KR100386923B1 - Back-Up & load balancing method and apparatus based on dual lines - Google Patents

Abstract

The present invention relates to a dual line based backup and load balancing method and apparatus. The method for backing up a line according to the present invention, wherein a first ISP corresponding to the first line and a second ISP corresponding to the second line are different from each other, and the operation of the first line and the second line is performed. Monitoring, detecting a malfunction on one of the first and second lines, and routing a packet transmitted and received through a line corresponding to the detected malfunction by a predetermined method to transmit and receive through another line And a line corresponding to the detected malfunction is restored, the normal port policy is applied to the first line and the second line.

Description

Back-Up & load balancing method and apparatus based on dual lines

The present invention relates to a dual line based backup and load balancing method and apparatus.

Conventional line backup methods include delta and dual line methods. The delta method is a way to bypass other paths when there is a problem with the path between the server and the client. In the dual line backup method, two lines provided by the same ISP (Internet Service Provider) are used to back up to the other line when an error occurs in one line.

However, in the delta method, when a packet is transmitted and received by a newly created bypass path between a server and a client, the delta method takes an excessively long time and has additional side effects such as packet loss. Although the delta method is safer than the dual line method, it is a general purpose case, and in case of performing a special purpose (for example, in-house use), a new path must be created separately, thus adding unexpected cost. There are also problems that can take place.

In addition, since the dual line system is supplied with a line from the same ISP, there is a fatal problem that a substantial backup is not possible when there is an error of the ISP itself rather than a line problem.

In order to overcome the problems of the prior art described above, an object of the present invention is to provide a dual line-based backup method and apparatus that can perform a stable line backup using two lines provided by different ISP.

Another object of the present invention is to provide a dual line-based backup and load balancing method and apparatus that can effectively distribute the load.

Still another object of the present invention is to provide a dual line based backup and load balancing method and apparatus suitable for a network for performing a specific purpose such as an enterprise.

1 is a diagram showing a system configuration for load balance according to a preferred embodiment of the present invention.

2 is a diagram illustrating a port policy table in accordance with a preferred embodiment of the present invention.

3 is a flowchart schematically illustrating a process of distributing a load in a bypass according to a preferred embodiment of the present invention.

4 is a diagram schematically illustrating a configuration of a system capable of backing up a line when a problem line occurs according to an exemplary embodiment of the present invention.

5 is a view schematically illustrating the configuration of a system capable of backing up a line when a problem line occurs according to another exemplary embodiment of the present invention.

6 is a flow chart showing a line backup process according to an embodiment of the present invention.

7 is a diagram schematically illustrating the configuration of a dual dual line based backup and load balancing system according to an embodiment of the present invention.

FIG. 8 is a flowchart schematically illustrating a dual dual line based line backup process according to an exemplary embodiment of the present invention. FIG.

9 is a diagram illustrating a configuration of a dual dual line based backup and load balancing system according to another embodiment of the present invention.

10 is a flowchart illustrating a dual dual line based backup and load balancing process on the server side according to an embodiment of the present invention.

11 is a flowchart illustrating a dual dual line based backup and load balancing process on a client side according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

101... Bypass 103... First ISP

105... Second ISP 107... Internet

109... First track 111... Second track

113... Router 115.. ADSL

117.. Switch 119... Ethernet

According to an aspect of the present invention for achieving the above objects, in backing up a line in a line backup router connected to a first line and a second line, wherein a first ISP (Internet) corresponding to the first line is used. Service Provider) and the second ISP corresponding to the second line are different from each other, monitor the operation of the first line and the second line, and detect a malfunction of any one of the first line and the second line. And routing the packet transmitted / received through the line corresponding to the detected malfunction by a predetermined method so as to be transmitted / received through another line, and when the line corresponding to the detected malfunction is restored, the first line and the second line It is possible to provide a line backup method to which a normal port policy is applied, a device and a recording medium corresponding to the method.

