KR100775768B1 - VRRP Router and Switchover Method Between VRRP Routers - Google Patents

Abstract

The present invention relates to a state transition method between a VRRP router and a VRRP router, wherein the version field in which the first router supports an advertisement interval in milliseconds and an advertisement interval in milliseconds are set. Generate and transmit a VRRP advertisement packet including the set advertisement interval field, determine whether the first router has lost the master function according to the advertisement interval value included in the advertisement packet received by the second router, and transition state By doing this, it is possible to quickly switch in the down of the master router.

Description

State Transition Method between VRPRP Router and VRPRP Router {VRRP Router and Switchover Method Between VRRP Routers}

1 is a diagram showing the structure of a network including a redundant router to which the present invention is applied.

2 is a diagram illustrating a structure according to a first embodiment of a VRRP packet according to the present invention;

3 is a diagram illustrating a structure according to a second embodiment of a VRRP packet according to the present invention;

* Description of the symbols for the main parts of the drawings *

101, 102: router 103: host

104: Internet 210: Version Field

270: Ad interval field 271: Nibble 1

272: nibble 2

The present invention relates to a state transition method between a VRRP router and a VRRP router.

It is common for multiple hosts located in a specific area connected by LAN to select one default router for communication with the external network and transmit packets through the router. The router receives the packet with the destination address, searches for the shortest path to the destination address, and transmits the data packet.

However, if a failure occurs due to a power failure, reboot, or waiting for scheduling in the default router, the host may lose a path to communicate with the outside. As a solution to this problem, there is a Virtual Router Redundancy Protocol (VRRP2338) and Hot Standby Router Protocol (RFC2281). Using this protocol, when a host uses a statically configured default router, it has a structure with one master router and one or more backup routers. One or more backup routers are called backup groups, and one of the backup routers is used for the host.

VRRP defines a dynamic election protocol that dynamically assigns responsibility for virtual routers to any of the VRRP routers on the LAN. Since all protocol messaging is performed using IP multicast datagrams, VRRP is a protocol that can be universally applied to networks that support IP multicast.

In VRRP, the master router periodically sends an Advertisement message to inform backup routers that it is operating, and the backup router receives this message to recognize that the master router is working. If the master router fails, the master router can no longer deliver advertising messages. Since the backup router does not receive the advertisement message, the backup router detects a failure of the master router, and the backup router becomes a master router and takes over the role. The master router and backup router use the same virtual ID and the same virtual IP address, and each host sets this virtual IP address as the address of the default gateway.

As described above, in the case of router duplication through VRRP, the interval unit of the advertisement message transmitted by the master router to the backup router is 1 second related to the time required for the backup router to recognize the failure of the master router.

In the case of router redundancy using VRRP, it is essential to provide a faster transition from backup to master to minimize service interruption. The 1 second time interval provided by conventional VRRP may not be sufficient. There is a need for ad message spacing for faster switchover between master and backup routers.

In order to solve the above problems, an object of the present invention is to provide a state transition method between a VRRP router and a VRRP router to develop a state transition in seconds between the master router and the backup router to achieve a faster state transition.

The VRRP packet structure according to an aspect of the present invention for achieving the above object, the VRRP version value is set to support the advertisement interval in milliseconds (milliseconds) unit and the advertisement interval in milliseconds is set Ad interval field.

The advertisement interval set according to the advertisement interval field is calculated by multiplying the value set in the advertisement interval field by a reference unit 100ms.

The advertisement interval field includes nibble 1 for setting an interval unit of an advertisement message and nibble 2 having a multiple factor for the nibble 1 as its set value.

The advertisement interval set according to the advertisement interval field is calculated by the formula of [advertisement interval ms = 10 * nibble 1 * nibble 2].

According to another aspect of the present invention, a redundant network includes: a first router for generating and transmitting a millisecond VRRP advertisement packet; an advertisement interval for receiving an advertisement packet from the first router and including the received advertisement packet; The second router determines whether the first router has lost a master function and performs a state transition.

The VRRP advertisement packet includes a version field in which a VRRP version value is supported that supports advertisement intervals in milliseconds, and an advertisement interval field in which advertisement intervals are set in milliseconds.

