if the above equation 1 is not satisfied in step S108, it is determined that the path cannot be set, and step S108 is determined.
Proceeding to 105, a Notify message is transmitted to the label switching router R1 with the lack of resources being a rejection factor.

On the other hand, in step S107, when there is a combination of existing paths in which the sum B of the bands allocated to the extracted existing path is equal to or more than the required band C of the label request message LR1, or in step S108, the above equation 1 is satisfied. In this case, the process proceeds to step S109. For example, if the sum of the required bandwidth C of LSP3 and the allocated bandwidth of LSP1 exceeds the threshold Th, and the bandwidth of LSP1 exceeds the required bandwidth C of LSP3, the condition of step S107 is true (yes). And step S
It will go to 109.

In step S109, the bandwidth sharing number of the existing path for performing bandwidth sharing is incremented, and the bandwidth sharing number of the newly set path for performing bandwidth sharing is set to 1. That is, the label switching router R2 increments the bandwidth sharing number of the LSP1 that has made the bandwidth sharing setting,
Further, the number of shared bands of LSP3 is set to 1. Thereafter, a bandwidth corresponding to [requested bandwidth C-shared bandwidth B] is allocated on the set path of LSP3 (in FIG. 19, a path between the label switching router R3 and the label switching router R2), and a label request is issued to the label switching router R3. The message LR2 is transmitted (Step S110). At this time, the LSPID of LSP1 is set in the field 13-a of the shared LSPID field 13 shown in FIG.

The label switching router R3, which has received the label request message LR2, determines whether to accept a path in accordance with the algorithm shown in FIG. 7, similarly to the label switching router R2. For example, as before, LS
If P3 is set as a backup path, step S10
If condition 4 is true (yes) and bandwidth sharing with another path is necessary (if the condition of step S107 is true (yes) or the condition of step S108 is true (yes)), it is on the same path as LSP3. If the LSP2 set in the (route between the label switching router R3 and the label switching router R4) can share the bandwidth and the number of shared bandwidths is less than the upper limit described above, this LSP2 is selected as the shared bandwidth path. Shared by the L label switching router R3
LSP to field 13-b of LSPID field 13
2 and set the label switching router R
Send to 4. At that time, the label switching router R3
Increments the bandwidth sharing number of LSP2 and sets the bandwidth sharing number of LSP3 to 1.

Upon receiving the label request message LR3, the label switching router R4 includes in the label message LM1, for example, a valid label value LA between the label switching router R3 and the label switching router R4.
Is transmitted to the label switching router R3. When the label switching router R3 receives the label message LM1, the label switching router R3 changes the label message LM2 to:
A valid label value LB is set between the label switching router R2 and the label switching router R3 instead of the label value LA, and this is set to the label switching router R2.
Send to The label switching router R2 similarly sets a valid label value LC between the label switching router R1 and the label switching router R2 instead of the label value LB in the label message LM3, and transmits this to the label switching router R1. . This allows
When the setting of LSP3 is completed, label switching router R
1 and a label value L between the label switching router R2.
C, using the label value LB between the label switching router R2 and the label switching router R3,
Data transfer becomes possible using the label value LA between the label switching router R3 and the label switching router R4.

In the process of setting up the label switching path described above, the label switching router R1, the label switching router R2, the label switching router R3, and the label switching router R4 each receive the label message LM when receiving the label message LM. The bandwidth sharing attribute, path type, and requested bandwidth of the LSP 3 read at the time of reception are held.

The label switching router R4 is
After receiving the label request message LR3, the shared LSPID field 13 of the label request message LR3
And if the LSPID is included, its LSPI
A bandwidth sharing setting notification message shared-notify is transmitted to the originating router of the path corresponding to D. For example, in the case of the first embodiment, since the LSPID of LSP1 is included in the field 13-a of the label request message LR3, the shared-notify 1 is transmitted to the label switching router R5 which is the originating router of LSP1. Since the LSPID of LSP2 is included in field 13-b, shared-notify2 is transmitted to label switching router R6 which is the originating router of LSP2.

In the shared-notify, as shown in FIG.
LSPID field 172 of shared bandwidth path and shared
The status field 171 is set. Therefore, share
LSP in LSPID field 172-a for d-notify 1
The LSPID field 172 is set in the shared status field 171-a and the "bandwidth sharing setting" is set in the shared status field 171-a.
Set the LSPID of LSP2 in -a and share
"Band sharing setting" is similarly set in the d status field 171-a. In this connection, when you remove the path of LSP3 it is, shared the shared-notify status field 171
May be set and transmitted to the label switching routers R5 and R6.

The LSPID is composed of the IP address 71 of the source edge router of the label request message LR and the unique ID 72 of the source edge router as shown in the LSPID field 7 of FIG. . Therefore, the IP address of the label switching router R5 that is the destination of the shared-notify 1 and the IP address of the label switching router R6 that is the destination of the shared-notify 2 are both the source edge router of the LSPID (= the path edge of the path). It can be derived from the IP address portion of the originating router). Also, shared indi
LSPID in list format in cation field 17
The reason why the path bandwidth sharing setting state can be stored is that the number of messages can be reduced by being able to simultaneously notify information of a plurality of paths whose path bandwidth sharing setting state has changed in one message. It is.

Next, the LS, which was a backup path at the time of setting,
The operation when P3 is switched to the working path will be described.

The label switching router R1, which is the originating router of the LSP3, has a path switching control function. When the LSP3 switches to the working path, as shown in FIG. 1, a path state notification message state-notify 1- a is transmitted to the label switching router R2. As shown in FIG. 6, the state-notify message includes a field 21 indicating the ID of the LSP whose path status has changed and its path status (path status). state-not
In ify 1-a, the ID of LSP3 is set in the LSPID field 212-a, and the path state “working” is set to p.
Set in the ath status field 211-a. Stat
L in list form in e notification field 21
The reason why the SPID and the path status can be stored is to reduce the number of messages by enabling information of a plurality of paths whose path status has changed at the same time to be notified by one message.

