JP2012175622A - Router in multi-home connection environment, program, and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a path switching method in multi-home connection environments at an extremely low cost by mounting a function for multi-home connection to a router only.SOLUTION: A multi-home router 1 comprises: path control means which controls a path of a data packet between an access network 3A or access network 3B and a local network; prefix pool means which holds a prefix A acquired from the access network 3A and a prefix B acquired from the access network 3B; and router notification transmission control means which transmits a first router notification (RA (Router Advertisement)) message where a router effective time (Router Life Time) is set to an extremely short time (0 second or more) to a host terminal connected to the local network when switching from an access network A in a transition source.

Description

  The present invention relates to a technique for switching a route of an access network in a multi-home connection environment connected to a plurality of access networks.

  As an Internet protocol, IPv4 (Internet Protocol Version 4) is generally used. However, IPv4 having a 32-bit address space has a problem of exhaustion of address resources. In order to solve this problem, there is a broadband router having a NAT (Network Address Translation) function. NAT is a technique for converting a plurality of private addresses used in a LAN (Local Area Network) and one global address used in a WAN (Wide Area Network). By simply installing the NAT function in the broadband router connected to the LAN, it is possible to reduce the consumption of IPv4 addresses.

  There is also a technology called “carrier grade NAT” in which an access network of an Internet service provider (hereinafter referred to as “ISP”) includes a large capacity NAT device. According to this technique, the ISP translates some global addresses into private addresses assigned to customers. However, the NAT device needs to be provided in a high-speed network of about 10 Gbit / second, and high speed performance is extremely necessary.

  In contrast, there has been IPv6 (Internet Protocol Version 6) having a 128-bit address space. In recent years, connection services using IPv6 are rapidly spreading due to the problem of IPv4 address resource exhaustion. According to IPv6, a global address for the Internet can be assigned to each host terminal connected to the LAN without requiring NAT.

  In addition, there is a technique called “multihome connection” for connecting to a plurality of access networks in order to improve fault tolerance in connection services to the Internet. Multi-home connection is a technology for connecting a broadband router connected to a LAN to access networks of two or more ISPs. According to this technology, it is possible to switch to the other access network in response to a failure of one access network, and to improve the fault tolerance of the network. This router has at least two WAN interface units and at least one LAN interface unit.

  According to IPv6, there is a PI address (Provider Independent Address) that can be used by a plurality of ISPs and is independent of the ISP. As a result, a plurality of access networks can be accessed with one PI address, and a multi-home connection can be realized. However, in order to use the PI address, it is necessary to manage an AS (Autonomous System) number of BGP (Border Gateway Protocol) for route control, which requires extremely high cost. Therefore, in order to realize multihome connection, generally, a host terminal connected to a LAN needs to acquire an IP address for each ISP. The host terminal needs to switch its IPv6 address each time the access network is switched.

  Conventionally, there is a technology of a multihoming connection device for multihome connection (see, for example, Patent Document 1). According to this technique, the multihoming connection apparatus distributes in advance an IPv6 address assigned to each access network to the host terminal as a policy table. A router installed between the access network and the home network transmits a control message based on the line quality state of the access network to the host terminal. The host terminal can transmit an IPv6 packet to a different access network via the multihoming connection device by switching the IPv6 address included in the policy table as the source address.

JP 2004-274129 A

  However, according to the technique described in Patent Document 1, the host terminal needs to hold the policy table distributed from the multihoming connection device. Further, the host terminal needs to switch the IPv6 address assigned from the ISP included in the policy table by a control message from the router. In order for the host terminal to execute such control, it is necessary to install application software corresponding to various operating systems (OS). In addition, when there are a large number of host terminals in the home network, when multihoming connection control is realized by the host terminals, the maintenance and management costs increase. Furthermore, a router connected between the access network and the home network also needs to implement a protocol based on a route table (label) for switching the multihome connection, which further increases costs. That is, according to this technique, it is necessary to install a new function in all the devices on the client side in the multihoming connection device, the host terminal, and the router.

  Accordingly, an object of the present invention is to provide a router, a program, and a method in a multihome connection environment at a very low cost by mounting a function for multihome connection only on a router.

