JP4180530B2 - Path switching method, path switching control device, and path switching program - Google Patents

Description

The present invention is, path switching method relates to the path switch control device and a path switching program, in particular, MPLS (Multi Protocol Label Switching: Multiprotocol Label Switching) or ATM (Asynchronous Transfer Mode: Asynchronous Transfer Mode) and packet networks, such as The present invention relates to a path switching method for performing dynamic path switching in consideration of both TDM (Time Division Multiplexing) and WDM (Wavelength Division Multiplexing) optical networks.

In recent years, IP traffic has increased explosively. In the conventional connectionless system that carries traffic via a large number of routers, there is a problem that the equipment cost of the core network that transfers increasing IP traffic increases.
Therefore, by passing through IP (Layer 3) and Ethernet (Layer 2) traffic in a connection-type network such as wavelength and TDM, the traffic accommodation efficiency is improved, and as a result, the economy of the network is realized. A method appeared.
A core network that realizes a large-capacity IP traffic network service economy by such a method has also been proposed (for example, see Non-Patent Document 1).
In a core network that achieves economics by performing such pass-through, a path with good bandwidth utilization efficiency can be obtained by performing route calculation independently in an upper layer such as a packet network and a lower layer such as a circuit switched network. It is difficult to switch to placement.
Therefore, recently, attention has been paid to a CSPF (Constrained Shortest Path First) algorithm capable of calculating a route for determining a path arrangement of a lower layer in consideration of traffic of an upper layer.
A typical CSPF that takes into account upper layer traffic and lower layer path placement is listed below.
(1) BXCQ (Branch Change with Quality-of-Service Constraint) method It is intended to perform dynamic route control in consideration of the traffic volume of the upper layer and the lower layer path.
By exchanging upper layer path traffic information between nodes, the topology of the lower layer path is set based on that information and dynamically changed, enabling the construction of a network that can adapt to changes in traffic demand. Become. The BXCQ method is used for actual route calculation.
This CSPF algorithm is effective when applied to a case where it is desired to set a path with priority given to the traffic accommodation efficiency of the network (see, for example, Non-Patent Document 2).

With the recent spread of streaming distribution of video and music, the optimal topology for networks has changed over time.
Therefore, a CSPF algorithm such as BXCQ for calculating an optimum topology is indispensable and frequently used.
For example, consider a network as shown in FIG.
First, as shown in FIG. 10A, it is assumed that traffic of 10 Mb flows from the point A to the points B, C, and D.
From that point in time, as shown in FIG. 10 (b), traffic from point A is only sent to point D, and 30Mb traffic is newly transmitted from point C to points A and B. Start to be.
As described above, when the ground-to-ground traffic exchange in the network changes with time, the optimum topology for the traffic exchange state also changes.
In order to calculate the optimum topology, a CSPF algorithm such as BXCQ mentioned above may be used.
However, the network topology has not changed with the CSPF algorithm alone, and the operation of “path switching” is indispensable in order to change to the optimum topology obtained by the CSPF algorithm and actually increase the bandwidth utilization efficiency of the network. It is.
So far, a path switching method in one layer has been proposed. One example is given below.
(1) Make-before-break method When switching traffic from an old path to a new path, the path is switched with less traffic interruption by deleting the old path after the traffic has been transferred. (For example, see Non-Patent Document 3)

As prior art documents related to the invention of the present application, there are the following.
Takashi Kurimoto, Takashi Miyamura, Michihiro Aoki, Ichiro Inoue, Nobuaki Matsuura, Hisashi Kojima, Shigeo Urushiya, “Proposal of Multi-layer Service Network Architecture,” IEICE Technical REPORT OF IEICE, PN2003-6 (2003-09). Kohei Shiomoto, Eiji Oki, Masaru Katayama, Wataru Imajuku and Naoaki Yamanaka, “Dynamic multi-layer traffic engineering in GMPLS networks,” ISS2002. “Extensions to RSVP for LSP Tunnels,” RFC 3209.