The label switching router R2 that has received the state-notify 1-a changes the path state of the LSP3 held therein from standby to working, and transmits state-notify 2-a to the label switching router R3. . The label switching router R3 similarly changes the path state of the LSP3 and transmits state-notify 3-a to the label switching router R4. Similarly, the label switching router R4 changes the path state of the LSP3.

The label switching router R1 further sends a band sharing status notification message P to the origin label switching router R5 of the LSP1 which is a band sharing path.
R1 is transmitted, and a band sharing status notification message PR2 is transmitted to the originating label switching router R6 of LSP2 which is a band sharing path. In this case, the label switching router R1 sends the bandwidth sharing status notification message P
I of the label switching router R5 that is the destination of R1
P address and bandwidth sharing status notification message PR2
The IP address of the label switching router R6 that is the transmission destination of the label message LM3
It is derived from the LSPID set in the LSPID field 13.

As shown in FIG. 5, the ID of the LSP whose path sharing state has changed is included in the bandwidth sharing state notification message PR.
And a shared bandwidth display field 19 for displaying the shared preemption status. In the bandwidth sharing status notification message PR1-a, the ID of LSP1 is set in the LSPID field 192-a, and sh
In the ared preemption status field 191-a, the path bandwidth sharing status “bandwidth sharing start” is set. In the bandwidth sharing status notification message PR2-a, the ID of the LSP2 is set in the LSPID field 192-a, and
In the red preemptionstatus field 191-a, the path bandwidth sharing status “bandwidth sharing start” is set. The reason that the LSPID and the path status can be stored in the list format in the bandwidth sharing display field 19 is that information on a plurality of paths whose path bandwidth sharing status has changed at the same time is notified by one message, and the number of messages can be reduced. This is because

Thereafter, when the LSP 3 is further switched from the working path to the protection path, the label switching router R1 sends a sta to the label switching router R2.
Send te-notify 1-b. In this case, the path status “standby” is set in the path status field 211-a. Thereafter, similarly, the label switching router R2 transmits state-notify 2-b to the label switching router R3, and the label switching router R3 transmits state-notify 3-b to the label switching router R4.
state-notify 1-b, state-notify 2-b, state-notify
The routers label switching router R2, label switching router R3, and label switching router R4 that respectively receive 3-b change the path state of the LSP3 from working to protection. Further, the label switching router R1
Transmits the bandwidth sharing status notification message PR1 to the origin label switching router R5 of the LSP1 which is a bandwidth sharing path, and transmits the bandwidth sharing status notification message PR2 to the origin label switching router R6 of the LSP2 which is a bandwidth sharing path. In this case, in the bandwidth sharing status notification message PR1-b, the ID of LSP1 is set in the LSPID field 192-a, and the path bandwidth sharing status “bandwidth sharing stopped” is set in the shared preemption status field 191-a. In the bandwidth sharing status notification message PR2-b, the ID of the LSP2 is set in the LSPID field 192-a, and the path bandwidth sharing status “bandwidth sharing stopped” is set in the shared preemption status field 191-a.

In the first embodiment, as shown in FIG. 1, a bandwidth sharing setting notification message shared-notify
1 and shared-notify 2 are transmitted from the destination label switching router R4 of the LSP 3, respectively, as shown in FIG.
Shared-notify 1 and shared-notify 2 may be transmitted from the originating label switching router R1 of LSP3.

As described above, according to the first embodiment, when a bandwidth for a newly set path is not allocated, the bandwidth between the set path that can share the bandwidth and the newly set backup path is determined. in order so that share bandwidth,
If a combination of a new working path and an existing protection path or a combination of a new protection path and an existing path is set, a path with a high priority for a newly set path is set even if the entire network lacks bandwidth. This makes it possible to effectively utilize resources in the entire network. In addition, since the paths for which the number of bandwidth sharing settings with other paths is equal to or greater than a predetermined upper limit value are excluded from the bandwidth sharing path candidates, the bandwidth sharing multiplexing setting can be limited, The occurrence frequency of sharing contention can be reduced. Furthermore, the bandwidth sharing settings, and whether shared bandwidth is actually used, since it is notified to the origin router target path, can grasp the use situation of a bandwidth in the appropriate origin router starts actually shared bandwidth is used In such a case, it becomes possible to reset the target path by another route at a necessary timing. For a user who uses a path that permits bandwidth sharing, a backup path is not completely guaranteed when the active path fails, but a flexible network service such as discounting charges may be provided instead.

Embodiment 2 In the first embodiment, when the node that has received the label request message extracts a candidate of an existing path that shares the bandwidth with the new path, the node whose bandwidth sharing number is equal to or more than the predetermined upper limit value is excluded. Things. On the other hand, in the following embodiment 2, the node that has transmitted the label request message and the label message including the number of paths for which the number of bandwidth sharing for each path is equal to or more than a predetermined upper limit value, and received the message When selecting a relay route of a new path starting from the node, a label switching path for excluding a route in which the number of paths whose bandwidth sharing number is equal to or more than a predetermined upper limit value is equal to or more than a predetermined threshold value is excluded. The setting method will be described.