The monitoring is by the Ping function. The malfunction is caused by an error in at least one of the line itself and the ISP corresponding to the line.

Packet transmission and reception may be distributed to the first line and the second line by the normal port policy. The distribution may correspond to a packet type.

According to another aspect of the present invention, in backing up a line in a first backup router connected to a first dual line, wherein the first dual line is connected to a second dual line and the Internet, The second dual line is connected to a second backup router, ISPs corresponding to each of the first dual lines are different from each other, and ISPs corresponding to each of the second dual lines are different from each other, Monitoring the operation of the second dual line, recognizing a malfunction of one of the second dual lines, and transmitting a packet to the second backup router through a line different from the line corresponding to the recognized malfunction; Route in a predetermined manner so that the second backup router receives the packet and sends the packet to the second backup router using a port number corresponding to the packet. It is possible to provide a dual dual line based line backup method for transmitting to a corresponding Sub Net, an apparatus and a recording medium corresponding to the method.

Recognizing a malfunction of one of the lines of the second dual line is to receive and recognize a notification of a malfunction of one of the lines of the second dual line from the second backup router. When a line corresponding to the recognized malfunction is restored, a normal port policy may be applied to each of the lines.

According to the normal port policy, transmission and reception of packets may be distributed to each of the second dual lines.

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

In the present specification, a line and a line are used in combination.

1 is a diagram illustrating a system configuration for load balance according to an embodiment of the present invention.

Referring to FIG. 1, a first line through a router 113 and an ADSL 115 where a backup and load balancing router (hereinafter referred to as dPass) 101 serves as a gateway. 109 and the second line 111 is connected. In addition, the bypass 101 is connected to the server 121 and the plurality of PCs 123 through the switch 117 and the Ethernet 119. Here, the IP address of each device will be described by way of example.

A first Internet Service Provider (ISP) 103 is connected to the first line, and a second ISP 105 is connected to the second line. In addition, the first ISP 103 and the second ISP 105 are connected to the Internet 107. In a preferred embodiment of the present invention, the first line 109 will be described as a main line (main line) as a dedicated line, the second line 111 is a sub line as a dedicated line or ADSL line. In addition, the first line has a C class public IP address set from 203.117.1.1 to 203.117.1.255 from the first ISP 103, and the second line has one IP address of 192.168.1.2 from the second ISP 105. Assume that has been set.

The first ISP 103 and the second ISP 105 may be the same ISP in terms of load balancing, but are preferably different ISPs in terms of backup to be described later.

The files configured by default include the track information file, the policy table file, the policy IP file, and the check IP file. Each file is described in detail as follows.

The track information file specifies information about the track. The format is as follows: However, if the line includes local, the client may include the IP address of the client.

eth0_ip = IP_addr

eth0_netmask = netmask address

eth0_network = network address

eth0_broadcast = broadcast address

eth0_gateway = gateway address

For example, for eth0 (125)

eth0_ip = 203.117.1.10

eth0_netmask = 255.255.255.0

eth0_network = 203.117.1.0

eth0_broadcast = 203.117.1.255

eth0_gateway = 203.117.1.1

[client]

203.117.1.5

203.117.1.6

203.117.1.7

203.117.1.8

In the case of eth1 (127)

eth0_ip = 192.168.1.2

eth0_netmask = 255.255.255.224

eth0_network = 192.168.1.0

eth0_broadcast = 192.168.1.6

eth0_gateway = 192.168.1.1

This can be

The policy table file designates a port to transmit a packet through an additional line (second line), and the policy IP file must be an IP address that transmits traffic through the main line (first line) regardless of what is described in the policy table file. Specifies.

