KR20140131480A - Method and apparatus of protection switching in rooted multipoint networks - Google Patents

Abstract

Disclosed is a method for operating a rooted node which transmits/receives a traffic and lift nodes through operation paths, respectively. A method for operating a rooted node according to an embodiment includes the steps of: receiving a first signal fail on working message which commands the generation of an error on the first operation path of the first lift node from the first lift node among lift nodes which transmits/receive a traffic; receiving the first lift node and the traffic by switching the first operation path with the first protection path; and maintaining the operation path with lift nodes excluding the first lift node and receiving the traffic.

Description

≪ Desc / Clms Page number 1 > METHOD AND APPARATUS OF PROTECTION SWITCHING IN ROOTED MULTIPOINT NETWORKS < RTI ID =

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection switching apparatus and method for rapid protection switching to an alternative path in the event of a failure of a transmission / reception path in a point-to-multipoint connection network, i.e., a rooted multipoint connection network.

Currently, APS (Automatic Protection Switching) messages are used for linear protection switching in Packet Transport Network technologies such as OTN (Optical Transport Network) and Ethernet and MPLS-TP (Multi-Protocol Label Switching-Transport Profile) (ITU-T G.873.1), Ethernet Linear Protection (ITU-T G.8031), and MPLS-TP Linear Protection Switching (IETF draft draft-zulr (eg, -mpls-tp-linear-protection-switching-03.txt, ITU-T G.8131.1), and a method of switching state management and path protection switching using protection state control (IETF RFC 6378, ITU-T G.8131.2).

Protection switching is a method for ensuring that traffic is resumed using a different path as soon as a traffic failure occurs due to a network failure. Currently, the linear protection switch sets the working path and the protection path so as not to meet each other for traffic flowing in both directions or unidirectionally between point-to-point, To carry traffic to the protection path at the time of failure of the operation path or at an operator's command.

In most packet transmission networks, the linear protection switching method creates a virtual connection path between management points, and uses a working path and a protection path as entities, As a protection group. If any connection path is damaged in the set protection group, it is recognized by the management end point (MEP) and protection switching is performed in the automatic protection switching processor.

FIG. 1 is a diagram illustrating an ITU-T G.8031 Ethernet linear protection switching structure without modification, and a linear protection switching function is performed by a protection switching processing unit (SNC (Protection Switching Process)) and a protection switching processing unit (Bridge / Selector) of the route.

However, in the conventional method of assigning individual VLANs for individual point-to-point connection, when multicast traffic or broadcast traffic is to be transmitted from a root node to a plurality of leaf nodes, when traffic is transmitted from a root node to a plurality of leaf nodes The number of leaf nodes or the number of leaf nodes is copied and transmitted using different VLANs, which causes a heavy load on the root node.

Recently, the IEEE 802.1Q standard has proposed a method of using an asymmetric VLAN for a rooted multipoint connection network. Asymmetric VLANs allocate different VLANs according to the direction of traffic, allocate one VLAN from the root node to all the leaf nodes, allocate another VLAN for traffic from all leaf nodes to the root node To form a rooted multipoint connection network. Two such asymmetric VLANs can be used to form the operations tree and another two asymmetric VLANs can be used to form a protection tree for protection of traffic in the operational tree. However, in order to apply leaf-specific protection switching to multi-point connection networks using four asymmetric VLANs as described above, the Ethernet frames transmitted from the leaf node to the root node all have the same VLAN ID, And the traffic transmitted from another leaf node is received by the protection tree. In order to know which Ethernet frame received from the Ethernet root node is transmitted from which leaf node, The Ethernet frame forwarding function and the new type of traffic forwarding function defined in IEEE 802.16 standard have to be defined in the standard.

Up to now, there has not been proposed a protection switching by leaf for a multi-pointed rooted rooted network using asymmetric VLANs, and a technology development for this has been requested.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method and apparatus for protecting switching when a network configuration is configured in a point-to-multipoint manner, and a node communicating logically with a plurality of multi- And more particularly to a method and apparatus for protection recovery in a rooted multipoint connection network comprising a plurality of nodes connected to a leaf node.

In the case of a rooted multi-point connection network, when there are many leaf nodes that interrupt the traffic delivery in case of failure of the operation tree, the protection tree is used by switching the entire network at once. However, there is a disadvantage in that a leaf node has a failure in the operation tree, and another leaf node has a leaf node that is not protected when a failure occurs in the protection tree. Therefore, it is necessary to propose the configuration and protection switching method and device for VLANs necessary for leaf-based protection switching by leaf-based protection switching method which makes use of protection tree only for failed leaf nodes in the operation tree. .