FIG. 9 is a diagram showing the format of the label request message LR used in the second embodiment. 131 is the LS of the shared LSPID field 13
A shared number display field 132 indicates the number of shared bandwidths of the path corresponding to the PID, and 132 is a shared LSPID field 13
Is a path ID display field for storing the ID of the path in which the path indicated by No. is stored. FIG. 10 is a diagram showing a format of the label message LM used in the second embodiment. The control message formats other than the label request message LR and the label message LM are the same as those in the first embodiment. FIG. 11 is a network configuration diagram of an MPLS domain showing an arrangement of label switching routers and a setting state of a label switching path used for explaining a label switching path setting method according to the second embodiment. FIG. 12 shows the second embodiment.
FIG. 7 is a diagram showing a path setting propriety and an algorithm for selecting a bandwidth sharing path to be used.

Hereinafter, a label switching path setting method according to the second embodiment will be described. As is clear from FIG. 11, the arrangement of the label switching router is the same as that of the first embodiment. The setting state of the label switching path LSP is the same as that of the first embodiment.
1. LSP2 that has already been set, LSP that starts with label switching router R1, and ends with label switching router R4 via label switching router R6 and label switching router R3
4 is set, and an LSP 5 starting from the label switching router R1 and ending at the label switching router R6 is set. It is assumed that LSP1 and LSP2 are both backup paths, and that LSP4 and LSP5 have a bandwidth sharing setting between the label switching routers R1 and R6. From this state, an attempt is made to set the working path LSP3. The control message flow is described in the first embodiment.
Is the same as

First, the label switching router R1
When LSP4 is set, share of label message LM
d LSPID field 13, shared number display field 1
31, the path ID display field 132 is read out, and based on the LSPID, the number of shared bandwidths, and the path ID contained therein,
It is stored that LSP4 and LSP5 on the path between the label switching router R1 and the label switching router R6 have the number of band sharing = 1.

Next, the originating label switching router R1
Collects information by a routing protocol before transmitting the label request message LR when setting the LSP3, and selects those candidates as relay routes of the LSP3 from the collected information. Further, among the selected relay route candidates, there is a route that includes a path having a bandwidth sharing number equal to or more than a predetermined upper limit value (here, 1) or more than a predetermined threshold value (here, 1). A check is made to see if they exist, and if they do exist, they are excluded from the selection candidates. For example, in FIG. 11, set1 (R1 → R2 → R3
→ R4) and set2 (R1 → R6 → R3 → R4) are selected as candidates. Among these, in set2, the number of bandwidth sharing of LSP4 and LSP5 between the label switching router R1 and label switching router R6 is 1, while in set1, a path having the number of bandwidth sharing of 1 or more on the path is set. not exist. Therefore, the label switching router R1 excludes the set2 from the selection candidates, and the set in which the path having the bandwidth sharing number of 1 or more does not exist.
Select only 1

Next, the label switching router R1
According to the selected set1, the label request message LR
1 to the label switching router R2. Upon receiving the label request message LR1, the label switching router R2 receives the requested bandwidth indicated in the traffic parameter field 6, the next-stage label switching router address indicated in the explicit route field 10, and the path bandwidth shared attribute field 11. Bandwidth sharing attribute,
The path type at the time of initial setting (discrimination of working / standby) indicated in the path type field 12 is read, and according to the procedure shown in FIG. Note that the processing flow based on the algorithm shown in FIG. 12 is the same except that step S110 of the first embodiment is replaced with step S120, and therefore, the steps other than step S120 are omitted.

Step S107 or step S10
When the path for performing the bandwidth sharing is determined in step 8, the number of bandwidth sharing of the bandwidth sharing path is incremented by 1 (step S109). After that, assign a label and LSP3
(In FIG. 19, the label switching router R
3) and a label request message LR to the label switching router R2.
Send 2. At this time, the shared LSPID shown in FIG.
LSP in field 13 LSPID field 13-a
1 LSPID is set. Further, since the number of shared bands of LSP1 is 1 from the configuration of FIG. 11, 1 is set in the shared number display field 131-a, and the route ID is set.
Label switching router R is displayed in display field 132-a.
Path ID between label 2 and label switching router R3
(IP address of label switching router R2 + IP address of label switching router R3 + physical line ID between both) is set (step S120).

Upon receiving the label request message LR2, the label switching router R3 determines that the bandwidth sharing between LSP3 and LSP2 is necessary, and
3 is transmitted, in step S120, the LSPI
D field 13-a, shared number display field 131-a,
In addition to the route ID display field 132-a, sharedL
LSPID field 13-b of SPID field 13
Set the LSPID of LSP2 to
Since the number of shared bandwidths = 1, 1 is set in the shared number display field 131-b, and the path ID display field 13-b is set to 1.
The route ID between the label switching router R3 and the label switching router R4 (the IP address of the label switching router R2 + the IP address of the label switching router R3 + the physical line ID between the two) is set in 2-b.

The label switching router R4 receiving the label request message LR3, as shown in FIG.
LSPID included in label request message LR3
The field 13-a, the shared number display field 131-a, the path ID display field 132-a, the LSPID field 13-b, the shared number display field 131-b, and the path ID display field 132-b are each labeled message LM1.
And sends it to the label switching router R3. Thereafter, similarly, the above information is transferred to the label switching router R1 via the label message LM2 and the label message LM3.

The label switching router R4, which has received the label request message LR3, sends a label sharing setting notification message shared-noti to the label switching routers R5 and R6.
The operation of transmitting fy, the operation after LSP3 switches from the working path to the protection path, and the operation after LSP3 switches from the working path to the protection path are described in the first embodiment.
Is the same as

As described above, according to the second embodiment, the label request message and the label message are transmitted including the number of paths for which the number of bandwidth sharing for each path is equal to or more than the predetermined upper limit, and the message is received. When the selected node selects a relay path of a new path starting from the node, a path in which the number of paths whose bandwidth sharing number is equal to or greater than a predetermined upper limit value is equal to or greater than a predetermined threshold value is excluded. As a result, the node previously notified of the information on the maximum number of shared paths on the path through the label request message and the label message can select another path and execute the path setting, and It is possible to reduce the frequency of failure in setting a route on the way.
As a result, not only can the time required for path setting be reduced, but also the number of paths sharing the bandwidth can be limited,
It is possible to prevent band sharing from occurring in multiplexing.

