JP6251654B2 - Communication system, identifier management apparatus, and identifier assignment method - Google Patents

Description

  The present invention relates to a communication network that constitutes a point-to-multipoint tunnel using a protocol in which an identifier is assigned to a packet and encapsulated and transferred.

  FIG. 1 shows an example of a communication network in the above technical field. The communication network is a network including a router and an L2 transfer device (may be referred to as an L2 switch). In the example illustrated in FIG. 1, the communication network includes routers R1 to R3 and L2 transfer devices SW1 to SW4, and the L2 transfer device SW2 The route is branched.

  In the communication network of FIG. 1, a protocol is used in which an identifier is assigned to a packet between the routers and encapsulated and transferred between the routers. Copy and perform multicast transfer. FIG. 1 shows that a packet is copied and transferred to a downstream apparatus by the L2 transfer apparatus SW2.

  Examples of techniques for assigning and transferring identifiers to packets include IP / MPLS multicast (Non-Patent Document 1), MPLS-TP P2MP LSP (Non-Patent Document 2), and the like. The outline of each technology is as follows.

<IP / MPLS multicast>
IP / MPLS multicast is a technique for realizing multicast distribution using an MPLS protocol that encapsulates and transfers a packet by an identifier called a label. In IP / MPLS multicast, as shown in FIG. 2, each router has a label table in which a tunnel ID (Tunnel ID) for identifying a P2MP tunnel, a label ID for identifying a label (Label), and an output IF are linked. The packet is transferred according to the table.

  With reference to FIG. 2, the procedure for creating a label table in the prior art will be described. First, the upstream router R1 notifies the tunnel ID to the downstream routers R2 and R3 (step 1). This message is called a label request message. As shown in FIG. 2, since router R2 is the end point of tunnel 1, "tunnel 1" is notified, and router R3 is the end point of tunnels 1 and 2, so that "tunnel 1" and "tunnel 2" Be notified.

  Next, the downstream routers R2 and R3 assign a label to the received tunnel ID and create a label table (step 2). As shown in FIG. 2, router R2 assigns label 1 to tunnel 1, and router R2 assigns labels 1 and 2 to tunnels 1 and 2, respectively.

  The downstream routers R2 and R3 notify the upstream router R1 of the assigned label ID (step 3). This message is called a label assignment message. Then, the upstream router R1 creates a label table according to the notified label ID (step 4).

<MPLS-TP P2MP LSP>
MPLS-TP P2MP LSP is a technique for performing packet copy in the L2 layer. In this technique, a point-to-multipoint L2 path is set in advance, and the packet is encapsulated with an MPLS-TP label so that the packet is transferred along the path. There is no mechanism for exchanging the label information between the switches, and the label table is created according to the preset path information.

https://kb.juniper.net/library/CUSTOMERSERVICE/GLOBAL_JTAC/technotes/2000320-en.pdf, Understanding junos next-generation multicast VPNs, searched August 13, 2014 http://tools.ietf.org/html/draft-fbb-mpls-tp-p2mp-framework-05, D. Frost, S. Bryant, M. Bocci and L. Berger, "A Framework for Point-to- Multipoint MPLS in Transport Networks, "2 Aug 2012, searched on August 13, 2014

  An object of the present invention exists in a protocol having a mechanism for exchanging label information between apparatuses. Here, a problem about IP / MPLS will be described as an example.

  As described above, in the conventional protocol, each downstream router independently assigns a label and transmits a label assignment message to the upstream router, and a label table is created by the message to realize packet transfer. However, there is a problem as shown in FIG. 3 in the network in which the L2 transfer apparatus that does not receive the label assignment message performs packet copying.

  In the case of the example shown in FIG. 3, as a result of each downstream router assigning a label independently, label 2 is assigned to tunnel 1 in router R2, label 1 is assigned to tunnel 1 in router R3, and tunnel 2 is assigned to tunnel 2. Label 2 is allocated, and this information is notified to router R3 by a label allocation message, and a label table is created.

