CN102006189A - Primary access server determination method and device for dual-machine redundancy backup - Google Patents

Abstract

The present invention provides a method and device for determining a primary access server, the method comprising: associating two groups of BFDs between the first access server and the second access server; when the first access server and/or the second When a group of BFDs associated with an access server is disconnected, the priority of the access server is lowered by one level from the current configuration priority; when two When the group BFD is disconnected, the priority of the access server is lowered by two stages from the predetermined reference priority, and the access server with the current higher priority is used as the active access server. In the present invention, by associating the appropriate dual BFD with the active and standby access servers, and setting the reference priority as a reference, the priorities of the active and standby access servers will not be the same, thereby avoiding the dual-system The problem of dual-active in hot backup.

Description

Method and device for determining primary access server for dual-machine redundant backup

technical field

The present invention relates to the field of communications, in particular to a method and device for determining a primary access server for dual-machine redundancy backup.

Background technique

Under the development trend of IP-based telecommunication services and IP network telecommunication, in order to meet the needs of NGN/3G and other services to access IP bearer networks, in the NGN (Next Generation Network, next-generation network) bearer network, NGN service system equipment is generally Dual-homing connection to two access routers to ensure the reliability of telecom services. The access router is used as a PE (Provider Edge, operator edge) device, and VRRP (Virtual Router Redundancy Protocol, Virtual Router Redundancy Protocol) runs between the two devices. agreement), to achieve active and standby redundancy backup. However, the basic VRRP protocol has the defect of long convergence time, which cannot meet the requirement of supporting 50 ms carrier-grade switching. On the basis of the basic VRRP protocol, the VRRP enhancement protocol associated with BFD (Bidirectional Forwarding Detection, bidirectional forwarding detection) improves the convergence speed, but these technologies have more or less defects.

Currently, there is a VRRP feature enhancement protocol in the industry. VRRP is bound to BFD and the operation of increasing the priority is added, which better expands the backup function on the basis of the original VRRP monitoring interface function. By adding a new command, the track command in VRRP can not only change the interface, but also increase, decrease or restore the previous priority when the state of the bound BFD changes. The default priority The unit of level change is 10. In this way, when the Master router is down, the router in the Backup state monitors the status of the specified interface or BFD Session. If it cannot be quickly detected, it can judge whether to quickly switch the VRRP state according to the BFD status, and the Slave actively and quickly upgrades to the Master. , to take over the upstream traffic.

However, this method has defects. When encountering BFD down, this method directly lowers the priority. When there are more than one group of BFD associated, if one Peer (router) of the VRRP encounters a group of BFD down, and another Peer encounters When the two groups of BFD are down, and the values of the two peers are equal after lowering the priority, there will be a problem that VRRP cannot be switched.

The existing dual-system hot backup method can avoid the above problems. In the dual-system hot backup method, when encountering BFD down, the priority is not lowered, but the primary device is directly down. The specific structure is shown in Figure 1, including the main BRAS (Broadband Remote Access Server, broadband remote access server), the switch SW1 directly connected to the main BRAS, the backup BRAS, and the switch SW2 directly connected to the backup BRAS. A group of BFDs are respectively associated with the link between the active BRAS and the standby BRAS, the link between the active BRAS and the switch SW1, and the link between the standby BRAS and the switch SW2.

In the dual-machine hot backup method, the switching of the main and standby machines follows the following two principles,

1. When the standby machine finds that the BFD status directly connected to the switch SW2 is UP, and the BFD status directly connected to the BRAS is DOWN, the standby machine switches to the main one;

2. When the active machine discovers that the BFD directly connected to the switch SW1 and the BFD directly connected to the BRAS are all in DOWN state, the active BRAS switches to the standby.

The reason for this is that if VRRP is only associated with BFD between BRASs, when this happens, the active and standby BRASs will mistakenly believe that the link between the active BRAS and the switch is down, resulting in a wrong VRRP switchover.

However, in the dual-machine hot backup method, there are the following problems: when the heartbeat line connected to the main machine on the standby machine is disconnected, according to the first principle, a dual-active situation will occur.