Embodiment 3 According to the second embodiment, the label request message and the label message are transmitted including the number of paths whose number of bandwidth sharing for each path is equal to or more than the upper limit, and the receiving node of the message relays a new path starting from the node. When selecting a route, a route in which the number of paths whose number of shared bandwidths is equal to or more than the upper limit is equal to or more than the threshold value is excluded. On the other hand, in the following third embodiment, label switching path setting for periodically notifying each node of the number of paths for which the number of bandwidth sharing is equal to or more than a predetermined upper limit and bandwidth information relating to the sharable bandwidth for each path. The method will be described.

FIG. 13 is a diagram showing the format of the bandwidth information message 22 used in the third embodiment. FIG.
, 23 is a band information field, 231 is a path ID display field of a path describing the band information, 232 is an empty band display field indicating an empty (unused) band of the path shown in the path ID display field 231, 233.
Is a sharable band display field indicating the sharable band of the path indicated in the path ID display field 231, and 234 is a band sharing number display field indicating the number of paths for which the band sharing number is equal to or more than the upper limit. FIG. 14 shows the third embodiment.
FIG. 5 is a diagram showing an algorithm of a relay route selection performed at a path origin node in FIG.

Hereinafter, a label switching path setting method according to the third embodiment will be described. The network configuration and the path setting configuration are the same as those of the second embodiment shown in FIG.
The control message used for path setting and its flow are the same as those in the second embodiment.

[0079] First, in the third embodiment, each router R that constitute the network, and periodically transmits the bandwidth information messages 22 in the format shown in FIG. 13 relative to the other routers R in the same domain I have. The bandwidth information message 22 to be transmitted includes a message header 46
, A code indicating a band information message is set, and band information corresponding to each field of the band information field 23 is set. For example, in the network configuration of FIG.
LSP4 and LSP5 share a band between the label switching router R1 and the label switching router R6, and the number of band sharing is 1 for both. Therefore, the label switching router R1 displays the path ID between the label switching router R1 and the label switching router R6 (the IP address of the label switching router R1 + the IP address of the label switching router R6 + the physical Line I
D) is set, and the free band display field 23 is set.
2 sets the free bandwidth of the route between the label switching router R1 and the label switching router R6, and further sets the sharable bandwidth display field 233 with the sharable bandwidth of the route between the label switching router R1 and the label switching router R6. Set. If the number of paths set in the bandwidth sharing number display field 234 is equal to or more than the bandwidth sharing number 1, the bandwidth sharing number display field 234 is displayed.
Is set to a total of “2” for LSP4 and LSP5. In FIG. 11, the destination of the bandwidth information message 22 from the label switching router R1 is the label switching router R2 and the label switching router R6.

On the other hand, each router R that has received the bandwidth information message 22 selects a relay route according to the algorithm shown in FIG. 14 when setting up a new path based on the bandwidth information indicated therein.

That is, when trying to set LSP3,
The label switching router R1 first selects a candidate for a relay route (step S201). In this case, the label switching router R1 uses, for example, set1 as a relay route from information collected by the routing protocol.
(R1 → R2 → R3 → R4) and set2 (R1 → R
6 → R3 → R4).

Next, one of the selected candidates is selected (step S202), and it is checked whether or not each free bandwidth on the relay route is equal to or larger than the required bandwidth of the new path (step S2).
03). For this process, the label switching router R1 refers to the available bandwidth display field 232 for the selected relay route in the bandwidth information message 22. If the condition of step S203 is true (yes), there is sufficient free bandwidth, so the process proceeds to step S205, and the label request message LR is transmitted to the selected relay route.

On the other hand, the condition of step S203 is false (no)
In the case of, it is checked whether or not the sum of each free band and each sharable band of the selected relay route is equal to or larger than the required band of the new path (step S204). In this process, the content of the sharable bandwidth display field 233 is referred to in addition to the free bandwidth display field 232 relating to the relay route targeted by the bandwidth information message 22. If the condition in step S204 is true (yes), it is checked whether or not the number of paths for which the number of bandwidth sharing settings is equal to or greater than a predetermined upper limit value is equal to or greater than a predetermined threshold T in each path (step S206). .
If the number of paths for which the set number of bandwidth sharing is equal to or greater than the predetermined upper limit does not exist equal to or greater than the above-described threshold T, step S205
To send a label request message LR to the selected relay route.

If the condition of step S204 is false (no) or the condition of step S206 is true (yes),
It is checked whether or not all investigations have been completed for the route candidate selected in step S201 (step S20).
7). If all investigations have not been completed, then the next candidate is selected in step S208, and a series of processing flows from steps S203 to S206 are repeatedly executed. For example, in step S202,
t2 (R1 → R6 → R3 → R4) is selected and step S
Assuming that the condition of 203 is false (no) and the condition of step S204 is true (yes), as shown in FIG.
LSP4 and LSP5 between the label switching router R1 and the label switching router R6 at t2.
Is 1 and the number of shared bandwidth display field 2
If the threshold T described in S.34 is 1, the value set in the bandwidth sharing number display field 234 is 2, and step S20 is performed.
Condition 6 becomes true (yes).