  That is, as shown in FIG. 3, different labels are assigned to the same P2MP tunnel, and the same labels are assigned to different P2MP tunnels.

  By assigning different labels to the same P2MP tunnel, there is a problem (problem 1) that a plurality of the same packets are transmitted, leading to increased router load and inefficient transmission bandwidth. Further, since the same label is assigned to different P2MP tunnels, the tunnel cannot be identified by the downstream router, so that there is a problem that normal transfer cannot be performed (problem 2).

  The present invention has been made in view of the above points, and in a communication system that performs communication through a point-to-multipoint tunnel using a protocol in which an identifier is attached to a packet and encapsulated and transferred, the present invention is efficient and normal. An object of the present invention is to provide a technique for performing multicast distribution.

According to an embodiment of the present invention, there is provided a communication system that performs communication through a point-to-multipoint tunnel between a plurality of routers by using a protocol that encapsulates and transfers packets with identifiers. ,
An identifier table in which a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier that is assigned to a packet that passes through the tunnel, and a router identifier that is an identifier of a router at the end of the tunnel,
Receiving means for receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control means for selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
Transmitting means for transmitting a packet identifier assignment message including the packet identifier selected by the assignment control means and the tunnel identifier to a router serving as an end point of the tunnel ;
The allocation control means determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and when the tunnel identifier exists on the identifier table, A communication system is provided that selects a packet identifier of an entry having an identifier, and selects one packet identifier that does not exist on the identifier table when the tunnel identifier does not exist on the identifier table. Is done.

Further, according to the embodiment of the present invention, in a communication system that performs communication through a point-to-multipoint tunnel between a plurality of routers by using a protocol that encapsulates and forwards packets with identifiers. An identifier management device used,
An identifier table in which a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier that is assigned to a packet that passes through the tunnel, and a router identifier that is an identifier of a router at the end of the tunnel,
Receiving means for receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control means for selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
Transmitting means for transmitting a packet identifier assignment message including the packet identifier selected by the assignment control means and the tunnel identifier to a router serving as an end point of the tunnel ;
The allocation control means determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and when the tunnel identifier exists on the identifier table, An identifier management apparatus that selects a packet identifier of an entry in which an identifier exists, and selects one packet identifier that does not exist on the identifier table when the tunnel identifier does not exist on the identifier table. Provided.

Further, according to the embodiment of the present invention, in a communication system that performs communication through a point-to-multipoint tunnel between a plurality of routers by using a protocol that encapsulates and forwards packets with identifiers. An identifier assignment method executed by the identifier management device used,
The identifier management device includes an identifier table that associates a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier given to a packet passing through the tunnel, and a router identifier that is an identifier of a router at a tunnel end point. ,
Receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control step of selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
A transmission step of transmitting a packet identifier assignment message including the packet identifier selected by the assignment control step and the tunnel identifier to a router serving as an end point of the tunnel ;
In the allocation control step, the identifier management device determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and the tunnel identifier exists on the identifier table. A packet identifier of an entry in which the tunnel identifier exists is selected, and when the tunnel identifier does not exist on the identifier table, one packet identifier that does not exist on the identifier table is selected. An identifier assignment method is provided.

  According to an embodiment of the present invention, multicast distribution is efficiently and normally performed in a communication system in which communication is performed via a point-to-multipoint tunnel using a protocol in which an identifier is attached to a packet and encapsulated and transferred. It becomes possible.

It is a figure which shows the structural example of a communication network. It is a figure for demonstrating the example of the conventional operation | movement of a communication network. It is a figure for demonstrating a subject. It is a block diagram of the communication system which concerns on embodiment of this invention. 2 is a configuration diagram of an identifier management device 100. FIG. 5 is a flowchart for explaining the operation of the identifier management apparatus 100. It is a figure for demonstrating the label allocation operation example 1. FIG. It is a figure for demonstrating the label allocation operation example 2. FIG. It is a figure for demonstrating the label allocation operation example 3. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiment described below is only an example, and the embodiment to which the present invention is applied is not limited to the following embodiment. In the following description, the P2MP tunnel is referred to as a “tunnel”.