The check IP file is used to check periodically whether the track is operating normally. You can specify the IP address. In addition, the check time can be specified in units of seconds (for example, 30 seconds). In a preferred embodiment of the present invention, the IP inspection uses the PING function, and it is considered that the line does not operate normally when a problem occurs by repeating the second time every 5 seconds after the first problem occurs. The format is as follows:

main = IP_addr

sub = IP_addr

checktime = n

An example may be as follows.

main = 203.117.0.1

sub = 192.168.10.1

checktime = 30

A process of performing load balancing by the bypass 101 according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3.

FIG. 2 is a diagram illustrating a port policy table according to an exemplary embodiment of the present invention, and FIG. 3 is a flowchart schematically illustrating a process of distributing load in a bypass according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the bypass may store a port policy table 201 describing a policy for determining a line for transmitting and receiving a packet for each port. The port policy table 201 includes a port number item 203, a packet type item 205 according to the port number, a first line item 207 for selecting a first line, and a second line for selecting a second line. It may include item 209. For example, if the port number is 80, which is a well known port, the packet corresponding thereto is HTTP, and a policy is set such that HTTP packets are transmitted and received on the second line, the port number item 203 is 80, the packet type item. The table can be constructed by selecting the HTTP and the second line item 209 at 205.

In the case of receiving a packet transmitted locally in a describing, referring to FIG. 3, the deferred packet is analyzed by a header after receiving the packet transmitted locally (step 301) (step 303). do. Thereafter, after the extract extracts the type of the packet, it determines the line using the above-described port policy table (step 305). If the first line is determined, the decode transmits the received packet to the first line (step 307), and if the second line is determined, transmits the received packet to the second line (step 309). For example, if the packet transmitted locally is HTTP, the decode determines the transmission line as the second line using the port policy table shown in FIG. The de-pass then transmits the received packet to the second line. It will be apparent that the load can be distributed through the above process.

4 is a diagram schematically illustrating a configuration of a system capable of backing up a line when a problem line occurs according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the system is almost the same as the system shown in FIG. 1, but a problem occurs in the first line and cannot be used. In addition, in the system for line backup, the first ISP 103 and the second ISP 105 must be different ISPs. In the above system, when the first line (the main line) goes down, since the packet cannot be transmitted and received through eth0 125, the default setting for load balancing is ignored. That is, all packets of eth2 129 are routed to eth1 127 to use only the second line (secondary line). In addition, the bypass 101 checks the check IP (CheckIP, 203.117.10.1) set in the eth0 125 using the Ping function at Checktime (for example, 30 seconds) intervals.

5 is a diagram schematically illustrating a configuration of a system capable of backing up a line when a problem line occurs according to another exemplary embodiment of the present invention.

Referring to FIG. 5, the system is almost identical to the system shown in FIG. 1, but a problem occurs in a second line and cannot be used. In addition, in the system for line backup, the first ISP 103 and the second ISP 105 must be different ISPs. In the above system, when the second line (secondary line) goes down, since the packet cannot be transmitted and received through eth1 127, the default setting for load balancing is ignored. That is, all packets of eth2 129 are routed to eth0 125 to use only the first line (the main line). In addition, the bypass 101 checks the check IP (CheckIP, 192.168.10.1) set in the eth1 127 using a Ping function at Checktime (for example, 30 seconds) intervals.

6 is a flowchart illustrating a line backup process according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the bypass first sets the policy state to P11 (step 601). The state of P11 is the basic backup policy, which concentrates the transmission and reception of all packets on the main line (the first line), and the secondary line (the second line) is composed of NAT (Network Address Translation), and the main line (the first line). It is specified to remain idle until a problem occurs. NAT translates an IP address on an internal network that uses a different IP address than what is known to the external network. In general, a system maps its internal network address to one or more public IP addresses. It then converts the public IP address on incoming packets back to a private IP address. NAT may be configured to statically define IP addresses or dynamically translate them.

