KR101235376B1 - Method and System for Protection Switching in Ethernet Ring - Google Patents

Abstract

The present invention relates to an Ethernet ring protection switching method and system, and includes an Ethernet lower layer failure signal (SSF), a remote defect indication (RDI) and a signal for informing a failure state to another port when a unidirectional failure occurs. Receiving ring-automatic protection switching (R-APS) information for requesting protection switching; Setting the states of the first and second Ethernet rings after comparing the SSF, the RDI and the R-APS information; Determining a protection switching priority of an Ethernet ring according to states of the first and second Ethernet rings; And protection switching of the first and second Ethernet rings according to the protection switching priority of the Ethernet ring.

Ethernet ring, protection switching, priority, status information

Description

Method and System for Protection Switching in Ethernet Ring

The present invention relates to an Ethernet ring protection switching method and system, and more particularly, to a method for supplementing and improving a protection switching method in an interconnected Ethernet ring as defined in ITU-T Recommendation G.8032 version 2. And to the system.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Telecommunication Research and Development. [Task management number: 2008-S-009-01, Task name: Packet-optical integrated switch technology development] ]

ITU-T Recommendation G.8032 designates one of the many links that make up an Ethernet ring as a Ring Protection Link (hereafter referred to as 'RPL'), and specifies a node connected to either of the ports of the RPL. By designating an RPL owner, the RPL owner prevents loops by blocking RPL normally. After that, if a link or node other than the RPL fails, the RPL is unblocked and then each node's Filtering DataBase (FDB) is initialized to allow service traffic to pass through the new path formed by MAC address learning. .

ITU-T Recommendation G.8032 is currently preparing version 2 as of October 2008 after version 1 was enacted. G.8032 version 1 only specifies protection switching within a single Ethernet ring, while G.8032 version 2 also includes protection switching for cases where two or more Ethernet rings are interconnected.

Ethernet rings are interconnected by shared nodes or shared links. In the case of Ethernet rings interconnected by shared nodes, two Ethernet rings are disconnected in the event of a failure in the shared nodes. Therefore, it is common to configure interconnected Ethernet rings using shared links in order to construct a reliable network.

1 illustrates an example of an Ethernet ring interconnected by a shared link.

Referring to FIG. 1A, an RPL of a first Ethernet ring and a second Ethernet ring may be assigned to one of arbitrary links (hereinafter, referred to as 'local links') except for a shared link. Link a-j is designated as RPL in the first Ethernet ring, node a is designated as the RPL owner, link e-f is designated as RPL in the second Ethernet ring, and node e is designated as the RPL owner. The active topology shown in FIG. 1 represents a logical connection between each node.

On the other hand, if a failure occurs on the local link, protection switching operates on the corresponding Ethernet ring. Referring to FIG. 1B, a failure occurs in link a-b, which is a local link of the first Ethernet ring, so that the RPL of the first Ethernet ring is unblocked and a logical connection between nodes is formed in a new active topology.

However, when a failure occurs in the shared link, as shown in (c) of FIG. 1, when protection switching is performed in both Ethernet rings, both RPLs of the first Ethernet ring and the second Ethernet ring are unblocked. The ring forms a single super loop, which causes the entire network to be fed by broadcast storming.

To address this, G.8032 version 2, which is currently under discussion, requires that only pre-designated Ethernet rings perform protection switching when a shared link fails. FIG. 1 (d) shows a case where the first Ethernet ring is set by the administrator to perform protection switching in preference to the second Ethernet ring when a shared link fails. Unlike FIG. 1 (c), a loop occurs. I never do that.

However, this method has a problem of disconnection between Ethernet ring nodes when a failure occurs on another local link besides the shared link. As shown in (e) of FIG. 1, when a failure occurs in the local link and the shared link of the first Ethernet ring having a high priority, only the first Ethernet ring performs the protection switching, and the Ethernet ring is transferred to the nodes bcde and the node fghija. There is a problem of separation.