On the other hand, if it is detected in step S207 that the investigation of all candidates has been completed, the path setting is canceled because there is no target route (step S209). In the network of FIG. 11, for example, s
Since there is a path whose number of shared bandwidths is equal to or greater than the threshold value (= 1) on the path of et2, a series of processing flows from steps S203 to S206 are executed for the path of set1. If the condition of step S203 is false (n
o) If the condition of step S204 is true (yes), the process proceeds to step S206. set1
Since there is no path on the route of (R1 → R2 → R3 → R4) whose bandwidth sharing number is equal to or more than the threshold value (= 1), the value of the bandwidth sharing number display field 234 becomes 0 for all the routes, and When the condition is false (no), the process proceeds to step S205, and the label request message LR is transmitted to the label switching router R2 according to the route of set1. The operation after the transmission of the label request message is the same as in the second embodiment.

[0086] As described above, according to the third embodiment, as the number of band sharing is to notify the bandwidth information about the number of passes and shareable bandwidth is equal to or greater than the upper limit value periodically to each node for each path Therefore, not only the node receiving the label request message or the label message, but also all nodes in the same domain can share the band information. Therefore,
It is possible to determine whether or not to set a path before actually transmitting a label request message, so that an optimal route can be selected and the time required for setting a path can be reduced. In addition, since the number of paths that share the bandwidth can be limited, it is possible to prevent the occurrence of multiplex bandwidth sharing.

Embodiment 4 As described above, in the first embodiment, a path in which the number of bandwidth sharing settings with another path is equal to or more than a predetermined upper limit is excluded from the bandwidth sharing path candidates. On the other hand, in the fourth embodiment, when the available bandwidth of the route is insufficient, and when the (unshared bandwidth / maximum available bandwidth) of the route through which the newly set path passes is less than a predetermined threshold value In the following, a label switching path setting method for rejecting the setting of a new path will be described.

FIG. 15 is a diagram showing an algorithm for determining whether or not a path can be set and selecting a shared bandwidth path used in the fourth embodiment. Hereinafter, a label switching path setting method according to the fourth embodiment will be described with reference to the algorithm in FIG.

First, in order to set LSP3 in a state where LSP1 and LSP2 have already been set, the originating label switching router R1 needs to be connected to the label switching router R2.
Sends a label request message LR1 to the Upon receiving the label request message LR1, the label switching router R2 sends the traffic parameter field 6
Requested bandwidth shown in explicit route field 10
Of the next-stage label switching router, the bandwidth sharing attribute shown in the path bandwidth sharing attribute field 11, and the path type at the time of initial setting shown in the path type field 12 (discrimination of working / standby).

Next, the label switching router R2
Is an explicit name included in the label request message LR1.
The setting route of LSP3 is determined from the next-stage label switching router address in the route field 10 and this LS
The total allocated bandwidth D of the paths already existing on the set path of P3
And the requested bandwidth C included in the label request message LR1
Is checked to see if the sum exceeds a predetermined threshold Th preset for the route (step S1).
01). If the sum of the allocated bandwidth D and the required bandwidth C of the existing path does not exceed the threshold Th, the path setting is accepted and the path is set on the LSP3 (in FIG. 19, the label switching router R3 and the label switching router R2 communicate with each other). Then, a label request message LR2 is transmitted to the label switching router R3 by allocating a bandwidth corresponding to the required bandwidth C in a path (intermediate route) (step S102).

On the other hand, if the sum of the allocated bandwidth D of the existing path and the required bandwidth C exceeds the threshold Th, the bandwidth sharing attribute of the bandwidth sharing attribute field 11 included in the label request message LR1 is changed to “ and checks shareable "or (step S103), if the" shared impossible ", the flow proceeds to step S105 it is determined that the path not be set. In step S105, a Notify message is transmitted to the label switching router R1 that is the transmission source of the label request message LR1 due to lack of resources as a rejection factor (not shown in FIG. 1).

On the other hand, if the bandwidth sharing attribute is “shareable”, the process proceeds to step S130, and the unshared bandwidth ratio E of the route for which a new path is to be set = (unshared bandwidth / maximum available bandwidth). It is checked whether or not is less than a predetermined threshold value Tb set in advance. Here, the unshared bandwidth ratio E is defined as the shared bandwidth of all paths on the target path with respect to the maximum available bandwidth of the target path (= the sum of the already allocated bandwidth and the unused and available bandwidth). This is the ratio of the total bandwidth that has not been used (= unused bandwidth + sharable bandwidth), and is used as an index of bandwidth sharing strength. For example, when the ratio is low, it is considered that the intensity of band sharing is high.

If the condition of step S130 is true (yes), the band sharing intensity is high, so no more band sharing is permitted, and a notification indicating that the band cannot be set is transmitted (step S105). On the other hand, if the condition of step S130 is false (no), it is determined that there is enough bandwidth sharing strength, and the process proceeds to step S104 to check whether the path type of the new path is a spare. Step S for backup path
132, while if the path is the working path, step S1
Go to 31. In step S132, a path that can share the bandwidth is extracted from the existing paths, and the process proceeds to step S107.
In step S131, a path whose status is “spare” and whose bandwidth can be shared is extracted from the existing paths, and the process proceeds to step S107.

Steps S107 and S108
Is the same as in the first embodiment. Step S107
Is true (yes) or the condition of step S108 is true (yes), the process proceeds to step S133, and the unshared bandwidth ratio E = (unshared bandwidth / maximum available bandwidth) of the path for setting the new path. ), And then step S1
Go to 10. The processing in step S110 is also the same as in the first embodiment.

As described above, according to the fourth embodiment, when the available bandwidth of the route is insufficient, and the unshared bandwidth ratio of the route passing through the newly set path = (unshared bandwidth)
(Maximum available bandwidth) is less than a predetermined threshold, so that the setting of a new path is rejected. For a route with a high bandwidth sharing strength, no more bandwidth sharing is allowed. It is possible to prevent band sharing from occurring in multiplexing.

