JP2008067118A - Network communication equipment, network system, and frame transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify label management of core MPLS (multi-protocol label switching) by ensuring end-to-end connection and reducing the number of labels to be identified by core MPLS communication equipment without increasing frame overheads. <P>SOLUTION: In this network communication equipment for transferring a frame, the frame to be transferred includes destination information showing the transfer destination of the frame, the network communication equipment is provided with: a plurality of interfaces to be connected to other network communication equipment; transfer information holding relation between frame destination and the interfaces; a transferring part for outputting the input frame to the interface corresponding to the destination referring to the transfer information; and a converting part for converting the destination information attached to the input frame. The converting part eliminates information other than information to be used by network communication equipment directly connected to the network communication network, and stores a portion of the eliminated destination information in the different area of the frame. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication apparatus that relays frames in a network, and more particularly to a communication apparatus that performs communication by setting multiple logical paths.

  In a large company, the penetration rate of LAN (Local Area Network) using Ethernet (registered trademark, the same applies hereinafter) as a data link layer has reached almost 100%. Against this background, the demand for wide-area Ethernet services is increasing rapidly in recent years as a service for seamlessly connecting LANs installed in remote locations. In the wide area Ethernet service, the accommodated user is identified by a 12-bit VLAN ID. For this reason, the number of accommodated users is determined by the number of bits of the VLAN ID, and there is a problem in that it is not scalable and not suitable for a large-scale network. Therefore, attention has been focused on MPLS (Multi-Protocol Label Switching) which is more expandable than VLAN. MPLS can provide connection-oriented network services. The connection-oriented network is characterized by establishing a communication connection that secures a band from end to end and transferring a frame using a preset communication connection, and is excellent in reliability. In particular, EoMPLS technology that can transfer frames regardless of the upper protocol is attracting attention.

  For example, as such EoMPLS technology, a VLAN ID and an MPLS label are associated with each other in an apparatus that interworkes a VLAN network and an MPLS network. In an apparatus that interworkes from a VLAN network to an MPLS network, an output MPLS label is determined from a set of VLAN ID, packet layer 3 and layer 4 header information. The output MPLS label is assigned an independent value for each VLAN. As an apparatus for interworking from an MPLS network to a VLAN network, one that associates an input MPLS label with a VLAN ID has been proposed (for example, see Patent Document 1).

  FIG. 3B shows an example of a format diagram of a frame transferred by EoMPLS.

  A general EoMPLS communication apparatus encapsulates an original Ethernet frame with a new L2 header 411, a tunnel label 412, and a VC label 413.

The tunnel label 412 includes information for determining the relay destination of the frame and is an MPLS label using the format shown in FIG. 3C. The VC label 413 is an MPLS label that includes information for identifying the VPN and uses the format shown in FIG. 3C. In the MPLS section, the transfer path is determined by the label ID 421 of the tunnel label 412.
JP 2001-345865 A

  In the conventional EoMPLS technology, for example, an MPLS tunnel is set as shown in FIG.

  The MPLS network system includes a core MPLS communication device 10, a plurality of relay MPLS communication devices 111, 151, and 161, MPLS networks 211, 251, and 261, and edge MPLS communication devices 311, 312, 313, 351, 352, and 361. The frame input from the edge MPLS communication apparatus 311 or the like is attached with an MPLS label, and is transferred to the destination edge MPLS communication apparatus 351 or the like via the MPLS tunnel based on the attached MPLS label.

  Specifically, MPLS tunnels 510 to 540 are set between the edge MPLS communication apparatuses. The core MPLS communication apparatus 10 transfers the frame based on the MPLS label attached to the frame. In MPLS, one MPLS tunnel is set for one-way communication. In the network illustrated in FIG. 7, an MPLS tunnel for transferring a frame from the edge MPLS communication apparatuses 311 to 313 to the edge MPLS communication apparatuses 351 to 361 is set. Although not shown, an MPLS tunnel for transferring frames in the reverse direction from the edge MPLS communication devices 351 to 361 to the edge MPLS communication devices 311 to 313 is also set.