Contents of the invention

The main purpose of the present invention is to provide a method and device for determining the primary access server for dual-machine redundant backup, so as to at least solve the dual-host problem that may be caused in the word-of-mouth network of dual-machine hot backup.

According to one aspect of the present invention, a method for determining an active access server for dual-machine redundancy backup is provided, including the following steps: the downlink between the first access server and the switch directly connected to it , the downlink between the second access server and the switch directly connected to it, and the link between the first access server and the second access server through the downlink are respectively associated with a group of bidirectional forwarding detection BFD; when When a group of BFDs associated with the first access server and/or the second access server is disconnected, the priority of the access server is lowered from the current configuration priority by one level; when the first access server and/or Or when the two groups of BFDs associated with the second access server are disconnected, reduce the priority of the access server by two levels from the predetermined base priority, where the base priority is less than or equal to the first access server and the second Configure the configuration priority of the access server with the lower priority in the second access server; compare the current priority of the first access server and the second access server, and use the access server with the higher current priority as the primary access server .

Further, the method further includes: when a group of BFDs associated with the first access server and/or the second access server restores the connection, increasing the current priority of the access server by one level; when the first access server When the two groups of BFDs associated with the ingress server and/or the second access server restore the connection, restore the current priority of the access server to its configured priority; compare the Current priority, the access server with the highest current priority is used as the primary access server.

Further, the range of the priority is 0-255, wherein the number of a series of the priority is 10.

Further, the first access server and the second access server determine the active access server through the preemption mode.

Further, the first access server and the second access server form logical interfaces through link aggregation, and the logical interfaces are connected using a bridging protocol.

According to another aspect of the present invention, a device for determining an active access server for dual-machine redundancy backup is provided, the device includes: an association module, between the first access server and the switch directly connected to it The downlink between the second access server and the directly connected switch, and the link between the first access server and the second access server through the downlink are respectively associated with a group of two-way forwarding Detecting BFD; a priority adjustment module, configured to reduce the priority of the access server by one from the current configuration priority when a group of BFD associated with the first access server and/or the second access server is disconnected Number of levels: when the two groups of BFDs associated with the first access server and/or the second access server are disconnected, the priority of the access server is lowered by two levels from the predetermined base priority, where the base priority The configuration priority of the access server with the lower configuration priority among the first access server and the second access server; the main access server determination module is used to compare the first access server and the second access server The current priority of the server, the access server with the highest current priority is used as the primary access server.

Further, the priority adjustment module is further configured to increase the current priority of the access server by one level when a group of BFDs associated with the first access server and/or the second access server restores the connection, and when When the two groups of BFDs associated with the first access server and/or the second access server restore the connection, the current priority of the access server is restored to its configured priority.

In the present invention, by associating dual BFDs with the active and standby access servers and setting the base priority, when the dual BFDs associated with the access server are disconnected, the priority of the access server is reduced by two levels from the base priority. A series, so as to avoid the problem of dual-active in dual-system hot backup.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is a schematic diagram of a dual-machine hot backup network structure according to related technologies;

FIG. 2 is a schematic diagram of a network structure to which a method for determining an active access server according to an embodiment of the present invention is applied;

FIG. 3 is a flowchart of a method for determining an active access server according to an embodiment of the present invention;

FIG. 4 is a structural block diagram of an apparatus for determining an active access server according to an embodiment of the present invention;

FIG. 5 is a flow chart when the BFD state is disconnected according to Embodiment 1 of the present invention; and

FIG. 6 is a flow chart of BFD state recovery connection according to Embodiment 1 of the present invention.

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the drawings and examples. It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

Fig. 2 is a schematic diagram of a network structure applied to a method for determining a primary access server according to an embodiment of the present invention. As shown in Fig. 2, the network is composed of a first access server, a first switch, a second switch and a second The first access server and the second access server are each associated with two sets of BFD. In the working state, one of the first access server and the second access server is the master The access server and the other serve as a standby access server. According to the state of the associated BFD, the first access server and the second access server can switch between active and standby states. VRRP uses the bridging protocol between the first access server and the second access server, and uses SMARTGROUP technology to ensure reliability (the logical interface formed by link aggregation is called SMARTGROUP, and SMARTGROUP can be used as a common port to ensure link Reliability), the bridging protocol enables two servers that are not physically on the same channel to be connected together through a logical interface or vlan (virtual local area network).

