JP4219300B2 - PATH SETTING METHOD, PATH SETTING SYSTEM, DEVICE USED FOR THE SAME, AND PROGRAM THEREOF - Google Patents

Description

  The present invention relates to a path setting method, a path setting system, an apparatus used therefor, and a program therefor, and in particular, an MPLS (encapsulating an arbitrary packet or frame and transferring it on a logical path set in a predetermined route) In the Multi Protocol Label Switching) technology, a protection method is provided that sets a backup path to be used when there is an abnormality on the working path, in addition to the working path that is used during normal operation, in order to suppress communication interruption time due to a failure in the network. In particular, the present invention relates to a system for supplying a protection scheme on Layer 2 frame over MPLS that encapsulates and transfers layer 2 frames.

In MPLS, there is a protection method as a technique for suppressing communication interruption time due to a failure in a network. As shown in FIG. 6, in this method, a spare path used when there is an abnormality on the working path 41 in the MPLS path connecting the router 1 and the router 2 separately from the working path 41 used in the normal state. 42 is set in advance. When a failure occurs on the network that relays the working path 41, the occurrence of the failure is notified to the switching end point router (in FIG. 6, the router 1 and the router 2 are the switching end point routers). It is a method of switching.
In FIG. 6, the operation order until switching to the backup path 42 is shown. First, (1) when a failure occurs in the working path 41, (2) the router 1 and 2 are notified of the failure. Next, (3) path switching, that is, switching from the working path 41 to the protection path 42 is performed. The switching end point router (edge router) includes a VC label termination unit 11 (21) and a tunnel label termination unit 12 (22).

Layer 2 frame over MPLS is a method of MPLS encapsulation of layer 2 frames as they are, and has a characteristic that information of layer 3 or higher can be transferred without being conscious of it. In Layer 2 frame over MPLS, packets are transferred in a format as shown in FIG. Here, label 1 is called a tunnel label and is an ID indicating a transfer destination, label 2 is called a VC label, and Layer 2 frame over MPLS Edge router (in FIG. 6, router 1 and router 2 are The ID indicates a mapping with a layer 2 connection to be transferred that is connected to the edge router.
In other words, in the protection method in the Layer 2 frame over MPLS path, switching the path due to the occurrence of a failure on the network means changing the tunnel label at the switching end point and sending the packet toward the transfer destination corresponding to the label. Is shown. On the other hand, before and after the path switching, the VC label is not changed, and by sending out the same value, the Edge router can identify the corresponding layer 2 connection without being aware of the path switching. it can.

  As for the trend of MPLS, “Current Trend of MPLS”, Murakami, [March 11, 2004 search] Internet URL <http: // www. jk. ws32. arena. ne. jp / wk0219 / pdf / a-2. pdf> (see Non-Patent Document 1). As for the failure recovery technology, there is an NTT R & D October 2001 issue (special issue HIKARI router “OA & M and failure recovery technology of photonic MPLS router”) (see Non-Patent Document 2).

“Current Trends in MPLS”, Murakami, [retrieved on March 11, 2004] Internet URL <http: // www. jk. ws32. arena. ne. jp / wk0219 / pdf / a-2. pdf> NTT R & D October 2001 issue (Special issue HIKARI router "OA & M and failure recovery technology of photonic MPLS router")

  As described above, in the conventional protection method, the Edge router that is the starting point or the ending point of the path is common regardless of which of the working path and the protection path. Here, considering that a point where a server device or the like that provides a service is installed and a point where each user terminal or the like is installed are connected by a Layer 2 frame over MPLS path, an important point at the point where the server device is installed is The failure is related to the survivability of the service itself.

(the purpose)
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a path setting method that can solve the conventional problems and can redundantly arrange devices that affect service provision in order to improve service continuity in the Layer 2 frame over MPLS path. To provide a path setting system, an apparatus used therefor, and a program therefor.
In addition, another object of the present invention is to provide a path setting method, a path setting system, and a path setting system capable of specifying a layer 2 connection without being aware that the reverse end edge router has switched the path. It is to provide an apparatus and a program thereof.