Up to now, path switching within one layer such as only in a circuit switched network and only in a packet network has been performed by the above-described Make-before-break method.
However, no path switching method that considers two layers has been proposed so far, in which lower layer path arrangement is determined in consideration of higher layer traffic.
Even in the BQCX method, which is the CSPF considering the two layers mentioned above, although it is supposed to perform dynamic route control considering the traffic volume of the upper layer and the path of the lower layer, the actual path switching method Until is not considered.
Further, in a path switching method in which a new path that is newly established for use instead of an old path that has been used so far is deleted, the time required for switching becomes long.
As a result, the instantaneous interruption of traffic becomes longer, and there arises a problem that, for example, video and music being distributed are temporarily interrupted.
In particular, in a network in which lower layer path arrangement is determined in consideration of upper layer traffic, path switching is performed in cooperation with the upper layer and lower layer, requiring a two-step switching procedure.
Therefore, it is important to shorten the time required for path switching and delete the old path and set the new path.

The present invention has been made to solve the above-described problem, and an object of the present invention is to add or delete a lower layer path as appropriate in a network in which a plurality of user groups exist, and continue to route the upper layer path. Path switching method and path for minimizing momentary interruptions and reducing the impact on flowing traffic in the process of performing dynamic path switching to achieve bandwidth efficient path placement by recalculating It is to provide a switching control device.
Another object of the present invention is to provide a path switching program for causing a computer to execute the above path switching method.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
In order to solve the above-described problems, in the present invention, when there are a plurality of user groups in a network in which an upper layer and a lower layer exist, a lower layer path is appropriately added / deleted, and the upper layer path continues. In the process of dynamic path switching to re-calculate the path of the path to achieve a path placement with good bandwidth accommodation efficiency, after switching traffic, delete the old upper layer path and the old lower layer path that can be deleted Therefore, it is characterized by minimizing the momentary interruption and reducing the influence on the flowing traffic.
Further, the present invention is characterized in that a node in an upper layer has a function of determining upper and lower paths, so that the node independently performs a series of dynamic path switching between the lower layer and the upper layer. To do.
Also, the present invention is characterized in that the path switching control apparatus for executing the above path switching method is used exclusively for the purpose of centrally managing and controlling each node in the network.
Also, the present invention is characterized in that a path switching control apparatus that executes the above-described path switching method manages and controls a node attached to each node in the network.
The present invention is also a program for causing a computer to execute the procedure of the path switching control device in the path switching method described above.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
According to the present invention, it is possible to dynamically switch paths while minimizing the influence on flowing traffic.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof is omitted.
[Example 1]
First, a network configuration to which the path switching control apparatus according to the first embodiment of the present invention is applied will be described.
FIG. 1 is a conceptual diagram of a network to which the path switching control device of this embodiment is applied, and is a conceptual diagram of a network in which a packet network is accommodated in a circuit switched network.
The network shown in FIG. 1 includes switches (A1, B1, C1, D1), routers (A2, B2, C2, D2), and a path switching control device 10.
The switches (A1, B1, C1, D1) have a role of transferring wavelength and TDM data, and the switches are connected by a physical link to form a circuit switching network.
The router (A2, B2, C2, D2) is connected to the switch (A1, B1, C1, D1), and has a function of transferring packets by passing data to each switch (A1, B1, C1, D1). Have.
Each router is connected by a logical path provided by setting a path of a lower layer, and constitutes a packet network.

In such a network, the upper layer is accommodated in the lower layer, and the lower layer provides a virtual topology to the upper layer.
The upper layer means a connectionless type or connection type network accommodated in a network relatively lower than the own network, and the lower layer means a network relatively higher than the own network. It means a connection type network to accommodate.
The upper layer is an IP or Ethernet or MPLS network that transfers IP packets with a label attached thereto, and the lower layer is a TDM or WDM network.
When there are a plurality of user groups in the network, the path switching control device 10 collects some information only for users belonging to the target user group, and only between users belonging to the same user group based on the information. The path calculation for path design is performed in step (3), and information necessary for path establishment is exchanged with each router based on the calculation result.