Of course, in the dual-machine redundant backup of the actual application, the network structure is relatively complicated, but basically it can be abstracted into the above-mentioned network structure model.

FIG. 3 is a flow chart of a method for determining a primary access server according to an embodiment of the present invention. The method is applied in the network structure environment shown in FIG. 2 , as shown in FIG. 3 , and includes the following steps:

Step S302, the link between the first access server and the first switch, the link between the second access server and the second switch, the first access server to the second switch through the first switch and the second switch Links between access servers are associated with a group of bidirectional forwarding detection BFD.

Step S304, when a group of BFDs associated with the first access server and/or the second access server is disconnected, lower the priority of the access server by one level from the current configuration priority; When the access server and/or the two groups of BFDs associated with the second access server are disconnected, the priority of the access server is lowered by two levels from the predetermined base priority, where the base priority is less than or equal to the first access server. The configuration priority of the access server with the lower configuration priority among the ingress server and the second access server.

Step S306, comparing the current priorities of the first access server and the second access server, and using the access server with the higher current priority as the primary access server.

In the above method, by associating dual BFDs with the active and standby access servers and setting the base priority, when the dual BFD associated with the access server is disconnected, the priority of the access server is reduced by two levels from the base priority. A series, so as to avoid the problem of dual-active in dual-system hot backup.

After step S306, it also includes: when a group of BFDs associated with the first access server and/or the second access server restores the connection, increasing the current priority of the access server by one level; when the first access server When the two groups of BFDs associated with the ingress server and/or the second access server restore the connection, restore the current priority of the access server to its configured priority; compare the For the current priority, the access server with the highest current priority is used as the active access server, and the number of priority levels can be set to 10, and the determination of the active access server adopts the preemptive mode. The bridge protocol is passed between the first access server and the second access server, and link reliability is guaranteed through SMARTGROUP.

Wherein, in the above method, two access servers form a VRRP group, each access server is a PEER of the VRRP group, and priority negotiation is performed through the VRRP protocol. The base priority means that when a certain peer of VRRP needs to lower the priority, the priority of the peer is lowered below the base priority based on the base priority. When the BFD state associated with a VRRP peer is down, the peer priority of the VRRP must be reduced to a certain range lower than the base priority. When the BFD state associated with the peer is all up, the peer priority of the VRRP must be restored to Configuration priority. The selection of the base priority can be configured as required, and the smaller priority of the two peers in the VRRP group can also be used, but it must be smaller than the smaller priority of the two peers in the VRRP group.

The base priority is used because: Suppose one peer priority is 60 and the other is 40. The link from the bras with a priority of 60 to the directly connected switch is down. Assuming that the priority is based on the original priority, one bfd is down and the priority is lowered by 10. Then the peer with the original priority of 60 has 2 bfds down. So the priority is 60-20=40, the priority of the peer with priority 40 is 40-10=30, which will cause the priority of the down peer to be 40, and the priority of the non-down peer to be 30, and vrrp cannot be switched . Therefore, when using the priority mode of vrrp switching and supporting dual BFD, there must be a priority that can be referred to, and the priority must be less than or equal to the minimum value of the two priorities of the VRRP peer.

Fig. 4 is a structural block diagram of an apparatus for determining an active access server according to an embodiment of the present invention. As shown in Fig. 4, the apparatus for determining includes: an association module 10 connected in sequence, a priority adjustment module 20, and an active access server determining module 30.