  In this way, all frames passing through the MPLS tunnel are relayed by the core MPLS communication apparatus 10. Therefore, the core MPLS communication apparatus 10 needs to hold a large-scale label transfer table in order to identify all LSPs (Label Switch Path). However, when the label transfer table becomes large, label management becomes complicated, and maintenance of the label transfer table (for example, addition and deletion of labels) becomes complicated. Further, when the label transfer table becomes large, the label search time becomes long, which affects the scalability of the network. Further, when the label transfer table becomes large, the capacity of the memory for storing the label transfer table becomes large, and there is a problem that the apparatus cost increases.

  As a method for suppressing the increase in the number of labels, there is a method for reducing the number of labels by integrating the values of labels of frames having the same destination. In the conventional apparatus, it is impossible to restore the original label before the label values are integrated from the new label after the label values are integrated. Therefore, there is a problem that the end-to-end connection is disconnected by the core MPLS communication apparatus 10. As another method, there is a method of newly adding an MPLS label for tunnel label integration outside the tunnel label. Although this method makes it possible to reduce the number of label management in the core MPLS communication apparatus 10, there is a problem that the throughput is lowered due to an increase in frame overhead.

  It is an object of the present invention to secure end-to-end connections and reduce the number of labels identified by a core MPLS communication apparatus without increasing frame overhead, thereby simplifying core MPLS label management. And

  As a means for solving this problem, the tunnel ID of the EoMPLS frame and the label ID of the VC label are divided into two parts, the first half address and the second half address. The label ID of the tunnel label is divided into an address referred to by the core MPLS communication apparatus and other addresses. The label ID of the VC label is divided into a specific fixed value and other addresses. The relay MPLS apparatus adjacent to the core MPLS communication apparatus transmits the frame to the core MPLS communication apparatus by exchanging the address referenced by the core MPLS communication apparatus of the tunnel label and the specific fixed value of the VC label, thereby transmitting the core MPLS to the core MPLS communication apparatus. Reduce route information of communication devices. In addition, when the relay MPLS device adjacent to the core MPLS communication device receives a frame from the core MPLS communication device, the relay label device replaces the label ID information that was replaced before transmission, and then transmits the tunnel label and VC label before transmission to the core MPLS communication device. Secure end-to-end connection by restoring.

  According to the present invention, since the number of labels identified by the core MPLS communication apparatus is reduced, label management of the core MPLS can be simplified. Therefore, even an existing communication device having a small label transfer table can be used without requiring the addition of a special function. Furthermore, end-to-end connection-type services can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. The present invention will be described below by taking EoMPLS as an example, but the present invention is also applied to a case where a communication protocol having a double structure of an address for frame transfer and an address for network identification is used as in EoMPLS. By doing so, the same effect is expected.

  FIG. 1 is a network diagram showing a configuration of a network system according to the embodiment of this invention.

  The network system according to the embodiment of the present invention is a large-scale MPLS VPN network including a core MPLS communication device 10, a plurality of relay MPLS communication devices 111 to 181, MPLS networks 211 to 281 and edge MPLS communication devices 311 to 281. . Frames input to the MPLS VPN network from the edge MPLS communication apparatuses 311 to 381 are assigned with MPLS labels, and are transferred to the destination edge MPLS communication apparatuses 311 to 381 according to the attached MPLS labels. A VLAN is set between the edge MPLS communication devices 311 to 381.

  The core MPLS communication device 10 is connected to a plurality of relay MPLS communication devices 111 to 181. The core MPLS communication device 10 and the plurality of relay MPLS communication devices 111 to 181 constitute a core network. The core MPLS communication apparatus 10 transfers the frames received from the relay MPLS communication apparatuses 111 to 181 to the destination relay MPLS communication apparatuses 111 to 181 using the MPLS label attached to the received frame.

  The network system shown in FIG. 1 includes one core MPLS communication apparatus 10, but may include a plurality of core MPLS communication apparatuses. Further, eight relay MPLS communication apparatuses 111 to 181 are connected to the core MPLS communication apparatus 10, but the number of connected relay MPLS communication apparatuses is not limited to this.