The bypass then determines the current policy state at step 603. Since the policy state is set to P11 in step 601, the bypass executes the P11 policy (step 605). In another preferred embodiment of the present invention, the bypass may further execute the process of setting the P11 policy before executing step 607. Thereafter, the bypass determines whether the main line (the first line) is operating (step 607). The method of determining uses a Ping function, which may be referred to the above description, and thus description thereof will be omitted. The bypass executes step 611 if the main line is normally operated as a result of the determination of step 607, and otherwise executes step 609.

At step 609, the bypass sets the policy state to P12. The P12 policy is to concentrate all transmission / receive packets on the secondary line (second line) when the main line (the first line) goes down, and is designated to use the NAT configured in the P11 policy. In addition, the P12 policy is specified to periodically check whether the main track (the first track) has been restored normally. Since the inspection method is as described above, the description thereof will be omitted. The bypass executes step 609 and then executes step 603 again.

In step 611, the bypass determines whether the auxiliary line (second line) is operating normally. The bypass returns to step 605 if the auxiliary line is normally operated as a result of the determination of step 611, and otherwise executes step 613.

In step 613, the bypass sets the policy state to P13. The P13 policy specifies that when an auxiliary line goes down, all incoming and outgoing packets should be concentrated on the main line (the first line) and periodically checked to see if the auxiliary line has been restored normally. Since the inspection method is as described above, the description thereof will be omitted. The bypass executes step 603 again after execution of step 613.

In step 603, if the current policy state is P12, the bypass executes the P12 policy (step 615). Since the P12 policy is as described above, a description thereof will be omitted. In another preferred embodiment of the present invention, the bypass may further execute the process of setting the P12 policy before performing step 615. Thereafter, the bypass determines whether the main line (the first line) is normally restored (step 617), and then executes step 619 if the restoration is normally performed, and otherwise executes step 615 again. In step 619, the bypass sets the policy state to P11. Since the P11 policy is as described above, a description thereof will be omitted.

In step 603, if the current policy state is P13, the bypass executes the P13 policy (step 621). Since the P13 policy is as described above, a description thereof will be omitted. In another preferred embodiment of the present invention, the bypass may further execute the process of setting the P13 policy before executing step 621. Thereafter, the bypass determines whether the auxiliary line (second line) is normally restored (step 623), and then executes step 625 if the restoration is normally performed, and otherwise executes step 621 again. At step 625, the bypass sets the policy state to P11. Since the P11 policy is as described above, a description thereof will be omitted.

A method of performing a line backup and load balancing process by differently specifying the P11 policy in the line backup process described with reference to FIG. 6 will be described. That is, the P11 policy designates specific ports and specific IP addresses to send and receive packets on additional lines (second line), and all unspecified ports and IP addresses to send and receive packets on the main line (first line). Thus, it will be apparent to those skilled in the art that the load can be distributed.

7 is a diagram schematically illustrating a configuration of a dual dual line based backup and load balancing system according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the bypass server 701 is connected to the server 705 and is connected to the Internet 107 through the third line 709 and the fourth line 711. In addition, the bypass client 703 is connected to the client 707 and is connected to the Internet 107 through the fifth line 713 and the sixth line 715. That is, both the server side and the client side have at least two lines, and as described above, load balancing can be performed using at least two lines. Here, the ISP corresponding to the third line and the ISP corresponding to the fourth line are different ISPs, and the ISP corresponding to the fifth line and the ISP corresponding to the sixth line are different ISPs. By such a configuration, it is possible to simultaneously perform line backup and load balancing. This will be described in detail with reference to FIG. 8.

8 is a flowchart schematically illustrating a dual dual line based line backup process according to an exemplary embodiment of the present invention.

Referring to FIG. 8, the bypass client directly checks whether the third line, which is the main line, is normally operated among the lines connected to the server or receives a check result (step 801). Thereafter, the bypass client determines whether the third line is normally operating (step 803), and if it is normally operated, performs the step 801 again, otherwise performs the step 805. In step 805, the bypass client transmits all packets transmitted to the server to an IP address corresponding to the fourth line, which is an auxiliary line, among the lines connected to the server.