According to the present invention, a first WAN (Wide Area Network) interface connected to a first access network, a second WAN interface connected to a second access network, and a local to which a plurality of host terminals are connected. In a multihomed router having a LAN (Local Area Network) interface connected to a network,
Route control means for controlling the route of the data packet between the first access network or the second access network and the local network;
Prefix pool means for holding a first prefix obtained from the first access network and a second prefix obtained from the second access network;
When switching from the first access network of the migration source, the first router notification (RA) in which the router valid time (Router Life Time) is set to a very short time (0 seconds or more) to the host terminal connected to the local network (Router Advertisement)) router notification transmission control means for transmitting a message.

According to another embodiment of the router of the present invention,
The router valid time of the first router notification message is also preferably set to 0 seconds.

According to another embodiment of the router of the present invention,
Router notification transmission control means
After sending the first router notification message, the host terminal waits for a predetermined period of time so that the pool address can be discarded,
After that, it is also preferable to transmit a second router notification message including the prefix of the second access network of the migration destination and the router valid time set as the default time.

According to another embodiment of the router of the present invention,
The protocol in the route control means is BGP (Border Gateway Protocol),
The default-route in multiple access networks is determined by LP (Local-Preference) value,
It is also preferable to further include a switching trigger detection unit that detects a change in the access network having the maximum LP value among the LP values for each access network and instructs the router notification control unit.

According to another embodiment of the router of the present invention,
The route control means detects a physical or protocol communication quality state for a plurality of access networks,
It is also preferable to further include a switching trigger detection means for detecting the occurrence of a failure according to the communication quality state of the route control means and instructing the router notification control means.

According to another embodiment of the router of the present invention,
The prefix is for IPv6 and is assigned by the Internet service provider equipment that operates the access network,
It is also preferable that the route control means controls the route of the IPv6 packet.

According to the present invention, the first WAN interface connected to the first access network, the second WAN interface connected to the second access network, and the LAN connected to the local network to which a plurality of host terminals are connected. In a program for causing a computer mounted on a multihomed router having an interface to function,
Route control means for controlling the route of the data packet between the first access network or the second access network and the local network;
Prefix pool means for holding a first prefix obtained from the first access network and a second prefix obtained from the second access network;
When switching from the first access network of the migration source, the first router notification message with the router valid time (Router Life Time) set to an extremely short time (0 seconds or more) is sent to the host terminal connected to the local network. A computer is caused to function as a router notification transmission control means for transmission.

According to the present invention, a first access network, a second access network, a local network, a host terminal connected to the local network, and a plurality of access networks and a router interconnected to the local network are provided. In a multi-home connection method in a system having:
The router has a prefix pool section that holds a first prefix of the first access network and a second prefix from the second access network;
A first step in which a host terminal has a first global address based on a first prefix and a data packet transmitted from the host terminal is routed to a first access network via a router;
When the router switches from the first access network to the second access network, the first router notification message in which the router valid time is set to a very short time (0 seconds or more) via the local network to the host terminal A second step of transmitting
A third step in which the router waits for a predetermined time such that the pool address is discarded by the host terminal;
A fourth step in which the router transmits a second router notification message including the prefix of the second access network of the migration destination and the router valid time set to the default time to the host terminal;
A fifth step in which the host terminal generates a second global address based on the second prefix;
A sixth step in which a data packet transmitted from the host terminal is routed to the second access network via the router;
It is characterized by having.

  According to the router, the program, and the method in the multihome connection environment of the present invention, the multihome connection function can be provided only at the router by using the existing host terminal to provide the multihome connection at an extremely low cost. To do.

It is a system configuration diagram in the present invention. It is a sequence diagram in the present invention. It is a functional block diagram of the router in this invention. It is explanatory drawing showing switching of the access network in this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram according to the present invention.

  According to FIG. 1, the multihome router 1 is interconnected between a first access network 3 </ b> A and a second access network 3 </ b> B and a LAN 5. A plurality of host terminals 2 are connected to the LAN 5. The host terminal 2 connects to the Internet 4 via the multi-home router 1 via either the first access network 3A or the second access network 3B.