  Each of the relay MPLS communication apparatuses 111 to 181 is connected to the MPLS networks 211 to 281, respectively. The relay MPLS communication apparatuses 111 to 181 transfer a frame between the core MPLS communication apparatus 10 and the MPLS network 211 in accordance with the MPLS label attached to the frame.

  Edge MPLS communication apparatuses 311 to 381 are connected to the MPLS networks 211 to 281, respectively. In the network system shown in FIG. 1, each of the MPLS networks 211 to 281 is connected to one edge MPLS communication device 311 to 381, but the number of connected MPLS communication devices is not limited to this.

  In each MPLS network 211 to 281, a plurality of communication devices (switches) are connected by signal lines. Each switch forwards the frame according to the MPLS label attached to the frame.

  Each edge MPLS communication device 311 to 381 is connected to a LAN (not shown) that accommodates computers such as user terminals and servers.

  FIG. 2 is a block diagram illustrating a configuration of the relay MPLS communication apparatus 111 according to the embodiment of this invention. In FIG. 2, the relay MPLS communication apparatus 111 will be described, but other relay MPLS communication apparatuses have the same configuration.

  The relay MPLS communication apparatus 111 includes a switch 610, a forwarding table 620, relay MPLS connection interfaces 631, 632, and 633, and a core switch connection interface 640. The core switch connection interface 640 includes an Ingress label conversion unit 642 and an Egress label conversion unit 645.

  The switch 610 refers to the MPLS label attached to the input frame, and outputs the frame input to the port (relay MPLS connection interface) corresponding to the destination. The forwarding table 620 stores the destination set in the MPLS label and the corresponding data of the output port, and is referred to when determining the destination of the input frame.

  Other relay MPLS communication devices and edge MPLS communication devices 311 are connected to the relay MPLS connection interface 631. In this embodiment, since Ethernet is used for frame transfer, the relay MPLS connection interface 631 generates a header conforming to the Ethernet protocol. Note that a relay MPLS communication device different from that connected to the relay MPLS connection interface 631 is connected to the other relay MPLS connection interfaces 632 and 633.

  The core MPLS communication device 10 is connected to the core switch connection interface 640.

  The Ingress label conversion unit 642 converts the label of the frame received from the edge MPLS communication apparatus and transmitted to the core MPLS communication apparatus 10. The Egress label conversion unit 645 converts the label of the frame received from the core MPLS communication apparatus 10 and transmitted to the edge MPLS communication apparatus. The Ingress label conversion unit 642 and the Egress label conversion unit 645 may be realized by a processor that executes a predetermined program, and may be realized by so-called hardware logic or firmware.

  3A to 3C are format diagrams of frames transferred in the network according to the embodiment of this invention.

  Frames input from outside the MPLS network to the MPLS edge switches 311 to 381 are transferred in layer 2. As shown in FIG. 3A, this input frame includes an L2 header 401, a VLAN header 402, and a payload 403 in order from the top of the frame.

  The L2 header 401 is a protocol header in layer 2 (data link layer), and includes information necessary for transferring a frame in layer 2. For example, when the MPLS network is constructed by Ethernet, the L2 header 401 becomes an Ethernet header. The VLAN header 402 includes information for identifying the VLAN (for example, VLAN ID). Payload 403 is data to be transferred in this frame.

  The MPLS edge switches 311 to 381 newly add a header to the input frame to generate an EoMPLS network frame having the format shown in FIG. 3B.

  The EoMPLS network frame includes an L2 header 411, a tunnel label 412, a VC label 413, an L2 header 401, a VLAN header 402, and a payload 403 in order from the top of the frame. Note that the L2 header 411, the tunnel label 412 and the VC label 413 are headers newly added by the MPLS edge switches 311 to 381.

  The L2 header 411 is a protocol header in the layer 2 (data link layer), and depends on the layer 2 protocol and includes information necessary for transferring a frame in the layer 2 in the MPLS section. For example, when the MPLS network is constructed by Ethernet, the L2 header 411 is an Ethernet header. Further, when the MPLS network is constructed by ATM, an ATM header is formed. The tunnel label 412 and the VC label 413 are as described in the background art section.