(System configuration)
FIG. 4 shows a configuration diagram of a communication system according to the embodiment of the present invention. The communication system according to the present embodiment includes routers R1 to R3 and L2 transfer devices SW1 to SW4. As shown in FIG. 4, each device is communicably connected and constitutes a network (network) in which the route is branched by the L2 transfer device SW2. Between routers, a protocol (for example, IP / MPLS) is used in which identifiers are assigned to packets and encapsulated and transferred. Multicast transfer is performed by copying packets between L2 transfer apparatuses according to a statically set point-to-multipoint (P2MP) L2 logical path. A tunnel is configured by the L2 logical path, and packet communication using the tunnel is performed between routers by the above protocol.

  As shown in FIG. 4, the identifier management apparatus 100 is provided in the communication system of the present embodiment. The identifier management device 100 can communicate with each router via a network such as an IP network. As will be described later, the function of the identifier management device 100 may be provided in any router.

  The identifier management device 100 is a device having a function of assigning a unique label to each tunnel in the network. That is, the identifier management apparatus 100 has an identifier management function for managing the tunnel ID and label ID of the entire network and performing label allocation.

  FIG. 5 shows a functional configuration diagram of the identifier management apparatus 100. The identifier management device 100 may be realized by a so-called server or a communication device such as a router or a switch.

  As shown in FIG. 5, the identifier management apparatus 100 includes a label request message receiving unit 101, a label assignment message transmitting unit 102, a label assignment control unit 103, and a label table storage unit 104.

  The label request message receiving unit 101 receives a label request message from a router or another device (such as a network management device). The label request message includes a tunnel ID (P2MP Tunnel ID) to be assigned a label, and an ID (eg, address) of a router serving as a destination for notifying the label ID assigned to the tunnel ID. The destination router that notifies the label ID assigned to the tunnel ID is a router at the end point of the tunnel identified by the tunnel ID. In this embodiment, the path that forms the tunnel is an LSP. The router as the destination can be called an LSP end point router. Further, one label request message may include only one LSP end point router ID as a destination to notify the label ID, or may include IDs of all routers at the end points of the tunnel. The IDs of some of the routers at the end points of the tunnel may be included.

  The label allocation message transmission unit 102 transmits a label allocation message to the destination LSP end point router that notifies the label ID. The label assignment message includes the ID of the LSP end point router that is the target of label assignment, the target tunnel ID, and the label ID assigned to the tunnel ID. One label assignment message may contain only one LSP end point router ID, may contain the IDs of all the routers at the tunnel end points, or all the routers at the end points of the tunnel. The IDs of some of the routers may be included.

  The label table storage unit 104 stores a label table. As shown in FIG. 5, the label table is a table in which tunnel IDs, label IDs, and LSP end point router IDs are associated with each other.

  The label assignment control unit 103 assigns a label ID to the tunnel ID included in the label request message by referring to the label table, and notifies the label assignment message transmission unit 102 of the assignment result.

  The identifier management apparatus 100 according to the present embodiment is a program in which, for example, one or a plurality of computers (which may be a server or a communication apparatus including a computer function) describes the processing content described in the present embodiment. This can be realized by executing. That is, the function of the identifier management apparatus 100 is realized by executing a program corresponding to the process executed by the identifier management apparatus 100 using hardware resources such as a CPU, a memory, and a hard disk built in the computer. Is possible. Further, the program can be recorded on a computer-readable recording medium (portable memory or the like), stored, or distributed. It is also possible to provide the program through a network such as the Internet or electronic mail.

(Operation example of identifier management apparatus 100)
FIG. 6 is a flowchart for explaining the operation of the identifier management apparatus 100. An example of the operation of the identifier management apparatus 100 will be described with reference to FIG.

  First, the label request message receiving unit 101 of the identifier management apparatus 100 receives a label request message (including a tunnel ID and an LSP end point router ID) (step 101). Next, the label allocation control unit 103 determines whether or not the tunnel ID specified by the label request message exists on the label table (step 102).