  Each access network is operated and managed by the ISP of the communication carrier. Each access network includes an address management device, and notifies each host terminal of a prefix that can be connected to the access network. Here, the “prefix” is a network address of an IPv6 address, and the address management apparatus manages a group of IPv6 addresses unique on the Internet.

  FIG. 2 is a sequence diagram in the present invention.

(S201) First, the multihome router 1 holds the first prefix A from the first access network 3A and the second prefix B from the second access network 3B. That is, the multihome router 1 holds a prefix for each access network (link other than the local link).

  The multihome router 1 is connected to the first access network 3A and the second access network 3B. First, it is assumed that the multihome router 1 is communicating with the Internet via the first access network 3A. The second access network 3B is maintained as a protection line for the first access network 3A.

  Each host terminal 2 holds its own global IPv6 address with the first prefix A of the first access network 3A as the network address. As a result, the data packet transmitted from the host terminal 2 is routed to the first access network 3A via the multihome router 1.

(S202) Here, it is assumed that a trigger for switching from the first access network 3A to the second access network 3B has occurred. Specific switching conditions will be described later with reference to FIG.

(S203) The multihomed router 1 transmits a router notification message to all the host terminals 2 connected to the LAN. The router advertisement message in IPv6 is an RA (Router Advertisement) message. Here, the router lifetime (Router Life Time) included in the RA message is set to an extremely short time, for example, 0 seconds.

In the RA message, a router notifies its existence to another node (host terminal or other router) on the same link. The RA message has two transmission forms as follows.
• The router periodically transmits to other nodes.
-When a router receives a router solicitation message from another node, it replies to the other node.

The RA message includes the following format parameters.
[Router LifeTime]
A 16-bit unsigned integer that is set in seconds. The maximum value is 18.2 hours and the minimum value is 0. The valid time = 0 means that the router is invalid.
[Prefix Information]
Includes prefixes on all links (access networks) other than local prefixes in the router. Thereby, the host terminal can determine whether or not the communication partner is on the same link.

Further, according to RFC 2461, the following interface-specific options are defined for transmission of RA messages from the router.
[MaxRtrAdvInterval]: RA message transmission interval
(4 to 1800 seconds) (default: 600 seconds)
[AddValidLifetime]: Valid lifetime of prefix information included in RA
(Maximum forever) (default: 7 days)
[AddPreferredLifetime]: Designated lifetime of prefix information included in RA
(Maximum forever) (default: 7 days)

According to the present invention, the RA message transmitted for S203 is set as follows.
Router life time = 0
Prefix information =
Second prefix B of the second access network 3B
The interface options are changed as follows.
[MaxRtrAdvInterval] = 5 seconds [AddValidLifetime] = 5 seconds [AddPreferredLifetime] = 5 seconds

(S204) All the host terminals 2 that have received the RA message determine that the multihome router 1 has become invalid, and discard all the pool addresses (prefixes).

(S205) The multihomed router 1 waits for a predetermined time that allows all the host terminals 2 to discard the pool address.

(S206) Next, the multihome router 1 acquires the prefix B of the second access network 3B to be switched from the prefix pool unit. Then, the multihome router 1 again transmits an RA message including the prefix B of the migration destination second access network 3B and the router valid time set as the default time.

(S207) The host terminal 2 that has received the RA message again generates an IPv6 address from the prefix and sets it as its own address.

For example, it is assumed that the RA message transmitted by the multihome router 1 includes the following prefix.
Prefix: [3ffe: fff: fff: a :: / 64]
On the other hand, the host terminal 2 generates a global IPv6 address as follows.
Link local address: [e80 :: 200: 00ff: fe01: 0203]
Global IPv6 address = [3ffe: fff: fff: a :: / 64] + [e80 :: 200: 00ff: fe01: 0203]
= [3ffe: ffff: ffff: a: 200: 0ff: fe01: 0203]

(S208) Thereby, the data packet transmitted from the host terminal 2 is controlled to the route of the second access network 3B via the multihome router 1.

  FIG. 3 is a functional configuration diagram of the router in the present invention.