  As shown in FIG. 3C, the MPLS label includes a 20-bit label ID 421, a 3-bit EXP field 422, a 1-bit stack bit 423, and an 8-bit TTL field 424 in order from the top of the label. The label ID 421 has a fixed length of 20 bits and includes information to be identified by an MPLS label such as a tunnel or VC. The EXP field 422 is an experimental field. The stack bit 423 indicates that the label is the last label in the label stack. The TTL field 424 stores a value representing the valid period of the packet, and is decreased by the number of times this frame has passed through the switch.

  FIG. 4 is an explanatory diagram of an MPLS tunnel set in the network according to the embodiment of this invention.

  The network system illustrated in FIG. 4 includes a core MPLS communication device 10, relay MPLS communication devices 111, 151, and 161, MPLS networks 211, 251, and 261, and edge MPLS communication devices 311, 312, 313, 351, 352, and 361. Other relay MPLS communication devices, MPLS networks, and edge MPLS communication devices are not shown.

  An MPLS label is attached to a frame input from the edge MPLS communication device 311 or the like, and an MPLS tunnel through which the frame passes is selected based on the attached MPLS label, and the frame is sent to the destination edge MPLS communication device 351 or the like. Is transferred.

  Specifically, an MPLS tunnel (LSP10) 510 and an MPLS tunnel (LSP20) 520 are set between the edge MPLS communication apparatus 311 and the relay MPLS communication apparatus 111. An MPLS tunnel (LSP30) 530 is set between the edge MPLS communication device 312 and the relay MPLS communication device 111. An MPLS tunnel (LSP 40) 540 is set between the edge MPLS communication device 313 and the relay MPLS communication device 111.

  An MPLS tunnel (LSP10) 510 is set between the relay MPLS communication apparatus 151 and the edge MPLS communication apparatus 351. An MPLS tunnel (LSP20) 520 is set between the relay MPLS communication apparatus 151 and the edge MPLS communication apparatus 352. An MPLS tunnel (LSP30) 530 and an MPLS tunnel (LSP40) 540 are set between the relay MPLS communication apparatus 161 and the edge MPLS communication apparatus 361.

  Further, a core MPLS tunnel (LSP 100) 550 is set between the relay MPLS communication apparatus 111 and the relay MPLS communication apparatus 151. Between the relay MPLS communication apparatus 111 and the relay MPLS communication apparatus 161, a core MPLS tunnel (LSP200) 560 is set.

  That is, a virtual logical communication path (virtual channel) is set between the edge MPLS communication apparatus 311 and the edge MPLS communication apparatus 351 by the MPLS tunnel (LSP10) 510 and the core MPLS tunnel (LSP100) 550. A virtual channel is set between the edge MPLS communication apparatus 311 and the edge MPLS communication apparatus 352 by the MPLS tunnel (LSP20) 510 and the core MPLS tunnel (LSP100) 550. A virtual channel is set between the edge MPLS communication apparatus 312 and the edge MPLS communication apparatus 361 by the MPLS tunnel (LSP30) 510 and the core MPLS tunnel (LSP200) 560. A virtual channel is set between the edge MPLS communication apparatus 313 and the edge MPLS communication apparatus 361 by the MPLS tunnel (LSP40) 540 and the core MPLS tunnel (LSP200) 560.

  Each virtual channel accommodates one or more VLANs.

  In the network system shown in FIG. 4, the relay MPLS communication apparatus 111 adjacent to the core MPLS communication apparatus 10 is input to the same interface of the core MPLS communication apparatus 10 and output from the same interface (output port) of the core MPLS communication apparatus 10. Is changed to the tunnel label of the 10 MPLS tunnel for the core MPLS communication apparatus. Similarly, the relay MPLS communication apparatuses 151 and 161 adjacent to the core MPLS communication apparatus 10 restore the tunnel label given to the frame before the change from the tunnel label of the MPLS tunnel for the core MPLS communication apparatus. As described above, the relay MPLS communication apparatus changes the tunnel label so that the number of tunnel labels accommodated in the core MPLS communication apparatus 10 is “label number = X (X−1)” (input ports and output ports are meshed). The number of MPLS tunnels necessary for connection can be reduced. X in the formula is the number of ports of the core MPLS communication apparatus.