According to another aspect of the present invention, there is provided a state transition method between VRRP routers, in which a first router generates and transmits a millisecond VRRP advertisement packet, and a second router receives an advertisement packet from the first router. And determining whether the first router has lost the master function according to the advertisement interval value included in the received advertisement packet, and performing a state transition.

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the drawings.

1 illustrates a structure of a network including a redundant router to which the present invention is applied.

In the network of FIG. 1, a plurality of hosts 103-1 to 103-n, a router 1 101, and a router 2 102 are connected to a local area network (LAN). One of router 1 101 and router 2 102 is a master router, and the other is a backup router. The master and backup routers actually have separate IP addresses and MAC addresses, but the same virtual IP address and MAC (Media Access Control) address are set. The host 103 sets the default router, that is, the IP address of the gateway to be the same as the virtual IP address, and transmits the packet through the master router before failure occurs.

In the event of a failure of the master router, the backup router detects the failure and subsequently acts as the default router for the hosts in the role of the master router.

According to the router duplication protocol, the master router is supposed to periodically advertise to the backup router that it is the master router. The destination address of the advertisement message is in multicast form, allowing network elements located on the LAN to receive it. Initially, the distinction between the master router and the backup router can be determined by priority. The router with the higher priority value becomes the master router. The priority value is set by the user at the time of router setting. If the priority value is higher than other routers, the priority value is set to the master state, and when the priority value is low, the router is in the backup state.

The backup router may determine whether the master router is down from the advertisement message sent by the master router. If the advertisement router does not receive the advertisement message for a certain time, the backup router assumes that the master router is down and acquires the qualification of the master router to take its role.

For example, suppose Router 1 101 is the master router and Router 2 102 is the backup router. In addition, the actual IP address of the router 1 101 is 1.1.1.1, the MAC address is 11: 11: 11: 11: 11: 11, the actual IP address of the router 2 102 is 2.2.2.2, the MAC address is 22 : 22: 22: 22: 22: 22, the virtual IP address is 1.2.3.4 and the virtual MAC address is 12: 12: 12: 12: 12: 12. It is set differently from actual IP address and MAC address.

If router 1 101 fails, router 2 102 transitions to the master state. Although Router 1 (101), which was the original Master, is restored during the routing of Router 2 (102), Router 2 (102), which has transitioned to the master state, serves as a master router. However, if a failure occurs while performing the master role of router 2 102, router 1 101 transitions to the master state again to serve as a master router.

In VRRP, only the master router sends periodic VRRP advertisement messages to the backup router to minimize network traffic. According to the present invention, the master router generates and transmits a VRRP advertisement packet in milliseconds, and the backup router receives the advertisement packet from the master router and according to the advertisement interval value included in the received advertisement packet. 1 Determine whether the router has lost the master function and perform state transition.

The parameters used in the VRRP router regarding router duplication include Advertisement_Interval, Skew_Time and Master_Down_Interval. Ad interval means the time interval between advertisement messages. Master_Down_Interval means the time interval that the backup router declares that the master router is down. The value is defined as [(3 * ad interval) + skew time]. Here, the skew time is defined as [(256-Priority) / 256].

2 shows a structure according to a first embodiment of a VRRP packet according to the present invention.

The version field 210 indicates the VRRP protocol version of the packet. The version according to the invention is defined as "15", which is the version that is set when the ad interval is defined in milliseconds. A specific implementation for the millisecond ad interval will be described in detail with the ad interval field 270 described below.

The type field 220 indicates the type of the VRRP packet. In general, there is only one VRRP packet type, and the VRRP packet type 1 is an advertisement message. The virtual router id (Virtual Rtr Id) field 230 indicates an ID of a router that is the target of the status report of the corresponding VRRP packet.

The priority field 240 indicates a priority to be selected as a virtual router. The higher the value, the higher the priority. In the case of a virtual router, that is, a master, the priority value is set to 255, and the backup router has a priority value between 0 and 254. When the priority value is 0, it has a special meaning. This means that the backup router should start operation because the current master is stopped.