After receiving the packet, the bypass server recognizes it per port (step 807). Thereafter, the bypass server transmits the received packet to the internal server (subnet) for each port (step 809).

9 is a diagram illustrating a configuration of a dual dual line based backup and load balancing system according to another embodiment of the present invention.

Referring to FIG. 9, since the dual dual line-based backup and load balancing system is configured in a symmetrical manner with reference to FIG. 1, the detailed description of the configuration will be omitted. Here, the bypass server and the bypass client have the same configuration as the bypass described with reference to FIG. 1. However, the third ISP and the fourth ISP connected to the bypass server are different ISPs. Similarly, the fifth and sixth ISPs connected to the bypass client are different ISPs.

The default configuration on the bypass server is:

First, all default settings of the bypass apply. However, the IP addresses 203.117.1.5 and 203.117.1.6 of the servers 905 and 906, which must always maintain the fail over on the server side, are set to use the third line, which is the main line of the server side. Second, the port to be used by the server program is specified. For example, the IP address 203.117.1.5 may be designated as 1010 and the IP address 203.117.1.6 as 1011. Third, when the third line, the server-side main line, goes down and the fourth line, the server-side auxiliary line, is used, an IP address and a port number to be converted into a server IP address are set. Fourth, in the case where the third line, which is the server-side main line, goes down, a bypass server program is executed to notify the corresponding client of the fact. Specifically, when the third line is down, the bypass server reads the bypass client file and notifies the fact to the TCP session.

Files that are configured by default on the bypass server include at least an IP address and port configuration file (server) and a bypass client file.

The IP address and port configuration file (server) is required to set the IP address and port number used when the third line, the main line on the server side, goes down. The format is as follows:

NAT_PORT1 = SERVER_IP1: Port Number

E.g,

1010 = 203.117.1.5: 1010

1011 = 203.117.1.5: 1011

It can be set as follows.

The bypass client file is used to set the IP address of the bypass client that will be notified when the third server, the server-side main line, goes down.

If set as above, the bypass server periodically checks the third line, which is the server-side main line, by using the above-described Ping function, and notifies the bypass client of the matter when the third line does not operate normally. . The bypass server reads the IP address and the port setting file (server), and converts the packet transmitted to the designated port among the packets transmitted to the fourth line to the designated IP address. For example, a packet corresponding to port 1010 is transmitted to 203.117.1.5, and a packet corresponding to port 1011 is transmitted to 203.117.1.6.

The default configuration on the bypass client is:

First, all default settings of the bypass apply. Secondly, in order to use the fourth line, which is the auxiliary line on the server side, when the third line, which is the main line on the server side, goes down, the IP address and port number of the fourth line on the server side are designated. Third, when the third line, which is the main line on the server side, goes down, a bypass client program to be notified of the matter is executed. Specifically, when the corresponding matter is notified, the IP table may be changed by using the IP address and port configuration file (client), and may be redone. The IP address and port configuration file (client) is used to set an IP address and a port number that can change the destination address when transmitting a packet from the client side. In that form

SEVER_IP1: port number = SUB_IP: port number

, For example,

203.117.1.5:1010=192.168.1.2:1010

203.117.1.6:1011=192.168.1.2:1010

Can be set.

If the above-mentioned setting is made, when the third line, which is the server-side main line, is notified of being down, the IP address and the port number setting file (client) are read to transmit all packets of the designated port number to the designated IP address. For example, packets of port numbers 1010 and 1011 transmitted from clients of 203.239.35.5 to 203.239.35.8 are both sent to 192.168.1.2.

10 is a flowchart illustrating a dual dual line-based backup and load balancing process at the server side according to an embodiment of the present invention.

Referring to FIG. 10, the backup and load balancing process is similar to the line backup process described with reference to FIG. 6. The difference between the backup and load balancing process compared to the line backup process described with reference to FIG. 6 is the content of each policy and the addition of steps 1015 and 1023. Therefore, description of overlapping portions will be omitted.