  More specifically, the MPLS tunnel (tunnel LSP10) 510 and the MPLS tunnel (tunnel LSP20) 520 are input to the same interface of the core MPLS communication apparatus 10 and transfer frames output from the same interface of the core MPLS communication apparatus 10. To do. Therefore, the relay MPLS communication apparatus 111 changes the tunnel labels of the MPLS tunnels 510 and 520 to the tunnel label of the MPLS tunnel (core tunnel LSP100) 550 for the core MPLS communication apparatus. The relay MPLS communication apparatus 151 that receives a frame from the core MPLS communication apparatus 10 receives a frame with the tunnel label of the MPLS tunnel (core tunnel LSP100) 550 for the core MPLS communication apparatus, and is assigned before the change. Change to the tunnel label that you had. The same applies to the MPLS tunnel (tunnel LSP30) 530 and the MPLS tunnel (tunnel LSP40) 540.

  Next, means for realizing the tunnel label conversion will be described with reference to FIG.

  FIG. 5 is an explanatory diagram of label conversion in the relay MPLS communication apparatus according to the embodiment of this invention.

  A tunnel label 412 and a VC label 413 are attached to a frame input from the edge MPLS communication apparatus to the relay MPLS communication apparatus (see FIG. 3B). Each label has a 20-bit label ID that can be used as a label (see FIG. 3C). In the preceding stage of the core MPLS communication apparatus 10, in the relay MPLS communication apparatus adjacent to the core MPLS communication apparatus 10, the tunnel label value is transferred from the MPLS tunnel (tunnel LSP) to the MPLS tunnel for the core MPLS communication apparatus (core tunnel LSP). change. Further, in the relay MPLS communication apparatus adjacent to the core MPLS communication apparatus 10 at the subsequent stage of the core MPLS communication apparatus 10, the frame is attached to the frame before the tunnel label change from the MPLS tunnel for the core MPLS communication apparatus (core tunnel LSP). The tunnel label value is changed to the MPLS tunnel (tunnel LSP). For this purpose, the label ID field is defined as follows.

  The VC label 413 is divided into two areas having a predetermined length. Similarly, the tunnel label 412 is also divided into two areas of the VC label 413 and two areas having the same length.

  A frame input from the edge MPLS communication apparatus 311 to the relay MPLS communication apparatus 111 is attached with a VC label 432 set by the administrator and a tunnel label 431 set by the administrator.

  The 20-bit VC label 432 is divided into two areas of a predetermined length, and an upper area is secured. At this time, it is preferable to set a predetermined value in the upper area and clarify the reserved area. In the lower area, a VC ID for identifying the VPN is stored. For example, the upper 11 bits are filled with “0”, and the lower 9 bits are used for the VC ID. The length of the upper area and the lower area is arbitrary as long as the tunnel label and the VC label 413 have the same length.

  The 20-bit tunnel label 431 is divided into two areas of a predetermined length. Then, the ID of the destination communication device in the network is set in the upper area, the ID of the MPLS network as the destination is set in the lower area, and the destination information is set hierarchically. For example, in the upper 11 bits, the ID of the edge MPLS communication apparatus provided in the MPLS network ahead of the core MPLS communication apparatus 10 is stored as the ID of the destination communication apparatus in the network. In the lower 9 bits, the ID of the MPLS network connected to the core MPLS communication apparatus 10 is stored as the ID of the MPLS network. When a tunnel LSP is set in a mesh shape for a combination of an input port and an output port, the MPLS network ID may be a combination of an input port number and an output port number.

  When a frame is input from the edge MPLS communication apparatus 311 to the relay MPLS communication apparatus 111, the Ingress label conversion unit 642 identifies a destination communication apparatus in the network set in the upper area (upper 11 bits) of the tunnel label 432 The ID (hereinafter referred to as a device identification ID in the NW) is exchanged with a predetermined value set in an area (upper 11 bits) secured in the upper part of the VC label 431. That is, the predetermined value set in the area secured above the VC label 431 is stored in the upper area of the tunnel label, and the device identification ID in the NW is stored in the upper area of the VC label.