In addition, G.8032 defines a way to recover from a failure only in the event of a single failure in an Ethernet ring. However, the current G.8032 shows perfect connectivity between nodes even when two failures occur while two Ethernet rings are interconnected as shown in FIG. 1 (e). There is a problem that does not provide.

The present invention has been made to solve the above problems, Ethernet ring protection switching method and system to build a more reliable interconnected Ethernet ring network by actively selecting the appropriate Ethernet ring according to the state of the individual Ethernet ring The purpose is to provide.

The present invention for achieving the above object, the first port management unit and the second port management unit for outputting the status information of the first Ethernet ring, the switching agent priority to perform the protection switching function according to the protection switching priority of the Ethernet ring 1 Ethernet ring protection control unit; A second Ethernet ring protection controller configured to output state information of a second Ethernet ring including a second port manager and a third port manager, and to perform a protection switching function according to the protection switching priority of the Ethernet ring; And receiving state information of each Ethernet ring from the first Ethernet ring protection control unit and the second Ethernet ring protection control unit, and determining a protection switching priority of the Ethernet ring according to the state information of each Ethernet ring. An Ethernet ring protection switching system including an Ethernet ring protection control unit and an Ethernet ring priority determination unit transmitted to the second Ethernet ring protection control unit.

The present invention provides an Ethernet ring protection switching in a system including first and second Ethernet ring protection controllers including local ports connected to local links of first and second Ethernet rings, respectively, and shared ports connected to shared links. In the method, the first and second Ethernet ring protection controller, SSF (Server Signal Fail) which is an Ethernet lower layer failure signal, RDI (Remote Defect Indication) and Ethernet which are signals for notifying a failure state to the other port when a unidirectional failure occurs. Receiving ring-automatic protection switching (R-APS) information for requesting ring protection switching; Setting, by the first and second Ethernet ring protection controllers, states of the first and second Ethernet rings after comparing the SSF, the RDI, and the R-APS information; Determining, by an Ethernet ring prioritization unit, protection switching priority of an Ethernet ring according to states of the first and second Ethernet rings; And protecting, by the first and second Ethernet ring protection controllers, the first and second Ethernet ring protection switching according to the protection switching priority of the Ethernet ring.

As described above, the present invention provides an Ethernet ring protection switching method and system for determining protection switching priority of each Ethernet ring according to the state of each Ethernet ring and performing protection switching on the Ethernet ring. In the Ethernet ring network, in case of a shared link and one local link failure, there is an effect of providing perfect connectivity between nodes that are not supported by G.8032 version 2.

In addition, by actively controlling the protection switching priority of each Ethernet ring in the interconnected Ethernet ring network, the network administrator can eliminate the trouble of manually specifying the protection switching priority according to the state of the Ethernet ring.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, in describing the present invention, if it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In the present invention, for convenience of description, two interconnected Ethernet rings are taken as an example, and when N Ethernet rings are shared by one shared link, N + 1 port management units and N Ethernet ring protection (Ehernet Ring Protection: hereinafter, ' ERP 'control section, the forwarding section interacts with the N + 1 port management section, the Ethernet ring prioritization section receives the status information of the Ethernet ring from the N ERP control section, the high protection switching to one of the N Ethernet ring Expanded to assign priority.

Example

2 is a block diagram showing an Ethernet ring protection switching system according to an embodiment of the present invention.

2, the Ethernet ring protection switching system according to the present invention includes a first port manager 210, a second port manager 220, a third port manager 230, a first ERP controller 240, and a second ERP control unit 250, forwarding unit 260 and Ethernet ring priority determining unit 270 and the like.

The first port manager 210, the second port manager 220, and the third port manager 230 may use an IEEE service to transmit Ethernet service traffic, an R-APS message and an OAM (Operation, Administration and Maintenance) message received from an Ethernet port. It is handled in the manner defined by conventional standards such as standard 802.1Q-2007, ITU-T Recommendation G.8032 version 2.