Embodiment 5 As described above, the third embodiment is to periodically notify each node of the bandwidth information on the number of paths and the sharable bandwidth for which the number of bandwidth sharing is equal to or more than the upper limit value for each path. On the other hand, in the following embodiment 5, a description will be given of a label switching path setting method in which each node periodically notifies the unshared bandwidth ratio of each path = (unshared bandwidth / maximum available bandwidth).

FIG. 16 is a diagram showing a format of a bandwidth information message used in the fifth embodiment. An unshared bandwidth ratio display field 235 indicates the unshared bandwidth ratio of the route indicated in the route ID display field 231 = (unshared bandwidth / maximum available bandwidth). FIG. 17 is a diagram illustrating an algorithm for selecting a relay route at a starting point node of a path used in the fifth embodiment. FIG. 18 shows Embodiment 5
FIG. 6 is a path setting configuration diagram showing a path setting state and an unshared band ratio of each path used for explaining the operation of FIG.

Hereinafter, a label switching path setting method according to the fifth embodiment will be described. First, in the fifth embodiment, each router R configuring the network is configured as shown in FIG.
Is periodically transmitted to another router R in the same domain. In the bandwidth information message 22 to be transmitted, a code indicating the bandwidth information message is set in the message header 46, and bandwidth information corresponding to each field of the bandwidth information field 23 is set.

For example, in the network configuration of FIG. 18, the maximum usable bandwidth between the label switching router R1 and the label switching router R6 is 100.
Mbit / s, unshared bandwidth (including free bandwidth) 30M
bit / s, and the unshared bandwidth ratio = (unshared bandwidth) /
(Maximum usable band) = 0.3. Therefore,
The label switching router R1 displays the path ID between the label switching router R1 and the label switching router R6 (the IP address of the label switching router R1 + the IP address of the label switching router R6 + the physical line ID between both) in the path ID display field 231. ) Is set, the free band of the path between the label switching router R1 and the label switching router R6 is set in the free band display field 232, and the label switching router R1 and the label switching router R6 are set in the sharable band display field 233. Set the sharable bandwidth of the route between Further, the above-mentioned “0.3” is set in the unshared bandwidth ratio display field 235. In FIG. 18, the destination of the bandwidth information message 22 from the label switching router R1 is the label switching router R2 and the label switching router R6.

Similarly, between the label switching router R2 and the label switching router R3, the maximum usable bandwidth is 100 Mbit / s, the unshared bandwidth (including the free bandwidth) is 90 Mbit / s, and the unshared bandwidth ratio is = 0.9. Accordingly, the label switching router R2 includes the label switching router R2 and the label switching router R in the path ID display field 231.
And a route ID (the IP address of the label switching router R2 + the IP address of the label switching router R3 + the physical line ID between the two), and
The vacant band display field 232 sets the vacant band of the path between the label switching router R2 and the label switching router R3, and the sharable band display field 233 further sets the vacant band of the path between the label switching router R2 and the label switching router R3. Set the sharable bandwidth. In addition, the above-mentioned “0.9” is set in the unshared band ratio display field 235. Bandwidth information message 22 from label switching router R2
Are the label switching router R1, the label switching router R3, and the label switching router R5 in the case of FIG.

On the other hand, each router R that has received the bandwidth information message 22 selects a relay route according to the algorithm shown in FIG. 17 when setting a new path based on the bandwidth information indicated therein.

That is, when trying to set LSP3,
The label switching router R1 first selects a candidate for a relay route (step S201). In this case, the label switching router R1 uses, for example, set1 as a relay route from information collected by the routing protocol.
(R1 → R2 → R3 → R4) and set2 (R1 → R
6 → R3 → R4).

Next, one of the selected candidates is selected (step S202), and it is checked whether or not each free band on the relay route is equal to or larger than the required band of the new path (step S2).
03). For this process, the label switching router R1 refers to the available bandwidth display field 232 for the selected relay route in the bandwidth information message 22. If the condition of step S203 is true (yes), there is sufficient free bandwidth, so the process proceeds to step S205, and the label request message LR is transmitted to the selected relay route.

On the other hand, the condition of step S203 is false (no)
In the case of, it is checked whether or not the sum of each free band and each sharable band of the selected relay route is equal to or larger than the required band of the new path (step S204). In this process, the content of the sharable bandwidth display field 233 is referred to in addition to the free bandwidth display field 232 relating to the relay route targeted by the bandwidth information message 22. If the condition of step S204 is true (yes), it is checked whether or not the unshared bandwidth ratio of each path is less than a predetermined threshold (step S204).
220). If the unshared bandwidth ratio is not less than the predetermined threshold, the process proceeds to step S205, where the label request message LR is transmitted to the selected relay route.

If the condition of step S204 is false (no) or the condition of step S220 is true (yes),
It is checked whether or not all investigations have been completed for the route candidate selected in step S201 (step S20).
7). If all investigations have not been completed, then the next candidate is selected in step S208, and a series of processing flows from steps S203 to S220 are repeatedly executed. For example, in step S202,
t2 (R1 → R6 → R3 → R4) is selected and step S
Assuming that the condition of 203 is false (no) and the condition of step S204 is true (yes), as shown in FIG.
At t2, the unshared bandwidth ratio between the label switching router R1 and the label switching router R6 is 0.3.
When the threshold value is 0.4, the value is lower than 0.4, so that the condition of step S220 is true (yes).