  That is, the tunnel label 412 is an administrator-set tunnel label 431 in the edge MPLS network 211, and is a core tunnel label 433 when passing through the core MPLS communication apparatus 10, and is mutually converted by the relay MPLS communication apparatus. . Similarly, the VC label 413 is an administrator-set VC label 432 in the edge MPLS network 211, and is a core VC label 434 when passing through the core MPLS communication apparatus 10, and is mutually converted by the relay MPLS communication apparatus. The

  In this way, the core VC label 434 and the core tunnel label 433 are generated, and the frame with the generated core VC label 434 and the core tunnel label 433 is converted into the core tunnel 550 (core MPLS communication apparatus). 10).

  By doing so, the core tunnel label 433 includes only the destination network ID (hereinafter referred to as the destination NW specific ID), and the core MPLS communication apparatus 10 can generate the frame by using only the destination NW specific ID. Can be transferred. For this reason, the number of labels that need to be managed by the core MPLS communication apparatus 10 is “number of labels = X (X” even when the MPLS tunnel is set in a mesh between the input port and the output port of the core MPLS communication apparatus 10. -1) "(the number of MPLS tunnels required to connect the input port and the output port in a mesh shape) can be reduced. X in the formula is the number of ports of the core MPLS communication apparatus. On the other hand, when a frame is input from the core MPLS communication apparatus 10 to the relay MPLS communication apparatus 111, the Egress label conversion unit 645 stores the apparatus specific ID in the NW stored in the upper area (upper 11 bits) of the core VC label 434. And the predetermined value set in the upper area (upper 11 bits) in the core tunnel label 433 are exchanged. That is, the device identification ID in the NW is stored in the upper area of the tunnel label, the predetermined value is stored in the upper area of the VC label, and the tunnel label and the VC label are restored.

  In this way, the VC label 432 and the tunnel label 431 are generated, and the frame with the generated VC label 432 and the tunnel label 431 is transmitted to the edge MPLS network 211. By doing so, the edge MPLS communication apparatus can restore the MPLS label (tunnel label and VC label) attached to the frame that has flowed into the MPLS network.

  FIG. 6 is a block diagram showing a detailed configuration of the core switch connection interface 640 according to the embodiment of this invention.

  The core switch connection interface 640 includes a switch reception circuit 641, an Ingress label conversion unit 642, a frame transmission circuit 643, a frame reception circuit 644, an Egress label conversion unit 645, and a switch transmission circuit 646.

  The switch reception circuit 641 executes a frame reception process for receiving the frame in the internal format of the relay MPLS communication apparatus 111 transferred from the switch 610. The switch transmission circuit 646 generates an internal format frame of the relay MPLS communication apparatus 111, and executes an internal format frame transmission process for transmitting the generated frame to the switch 610.

  The Ingress label conversion unit 642 moves the intra-NW device identification ID stored in the tunnel label 431 to an area (ALL 0 area) reserved in the VC label 432 and transmits it to the core MPLS communication apparatus 10 Convert to label. The Egress label conversion unit 645 moves the device identification ID in the NW stored in the core VC label 434 to the region (ALL 0 region) in the core tunnel label 433, and transmits it to the edge MPLS communication device. Convert to label.

  The frame transmission circuit 643 processes the frame in a layer below the MPLS layer, and generates a frame to be transmitted to the core MPLS communication apparatus 10. For example, since Ethernet is used for frame transfer in this embodiment, FCS (Frame Check Sequence) calculation is performed to give FCS to the frame. The frame reception circuit 644 processes the frame in a layer below the MPLS layer and receives the frame from the core MPLS communication apparatus 10. For example, in this embodiment, since Ethernet is used for frame transfer, the FCS of the received frame is confirmed.

  Referring now to FIG. 2, the MPLS label is converted at the core switch connection interface 640. Therefore, inside the relay MPLS communication apparatus, except for the core switch connection interface 640, the tunnel label 431 (see FIG. 5) in which the intra-NW apparatus specific ID and the destination NW specific ID are stored is used. On the other hand, the core switch connection interface 640 uses the tunnel label 433 (see FIG. 5) in which only the destination NW specific ID is stored.