  According to FIG. 3, the multihome router 1 includes a first WAN interface unit 101, a second WAN interface unit 102, and a LAN interface unit 103. The first WAN interface unit 101 is connected to the first access network 3A in the first ISP. The second WAN interface unit 102 is connected to the second access network 3B in the second ISP. Furthermore, the LAN interface unit 103 connects to a home network to which a plurality of host terminals are connected.

  The multihome router 1 includes a route control unit 111, a prefix pool unit 112, a switching trigger detection unit 113, and a router notification control unit 114. These functional components are realized by executing a program that causes a computer mounted on the router to function.

  The route control unit 111 controls the route of the IPv6 packet between the first access network 3A or the second access network 3B and the local network. Perform existing routing on the router.

  The prefix pool unit 112 holds the first prefix A acquired from the first access network 3A and the second prefix B acquired from the second access network 3B.

  The switching trigger detection unit 113 detects an access network switching trigger and instructs the router notification control unit 114 to switch the access network. Specific switching conditions will be described later with reference to FIG.

  The router notification transmission control unit 114 includes a first router notification transmission unit 1141, an address discard time standby unit 1142, and a second router notification transmission unit 1143.

  When switching from the first access network that is the migration source, the first router notification transmission unit 1141 sends a router lifetime (Router Life Time) to the host terminal 2 connected to the local network for an extremely short time (0 seconds or more). The first RA message set in () is transmitted (the same processing as S203 in FIG. 2 is executed).

  After transmitting the first RA message, the address discard time waiting unit 1142 waits for a predetermined time that allows all the host terminals 2 to discard the pool address (similar to S205 in FIG. 2).

  The second router notification transmission unit 1143 transmits the second RA message including the prefix of the migration destination second access network and the router valid time set as the default time (the same processing as S206 in FIG. 2). Run).

  FIG. 4 is an explanatory diagram showing access network switching in the present invention.

  The switching trigger detection unit 113 of the multihome router 1 detects the timing of access network switching. The protocol in the route control unit 111 is, for example, BGP (Border Gateway Protocol). BGP is a route control protocol for exchanging route information between organizations on the Internet. In BGP, a unique AS (Autonomous System) number on the Internet is assigned to each organization that controls routes.

  In BGP, in general, any one route selected for routes to a plurality of counterpart routers is represented as default-route. The default-route is determined by an LP (Local-Preference) value. A multihomed router connected to a plurality of access networks holds an LP value for each access network. For example, when the LP value of the access network A = 100 and the LP value of the access network B = 90, the access network A is selected. Further, when connected to three or more access networks, the access network having the maximum LP value is selected from among these LP values.

  When the maximum LP value is changed among the LP values for each access network, the switching trigger detection unit 113 detects the change and instructs the router notification control unit 114. As a result, the access network having the maximum LP value is selected.

  Further, the switching trigger detection unit 113 may detect a physical or protocol communication quality state for a plurality of access networks. As a result, it is possible to switch an access network having a deteriorated communication quality state with or without using the LP value of BGP. When the BGP LP value is not used, it is necessary to set a metric value for the priority of default-route in advance.

  For example, when BGP is not used, a physical interface disconnection or PPP (Point to Point Protocol) protocol disconnection may be detected as an access network failure detection. Further, it may be one using ICMP (Internet Control Message Protocol). ICMP is a protocol for transferring IP error messages and control messages, and is used to check the status between devices connected by TCP / IP. Ping is used for network diagnosis.

  As described above in detail, according to the router, the program, and the method in the multihome connection environment of the present invention, by using the existing host terminal, by implementing the function for multihome connection only in the router, A multi-home connection can be provided at a very low cost. A multi-homed connection environment can increase fault tolerance in the access network.

  Further, according to the present invention, it is possible to make a multi-home connection to a plurality of ISPs (Internet service providers) without using PI (provider independent) addresses in the Internet protocol (IPv6).

  Furthermore, according to the present invention, by updating only a part of functions in a router connected between a plurality of WANs and at least one LAN, the host terminal can maintain the existing functions and No software changes or additional installations are required. In addition, the multihome router can switch the access network based on its own judgment by monitoring the communication quality state of the access network.