The Count IP Addrs field 260 indicates the number of IP addresses included in the VRRP packet. The Authentication Type field 260 is a field indicating an authentication method to be used, and 8 bits are allocated.

The Advertisement Interval field 270 is an Ad Interval field indicating a time interval between advertisement messages. The default value of the advertisement interval field in a typical VRRP packet is 1 second. However, the minimum unit of the advertising interval according to the present invention is 100 msec. Therefore, when the advertisement interval field 270 is set to 1, the advertisement interval is 100 ms.

As the ad interval changes, the master_down_interval also changes. The value of the master_down_interval is defined as [3 * ad interval) + skew time as described above.

The checksum field 280 is a field for detecting data corruption of a corresponding VRRP message. The IP address field 290 includes at least one IP address associated with the virtual router, so that the authentication data 261 includes an authentication string.

In summary, the VRRP packet according to the first embodiment of the present invention has a structure in which the version field and the advertisement interval field have different values as compared with the conventional VRRP packet.

3 shows a structure according to a second embodiment of a VRRP packet according to the present invention.

As shown in FIG. 3, it can be seen that the second embodiment of the VRRP packet according to the present invention has a large change in the advertisement interval fields 271 and 272 as compared with the first embodiment.

The version field 210 has a value of 15 as in the first embodiment, which means that the advertisement field in milliseconds is to be implemented.

The advertisement interval field is divided into a field 271 for setting an interval unit and a field 272 for a multiplication factor. The full advertisement interval field is divided into two bytes (nibble, four bits) by one byte (8 bits). Nibble 1 is a field for setting the interval unit of the advertisement message. If the minimum unit is set to 10 ms, when the value of 2 is set in nibble 1, the interval unit is 20 ms. Also nibble 1 cannot have a value of zero.

On the other hand, since nibble 2 represents a product factor, when the minimum interval is set to 10 ms, the advertisement interval is calculated as in Equation 1 below.

Advertisement Interval = 10 * Nibble1 * Nibble2

In the second embodiment according to the present invention, as in the first embodiment, the master_down_interval is also changed according to the change of the advertisement interval. That is, as the advertisement interval decreases, the master_down_interval {(3 * advertisement interval) + skew time} also decreases, resulting in a faster state switchover between the master router and the backup router.

The present invention, by realizing the switchover of the millisecond unit in the router duplication system through the VRRP, it is possible to implement a router duplication in the true sense by enabling a quick switchover when the master router down.

Claims (8)

In the Virtual Router Redundancy Protocol (VRRP) packet structure for router duplication, A version field in which a VRRP version value is set to support an advertisement interval in milliseconds; Wow VRRP packet structure containing an Ad Interval field with Ad Interval in milliseconds set. The method of claim 1, The advertisement interval set according to the advertisement interval field is The VRRP packet structure, characterized in that calculated by multiplying the reference unit 100ms by the value set in the advertisement interval field. The method of claim 1, The ad interval field, Nibble 1 for setting an interval unit of an advertisement message; and And a nibble 2 having a multiple factor for the nibble 1 as its set value. The method of claim 3, wherein The advertisement interval set according to the advertisement interval field is calculated according to the following equation. Ad interval (ms) = 10 * Nibble1 * Nibble2 In a network that implements redundancy using VRRP, Create a millisecond VRRP Advertisement packet that contains a version field with a VRRP version value that supports milliseconds ad intervals and an ad interval field with a millisecond ad interval. A first router transmitting; Wow And a second router that receives an advertisement packet from the first router, determines whether the first router has lost a master function according to an advertisement interval value included in the received advertisement packet, and performs a state transition. delete In the state transition method between at least one router that implements VRRP redundancy, The millisecond VRRP Advertisement includes a version field with a VRRP version value that supports the first milliseconds Advertisement Interval and an ad interval field with an Ad Interval that is set in milliseconds. Generating and transmitting a packet; Wow And a second router receiving an advertisement packet from the first router, determining whether the first router has lost the master function according to the advertisement interval value included in the received advertisement packet, and performing a state transition. How to transition state between routers. delete

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