Among them, the association module 10 is used for the link between the first access server and the first switch, the link between the second access server and the second switch, the first access server via the first switch and the second The links between the switch and the second access server are respectively associated with a group of bidirectional forwarding detection BFD; the priority adjustment module 20 is configured to disconnect a group of BFD associated with the first access server and/or the second access server When enabled, the priority of the access server is lowered by one level from the current configuration priority; when the two groups of BFDs associated with the first access server and/or the second access server are disconnected, the access server The priority of the server is lowered by two levels from the predetermined reference priority, wherein the reference priority is less than or equal to the configuration priority of the access server with the lower configuration priority among the first access server and the second access server; The access server determination module 30 is configured to compare the current priorities of the first access server and the second access server, and use the access server with the higher current priority as the primary access server.

In the above device, by associating dual BFDs with the active and standby access servers and setting the base priority, when the dual BFDs associated with the access server are disconnected, the priority of the access server is reduced by two levels from the base priority. A series, so as to avoid the problem of dual-active in dual-system hot backup.

In the above-mentioned device for determining the primary access server, the priority adjustment module is further configured to: when a group of BFDs associated with the first access server and/or the second access server resumes connection, the current The priority is increased by one level, and when the two groups of BFDs associated with the first access server and/or the second access server recover the connection, the current priority of the access server is restored to its configured priority.

Embodiment one

In this example, the network structure shown in Figure 2 is adopted. When each peer of VRRP is associated with two sets of BFD, the BFD state causes the priority of VRRP peers to change, as follows:

When an associated BFD state is down, the VRRP priority of the peer is lowered by an amount, for example, 10, than the "self priority".

When two BFD states are down, the VRRP priority of the peer is lower than the "base priority" by two numbers.

When a BFD state is UP, the VRRP priority of the peer is increased by an amount higher than the base priority.

When the two BFD states are UP, the VRRP priority of the peer returns to the original configured priority.

In the above process, when the VRRP Peer priority changes, the active change party immediately starts the re-election of the primary PEER.

Fig. 5 is a flowchart according to the first embodiment of the present invention when the BFD state is disconnected. In this embodiment, assuming that the original VRRP priority of bras1 is 50, bras2 is 40, and the reference priority is 40, then when there is an associated The situation when the BFD state is disconnected is shown in Figure 5, including the following steps:

In step S502, a link or node fails, and the BFD state is down. For example, the link between bras1 and sw1 is down.

Step S504, the peer starts to lower the VRRP priority according to the number of down links. The BFD1 and BFD3 associated with the vrrp of bras1 are all down, and the priority is reduced to 40-20=10; while bras2 only downs bfd3, the priority is reduced to 40-10=30.

Step S506, restart VRRP master-standby election immediately, wherein, master-standby election adopts preemption mode, and preemption mode is a kind of mode of VRRP agreement, after the Backup router receives VRRP notification message, can compare its priority with the notification message The priority in the message is compared; if it is higher than the priority in the notification message, it will become the active device, otherwise it will remain in the standby state. In this embodiment, the current priority of bras2 is higher than the current priority of bras1, and bras1 acts as the master device.

Step S508, judging whether VRRP master/standby switching, if yes, go to step S510, otherwise go to step S512. bras1 is selected as the master device, and a master-standby switchover is required.

Step S510, triggering active/standby switching and routing processing, bras1 is switched to be the active server, and bras2 is switched to be the standby server.

Step S512, do not process.

In the above steps, the following two situations also exist:

When the link between sw1 and sw2 is down: both bras1 and bras2 have only one bfd state down, so the priority of bras1 is reduced to 50-10=40; bras2 is reduced to 40-10=30, according to the vrrp rule, bras1 is still the main .

When the link between bras2 and sw2 is down: bras1 only down bfd3, the priority is reduced to 50-10=40, the bfd associated with the two vrrp of bras2 is all down, the priority is reduced to 40-20=10 according to vrrp switching As a rule, bras1 is the main one.

In the above two cases, the problem of dual active use is also avoided by reducing the priority.

Fig. 6 is a flow chart according to the first embodiment of the present invention when the BFD state restores the connection, as shown in Fig. 6, including the following steps:

Step S602, the BFD state of the Peer is up.

Step S604, judge whether all BFDs are up, if yes, go to step S606, otherwise go to step S608

Step S606, the VRRP priority of the Peer is restored to the configured priority.