The first ERP controller 240 performs the protection switching function and the ring state management function defined in G.8032 version 2 for the first Ethernet ring including the first port manager 210 and the second port manager 220. do.

The second ERP control unit 250 performs the protection switching function and the ring state management function defined in G.8032 version 2 for the second Ethernet ring including the second port manager 220 and the third port manager 230. do.

The forwarding unit 260 transmits the service traffic, the R-APS message, and the OAM message input and output from the first port manager 210, the second port manager 220, and the third port manager 230 to the IEEE standard 802.1Q-2007. In this case, they are communicated in the manner specified by conventional standards such as ITU-T Recommendation G.8032 Version 2.

The Ethernet ring priority determining unit 270 receives the state information R_Stat of each Ethernet ring from the first ERP control unit 240 and the second ERP control unit 250 and indicates the protection switching priority indicating the protection switching order of each Ethernet ring. The priority is determined and transmitted to the first ERP control unit 240 and the second ERP control unit 250, so that the protection switching is performed only in one Ethernet ring when a shared link failure occurs by the priority determined according to the state of the individual Ethernet ring. .

The first port manager 210 connected to the first ERP controller 240 is connected to the local link of the first Ethernet ring, and the third port manager 230 connected to the second ERP controller 250 is connected to the second Ethernet ring. The second port manager 220 is connected to a shared link shared by the first Ethernet ring and the second Ethernet ring. In addition, each of the first ERP controller 240 and the second ERP controller 250 is connected to the local link and the shared link of each Ethernet ring through the local port L and the shared port S. FIG.

The first port manager 210, the second port manager 220, the third port manager 230, and the forwarding unit 260 are IEEE standards 802.1Q-2007, ITU-T Recommendation G.8032 Version 2, ITU -T behave as specified in Recommendation Y.1731. That is, the first port manager 210, the second port manager 220, and the third port manager 230 classify the Ethernet frame received at the physical layer into service traffic, R-APS message, and OAM message and forwarding unit ( 260, and at the same time, the R-APS information extracted from the R-APS message and the state information (SSF) of the Ethernet lower layer are extracted and output to the first ERP control unit 240 and the second ERP control unit 250. On the contrary, the first port manager 210, the second port manager 220, and the third port manager 230 convert the service traffic, R-APS message, and OAM message received from the forwarding unit 260 into an Ethernet frame. The R-APS message is generated from the first ERP control unit 240 and the second ERP control unit 250, and an R-APS message is generated and output to the physical layer.

The first ERP control unit 240 and the second ERP control unit 250 perform the same operation as that of FIG. 3 in addition to the Ethernet ring protection switching protocol defined in the conventional ITU-T Recommendation G.8032 version 2.

3 is a flowchart illustrating a method of determining a state of an Ethernet ring according to an embodiment of the present invention.

The two nodes connected to the shared link have information about their node IDs so that the node ID in the received R-APS message can be used to determine if it is caused by itself or a peer node connected to the shared link. have.

Referring to FIG. 3, SSF, RDI, and R-APS (Signal Fail) information is monitored in a local port and a shared port (S310). Here, the SSF is from the Ethernet lower layer failure signal input from the port managers 210 and 230 connected to the local ports of the ERP controllers 240 and 250 or from the port manager 220 connected to the shared ports of the ERP controllers 240 and 250. It means the input signal of Ethernet lower layer failure. RDI is a signal for notifying failure status to the other port when a one-way failure occurs in which only one of the ports connected to the link is detected.It is included in the Continuity Check Message (CCM) message, which is one of the OAM messages in ITU-T Recommendation Y.1731. A signal defined by a field.

It is determined whether SSF is detected at the local port (S320), and when the SSF is detected at the local port, the state of the Ethernet ring is determined as a local link failure state (Local_link_Fail) (S322).