FIG. 2 is a block diagram illustrating a schematic configuration of the path switching control device 10 according to the present embodiment.
As shown in the figure, the path switching control device 10 includes a route calculation unit 11, a path information storage unit 12, a routing information storage unit 13, a membership information storage unit 14, an upper layer information storage unit 15, A path information control unit 16, a control interface 17 with an external device, and a routing information control unit 18 are provided.
The table of FIG. 3 shows how the functions of each unit and the information necessary to implement the above-described algorithm correspond to the function blocks.
(1) The route calculation unit 11 performs network path calculation.
(2) The path information storage unit 12 collects and stores upper / lower layer path information in the network, lower layer link information used by the upper layer path, and upper layer path traffic information.
(3) The routing information storage unit 13 stores upper / lower layer topology information and link cost / residual bandwidth information.
(4) The membership information storage unit 14 manages and stores user information.
(5) The upper layer information storage unit 15 creates upper layer information for each user from the information in the path information storage unit and the membership information storage unit, and stores it in the internal database 151.
(6) The path information control unit 16 controls the flow of path establishment in the upper layer and the lower layer.
(7) The control interface 17 with the external device sends a path establishment / cancellation command and accompanying information to the external device (in this case, a router).
(8) The routing information control unit 18 collects information for attaching a cost to a link in the network, and transmits link cost information necessary for route calculation to the routing information storage unit 13.

So far, path switching within one layer has been performed. However, this is a method of switching paths between both layers while considering the upper layer and lower layer paths at the same time, which is important in a network that determines lower layer path arrangement in consideration of upper layer traffic. Not taken into account.
In this embodiment, in the process of performing dynamic path switching to make a path placement with a high bandwidth accommodation efficiency by adding / deleting a path of a lower layer as appropriate and subsequently recalculating a path of a path of an upper layer. The above problem is solved by providing a path switching method for minimizing the momentary interruption and reducing the influence on the flowing traffic.
For example, the MILP (Mixed Integer Linier Program) method is used as a route calculation for performing path switching.
FIG. 4 is a flowchart for explaining a path switching method according to the embodiment of the present invention, and describes a dynamic path switching operation in a network in which lower layer path arrangement is determined in consideration of upper layer traffic. It is a flowchart for.
In FIG. 4, it is assumed that a route for establishing a path only between users belonging to the same user group has already been calculated.
First, a lower layer path that is to be newly added as a result of route calculation is set (step 101).
Next, an upper layer path is set on the new lower layer topology completed in step 101 (step 102).
The upper layer path may be established between all routers in the network, or may be established only between specific routers.

When both the upper and lower paths have been established, the flowing traffic is switched from the old path to the new path (step 103).
Then, after switching the traffic, the old upper layer path is deleted (step 104).
In this way, by deleting the old upper layer path after switching the traffic, it is possible to minimize instantaneous interruption and reduce the influence of the flowing traffic.
Next, when the old upper layer path is deleted, it is checked whether there is an old lower layer path that can be deleted (step 105).
Since a plurality of upper layer paths may be accommodated in one lower layer path, a lower layer path accommodating even an upper layer path cannot be deleted.
By deleting unnecessary lower layer paths when the path switching is completed, it becomes possible to use the bandwidth without waste in the entire network.
If there is no lower layer path that can be deleted in step 105, the path switching is completed at this point, and a new path arrangement is completed.
In step 105, if there is a lower layer path that can be deleted, the lower layer path is deleted (step 106), and the path switching is terminated.

Next, what kind of exchange is performed between the path switching control device 10 and the routers (A2, B2, C2, D2) in order to perform the path switching operation described above will be described.
Here, it is assumed that the router (A2, B2, C2, D2) has a function of setting and deleting a path, but the same operation is performed by an external device different from the router (A2, B2, C2, D2). You can go there.
FIG. 5 shows how exchanges are performed between the path switching control device 10 and the routers (A2, B2, C2, D2) when switching the paths of the upper and lower layers in the path switching method of this embodiment. It is a sequence diagram for demonstrating.
In FIG. 5, it is assumed that a route for establishing a path only between users belonging to the same user group has already been calculated.
First, a request is made from the path switching control device 10 to the routers (A2, B2, C2, D2) so as to establish a lower layer path determined to be newly established by route calculation (111 in FIG. 5).
This request is issued from the control interface 17 with an external device in the path switching control device.
This request may be issued only to routers (A2, B2, C2, D2) related to path establishment, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.
Further, the order of the paths for issuing this request may be based on the traffic volume or the number of hops.

The router (A2, B2, C2, D2) receiving the lower layer path establishment request establishes the lower layer path in accordance with the request (112 in FIG. 5).
When the extension of the lower layer path is completed, the router (A2, B2, C2, D2) sends a completion notification to the path switching control device 10 (113 in FIG. 5).
By this notification, the path switching control device 10 can confirm that the lower layer path has been successfully established, and proceeds to the next procedure.
This is the exchange for establishing the lower layer path.
When establishing multiple lower layer paths by switching operation, exchange of path establishment requests, path establishment, and path establishment completion notifications for all lower layer paths to be established may be performed at once, or lower layer paths to be established A path establishment request, a path establishment, and a path establishment completion notification may be exchanged for each one.
In the latter case, steps 111, 112 and 113 in FIG. 5 are repeated until all lower layer paths to be established are established.
Further, the order of paths for issuing requests may be based on traffic volume or hop count.

