JP2007068220A - Virtual router - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a virtual router that enables packet transfer, using a pass-through table. <P>SOLUTION: There is provided the virtual router, equipped with an input interface unit for receiving input IP (Internet Protocol) packets, an IP router unit for routing the input IP packets received by the input interface unit, and an output interface unit for outputting the input IP packets routed in the IP router unit. In the virtual router, the input interface unit is equipped with a plurality of logical input interfaces for each private network identification number; the IP router unit is equipped with a virtual router unit for each the private network identification number, the input interface unit; and the pass-through table, having correspondence of the input interface unit, output interface unit and private network identification numbers; and the output interface unit is equipped with a logical interface for each the private network identification number. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a router for routing IP (Internet Protocol) packets in a network such as the Internet.

  Conventionally, routers that route IP packets have become widespread. The router has a routing table for deciding to which router the input IP packet is routed, and the IP address in the input IP packet is assigned to the router having the IP address associated with the routing table. Route the packet.

  On the other hand, VPN (Virtual Private Network) has become widespread in recent years. A VPN connects a plurality of intranets via the Internet, and the plurality of intranets function as one intranet. To realize VPN, when IP packets are sent from the intranet to the Internet, the private IP address is converted to a global IP address. When IP packets are sent from the Internet to the intranet, the global IP address is converted to a private IP address. For this purpose, a NAT (Network Address Translator) is used.

  However, the prior art has the following problems.

  The first problem is that when a VPN is constructed with a router, it is necessary to connect a NAT to each virtual private network. The reason is that routers using existing technology cannot handle private IP addresses. Therefore, when a plurality of VPNs are constructed, the cost increases.

  The second problem is that the conventional router cannot transfer the IP packet using the pass-through table. The reason is that the router performs TTL (Time To Live) subtraction at the time of packet transfer.

  An object of the present invention is to provide a virtual router that enables packet transfer using a pass-through table.

  According to the present invention, an input interface unit that receives an input IP (Internet Protocol) packet, an IP router unit that routes the input IP packet received by the input interface, and an input IP packet routed by the IP router unit An output interface unit for outputting, wherein the input interface includes a plurality of logical input interfaces for each private network identification number, and the IP router unit is a virtual router unit for each private network identification number And a pass-through table having a correspondence relationship between the input interface, the output interface, and the private network identification number, and the output interface unit has a logical output interface for each private network identification number. A virtual router characterized by comprising an interface is provided.

  In the above virtual router, the input interface unit may include means for identifying the private network identification number by a logical interface of a data link layer for the input IP packet.

  In the above virtual router, the virtual router unit may search the pass-through table for an output interface corresponding to the set of the private network identification number of the input IP packet and the input interface to which the input IP packet is input.

  According to the present invention, packet transfer using a pass-through table is possible.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  According to the present invention, in a VPN used in a router, a plurality of virtual routers are logically arranged in the router so that private IP addresses can be arbitrarily handled.

[Embodiment 1]
Referring to FIG. 1, the virtual router device according to the first embodiment of the present invention includes an input interface unit 1 that receives an IP packet, an IP router unit 2 that searches for a transfer destination of the received packet, and an output that outputs the IP packet. An interface unit 3 is provided.

  The input interface unit 1 has a plurality of logical input interfaces, and a VPNID (virtual private network identification number) is defined for each input interface. In FIG. 1, the input interface unit 1 includes only the input interface 11 whose VPNID is 1, but actually includes other input interfaces. The IP router unit 2 includes a virtual router unit 21 and a routing table 22. There are a plurality of virtual router units 21 for each VPNID. In FIG. 1, the virtual router unit 21 is only the one having the VPNID of 1, but actually there are other virtual router units. The routing table 22 includes a routing table for each VPNID. The output interface unit 3 has a plurality of logical output interfaces 31, and a VPNID is defined for each output interface. However, when the output interface is connected to the Internet, no VPNID is defined for the output interface. In FIG. 1, the output interface unit 3 includes only the output interface 31 whose VPNID is 1, but actually includes other output interfaces.