If the SSF is not detected at the local port in step S320, it is determined whether the R-APS information is received (S330), and if the R-APS information is not received, the state of the Ethernet ring is determined as a normal state (Idle) ( S332). When SSF is detected in the shared port, it is possible when SSF is detected in the local port because SSF is detected in the opposite node connected by the shared link and the other node transmits R-APS information. .

When the R-APS information is received in step S330, it is determined whether the node ID in the R-APS information is the same as its node ID (S340), and when the node ID in the R-APS information is the same as its node ID. This is the case when SSF occurs in the shared link, and therefore, the state of the Ethernet ring is determined as the shared link failure state (Shared_Link_Fail) (S370).

If the node ID in the R-APS information is not the same as its node ID in step S340, it is determined whether the node ID in the R-APS information is the same as the node ID of the opposite node (S350), and in the R-APS information. If the node ID is not the same as the node ID of the other node, the state of the Ethernet ring is determined to be a local link failure state (S322). That is, since the received R-APS information is generated by another node in the Ethernet ring rather than itself or the other node, it is determined that a failure occurs in the local link, and the state of the Ethernet ring is determined to be a local link failure state (S322).

If the node ID in the R-APS information is the same as the node ID of the other node in step S350, the RDI or SSF is detected on the shared link to determine whether the shared link is broken (S360), and if the failure is not detected on the shared link, R Since the APS information detects a failure on the local link and outputs a message, the APS information determines the state of the Ethernet ring as the local link failure (S322).

When a failure is detected in the shared link in step S360, since the R-APS information detects a failure on the shared link and outputs a message, the R-APS information determines the state of the Ethernet ring as the shared link failure state (S370).

Meanwhile, although node c and node h connected by the shared link in FIG. 1 include the ERP control unit according to the present invention, the remaining nodes may operate only with the conventional protection switching function. However, if the remaining nodes do not support RDI as specified in ITU-T Recommendation Y.1731, when the one-way failure occurs at the local port of the other node and at the same time the shared port fails, the state of the Ethernet ring is changed to the local link failure state. Although it should be determined, there is a problem that the determination is made to the shared link failure state by step S360 of FIG.

In order to solve this problem, as shown in FIG. 4, RDI is configured and released on a shared port. Here, RDI means an RDI field in a CCM message output through a shared port. This is an example of following a signal defined in the conventional ITU-T recommendation Y.1731. In addition, the reserved bits in the R-APS message may be used to convey RDI information or may be delivered by a separate control message.

4, the SSF is monitored at the local port and the shared port (S410).

It is determined whether the SSF is detected in the shared port (S420), and if the SSF is not detected in the shared port, the RDI is released from the shared port (S440).

If SSF is detected in the shared port in step S420, it is determined whether SSF is detected in the local port (S430), and if the SSF is not detected in the local port, RDI is set in the shared port (S432).

If SSF is detected at the local port in step S430, RDI is released from the shared port (S440).

5 is a flowchart illustrating a method of determining the protection switching priority of an Ethernet ring according to the state of the Ethernet ring according to an embodiment of the present invention.

First, the initial protection switching priorities of the first Ethernet ring and the second Ethernet ring are designated as high and low, respectively, so that in case of a shared link failure, protection switching is first performed on the first Ethernet ring. do.

Referring to FIG. 5, the states of the first Ethernet ring and the second Ethernet ring are compared (S510).

If the first Ethernet ring is in a local link failure state and the second Ethernet ring is in a normal state, the protection switching priority of the second Ethernet ring is higher than that of the first Ethernet ring (S512). Here, when the second Ethernet ring is not in the local link failure state, the second Ethernet ring may have a shared link failure state or a normal state. However, since the second Ethernet ring has a lower protection switching priority than the first Ethernet ring, the failure of the shared link does not affect the second Ethernet ring and is therefore considered to be the same as the normal state.