[0106] On the other hand, when it is detected that the investigation of all candidates is completed step S207, since the path of interest is not present, cancel the path setting (step S209). For example, in the network of FIG.
Since the path of et2 includes a path (between the label switching router R1 and the label switching router R6) whose unshared bandwidth ratio is less than the threshold value (= 0.4), se
A series of processing flows from steps S203 to S220 are executed for the route at t1. If the condition of step S203 is false (no) and the condition of step S204 is true (yes) for set1, the process proceeds to step S220. set1 (R1 → R2 → R3 → R4)
No path with an unshared bandwidth ratio of less than the threshold value (= 0.4) exists on the path No. including the path between the label switching router R2 and the label switching router R3. Therefore, the condition of step S220 is false (no). Then, the process proceeds to step S205, and the label request message LR is transmitted to the label switching router R2 according to the path of set1. The operation after the transmission of the label request message is the same as in the fourth embodiment.

As described above, according to the fifth embodiment, each node periodically sets the unshared bandwidth ratio =
(Unshared bandwidth / maximum available bandwidth) and the sharable bandwidth are notified, so that all nodes in the same domain can share these bandwidth information. Therefore, it is possible to determine whether or not a path can be set before actually transmitting the label request message, so that it is possible to select an optimal route and to shorten the time required for setting the path.
In addition, since the number of paths that share the bandwidth can be limited, it is possible to prevent the occurrence of multiplex bandwidth sharing.

[0108]

As described above, according to the present invention, the sum of the required bandwidth of a newly set path and the total bandwidth of existing paths already existing on the set path of the newly set path is added to the path. On the other hand, even when the bandwidth exceeds a predetermined threshold value set in advance, the bandwidth can be shared from the existing paths, and the bandwidth with another path can be shared on the condition that the newly set path can share the bandwidth. The number of shares falls below a predetermined upper limit set in advance, and a combination of the newly set path and the backup path and the backup path or the current path and the backup path is extracted and assigned to the extracted existing paths. When the total allocated bandwidth is equal to or more than the required bandwidth of the newly set path, the extracted existing path can be selected as a shared bandwidth path, so that the bandwidth can be effectively used in the entire network. There is an effect that kill. In addition, it is possible to limit the multiplex setting of the bandwidth sharing, and it is possible to reduce the frequency of occurrence of contention for bandwidth sharing.

According to the next invention, a relay route can be set by excluding a route including a path that is highly likely to be unable to set a path, so that the frequency of failures during path setting can be suppressed. As a result, it is possible to reduce the time required for path setting without causing a situation in which multiplexed bandwidth sharing occurs.

According to the next invention, it is possible to obtain information relating to the number of shared bandwidths of each node through a label request message or a label message required for setting a path, so that it is necessary to separately notify only information. There is an effect that there is no.

According to the next invention, since information relating to the number of shared bandwidths can be shared by all nodes for which a label switching path is to be set, optimal route selection is always possible, and as a result, multiplexing is possible. Thus, there is an effect that the time required for path setting can be reduced without causing a situation in which bandwidth sharing occurs.

According to the next invention, the sum of the required bandwidth of the newly set path and the total bandwidth of the existing paths already existing on the set path of the new set path is determined by a predetermined value set for the path. Even if the threshold value is exceeded, the bandwidth of the existing path can be shared, and the ratio of the unshared bandwidth to the maximum available bandwidth on the path, provided that the newly set path can share the bandwidth. Is equal to or greater than a predetermined threshold value, and the combination of the newly set path and the backup path and the backup path or the working path and the backup path is extracted. it is possible sum is selected as the band shared path existing path the extracted when equal to or more than the required bandwidth of the new configuration path, effective utilization of bandwidth across the network An effect that theft can be. Moreover, it is possible to limit the multiplex set bandwidth sharing, an effect that the bandwidth sharing is possible to reduce the frequency of occurrence of a situation to compete.

According to the next invention, a relay route can be set by excluding a route which is likely to be unable to set a path in advance, so that the frequency of failures during path setting can be suppressed. As a result, there is an effect that the time required for path setting can be reduced without causing a situation in which multiplexed bandwidth sharing occurs.

According to the next invention, since information relating to the ratio of the unshared band to the maximum available band on the path can be shared by all nodes for which the label switching path is set, the optimum path is always set. This makes it possible to make selections, resulting in an effect that the time required for path setting can be reduced without incurring a situation in which multiplexed bandwidth sharing occurs.

According to the next invention, even if the total allocated bandwidth allocated to the extracted existing path is less than the required bandwidth of the newly set path, the total of the allocated bandwidth and the newly set path are compared. it is possible to sum of the free bandwidth that exists on the set path of said exceeds the requested bandwidth of the new configuration path, and selects a band shared path existing path to the extracted when a predetermined condition is satisfied as described above, There is an effect that the bandwidth can be effectively used in the entire network.

According to the next invention, since the originating node can know the bandwidth sharing setting and whether or not the shared bandwidth is actually used, it is necessary to set the bandwidth sharing when the shared bandwidth is actually started. There is an effect that the target path can be reset to another path at an appropriate timing.

According to the next invention, since a change in the state of the path is notified, control according to the change in the state of the path can be performed at each node, so that the setting of the used band can be performed more flexibly. To play.

[Brief description of the drawings]

FIG. 1 is a sequence diagram showing a control message flow of a label switching path setting method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a format of a label request message shown in FIG. 1;

FIG. 3 is a diagram showing a format of a label message shown in FIG. 1;

FIG. 4 is a diagram showing a format of a bandwidth sharing setting notification message shown in FIG. 1;

FIG. 5 is a diagram showing a format of a bandwidth sharing status notification message shown in FIG. 1;

FIG. 6 is a diagram showing a format of a path status notification message shown in FIG. 1;

FIG. 7 is a diagram showing an algorithm for selecting whether or not a path can be set and selecting a shared bandwidth path when a relay label switching node receives a new label request message.