When the establishment of the lower layer path is completed, next, exchange for establishing a new upper layer path is performed.
When the route of the upper layer path accommodated therein is determined by calculation based on the new lower layer topology, the path switching control device 10 requests the routers (A2, B2, C2, D2) to establish the upper layer path. (114 in FIG. 5).
This request is sent from the control interface 17 with an external device in the path switching control device. This request may be issued only to routers (A2, B2, C2, D2) related to path establishment, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.
The upper layer path may be established between all routers (A2, B2, C2, D2) in the network, or may be established only between specific routers (A2, B2, C2, D2). Further, the order of the paths for issuing this request may be based on the traffic volume or the number of hops.
The router (A2, B2, C2, D2) that has received the upper layer path establishment request establishes the upper layer bus in accordance with the request (115 in FIG. 5).

When the upper layer path is completed, the router (A2, B2, C2, D2) sends a completion notification to the path switching control device 10 (116 in FIG. 5).
By this notification, the path switching control device 10 can confirm that the upper layer path has been successfully established, and proceeds to the next procedure.
This is the exchange for establishing the upper layer path.
When establishing an upper layer path by the switching operation, exchange of path establishment requests, path establishment, and path establishment completion notifications for all upper layer paths to be established may be performed at once, or the upper layer path 1 to be established A path establishment request, a path establishment, and a path establishment completion notification may be exchanged for each one.
In the latter case, steps 114, 115 and 116 in FIG. 5 are repeated until all upper layer paths to be established are established.
Further, the order of paths for issuing requests may be based on traffic volume or hop count.

When both the upper and lower paths have been established, an exchange is performed to switch the flowing traffic from the old path to the new path.
First, the path switching control device 10 requests the routers (A2, B2, C2, D2) to switch traffic from the old path to the corresponding new path (117 in FIG. 5).
This request is sent from the control interface 17 with an external device in the path switching control device. This request may be issued only to routers (A2, B2, C2, D2) related to path establishment, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.
Further, the order of the paths for issuing this request may be based on the traffic volume or the number of hops.
The router (A2, B2, C2, D2) that has received the traffic switching request switches traffic from the old path to the new path according to the request (118 in FIG. 5).

When the traffic is switched from the old path to the new path, the router (A2, B2, C2, D2) sends a completion notification to the path switching control device 10 (119 in FIG. 5).
By this notification, the path switching control device 10 can confirm that the traffic has switched from the old path to the new path, and proceeds to the next procedure.
This is the exchange for switching traffic from the old path to the new path.
When switching traffic, the traffic switching request, traffic switching, traffic switching completion notification may be exchanged at once for the old and new paths to which traffic is to be switched. A traffic switching request, a traffic switching, and a traffic switching completion notification may be exchanged with the group.
In the latter case, steps 117, 118, and 119 in FIG. 5 are repeated until the traffic switching is completed for all paths that should be switched.

When the traffic switching is completed, an exchange for deleting the old upper layer path is performed next.
First, the path switching control device 10 requests the routers (A2, B2, C2, D2) to delete the old upper layer path (120 in FIG. 5).
This request is sent from the control interface 17 with an external device in the path switching control device. This request may be issued only to routers (A2, B2, C2, D2) related to path deletion, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.
Further, the order of the paths for issuing this request may be based on the traffic volume or the number of hops.
The router (A2, B2, C2, D2) that has received the old upper layer path deletion request deletes the old upper layer path in accordance with the request (121 in FIG. 5).

When the old upper layer path has been deleted, the router (A2, B2, C2, D2) sends a completion notification to the path switching control device 10 (122 in FIG. 5).
By this notification, the path switching control device 10 can confirm that the old upper layer path has been successfully established, and proceeds to the next procedure.
This is the exchange for deleting the old upper layer path.
When deleting an old upper layer path, all the old upper layer paths to be deleted may be exchanged at once, a path deletion request, a path deletion, a path deletion completion notification, or the old upper layer path to be deleted. A path deletion request, a path deletion, and a path deletion completion notification may be exchanged for each upper layer path.
In the latter case, steps 120, 121, and 122 in FIG. 5 are repeated until all the old upper layer paths to be deleted are deleted.
Further, the order of paths for issuing requests may be based on traffic volume or hop count.
In this way, by deleting the old upper layer path after switching the traffic, instantaneous interruption can be minimized and the influence on the flowing traffic can be reduced.