In the present invention, as shown in FIG. 1, on the Layer 2 frame over MPLS path, the working path 41 used in the normal state and the protection path 42 used when there is an abnormality on the working path 41 are different Edge routers. A path is set so as to go to 3.
Here, in the path setting method as shown in FIG. 1, when performing transfer from the router 2 that is an edge router at the normal time and the router 3 that is an edge router at the time of an abnormality to the router 1, the router that is an ingress router 2 and the packet arriving from the router 3 are different from each other, the router 1 which is an egress router identifies the corresponding layer 2 connection in consideration of the path switching at the switching end point router. There is a need.

Therefore, in the present invention, the MPLS label usage status of each router in the network is managed, a label value that is not used in all Edge routers in the set path is searched, and the label value is distributed to each Edge router. In each router, the Layer 2 frame over MPLS path is set with the distribution level value as the VC label.
The system of the present invention also includes means for managing the used MPLS label of each router in the network, means for searching for a label value that is not used in all Edge routers in the set path, and the label value for each Edge. Means for distributing to routers and setting as a common VC label value.

According to the present invention, in the Layer 2 frame over MPLS path, by setting the path so that the working path used in the normal state and the backup path used when there is an abnormality on the working path are directed to different Edge routers. , Equipment that affects service provision can be placed at another point for redundancy, and if there is an important failure at a point connected to the working path, service should continue on the device connected to the backup path Can do.
In such a Layer 2 frame over MPLS path, in a path configuration in which a working path used in a normal state and a backup path used in the event of an abnormality on the working path are directed to different Edge routers, a Layer is previously stored. 2 Frame over MPLS path Edge router searches for an unused label value, and the label value is used as a common VC label value for the Layer 2 frame over MPLS path, so the working path and backup path are ingress. Even if the routers are different, the VC label value of the packet that arrives at the edge router does not change before and after the path switching, so the edge router identifies the layer 2 connection without being aware of the path switching. Thus, packet transmission can be performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of an MPLS path setting system according to an embodiment of the present invention, in which an active path used in a normal state and a backup path used when an abnormality occurs on the active path are different Edges. A configuration for setting a path to the router is shown.
During normal operation, frame transfer is performed between the switching end point router (Edge router) 1 and the Edge router 2 via the working path 41 on the MPLS network. When an abnormal situation occurs on the working path 41, a failure is notified to the switching end point router (Edge router) 1, and the path is switched from the working path 41 on the MPLS network to the protection path. As a result, frame transfer is performed from the switching end point router (Edge router) 1 to the Edge router 3 via the backup path 42.
As described above, in this embodiment, the working path 41 used in the normal state on the Layer 2 frame over MPLS path and the protection path 42 used when there is an abnormality on the working path 41 are different in the Edge router. A path is set to head.

  In FIG. 1, 11, 21, and 31 are all VC label termination units, and 12, 22, and 32 are all tunnel label termination units. When VC = X is input from the left side of the switching end point router 1, the VC label termination unit 11 converts VC = X into the label 2 or 3 with reference to the table and sends it to the tunnel label termination unit 12. The tunnel label termination unit 12 refers to the table and assigns a label α or β depending on whether it is active or spare and sends it to the MPLS network. In the case of working, the tunnel label α and the VC label 2 are formed as the header of the MPLS packet, and then a layer 2 header, an arbitrary packet, a trailer such as layer 2 and the like are carried and sent to the working path 41. In the case of the backup, after forming the tunnel label β and the VC label 3 as the header of the MPLS packet, a layer 2 header, an arbitrary packet, a layer 2 trailer, and the like are placed and transmitted to the backup path 42. The Edge routers 2 and 3 perform the reverse processing described above, and output with VC = Y or VC = Z shown on the right side.