  If the tunnel ID exists in the label table in step 102, the process proceeds to step 103, and the label allocation control unit 103 selects the label ID of the entry in which the tunnel ID exists on the label table. By performing such processing, it can be avoided that a plurality of label IDs are assigned to the same tunnel ID.

  If the tunnel ID specified in the label request message does not exist on the label table in step 102, the process proceeds to step 104, and the label allocation control unit 103 selects (determines) one label ID that does not exist on the label table. To do. By performing such processing, it is possible to avoid assigning the same label ID to different tunnel IDs.

  Subsequently, the label allocation control unit 103 updates the label table with the selected label ID, the received tunnel ID, and the LSP end point router ID (step 105). As an example, if the received tunnel ID does not exist on the label table, for example, if (selected label ID, tunnel ID, LSP endpoint router ID) = (1, 1, 10 and 20), (1 , 1, 10) and (1, 1, 20) are added to the label table. Further, when the received tunnel ID exists on the label table, for example, if (selected label ID, tunnel ID, LSP end point router ID) = (1, 1, 30), (1, 1, 30) 30) is added to the label table.

  Then, the label allocation control unit 103 passes the allocation result to the label allocation message transmitting unit 102, and the label allocation message transmitting unit 102 transmits a label allocation message including the allocation result to the LSP end point router that needs label allocation. (Step 106).

(Example of label assignment operation in communication system)
Next, an allocation operation example in the communication system will be described with reference to FIGS. FIG. 7 shows an operation example when the identifier management apparatus 100 exchanges identifier information with all routers that are LSP end points (tunnel end points) in the communication system.

  In the example shown in FIG. 7, when each router constructs a label table for tunnel 1 (tunnel identified by 1), for example, each router uses a tunnel ID as a tunnel ID as shown in steps 201, 202, and 203. 1 and a label request message including its own router ID are sent to the identifier management device 100, and the identifier management device 100 assigns one label ID to the tunnel 1 and assigns a label to the router that is the source of the label request message. Returns a message.

  Further, for example, one router transmits a label request message including the tunnel 1 and all LSP end point router IDs to the identifier management apparatus 100, and the identifier management apparatus 100 becomes an LSP end point after performing label allocation. A label assignment message may be transmitted to each router.

  FIG. 8 shows an operation example when the identifier management apparatus 100 exchanges identifier information with some routers among all routers that are LSP end points (tunnel end points) in the communication system. A router that does not communicate with the identifier management apparatus 100 receives identifier information from another router.

  In the example shown in FIG. 8, when each router constructs a label table for tunnel 1 (tunnel identified by 1), for example, router R2 uses tunnel 1 and router R2 as tunnel IDs in step 301. A label request message including the router ID of the router R1 is sent to the identifier management apparatus 100. The identifier management apparatus 100 assigns one label ID to the tunnel 1 and returns a label assignment message to the router R2 that is the source of the label request message. Next, in step 302, the router R2 notifies the router R1 of the label ID assigned to the tunnel 1. In Step 303, the router R3 sends a label request message including the tunnel ID and the router ID of the router R3 to the identifier management device 100. The identifier management device 100 assigns a label ID, and the router of the label request message transmission source. A label allocation message is returned to R3.

  FIG. 9 shows an example in which some routers in the communication system have the function of the identifier management device 100. Although any router may have the function of the identifier management apparatus 100, in the example of FIG. 9, the router R1 includes an identifier management function unit 200 corresponding to the function of the identifier management apparatus 100.

  In this example, for example, in step 401, the router R2 sends a label request message including the tunnel 1 and all LSP endpoint router IDs to the router R1, and one identifier is assigned to the tunnel 1 by the identifier management function unit 200 in the router R1. An ID is assigned, a label table is constructed in the router R1 based on the assignment result, and a label assignment message is transmitted from the router R1 to the router R2 and the router R3 (steps 401 and 402).

  The above description is an example. In addition to the above contents, the label request message / label allocation message can be transmitted and received by various methods between the router and the identifier management device 100 and between the router and the router.