When the old upper layer path has been deleted, the old lower layer path is then deleted.
First, the path switching control device checks whether or not the upper layer path is accommodated in the lower layer path, and searches for a lower layer path that does not contain the upper layer path and can be deleted (123 in FIG. 5).
Here, if there is no lower layer path that can be deleted, the path switching is terminated at this point, and traffic exchange is performed with the new topology.
If there is an old lower layer path that can be deleted, the path switching control device 10 requests the router (A2, B2, C2, D2) to delete the old lower layer path that is determined to be deleted first ( 124 of FIG.
This request is sent from the control interface 17 with an external device in the path switching control device. This request may be issued only to routers (A2, B2, C2, D2) related to path deletion, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.
Further, the order of the paths for issuing this request may be based on the traffic volume or the number of hops.
The router (A2, B2, C2, D2) that has received the old lower layer path deletion request deletes the lower layer path in accordance with the request (125 in FIG. 5).

When the deletion of the old lower layer path is completed, the router (A2, B2, C2, D2) sends a completion notification to the path switching control device 10 (126 in FIG. 5).
By this notification, the path switching control device 10 can confirm that the lower layer path has been deleted successfully.
This is the exchange for deleting the old lower layer path.
When deleting multiple old lower layer paths with the old lower layer path deletion operation, the path deletion request, path deletion, and path deletion completion notification can be exchanged at once for all the old lower layer paths to be deleted. Alternatively, a path deletion request, a path deletion, and a path deletion completion notification may be exchanged for each lower layer path to be deleted.
In the latter case, steps 124, 125, and 126 in FIG. 5 are repeated until all lower layer paths to be deleted are deleted.
Further, the order of paths for issuing requests may be based on traffic volume or hop count.
Thus, the path switching considering the upper layer and the lower layer is completed.

FIG. 6 shows a network topology state associated with this exchange.
A network topology immediately before path switching is assumed as shown in FIG.
The dotted line represents the upper layer path, the thick dotted line passes through only one lower layer path and the start and end nodes are connected, and the thin dotted line passes through multiple lower layer paths and the start and end nodes are connected It is the path that is.
The purpose of path switching in FIG. 6 is to change the bandwidth to a network topology that can use the bandwidth more effectively by connecting the start and end nodes with high traffic with only one lower layer path and deleting unnecessary lower layers. .
The network topology after the steps 111, 112, and 113 in FIG. 5 from the state of FIG. 6A is as shown in FIG. 6B.
The new lower layer path is established while the old lower / upper layer path is left as it is.
From the state of FIG. 6B, the network topology after the steps 114, 115, and 116 of FIG. 5 are finished is as shown in FIG. 6C.
Based on the new lower layer topology, the path of the upper layer path is recalculated, and the ground with high traffic is connected by only one lower layer path, and the ground with low traffic passes through multiple lower layer paths. Tied.
After the traffic is switched from the old path to the new path through steps 117, 118, and 119 in FIG. 5 from the state of FIG. 6C, the old upper layer path is deleted in steps 120, 121, and 122 in FIG. Furthermore, the network topology after deleting the old lower layer path in steps 124, 125, and 126 in FIG. 5 is as shown in FIG.
This finally completes the new network topology.

In the path switching method described above, the procedure of the path switching control device 10 can be executed by a computer. In this case, the computer executes a path switching program stored in a hard disk or the like in the computer. Is done.
This path switching program is supplied by a recording medium such as a CD-ROM or a transmission medium having a function of transmitting information such as a network such as the Internet or a communication line such as a telephone line.
The path switching program may be for realizing a part of the processing described above. Furthermore, what can implement | achieve the process mentioned above in combination with the program already recorded on another apparatus, what is called a difference file (difference program) may be sufficient.
Thus, according to the present embodiment, the path of the upper layer is accommodated in the path of the lower layer, and the path of the lower layer is taken into account in the network that cooperates with the upper layer and the lower layer in consideration of predetermined information of the upper layer Is added and deleted as needed, and the path of the upper layer path is continuously recalculated to minimize the instantaneous interruption in the process of dynamic path switching to achieve a path placement with high bandwidth accommodation efficiency. It is possible to reduce the influence on traffic.