FIG. 8 is a sequence diagram showing a modified example of the control message flow shown in FIG.

FIG. 9 is a diagram showing a format of a label request message used in the second embodiment.

FIG. 10 is a diagram showing a format of a label message used in the second embodiment.

FIG. 11 is a network configuration diagram of an MPLS domain showing an arrangement of label switching routers and a setting state of a label switching path used for describing a label switching path setting method according to a second embodiment.

FIG. 12 is a diagram showing whether a path can be set and an algorithm for selecting a shared bandwidth path used in the second embodiment.

FIG. 13 is a diagram showing a format of a bandwidth information message used in the third embodiment.

FIG. 14 is a diagram illustrating an algorithm for selecting a relay route performed in a starting point node of a path according to the third embodiment.

FIG. 15 is a diagram illustrating an algorithm for selecting whether or not to set a path and selecting a shared bandwidth path used in the fourth embodiment.

FIG. 16 is a diagram showing a format of a bandwidth information message used in the fifth embodiment.

FIG. 17 is a diagram illustrating an algorithm for selecting a relay route at a starting point node of a path used in the fifth embodiment.

FIG. 18 is a path setting configuration diagram showing a path setting state and an unshared band ratio of each path used for explaining the operation of the fifth embodiment.

FIG. 19 is a network configuration diagram of an MPLS domain showing an arrangement of label switching routers and a setting state of label switching paths used for describing a label switching path setting method.

FIG. 20 is a diagram showing a control sequence for setting a label switching path of LSP3, showing an example of successful setting.

FIG. 21 is a diagram showing a control sequence for setting a label switching path of LSP3, showing an example of unsuccessful setting.

[Explanation of symbols]

22 Band information message, LM label message,
LR label request message, LSP label switching path, PR band sharing status notification message, R label switching router.

Claims (10)

[Claims] 1. A downstream node secures a bandwidth in accordance with an information element included in a label request message transmitted from an upstream node to a downstream node, allocates a label to be used for data transfer, and allocates the allocated label. by returning a label message containing the information to the upstream node, a method of setting a label switched path between these upstream nodes and downstream nodes, and the required bandwidth for the new configuration path indicated on the label request message When the sum of the bandwidth of the existing path already existing on the set path of the newly set path exceeds a predetermined threshold value set in advance for the path, the band of the newly set path can be shared. A predetermined upper limit value in which the bandwidth can be shared among the existing paths and the number of bandwidth sharing with other paths is set in advance And the combination of the newly set path and the backup path and the backup path or the working path and the backup path is extracted, and the sum of the allocated bandwidths allocated to the extracted existing paths is determined by the request of the newly set path. A label switching path setting method, wherein the extracted existing path is selected as a shared bandwidth path when the bandwidth exceeds the bandwidth. 2. Before transmitting a label request message in an upstream node, a relay route of a path is set by excluding a path including a path in which the bandwidth sharing number is equal to or more than a predetermined upper limit value. The label switching path setting method according to claim 1, wherein: 3. The label switching path setting method according to claim 2, wherein information relating to the number of shared bandwidths of each node is transmitted in the label request message or the label message. 4. The label switching path setting method according to claim 2, wherein the information relating to the number of bandwidth sharing is notified at a predetermined cycle between the respective nodes to be set as label switching paths. 5. A downstream node secures a band according to an information element included in a label request message transmitted from an upstream node to a downstream node, allocates a label used for data transfer, and allocates the allocated label. By returning a label message including information to the upstream node, a label switching path is set between the upstream node and the downstream node. When the sum of the bandwidth of the existing path already existing on the set path of the newly set path exceeds a predetermined threshold value set in advance for the path, the band of the newly set path can be shared. The ratio of the unshared bandwidth to the maximum available bandwidth on the route, with the condition that there is A threshold value which is equal to or greater than a predetermined threshold value, and a combination of the newly set path and a backup path and a backup path or a working path and a backup path are extracted, and the total of the allocated bandwidths allocated to the extracted existing paths is extracted. Selecting the extracted existing path as a shared bandwidth path when the bandwidth exceeds the required bandwidth of the newly set path. 6. Before a label request message is transmitted in an upstream node, a route in which a ratio of an unshared bandwidth to a maximum available bandwidth is less than a predetermined threshold is set in advance to set a relay route of a path. The label switching path setting method according to claim 5, wherein 7. The method according to claim 6, wherein information relating to the ratio of the unshared band to the maximum usable band on the path is notified at a predetermined cycle between the nodes to be set as the label switching path. Label switching path setting method. 8. When the total allocated bandwidth allocated to the extracted existing path is less than the required bandwidth of the newly set path, the total of the allocated bandwidth and the new allocated path exist on the set path. The method according to any one of claims 1 to 7, wherein the extracted existing path is selected as a shared bandwidth path when a sum with an available bandwidth exceeds a required bandwidth of the newly set path and the following conditions are satisfied. Label switching path setting method. D + CB−Th, where D is the total bandwidth of the existing paths already existing on the setting path of the newly set path, C is the requested bandwidth of the newly set path, B is the total allocated bandwidth assigned to the extracted existing path, T
h is a preset threshold value for the set route of the newly set path 9. The node that has selected the shared bandwidth path,
While transmitting the label request message to the downstream node by adding the identification information of the selected bandwidth sharing path, the downstream node receiving the label request message determines the starting node of the bandwidth sharing path from the identification information, The method according to any one of claims 1 to 8, wherein the originating node is notified that the band is shared. 10. The method according to claim 1, wherein when the working / standby state of the path changes, the switching of the working / standby state is notified to a node on the path of the path. Label switching path setting method.