Therefore, since the first Ethernet ring is in a state of protection switching due to a local link failure, the protection switching priority of the second Ethernet ring is increased so that protection switching is performed in the second Ethernet ring in the event of a shared link failure.

When both the first Ethernet ring and the second Ethernet ring are in a normal state, the current protection switching priority is initialized (S520). In this case, when the protection switching priority is to operate in the non-restored mode, step S520 may be omitted.

If the second Ethernet ring is in a local link failure state and the first Ethernet ring is in a normal state, the protection switching priority of the first Ethernet ring is higher than that of the second Ethernet ring (S514).

6 is a view for explaining the protection switching operation of the Ethernet ring according to an embodiment of the present invention.

Referring to (a) of FIG. 6, the initial state is shown. The first Ethernet ring has a higher protection switching priority than the second Ethernet ring.

Referring to (b), if a failure occurs in the local link of the first Ethernet ring, the first Ethernet ring performs protection switching to unblock the RPL of the first Ethernet ring. At this time, the states of the first Ethernet ring and the second Ethernet ring are in a local link failure state and a normal state, respectively, so that the protection switching priority of the second Ethernet ring is changed to be higher than that of the first Ethernet ring.

Referring to (c), if an additional failure occurs in the shared link, the second Ethernet ring performs protection switching according to the protection switching priority of the Ethernet ring to release the RPL of the second Ethernet ring. Therefore, the Ethernet ring protection switching method according to the present invention can ensure the connectivity of each node even if a failure occurs in the shared link and one local link. In addition, the connectivity of each node can be guaranteed for various combinations of one local link failure and a shared link failure.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 shows an example of an Ethernet ring interconnected by a shared link,

2 is a block diagram showing an Ethernet ring protection switching system according to an embodiment of the present invention,

3 is a flowchart illustrating a method of determining a state of an Ethernet ring according to an embodiment of the present invention;

4 is a flowchart illustrating a method of setting and releasing an RDI in a shared port according to an embodiment of the present invention;

5 is a flowchart illustrating a method of determining the protection switching priority of an Ethernet ring according to the state of the Ethernet ring according to an embodiment of the present invention;

6 is a view for explaining the protection switching operation of the Ethernet ring according to an embodiment of the present invention.

Description of the Related Art

210: first port manager 220: second port manager

230: third port management unit 240: first ERP control unit

250: second ERP control unit 260: forwarding unit

270: Ethernet ring prioritization unit

Claims (11)