FIG. 2 is a flowchart of label setting processing in the edge router according to an embodiment of the present invention, and FIG. 3 is a configuration diagram of an MPLS label value usage situation table in the edge router.
Here, first, an MPLS path directed to an Edge router having a different working path and backup path is set in each router of the network by the existing technology. When the VC label setting is started (step 102), an MPLS label value use situation table of each router in the network as shown in FIG. 3 is created in advance, and the Layer 2 frame over to be set is set based on this table. An empty label value common to each Edge router in the MPLS path is searched (step 103). Here, if there is no empty label value, the process ends as setting NG (step 105). If an empty label value can be retrieved, the value n is distributed and set as a VC label to each Edge router (step 104), and the VC label setting is terminated (step 106).

4 and 5 are diagrams for explaining the operation of the MPLS path setting system according to an embodiment of the present invention. FIG. 4 shows a case where an MPLS label usage status search server 51 is arranged, and FIG. 5 shows a search server. The case where no is arranged is shown.
First, in FIG. 4, a server 51 for managing and retrieving the MPLS usage status is arranged separately from the router 1 for setting the MPLS path. Layer 2 frame over MPLS path setting is performed according to the following flow.
(Step 0): An MPLS path is set. That is, the working path 41 and the protection path 42 are set on the MPLS network.

(Step 1): The MPLS usage status search server 51 searches for an empty label value common to each Edge router of the Layer 2 frame over MPLS path to be set, using the MPLS label value usage status table created in advance. That is, an empty label value common to the router 1, the router 2, and the router 3 is searched.
(Step 2): Distribute a label value as a search result to each Edge router as a VC label value, and set it as a VC label value of an already set MPLS path. That is, as indicated by the broken line arrows in FIG. 4, the VC label values are distributed to the router 1, router 2, and router 3 tables and set on the sending side and the receiving side, respectively.
In this embodiment, since γ is a common empty label value, γ is set as the VC label value in the router 1, the router 2, and the router 3.

Next, the process of FIG. 5 will be described.
FIG. 5 shows a configuration in which an empty label value search setting function is installed in each Edge router, and a Layer 2 frame over MPLS path is set according to the following flow.
(Step 0): An MPLS path is set. That is, a path having the router 1 and the router 2 as the edge server is set as the working path 41, and a path having the router 1 and the router 3 as the edge server is set as the backup path 42, respectively.
(Step 1): In the empty label value search setting function unit, an empty label value common to each Edge router of the Layer 2 frame over MPLS path to be set is searched based on a previously created MPLS label value usage situation table. That is, an empty label value common to the router 1, the router 2, and the router 3 is searched.

(Step 2): Distribute a label value as a search result to each Edge router as a VC label value, and set it as a VC label value of an already set MPLS path.
In this embodiment, since γ is a common empty label value, γ is set as a VC label value in router 1, router 2, and router 3.

  Each step of the flowchart shown in FIG. 2 and steps 0 to 2 shown in FIG. 4 or 5 are programmed, and the completed program is stored in a recording medium such as a hard disk, so that the path setting program according to the present invention is sold. In addition, the present invention can be easily implemented by installing a recording medium on the computer of the Edge router 1, 2, 3 or the MPLS label usage status search server 51, installing the program, and executing the program. Can be realized.

1 is a configuration diagram of an MPLS path setting system according to an embodiment of the present invention. 6 is an MPLS path setting operation flowchart of an edge router according to an embodiment of the present invention. It is a block diagram of the MPLS label value utilization status table according to an embodiment of the present invention. It is operation | movement explanatory drawing of the MPLS label utilization condition search server which concerns on one Example of this invention. It is operation | movement explanatory drawing of the MPLS label value utilization condition search function of the Edge router which concerns on one Example of this invention. It is explanatory drawing of the MPLS protection system in the conventional Layer 2 frame over MPLS. It is a block diagram of an MPLS packet on a Layer 2 frame over MPLS path.

Explanation of symbols

1 ... switching end point router (Edge router), 2, 3 ... Edge router,
11, 21, 31 ... VC label termination, 12, 22, 32 ... tunnel label termination,
41 ... active path, 42 ... backup path, 51 ... MPLS label usage status search server.