  The IP packet input to the input interface unit 1 has a VPNID identified by the logical interface of the data link layer, and is supplied to the input interface corresponding to the identified VPNID. The input interface 11 checks the validity of the received IP packet as an IP packet, and then transfers the IP packet to the IP router unit 2. The IP router unit 2 transfers the received IP packet to the virtual router unit 21 corresponding to the VPNID to which the IP packet belongs. The virtual router unit 21 has an IP routing function, searches the routing table 22 based on the destination IP address and VPNID of the received IP packet, replaces the destination IP address with the IP address obtained from the routing table, The data is transferred to the output interface corresponding to the VPNID in the output interface unit 3. The output interface transmits the transferred IP packet to the network.

  Next, the operation of this embodiment will be described in detail with reference to FIGS. VPNID is defined for each input interface and each output interface of the input interface unit 1 and the output interface unit 2 in FIG. 1 (step a1). When receiving the packet (step a2), the input interface 11 transfers the packet to the IP router unit 2 (step a3). The IP router unit 2 transfers the received packet to the virtual router unit 21 corresponding to the VPNID defined in step a2 (step a4). In the virtual router 21, the routing destination IP address corresponding to the transmission destination IP address of the received packet is searched from the routing table 22 corresponding to the VPNID to which the input interface belongs (step a5), and the TTL subtraction of the received packet is performed (step a6). The received packet is transferred to the output interface corresponding to the VPN (step a7 in FIG. 2). The output interface transmits the transferred IP packet to the network (step a8).

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 3, the second embodiment has a configuration in which the routing table 22 in the IP router unit 2 is replaced with a pass-through table 23. FIG. 4 shows the configuration of the pass-through table. Each record of the pass-through table includes an input interface, an output interface, and a VPNID. In general, a plurality of input interfaces and a plurality of output interfaces are associated with one VPNID, but one input interface and one output interface may be associated with one VPNID. FIG. 4 shows the latter case. FIG. 5 is a flowchart of the second embodiment. VPNID is defined for each input interface of the input interface unit 1 and each output interface of the output interface unit 2 in FIG. 3 (step a21). When receiving the IP packet (step a22), the input interface 11 transfers the IP packet to the IP router unit 2 (step a23). The IP router unit 2 transfers the received IP packet to the virtual router unit 21 corresponding to the VPNID defined in step a22 (step a24). The virtual router 21 searches the pass-through table 22 for the input interface of the received IP packet and the output interface corresponding to the VPNID (step a25), and transfers the received IP packet to the searched output interface (step a26). Transmit to the network (step a27).

It is a block diagram which shows the structure of the virtual router by Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the virtual router by Embodiment 1 of this invention. It is a block diagram which shows the structure of the virtual router by Embodiment 2 of this invention. It is a figure which shows the content of the pass-through table which the virtual router shown in FIG. 3 has. It is a flowchart which shows operation | movement of the virtual router by Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input interface part 2 IP router part 3 Output interface part 11 Input interface 21 Virtual router part 22 Routing table 23 Pass-through table 31 Output interface

Claims (3)

An input interface unit for receiving an input IP (Internet Protocol) packet;
An IP router for routing an input IP packet received by the input interface;
An output interface unit for outputting an input IP packet routed by the IP router unit;
In a virtual router comprising
The input interface comprises a plurality of logical input interfaces for each private network identification number;
The IP router unit includes a virtual router unit for each private network identification number, and a pass-through table having a correspondence relationship between the input interface, the output interface, and the private network identification number,
The virtual router, wherein the output interface unit includes a logical output interface for each private network identification number. The virtual router according to claim 1,
The virtual router, wherein the input interface unit comprises means for identifying the private network identification number by a data link layer logical interface for the input IP packet. In the virtual router according to claim 1 or 2,
The virtual router unit searches the pass-through table for an output interface corresponding to a set of the input interface to which the private network identification number of the input IP packet and the input IP packet are input.

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