First, the P21 policy assigns specific ports and specific IP addresses to distribute incoming and outgoing packets to the server-side secondary line, the fourth line, and all unspecified ports and IP addresses to use the server-side primary line, the third line. do. In addition, the P21 policy specifies the IP address of the server and the port number used so that all packets are transmitted and received on the fourth line, which is the server-side auxiliary line, when the third line, which is the server-side main line, is down. The P22 policy specifies that when the third line, the server-side main line, goes down, all transmission and reception packets are concentrated on the fourth line, the server-side auxiliary line, and then periodically checked whether the third line is normally restored. In addition, the P22 policy is specified to convert packets sent to the port specified in the P21 policy into the designated port number. Since the P23 policy is the same as the P13 policy described above, a description thereof will be omitted.

In operation 1015, the deferred server notifies the deceased client that the third main line, which is the server-side main line, is down, and notifies the deceased client that the third line is normally restored.

11 is a flowchart illustrating a dual dual line based backup and load balancing process on a client side according to an embodiment of the present invention.

Referring to FIG. 11, the backup and load balancing process is similar to the line backup process described with reference to FIG. 6. The difference between the backup and load balancing process compared to the line backup process described with reference to FIG. 6 is the content of each policy and the addition of steps 1105, 1117, and 1125. Therefore, description of overlapping portions will be omitted.

First, the P31 policy assigns specific ports and specific IP addresses to distribute incoming and outgoing packets to the sixth line, the client side secondary line, and specifies that all unspecified ports and IP addresses use the fifth line, the client side main line. do. Basically, NAT is configured in the sixth line and operates in a private IP format. In addition, the P31 policy designates the IP address and port number of the server as the IP address of the fourth line, which is an auxiliary line on the server side, in order to maintain a fail over on the server side. The P32 policy specifies that when the fifth line, the client-side main line, goes down, all transmission / receive packets are concentrated on the sixth line, the client-side auxiliary line, and then periodically checked whether the fifth line is normally restored. In addition, the P32 policy is specified to convert packets transmitted to the port specified in the P31 policy to the specified port number. Since the P33 policy is the same as the P13 policy described above, a description thereof will be omitted. In addition, the P31, P32, and P33 policies, if notified that the main line on the server side is down as a result of the execution of steps 1105, 1117, and 1125, in order to maintain the Fail Over on the server side, the IP address in the original content And read the port configuration file (client) and send all packets of the specified port to the specified IP address.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

According to the present invention, a dual line-based backup method and apparatus capable of performing stable line backup using two lines provided by different ISPs can be provided.

In addition, according to the present invention, it is possible to provide a dual line-based backup and load balancing method and apparatus that can effectively distribute the load.

In addition, the present invention can provide a dual line-based backup and load balancing method and apparatus suitable for a network for performing a specific purpose such as an enterprise.

Claims (15)