[Example 2]
In the first embodiment described above, after the request from the path switching control device 10, the routers (A2, B2, C2, D2), which are higher layer nodes, establish or delete the lower layer path and the upper layer path.
In the path switching method described above, a node in an upper layer has a function of determining an upper / lower path (for example, a function like the path information control unit 16 in the path switching control device), so that the node can uniquely The present invention is also applicable when a series of dynamic path switching between the lower layer and the upper layer is performed. As described above, the same operation may be performed by preparing an external device different from the routers (A2, B2, C2, D2).
In this case, the sequence for explaining what exchange is performed between the path switching control device 10 and the routers (A2, B2, C2, D2) when switching the paths of the upper and lower layers is as follows. As shown in FIG.
The order of establishing a new path, switching traffic, and deleting an old path may be based on traffic volume or hop count.

First, a request is made from the path switching control device 10 to the routers (A2, B2, C2, D2) so as to establish a new path determined to be newly established by route calculation (131 in FIG. 7).
This request is issued from the control interface 17 with an external device in the path switching control device. This request may be issued only to routers (A2, B2, C2, D2) related to path establishment, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.
The router (A2, B2, C2, D2) that has received the new path establishment request establishes the lower and upper layer paths in accordance with the request (132, 133 in FIG. 7).
When the new path is completed, the router (A2, B2, C2, D2) sends a new path completion notification to the path switching control device 10 (134 in FIG. 7).
By this notification, the path switching control device 10 can confirm that the lower layer path has been successfully established, and proceeds to the next procedure.
Next, the path switching control device 10 requests the routers (A2, B2, C2, D2) to switch traffic from the old path to the new path corresponding to the old path (135 in FIG. 7).
This request is sent from the control interface 17 with an external device in the path switching control device. This request may be issued only to routers (A2, B2, C2, D2) related to path establishment, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.
Further, the order of the paths for issuing this request may be based on the traffic volume or the number of hops.

The router (A2, B2, C2, D2) that has received the traffic switching request switches traffic from the old path to the new path according to the request (136 in FIG. 7).
When the traffic is switched from the old path to the new path, the router (A2, B2, C2, D2) sends a traffic switching completion notification to the path switching control device 10 (137 in FIG. 7).
By this notification, the path switching control device 10 can confirm that the traffic has switched from the old path to the new path, and proceeds to the next procedure.
Next, the path switching control device checks whether or not the upper layer path is accommodated in the lower layer path, and searches for a lower layer path that does not accommodate the upper layer path and can be deleted (138 in FIG. 7).
If there is a lower layer path that can be deleted, the path switching control device 10 requests the router (A2, B2, C2, D2) to delete the old path (139 in FIG. 7).
This request is sent from the control interface 17 with an external device in the path switching control device. This request may be issued only to routers (A2, B2, C2, D2) related to path deletion, or to all routers (A2, B2, C2, D2) in the target user network. It may be issued to share information.

Further, the order of the paths for issuing this request may be based on the traffic volume or the number of hops.
The routers (A2, B2, C2, D2) that have received the old path deletion request delete the old upper layer path and the old lower layer path in accordance with the request (140, 141 in FIG. 7).
When the deletion of the old path is completed, the router (A2, B2, C2, D2) sends an old path deletion completion notification to the path switching control device 10 (142 in FIG. 7).
Thus, the path switching considering the upper layer and the lower layer is completed.
In this way, by deleting the old upper layer path after switching the traffic, instantaneous interruption can be minimized and the influence on the flowing traffic can be reduced.
Further, in this embodiment, since it is assumed that the upper layer node has a function of determining the upper / lower path, requests for establishing / deleting the path of the lower / upper layer from the path switching control device side are batched. Done. Therefore, the completion notification for the request is also collectively performed.
Furthermore, since the node side has the function of determining the upper / lower paths, the exchange between the path switching control device 10 and the routers (A2, B2, C2, D2) can be simplified.