  In particular, according to the present invention, the access network can be switched even by a host terminal not equipped with the DHCPv6 function. Note that the processing function for the RA message is a function generally installed in most host terminals.

  Various changes, modifications, and omissions of the above-described various embodiments of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

DESCRIPTION OF SYMBOLS 1 Multihome router 101 1st WAN interface part 102 2nd WAN interface part 103 LAN interface part 111 Path control part 112 Prefix pool part 113 Switching trigger detection part 114 Router notification transmission control part 1141 1st router notification transmission part 1142 Address discard time waiting unit 1143 Second router notification transmission unit 2 Host terminal 3A Access network A, first access network 3B access network B, second access network 4 Internet

Claims (8)

A first WAN (Wide Area Network) interface that connects to the first access network, a second WAN interface that connects to the second access network, and a LAN that connects to a local network to which a plurality of host terminals are connected ( In a multihomed router having a (Local Area Network) interface,
Route control means for controlling a route of a data packet between the first access network or the second access network and the local network;
Prefix pool means for holding a first prefix obtained from the first access network and a second prefix obtained from the second access network;
When switching from the first access network of the migration source, the first router notification in which the router valid time (Router Life Time) is set to a very short time (0 seconds or more) to the host terminal connected to the local network A router characterized by comprising router advertisement transmission control means for transmitting an (RA (Router Advertisement)) message.   The router according to claim 1, wherein the router valid time of the first router advertisement message is set to 0 seconds. The router notification transmission control means includes:
After sending the first router notification message, the host terminal waits for a predetermined time enough to discard the pool address,
3. The router according to claim 1, further comprising: transmitting a second router advertisement message including a prefix of the second access network to be migrated and a router valid time set as a default time. 4. The protocol in the route control means is BGP (Border Gateway Protocol),
The default-route in multiple access networks is determined by LP (Local-Preference) value,
4. The apparatus according to claim 1, further comprising switching trigger detection means for detecting a change in an access network having a maximum LP value among LP values for each access network and instructing the router notification control means. The router according to any one of the above items. The path control means detects a physical or protocol communication quality state for a plurality of access networks,
4. The switching trigger detection unit according to claim 1, further comprising a switching trigger detection unit that detects occurrence of a failure according to the communication quality state of the route control unit and instructs the router notification control unit. 5. Router. The prefix is for IPv6 and assigned from an Internet service provider facility operating the access network;
The router according to any one of claims 1 to 5, wherein the route control unit controls a route of an IPv6 packet. Multi-home having a first WAN interface connected to a first access network, a second WAN interface connected to a second access network, and a LAN interface connected to a local network to which a plurality of host terminals are connected In the program that causes the computer installed in the router for
Route control means for controlling a route of a data packet between the first access network or the second access network and the local network;
Prefix pool means for holding a first prefix obtained from the first access network and a second prefix obtained from the second access network;
When switching from the first access network of the migration source, the first router notification in which the router valid time (Router Life Time) is set to a very short time (0 seconds or more) to the host terminal connected to the local network A program for a router, which causes a computer to function as a router notification transmission control means for transmitting a message. Multihome in a system having a first access network, a second access network, a local network, a host terminal connected to the local network, a plurality of access networks and a router interconnected to the local network In the connection method,
The router has a prefix pool section for holding a first prefix of a first access network and a second prefix from a second access network;
A first step in which the host terminal has a first global address based on a first prefix, and a data packet transmitted from the host terminal is routed to a first access network via the router; When,
When the router switches from the first access network to the second access network, the router valid time is set to a very short time (0 seconds or more) via the local network to the host terminal. A second step of sending a router advertisement message;
A third step in which the router waits for a predetermined time such that a pool address is discarded by the host terminal;
A fourth step in which the router transmits a second router notification message including a prefix of the migration destination second access network and a router valid time set to a default time to the host terminal;
A fifth step in which the host terminal generates a second global address based on a second prefix;
A sixth step in which a data packet transmitted from the host terminal is routed to a second access network via the router;
A multi-home connection method characterized by comprising:

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