A line backup method in a line backup router connected to a first line and a second line, wherein the first Internet service provider (ISP) corresponding to the first line and the second ISP corresponding to the second line are connected to each other. Different-, Monitoring the operation of the first line and the second line; Detecting a malfunction of any one of the first line and the second line; Routing packets transmitted and received through a line corresponding to the detected malfunction by a predetermined method so as to be transmitted and received through another line Including, When the line corresponding to the detected malfunction is restored, normal port policy is applied to the first line and the second line. Track backup method characterized in that. The method of claim 1, The surveillance By the Ping function Track backup method characterized in that. The method of claim 1, The malfunction is By an error in at least one of the line itself and the ISP corresponding to the line Track backup method characterized in that. The method of claim 1, As per normal port policy Sending and receiving of packets to the first line and the second line Track backup method characterized in that. The method of claim 4, wherein The distribution is Corresponding to the packet type Track backup method characterized in that. A line backup method in a first backup router connected to a first dual line, wherein the first dual line is connected to a second dual line and the internet, and the second dual line is a second backup router. Internet service providers (ISPs) corresponding to each of the first dual lines are different from each other, and ISPs corresponding to each of the second dual lines are different from each other. Monitoring the operation of the second dual line; Recognizing a malfunction of one of the second dual lines; Routing the packet transmitted to the second backup router in a predetermined manner to be transmitted through a line different from the line corresponding to the recognized malfunction; Including, The second backup router Receiving the packet and transmitting the received packet to a subnet corresponding to the second backup router using a port number corresponding to the packet. Dual line based line backup method for both sides. The method of claim 6, The surveillance By the Ping function Dual line based line backup method for both sides. The method of claim 6, Recognizing a malfunction of one of the second dual lines is Receiving and recognizing a notification of a malfunction of one of the second dual lines from the second backup router. Dual line based line backup method for both sides. The method of claim 6, When a line corresponding to the recognized malfunction is restored, a normal port policy is applied to each of the lines. Dual line based line backup method for both sides. The method of claim 9, As per normal port policy Transmission and reception of packets to each of the second dual lines Dual line based line backup method for both sides. The method of claim 6, The distribution is Corresponding to the type of packet Dual line based line backup method for both sides. A line backup router connected to a first line and a second line, wherein a first Internet Service Provider (ISP) corresponding to the first line and a second ISP corresponding to the second line are different from each other. Means for monitoring the operation of said first and second lines; Means for detecting a malfunction of any one of the first and second lines; Means for routing packets transmitted and received through a line corresponding to the detected malfunction in a predetermined manner to be transmitted and received through another line Provided with When the line corresponding to the detected malfunction is restored, normal port policy is applied to the first line and the second line. A track backup router, characterized in that. 1. A first line backup router connected to a first dual line, wherein the first dual line is connected to a second dual line and the Internet, and the second dual line is connected to a second line backup router. ISPs corresponding to each of the first dual lines are different from each other, and ISPs corresponding to each of the second dual lines are different from each other. Means for monitoring operation of the second dual line; Means for recognizing a malfunction of one of the second dual lines; Means for routing the packet transmitted to the second line backup router in a predetermined manner to be transmitted through a line different from the line corresponding to the recognized malfunction Provided with The second line backup router Receiving the packet and transmitting the received packet to a subnet corresponding to the second line backup router using a port number corresponding to the packet. Dual line-based line backup device for both sides. In order to perform the line backup method in the line backup router connected to the first line and the second line, a program of instructions that can be executed by the digital processing device is tangibly embodied and recorded on a recording medium that can be read by the digital processing device. Wherein the first Internet Service Provider (ISP) corresponding to the first line and the second ISP corresponding to the second line are different from each other, The line backup method, Monitoring the operation of the first line and the second line; Detecting a malfunction of any one of the first line and the second line; Routing packets transmitted and received through a line corresponding to the detected malfunction by a predetermined method so as to be transmitted and received through another line Including, When the line corresponding to the detected malfunction is restored, normal port policy is applied to the first line and the second line. And a recording medium. In order to perform the line backup method in the first backup router connected with the first dual line, a program of instructions that can be executed by the digital processing device is tangibly embodied and can be read by the digital processing device. In the medium, wherein the first dual line is connected to a second dual line and the Internet, the second dual line is connected to a second backup router, and an Internet Service Provider corresponding to each of the first dual lines. ) Are different from each other, and ISPs corresponding to each of the second dual lines are different from each other, The two dual line based line backup method, Monitoring the operation of the second dual line; Recognizing a malfunction of one of the second dual lines; Routing the packet transmitted to the second backup router in a predetermined manner to be transmitted through a line different from the line corresponding to the recognized malfunction; Including, The second backup router Receiving the packet and transmitting the received packet to a subnet corresponding to the second backup router using a port number corresponding to the packet. And a recording medium.