[Example 3]
In the first and second embodiments described above, after all the lower and upper layer paths have been established, the traffic is switched and the old path is deleted.
In the above path switching method, after all new lower layer paths have been established, a series of flow of establishing a new upper layer path, switching traffic, deleting an old upper layer path, deleting a lower layer path that can be deleted is performed for each path. But it is possible.
A flowchart of path switching in this case is as shown in FIG.
First, all lower layer paths to be newly added as a result of route calculation are stretched (step 151).
Next, only one of the upper layer paths to be newly established is put on the new lower layer topology completed in step 151 (step 152).
When one new upper layer path is completed in step 152, the flowing traffic is switched from the old path to the new path (step 153).
Then, after switching the traffic, the corresponding old upper layer path is deleted (step 154).
In this way, by deleting the old upper layer path after switching the traffic, instantaneous interruption can be minimized and the influence on the flowing traffic can be reduced.

When the corresponding old upper layer path has been deleted, it is checked whether there is anything that can be deleted in the old lower layer (step 155).
Since a plurality of upper layer paths may be accommodated in one lower layer path, a lower layer path accommodating even an upper layer path cannot be deleted.
If there is a path that can be deleted in step 155, the lower layer path is deleted (step 156).
In this way, by deleting unnecessary lower layer paths when switching is completed for each path, it is easy to secure a band for a new path, particularly when the entire network has insufficient bandwidth. Is possible.
After completing the deletion of the path that can be deleted in step 156, or if there is no lower layer path that can be deleted in step 155, it is checked whether there is another new upper layer path to be established (step 157). ).
If there is no new upper layer path to be established, path switching is completed at this point, and a new path arrangement is completed.
If another new upper layer path to be established exists, the next new upper layer path is selected (step 158), and the processing from step 152 is repeated for the new upper layer path.

[Example 4]
In the above-described first to third embodiments, the path switching control device 10 is used exclusively for the purpose of centrally managing and controlling each node in the network.
In this embodiment, the path switching control device 10 is an embodiment arranged inside each router.
FIG. 9 is a conceptual diagram of the network of this embodiment. As shown in FIG. 9, in this embodiment, the routers (A2, B2, C2, D2) are routers with a path switching function.
As described above, in this embodiment, the path switching control device 10 is arranged inside each router (A2, B2, C2, D2), and manages and controls the node attached to each node in the network.
In the present embodiment, the path switching method and the path switching control device can use the same ones as in the first to third embodiments. Similarly, the path switching method of the present embodiment is a path switching program. By this, it is possible to make the computer execute.
As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

1 is a conceptual diagram of a network to which a path switching control device according to a first embodiment of the present invention is applied. It is a block diagram which shows schematic structure of the path | pass switching control apparatus of Example 1 of this invention. It is a figure explaining the information which each part handles in the passing path switching control apparatus of Example 1 of this invention, and the function of each part. It is a flowchart for demonstrating the path | pass switching method of Example 1 of this invention. FIG. 6 is a sequence diagram for explaining what kind of exchange is performed between a path switching control device and a router when switching paths of upper and lower layers in the path switching method according to the first exemplary embodiment of the present invention. . It is a figure which shows an example of the state change of a network topology in the path | route switching method of Example 1 of this invention. FIG. 10 is a sequence diagram for explaining what kind of exchange is performed between a path switching control device and a router when switching paths of upper and lower layers in the path switching method according to the second embodiment of the present invention. . It is a flowchart for demonstrating the path | pass switching method of Example 3 of this invention. It is a conceptual diagram of the network to which the path | route switching control apparatus of Example 4 of this invention is applied. It is a figure which shows a mode that the traffic exchange between grounds in a network changes with time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Path switching control apparatus 11 Path | route calculation part 12 Path information storage part 13 Routing information storage part 14 Membership information storage part 15 Upper layer information storage part 16 Path information control part 17 Control interface with an external apparatus 18 Routing information control part 151 Database A1, B1, C1, D1 switch A2, B2, C2, D2 router

Claims (8)