(Summary of the embodiment, effects, etc.)
As described above, according to the present embodiment, a communication system that performs communication via a point-to-multipoint tunnel between a plurality of routers by using a protocol that assigns an identifier to a packet and encapsulates and transfers the packet. An identifier table in which a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier to be given to a packet passing through the tunnel, and a router identifier that is an identifier of a router at the end of the tunnel are associated with each other, Receiving means for receiving a packet identifier request message including a tunnel identifier of a tunnel between the routers and a router identifier of the router serving as an end point of the tunnel, and selecting a packet identifier to be assigned to the tunnel by referring to the identifier table And the selected packet identifier An assignment control means for updating the identifier table with a channel identifier and the router identifier, and a packet identifier assignment message including the packet identifier selected by the assignment control means and the tunnel identifier is transmitted to the router serving as the end point of the tunnel. A communication system comprising a transmission means is provided.

  The allocation control means determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and when the tunnel identifier exists on the identifier table, A packet identifier of an entry having an identifier is selected, and when the tunnel identifier does not exist on the identifier table, one packet identifier that does not exist on the identifier table can be selected.

  An identifier management device having the identifier table, the allocation control unit, the receiving unit, and the transmission unit may be provided outside a router in the communication system, or the identifier table, the allocation control unit, and the reception And an identifier management unit including the transmission unit may be provided inside any router in the communication system.

  In addition, a router that does not receive the packet identifier assignment message from the transmitting unit among a plurality of routers that are the end points of the tunnel may receive a packet identifier assigned to the tunnel from another router.

  In the existing protocol, each router independently manages the identifier of the packet transferred by the router. In this embodiment, the identifier of all the packets passing through the network is managed by a common table. Therefore, it is possible to normally and efficiently realize multicast transfer such as IP / MPLS on the network where packet copying is performed by the L2 transfer apparatus.

(Section 1)
A communication system that performs communication through a point-to-multipoint tunnel between a plurality of routers by using a protocol that encapsulates and transfers packets with identifiers,
An identifier table in which a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier that is assigned to a packet that passes through the tunnel, and a router identifier that is an identifier of a router at the end of the tunnel,
Receiving means for receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control means for selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
Transmitting means for transmitting a packet identifier assignment message including the packet identifier selected by the assignment control means and the tunnel identifier to a router serving as an end point of the tunnel;
A communication system comprising:
(Section 2)
The allocation control means determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and when the tunnel identifier exists on the identifier table, A packet identifier of an entry having an identifier is selected, and if the tunnel identifier does not exist on the identifier table, one packet identifier that does not exist on the identifier table is selected.
The communication system according to item 1, characterized in that:
(Section 3)
An identifier management device having the identifier table, the allocation control unit, the reception unit, and the transmission unit is provided outside a router in the communication system.
The communication system according to item 1 or 2, characterized by the above.
(Section 4)
An identifier management unit having the identifier table, the allocation control unit, the reception unit, and the transmission unit is provided inside any router in the communication system.
The communication system according to item 1 or 2, characterized by the above.
(Section 5)
Among a plurality of routers serving as end points of the tunnel, a router that does not receive the packet identifier assignment message from the transmission unit receives a packet identifier assigned to the tunnel from another router.
The communication system according to any one of claims 1 to 4, characterized in that:
(Section 6)
An identifier management device used in a communication system that performs communication via a point-to-multipoint tunnel between a plurality of routers by using a protocol that adds an identifier to a packet and encapsulates and transfers the packet,
An identifier table in which a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier that is assigned to a packet that passes through the tunnel, and a router identifier that is an identifier of a router at the end of the tunnel,
Receiving means for receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control means for selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
Transmitting means for transmitting a packet identifier assignment message including the packet identifier selected by the assignment control means and the tunnel identifier to a router serving as an end point of the tunnel;
An identifier management device comprising:
(Section 7)
An identifier assignment method executed by an identifier management device used in a communication system that performs communication through a point-to-multipoint tunnel between a plurality of routers by using a protocol that assigns an identifier to a packet and encapsulates and transfers the packet. There,
The identifier management device includes an identifier table that associates a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier given to a packet passing through the tunnel, and a router identifier that is an identifier of a router at a tunnel end point. ,
Receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control step of selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
A transmission step of transmitting a packet identifier assignment message including the packet identifier selected by the assignment control step and the tunnel identifier to a router serving as an end point of the tunnel;
An identifier assignment method comprising:
The present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the claims.