A first Ethernet ring protection controller configured to output state information of a first Ethernet ring including a first port manager and a second port manager, and to perform a protection switching function according to the protection switching priority of the Ethernet ring; A second Ethernet ring protection controller configured to output state information of a second Ethernet ring including a second port manager and a third port manager, and to perform a protection switching function according to the protection switching priority of the Ethernet ring; And Receiving state information of each Ethernet ring from the first Ethernet ring protection control unit and the second Ethernet ring protection control unit, and determines the protection switching priority of the Ethernet ring according to the state information of each Ethernet ring to determine the first Ethernet An Ethernet ring priority determining unit transmitting to a ring protection controller and the second Ethernet ring protection controller; Ethernet ring protection switching system comprising a. The method of claim 1, The state information of each Ethernet ring is an Ethernet ring protection switching system, characterized in that any one of a local link failure state, a shared link failure state and a normal state. 3. The method of claim 2, When the first Ethernet ring is in the local link failure state and the second Ethernet ring is in the normal state, the Ethernet ring priority determining unit increases the protection switching priority of the second Ethernet ring higher than the first Ethernet ring. If the first Ethernet ring is in the normal state and the second Ethernet ring is in the normal state, initializing the protection switching priority of the current Ethernet ring, wherein the first Ethernet ring is in the normal state and the second Ethernet ring is And, if the local link failure state, the protection switching priority of the first Ethernet ring higher than the second Ethernet ring. In the system including the first and second Ethernet ring protection control unit including a local port connected to the local link of the first and second Ethernet ring, respectively, and a shared port connected to the shared link, the Ethernet ring protection switching method, The first and second Ethernet ring protection controllers perform SSF (Server Signal Fail), which is an Ethernet lower layer failure signal, RDI (Remote Defect Indication) and Ethernet ring protection switching, which are signals for notifying a failure state to the other port when a unidirectional failure occurs. Receiving ring-automatic protection switching (R-APS) information for requesting; Setting, by the first and second Ethernet ring protection controllers, states of the first and second Ethernet rings after comparing the SSF, the RDI, and the R-APS information; Determining, by an Ethernet ring prioritization unit, protection switching priority of an Ethernet ring according to states of the first and second Ethernet rings; And Protecting and switching, by the first and second Ethernet ring protection controllers, the first and second Ethernet rings according to the protection switching priority of the Ethernet ring; Ethernet ring protection switching method comprising a. The method of claim 4, wherein setting the states of the first and second Ethernet rings comprises: Determining whether the SSF is detected at the local port; Determining whether to receive the R-APS information when the SSF is not detected at the local port; When receiving the R-APS information, determining whether a node ID in the R-APS information is identical to a node ID of one end of the shared link; When the node ID in the R-APS information is not the same as the node ID of the shared link end, determining whether the node ID in the R-APS information is the same as the node ID at the other end of the shared link; If the node ID in the R-APS information is the same as the node ID at the other end of the shared link, determining whether the local link supports RDI; Determining whether RDI or SSF is detected on the shared link when the RDI is supported on the local link; And Determining the state of the first and second Ethernet rings as a shared link failure state when the RDI or the SSF is detected on the shared link; Ethernet ring protection switching method comprising a. The method of claim 5, When the SSF is detected at the local port, the state of the first and second Ethernet rings is determined as a local link failure state, and when the R-APS information is not received, the state of the first and second Ethernet rings is determined. If the state is determined to be normal, and the node ID in the R-APS information is the same as the node ID of one end of the shared link, the state of the first and second Ethernet rings is determined as a shared link failure state, and the R- If the node ID in the APS information is not the same as the node ID of the other end of the shared link, the state of the first and second Ethernet rings is determined as a local link failure state, and the RDI or the SSF is not detected in the shared link. If not, Ethernet ring protection switching method characterized in that it determines the state of the first and second Ethernet ring as a local link failure state. The method of claim 5, Setting or releasing RDI at the shared port according to whether SSF is detected at the local port and the shared port if the RDI does not support the RDI; Ethernet ring protection switching method further comprising. The method of claim 7, wherein the setting or clearing the RDI in the shared port, Monitoring SSF on the local port and the shared port; Determining whether the SSF is detected at the shared port; If the SSF is detected at the shared port, determining whether the SSF is detected at the local port; And Releasing the RDI at the shared port if the SSF is detected at the local port; Ethernet ring protection switching method further comprising. 9. The method of claim 8, Ethernet ring protection, characterized in that if the SSF is not detected at the shared port, the RDI is released at the shared port, and if the SSF is not detected at the local port, the RDI is configured at the shared port. Transfer method. The method of claim 4, wherein determining the protection switching priority of the Ethernet ring comprises: Comparing the states of the first and second Ethernet rings; And If the first Ethernet ring is in a local link failure state and the second Ethernet ring is in a normal state, increasing the protection switching priority of the second Ethernet ring over the first Ethernet ring; Ethernet ring protection switching method comprising a. The method of claim 10, If the first Ethernet ring is in a normal state and the second Ethernet ring is in a normal state, the protection switching priority of the current Ethernet ring is initialized, the first Ethernet ring is in a normal state, and the second Ethernet ring is a local link. If the failure state, the Ethernet ring protection switching method characterized in that the priority of the protection switching priority of the first Ethernet ring than the second Ethernet ring.

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