  In other words, in the core MPLS communication device 10, the frame is transferred only with the ID (destination NW specific ID) of the MPLS network connected to the core MPLS communication device 10. On the other hand, in a portion other than the core MPLS communication device 10, the frame is transferred by the tunnel label (intra-NW device specific ID and destination NW specific ID) given by the edge MPLS communication device.

  As described above, according to the embodiment of the present invention, since the relay MPLS communication apparatus converts the label to include the destination information necessary for the core MPLS communication apparatus, the number of labels identified by the core MPLS communication apparatus is reduced. As a result, the label management of the core MPLS can be simplified and the device cost can be reduced.

  In addition, since the relay MPLS communication device converts the MPLS communication device as the final destination into a label that can be specified, even if a part of the destination information is omitted when passing through the core MPLS communication device, the relay MPLS communication device passes through the MPLS tunnel. Frame can be transferred.

  The present invention can be applied to a network that encapsulates and transfers a frame (packet) using a label, such as an MPLS network. Further, it is possible to adapt to a network in which logical paths are set in multiple stages without using labels.

It is a network diagram which shows the structure of the large scale MPLS VPN network of embodiment of this invention. It is a block diagram which shows the structure of the relay MPLS communication apparatus of embodiment of this invention. It is a format figure of the frame input into the MPLS edge communication apparatus of embodiment of this invention. It is a format diagram of a frame of the EoMPLS network transferred in the network according to the embodiment of this invention. It is a block diagram of the MPLS label attached | subjected to the flame | frame transferred by the network of embodiment of this invention. It is explanatory drawing of the MPLS tunnel set to the network of embodiment of this invention. It is explanatory drawing of label conversion in the relay MPLS communication apparatus of embodiment of this invention. It is a block diagram which shows the structure of the core switch connection interface of embodiment of this invention. It is explanatory drawing of the MPLS tunnel set to the conventional network.

Explanation of symbols

10 Core MPLS communication apparatuses 111 to 181 Relay MPLS communication apparatuses 211 to 281 MPLS networks 311 to 281 Edge MPLS communication apparatuses 610 Switch 620 Transfer tables 631 to 633 Relay MPLS connection interface 640 Core switch connection interface 642 Ingress label conversion unit 645 Egress label conversion Part

Claims (13)