When a connectionless type or connection type network accommodated in a network relatively lower than the own network is an upper layer, and a connection type network accommodating a network relatively higher than the own network is a lower layer, There is an upper layer and a lower layer, and there are at least two upper layer routers connected to the lower layer switch. The network exchanges traffic only with users belonging to the same group in the network, This is a path switching method for switching paths between users belonging to the same user group in a network where there is at least one user group defined not to exchange traffic with users belonging to the group. ,
Step 1 of adding a lower layer path;
Establishing a new upper layer path accommodated on the new lower layer topology completed in step 1; and
Step 3 of switching the flowing traffic from the old path to the new path,
Step 4 for deleting the old upper layer path;
And a step 5 for deleting a lower layer path that can be deleted in the old lower layer path. When a connectionless type or connection type network accommodated in a network relatively lower than the own network is an upper layer, and a connection type network accommodating a network relatively higher than the own network is a lower layer, There is an upper layer and a lower layer, and there are at least two upper layer routers connected to the lower layer switch. The network exchanges traffic only with users belonging to the same group in the network, This is a path switching method for switching paths between users belonging to the same user group in a network where there is at least one user group defined not to exchange traffic with users belonging to the group. ,
Has a path switching control device in the network,
Step 1 in which the path switching control device sends a request for adding a lower layer path to the router;
Step 2 in which the router adds a lower layer path;
Step 3 in which the path switching control device sends a request for establishing a new upper layer path accommodated on the new lower layer topology completed in Step 2 to the router;
Step 4 in which the router establishes a new upper layer path;
Step 5 in which the path switching control device sends a traffic switching request to the router;
Step 6 in which the router switches the flowing traffic from the old path to the new path;
Step 7 in which the path switching control device sends a request to delete the old upper layer path to the router;
The router deletes the old upper layer path, step 8;
A step 9 in which the path switching control device sends a request to delete the old lower layer path that can be deleted in the old lower layer path to the router;
A path switching method, wherein the router includes a step 10 of deleting an old lower layer path. When a connectionless type or connection type network accommodated in a network relatively lower than the own network is an upper layer, and a connection type network accommodating a network relatively higher than the own network is a lower layer, There is an upper layer and a lower layer, and there are at least two upper layer routers connected to the lower layer switch. The network exchanges traffic only with users belonging to the same group in the network, This is a path switching method for switching paths between users belonging to the same user group in a network where there is at least one user group defined not to exchange traffic with users belonging to the group. ,
Has a path switching control device in the network,
The path switching control device sends a new path establishment request to the router;
The router establishes a new lower layer path and a new upper layer path;
Step 3 in which the path switching control device sends a traffic switching request to the router;
Step 4 in which the router switches the flowing traffic from the old path to the new path;
Step 5 in which the path switching control device sends a request to delete the old lower layer path and the old lower layer path that can be deleted in the old lower layer path to the router;
The path switching method, wherein the router includes a step 6 of deleting an old upper layer path and an old lower layer path.   A path switching program for causing a computer to execute the procedure of the path switching control device in the path switching method according to claim 2 or 3. When a connectionless type or connection type network accommodated in a network relatively lower than the own network is an upper layer, and a connection type network accommodating a network relatively higher than the own network is a lower layer, There is an upper layer and a lower layer, and there are at least two upper layer routers connected to the lower layer switch. The network exchanges traffic only with users belonging to the same group in the network, A path switching control device that switches paths between users belonging to the same user group in a network where there is at least one user group defined not to exchange traffic with users belonging to the group. I,
Means for sending a request to add a lower layer path to the router;
Means for sending a request for establishing a new upper layer path accommodated on a new lower layer topology to the router;
Means for sending a traffic switching request to the router;
Means for sending a request to delete the old upper layer path to the router;
A path switching control device comprising means for sending a request to delete an old lower layer path that can be deleted in an old lower layer path to the router. When a connectionless type or connection type network accommodated in a network relatively lower than the own network is an upper layer, and a connection type network accommodating a network relatively higher than the own network is a lower layer, There is an upper layer and a lower layer, and there are at least two upper layer routers connected to the lower layer switch. The network exchanges traffic only with users belonging to the same group in the network, A path switching control device that switches paths between users belonging to the same user group in a network where there is at least one user group defined not to exchange traffic with users belonging to the group. I,
Means for sending a request to establish a new path to the router;
Means for sending a traffic switching request to the router;
A path switching control device comprising: an old upper layer path; and a means for sending to the router a request to delete an old lower layer path that can be deleted in the old lower layer path.   7. The path switching control apparatus according to claim 5, wherein the path switching control device is connected to each router in the network and centrally manages and controls each node in the network. The path switching control device described. The path switching control device according to claim 5 or 6 , wherein the path switching control device is arranged in each router in the network, and manages and controls the node attached to each node in the network. apparatus.

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