Step S608, increasing the current VRRP priority of the Peer by 1 amount.

In step S610, the VRRP master/standby election is restarted immediately, wherein the master/standby election adopts a preemptive mode.

Step S612, whether VRRP master/standby switching, if yes, go to step S614, otherwise go to step S616

Step S614, triggering active/standby switchover and routing processing.

Step S616, do not process.

In the above embodiments of the present invention, by associating appropriate dual BFDs with the active and standby access servers, and setting the reference priority as a reference, when the dual BFD associated with the access server is disconnected, the access server The priority of the server is lowered by two levels from the baseline priority, so that the priority of the active and standby access servers will not be the same, thereby avoiding the problem of dual active use in dual-machine hot backup.

Obviously, those skilled in the art should understand that each module or each step of the above-mentioned present invention can be realized by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed in a network formed by multiple computing devices Alternatively, they may be implemented in program code executable by a computing device so that they may be stored in a storage device to be executed by a computing device, and in some cases in an order different from that shown here The steps shown or described are carried out, or they are separately fabricated into individual integrated circuit modules, or multiple modules or steps among them are fabricated into a single integrated circuit module for implementation. As such, the present invention is not limited to any specific combination of hardware and software.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. A method for determining an active access server for dual-machine redundant backup, characterized in that it comprises: The downlink between the first access server and the switch directly connected to it, the downlink between the second access server and the switch directly connected to it, the first access server through the downlink Links to the second access server are respectively associated with a group of bidirectional forwarding detection BFD; When a group of BFDs associated with the first access server and/or the second access server is disconnected, lower the priority of the access server by one level from the current configuration priority; when the When the two groups of BFDs associated with the first access server and/or the second access server are disconnected, reduce the priority of the access server by two levels from a predetermined reference priority, wherein the reference priority The priority is less than or equal to the configuration priority of the access server with the lower configuration priority among the first access server and the second access server; The current priorities of the first access server and the second access server are compared, and the access server with the higher current priority is used as the active access server. 2. The method for determining the primary access server according to claim 1, further comprising: When a group of BFD associated with the first access server and/or the second access server restores the connection, increase the current priority of the access server by one level; when the first access server And/or when the two groups of BFDs associated with the second access server restore the connection, restore the current priority of the access server to its configuration priority; The current priorities of the first access server and the second access server are compared, and the access server with the higher current priority is used as the active access server. 3 . The method for determining the primary access server according to claim 2 , wherein the priority ranges from 0 to 255, and the number of priority levels is 10. 4 . 4. The method for determining the active access server according to claim 3, wherein the first access server and the second access server determine the active access server through a preemptive mode. 5. The method for determining an active access server according to any one of claims 1 to 4, wherein the first access server and the second access server form a logical interface through link aggregation, so The above logical interfaces are connected by bridging protocol. 6. A device for determining an active access server for dual-machine redundant backup, characterized in that it comprises: Associating module, the downlink between the first access server and the switch directly connected to it, the downlink between the second access server and the switch directly connected to it, the first access server via The links between the downlink and the second access server are respectively associated with a group of bidirectional forwarding detection BFD; A priority adjustment module, configured to reduce the priority of the access server from the current configuration priority when a group of BFDs associated with the first access server and/or the second access server is disconnected A number of levels; when the two groups of BFDs associated with the first access server and/or the second access server are disconnected, the priority of the access server is lowered by two levels from a predetermined reference priority number, wherein the reference priority is less than or equal to the configuration priority of the access server with the lower configuration priority among the first access server and the second access server; The active access server determination module is configured to compare the current priorities of the first access server and the second access server, and use the access server with the higher current priority as the active access server. 7. The device for determining the primary access server according to claim 6, wherein the priority adjustment module is further configured to: when the first access server and/or the second access server are associated When a group of BFDs associated with the first access server and/or the two groups of BFDs associated with the second access server restore the connection, the current priority of the access server is increased by one level. , restore the current priority of the access server to its configured priority.

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