R1 to R3 Router SW1 to SW4 L2 transfer device 100 Identifier management device 101 Label request message receiving unit 102 Label assignment message sending unit 103 Label assignment control unit 104 Label table storage unit 200 Identifier management function unit

Claims (6)

A communication system that performs communication through a point-to-multipoint tunnel between a plurality of routers by using a protocol that encapsulates and transfers packets with identifiers,
An identifier table in which a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier that is assigned to a packet that passes through the tunnel, and a router identifier that is an identifier of a router at the end of the tunnel,
Receiving means for receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control means for selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
Transmitting means for transmitting a packet identifier assignment message including the packet identifier selected by the assignment control means and the tunnel identifier to a router serving as an end point of the tunnel ;
The allocation control means determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and when the tunnel identifier exists on the identifier table, A communication system , wherein a packet identifier of an entry having an identifier is selected, and one packet identifier that does not exist on the identifier table is selected when the tunnel identifier does not exist on the identifier table . The identifier table, the allocation control unit, the receiving unit, and a communication system according to claim 1, wherein the identifier management apparatus having a transmission means, characterized in that provided outside of the router in the communication system. The identifier table, the assignment control unit, a communication system according to claim 1 wherein the receiving means and the identifier management unit having the transmitting means, characterized in that it comprises in the interior of any of the routers in the communication system. The router that does not receive the packet identifier assignment message from the transmission unit among the plurality of routers that are the end points of the tunnel receives the packet identifier assigned to the tunnel from another router. 4. The communication system according to any one of items 3 to 3 . An identifier management device used in a communication system that performs communication via a point-to-multipoint tunnel between a plurality of routers by using a protocol that adds an identifier to a packet and encapsulates and transfers the packet,
An identifier table in which a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier that is assigned to a packet that passes through the tunnel, and a router identifier that is an identifier of a router at the end of the tunnel,
Receiving means for receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control means for selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
Transmitting means for transmitting a packet identifier assignment message including the packet identifier selected by the assignment control means and the tunnel identifier to a router serving as an end point of the tunnel ;
The allocation control means determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and when the tunnel identifier exists on the identifier table, An identifier management apparatus that selects a packet identifier of an entry having an identifier, and selects one packet identifier that does not exist on the identifier table when the tunnel identifier does not exist on the identifier table . An identifier assignment method executed by an identifier management device used in a communication system that performs communication through a point-to-multipoint tunnel between a plurality of routers by using a protocol that assigns an identifier to a packet and encapsulates and transfers the packet. There,
The identifier management device includes an identifier table that associates a tunnel identifier that is an identifier of a tunnel, a packet identifier that is an identifier given to a packet passing through the tunnel, and a router identifier that is an identifier of a router at a tunnel end point. ,
Receiving a packet identifier request message including a tunnel identifier of a tunnel between the plurality of routers and a router identifier of a router serving as an end point of the tunnel;
An allocation control step of selecting a packet identifier to be assigned to the tunnel by referring to the identifier table, and updating the identifier table with the selected packet identifier, the tunnel identifier, and the router identifier;
A transmission step of transmitting a packet identifier assignment message including the packet identifier selected by the assignment control step and the tunnel identifier to a router serving as an end point of the tunnel ;
In the allocation control step, the identifier management device determines whether or not the tunnel identifier specified by the packet identifier request message exists on the identifier table, and the tunnel identifier exists on the identifier table. A packet identifier of an entry in which the tunnel identifier exists is selected, and when the tunnel identifier does not exist on the identifier table, one packet identifier that does not exist on the identifier table is selected. An identifier assignment method.

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