A network communication device for transferring a frame,
The transferred frame includes destination information indicating a transfer destination of the frame,
The network communication device is:
A plurality of interfaces connected to other network communication devices;
Transfer information that holds the relationship between the destination of the frame and the interface;
A transfer unit that refers to the transfer information and outputs the input frame to an interface corresponding to a destination;
A conversion unit that converts the destination information attached to the input frame,
The conversion unit leaves only the information used by the network communication device directly connected to the network communication device, deletes other information, and removes part of the deleted destination information from the destination information. A network communication device storing in another area of the frame.   The network communication device according to claim 1, wherein the conversion unit sets a predetermined code in an area where a part of the destination information is deleted. The transferred frame includes a first label including destination information indicating a transfer destination of the frame, and a second label including a reserved area in which a part of the destination information included in the first label is to be stored. Including
The conversion unit leaves only the information used by the network communication device directly connected to the network communication device, deletes other information, and removes part of the deleted destination information from the destination information. The network communication device according to claim 1, wherein the network communication device is stored in the reserved area of the second label. The first label includes first destination information indicating a transfer destination of a frame in a network provided in the network communication device, and a second destination indicating a frame transfer destination from the network communication device to which the network communication device is directly connected. Including information,
4. The conversion unit according to claim 3, wherein the conversion unit deletes the first destination information from the first label and stores the deleted first destination information in the reserved area of the second label. Network communication device.   The network communication apparatus according to claim 1, wherein the conversion unit writes part of the destination information deleted by the conversion unit into the frame to restore the destination information. A network system comprising a first network communication device, a second network communication device, and a third network communication device for transferring a frame,
The transferred frame includes destination information indicating a transfer destination of the frame,
The network system includes:
At least the first network communication device and the second network communication device are connected, and at least the second network communication device and the third network communication device are connected;
Each of the network communication devices includes a plurality of interfaces connected to other network communication devices, transfer information that holds a relationship between the destination of the frame and the interface, and the input that has been input with reference to the transfer information. A transfer unit that outputs the frame to an interface corresponding to the destination,
The first network communication device includes a first conversion unit that converts destination information attached to an input frame. The third network communication device converts a destination information attached to the input frame. The first conversion unit leaves only information used by the second network communication device among the destination information, deletes other information, and removes a part of the deleted destination information. Store it in other areas of the frame,
The first network communication device transmits the frame in which the destination information is converted to the second network communication device;
The second network communication device determines a transfer destination of the input frame based on the converted destination information, transfers the frame to the third network communication device that is a transfer destination,
When a frame is input to the third network communication device, the second conversion unit writes a part of the destination information deleted by the first conversion unit to the frame to restore the destination information,
The network system according to claim 3, wherein the third network communication device transfers the input frame based on the restored destination information.   The network system according to claim 6, wherein the first conversion unit sets a predetermined code in an area where a part of the destination information is deleted. The transferred frame includes a first label including destination information indicating a transfer destination of the frame, and a second label including a reserved area in which a part of the destination information included in the first label is to be stored. Including
The first conversion unit deletes only the information used by the second network communication device from the destination information, leaving the first label, and deleting other information from the first label. The network system according to claim 6, wherein a part of destination information is stored in the reserved area of the second label. The first label includes first destination information indicating a transfer destination of a frame in a network provided in the network communication device, and a second destination indicating a transfer destination of a frame of the network communication device to which the network communication device is directly connected. Including information,
The first conversion unit deletes the first destination information from the first label, stores the deleted first destination information in the reserved area of the second label,
The first network communication device transmits a frame with the first label from which the first destination information has been deleted to the second network communication device,
The second network communication device determines a transfer destination of the input frame based on the converted first label, transfers the frame to the third network communication device which is a transfer destination,
When a frame is input to the third network communication device, the second conversion unit writes the first destination information stored in the reserved area to the first label, and restores the first label.
9. The network system according to claim 8, wherein the third network communication device transfers the input frame based on the restored first label. A frame transfer method in a network system comprising a plurality of network communication devices for transferring a frame,
The transferred frame includes destination information indicating a transfer destination of the frame,
The network system includes a first sub-network, a second sub-network, and a core network connected to the first and second sub-networks via the network communication device,
Each of the network communication devices includes a plurality of interfaces connected to other network communication devices, transfer information that holds a relationship between the destination of the frame and the interface, and the input that has been input with reference to the transfer information. A transfer unit that outputs the frame to an interface corresponding to the destination,
When a frame is transferred from the first subnetwork to the core network, only the information necessary for frame transfer in the core network is left out of the destination information, and other information is deleted, and the deleted information is deleted. Storing a part of the destination information in another area of the frame;
The core network determines a transfer destination of the input frame based on the converted destination information, transfers the frame to the second sub-network that is a transfer destination,
When a frame is transferred from the core network to the second sub-network, a part of the deleted destination information is written to the frame, and the destination information is restored.
In the second sub-network, the input frame is transferred based on the restored destination information.   The frame according to claim 10, wherein when a frame is transferred from the first subnetwork to the core network, a predetermined code is set in an area from which a part of the destination information is deleted. Frame transfer method. The transferred frame includes a first label including destination information indicating a transfer destination of the frame, and a second label including a reserved area in which a part of the destination information included in the first label is to be stored. Including
When a frame is transferred from the first subnetwork to the core network, only the information used in the core network among the destination information is left in the first label, and other information is stored in the first label. 11. The frame transfer method according to claim 10, wherein the frame transfer method deletes and stores a part of the deleted destination information in the reserved area of the second label. The first label is used in the first and second sub-networks and includes first destination information indicating a destination of a frame in the network and second destination information indicating a forwarding destination of the frame in the core network. ,
When a frame is transferred from the first subnetwork to the core network, the first destination information is deleted from the first label, and the deleted first destination information is stored in the reserved area of the second label. Store and
The core network determines a transfer destination of the input frame based on the converted first label, transfers the frame to the second sub-network that is a transfer destination,
When a frame is transferred from the core network to the second sub-network, the first label is restored by writing the first destination information stored in the reserved area to the first label. The frame transfer method according to claim 10.

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