Claims (9)

In the Layer 2 frame over MPLS path setting method for encapsulating and transferring layer 2 frames,
While setting the working path to be used at normal time and the backup path to be used when there is an abnormality on the working path to be directed to different Edge routers ,
Determining and managing the MPLS label value usage status of each router in the network when setting the working path and the protection path;
A step of searching a label value usage table for a label value that is not used in all Edge routers of the Layer 2 frame over MPLS path to be set;
Distributing to each Edge router of the path for setting the label value;
Setting a Layer 2 frame over MPLS path using the label value distributed in each router as a VC label;
Path setting method characterized by having a. The path setting method according to claim 1 ,
The path setting method characterized in that, in the step of searching from the label value usage status table, a free label value common to each Edge router of the Layer 2 frame over MPLS path to be set is searched. In a Layer 2 frame over MPLS path setting system for encapsulating and transferring layer 2 frames,
Opposite Edge router connected to the switching endpoint router via the working path used at normal time, and
Via the backup path to be used when there is abnormality on the developing for the path is connected to the switching endpoint router, it provided the different second opposing Edge Router and the opposing Edge Router,
And,
For the switching end point router, means for determining and managing the MPLS label usage status of each router in the network and label values that are not used in all Edge routers of the Layer 2 frame over MPLS path to be set are used as label value usage. A path setting system comprising: means for searching from a situation table; and means for distributing and setting to each edge router of a path for setting the label value . In the path setting system according to claim 3 ,
The path setting system characterized in that the means for searching from the label value usage status table searches for an empty label value common to each Edge router of the Layer 2 frame over MPLS path to be set. In the Edge router device of the Layer 2 frame over MPLS system that encapsulates and transfers layer 2 frames,
A path is configured to transfer the layer 2 frame to the opposite edge router or the second opposite edge router different from the opposite edge router through the working path used in the normal state or the backup path used in the abnormal state. A switching endpoint comprising: a means for searching and selecting a free VC value of a router to be used from a label value utilization status table and distributing the free VC value to the opposing Edge router and the second opposing Edge router Edge router device which is a router. In a search server device provided in a switching end point router of a Layer 2 frame over MPLS system for encapsulating and transferring a layer 2 frame,
The layer 2 frame is transferred from the switching end point router to the opposite edge router or a second opposite edge router different from the opposite edge router through the working path used in the normal state or the backup path used in the abnormal state. Therefore, there is provided means for searching and selecting a free VC value of a router constituting a path from the label value utilization status table, and distributing the free VC value to the opposite Edge router and the second opposite Edge router. A characteristic MPLS label usage status search server device. In the opposite Edge router device of the Layer 2 frame over MPLS system that encapsulates and forwards the layer 2 frame,
When the switching endpoint router searches and selects the free VC value of the router constituting the path from the label value usage status table, and the free VC value is distributed, the free VC value is stored in the VC label value usage status table. A counter edge router device comprising means for storing, disassembling a frame transferred from the switching end point router, storing and outputting the VC label value. In the Layer 2 frame over MPLS path setting program for encapsulating and transferring layer 2 frames,
Procedures for determining and managing the MPLS label value usage status of each router in the network in order to set the working path and the backup path in the switching end point router computer, used in all Edge routers of the Layer 2 frame over MPLS path to be set A procedure for retrieving a label value that has not been performed from the label value utilization status table, a procedure for distributing the label value to each Edge router in the path for which the label value is set, and a Layer 2 frame over with the label value distributed at each router as a VC label An MPLS path setting program for executing a procedure for setting an MPLS path. The MPLS path setting program according to claim 8 ,
In order to set the working path and the backup path in the computer of the MPLS label usage status search server, the procedure for determining and managing the MPLS label value usage status of each router in the network, and all Edges of Layer 2 frame over MPLS paths to be set A procedure for retrieving a label value that is not used in a router from a label value utilization status table, a procedure for distributing to each Edge router of a path for setting the label value, and a label value distributed to each router as a VC label Layer 2 frame over An MPLS path setting program for executing a procedure for setting an MPLS path.

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