A method of operating a root node according to an exemplary embodiment is a method of operating a root node from among a plurality of leaf nodes transmitting and receiving at least one of a transmission traffic and a reception traffic through a plurality of operation paths, Receiving a first SF message (Signal Fail for working message) indicating that a failure occurs in the first operational path, receiving a first SF message (Signal Fail for working message) indicating a failure in the first operational path, And receiving received traffic from each of the leaf nodes other than the first leaf node through each of the operational paths other than the first operational path.

On the other hand, the operation method of the root node may include transmitting a first NR message (No Request message) to each of the plurality of leaf nodes, and receiving a second NR message from each of the plurality of leaf nodes .

In addition, when the SF message is received, the operation of the root node may further include copying the transmission traffic and simultaneously transmitting the copied transmission traffic through the first operation path and the first protection path.

In addition, the operation method of the root node may further include transmitting a third NR message to the first leaf node indicating that the transfer is completed.

In this case, the operation method of the root node may further include transmitting a fourth NR message to the leaf node other than the first leaf node to maintain transmission and reception of the transmission traffic and the reception traffic to the operation path.

The operation method of the root node may further include receiving a return wait message indicating that the failure is eliminated from the first leaf node.

The method of operation of the root node may further include determining that the failure at the first leaf node is eliminated and receiving a fifth NR message indicating that the return waiting timer is terminated from the first leaf node .

The method of operation of the root node may further include, upon receiving the fifth NR message, switching the first protection path to the first operation path to receive the received traffic.

A method of operating a leaf node according to another embodiment includes transmitting and receiving at least one of a transmission traffic and a reception traffic through a root node and an operation path, detecting that a failure occurs in the operation path, Transmitting a SF (Message Fail on Working) message indicating that a failure has occurred to the operation path, and transmitting a first NR message (No Request message from the mobile terminal.

On the other hand, a method of operating a leaf node may further include transmitting a second NR message to the root node and receiving a third NR message from the root node.

In addition, the leaf node may further include a step of copying the transmission traffic and transmitting the transmission traffic simultaneously through the protection path or the operation path, or transmitting the transmission traffic through the protection path.

The operation method of the leaf node may further include transmitting the fourth NR message to the root node after the switching.

In addition, the operation method of the leaf node may include detecting that the fault is eliminated

As shown in FIG.

In this case, the operation method of the leaf node may further include transmitting, to the root node, a Wait to Restore message indicating that the failure is eliminated.

The method of operation of a leaf node further comprises transmitting the return waiting message, initiating a Wait to Restore timer, and, when the return waiting timer expires, transmitting a fifth NR message to the root node As shown in FIG.

At this time, the fifth NR message may be a message that causes the root node to switch from the protection path to the operational path to receive received traffic.

The method of operating a leaf node may further include transmitting and receiving at least one of transmission traffic and reception traffic by switching from the protection path to the operation path when the return waiting timer is completed.

Meanwhile, the root node according to another embodiment of the present invention includes a plurality of leaf nodes transmitting and receiving at least one of a transmission traffic and a reception traffic through each of a plurality of operation paths, A communication unit for receiving a first SF message (Signal Fail on Working Message) indicating that a failure occurs in the first operational path, And a control unit for controlling the communication unit to receive traffic received from the leaf nodes other than the first leaf node through each of the operational paths other than the first operational path.

According to another embodiment of the present invention, there is provided a leaf node comprising: a communication unit for transmitting and receiving at least one of a transmission traffic and a reception traffic through a root node and an operation path; and a communication unit for switching the operation path to a protection path And a control unit for controlling the communication unit to receive received traffic, wherein the communication unit transmits an SF (Signal Fail on Working) message indicating that a failure has occurred to the operation path, A first NR message (No Request message) may be received.

In this case, the communication unit may copy the transmission traffic and simultaneously transmit the transmission traffic through the operation path and the protection path, or may transmit the copy through the protection path.

According to an embodiment of the present invention, the present invention performs point-to-multipoint protection switching for a path for transmitting and receiving a packet in a rooted multipoint connection and a connection experiencing a failure in a failure of a connection node.

The present invention can perform rapid protection switching to an alternative path in the event of a failure of a transmission / reception path in a point-to-multipoint connection network, that is, in a rooted multipoint connection network.

Fig. 1 is a diagram showing an ITU-T G.8031 Ethernet linear protection switching structure.
FIG. 2 shows an example of a network configuration to which leaf-based protection switching is applied in a rooted multi-point connection path.
FIG. 3A shows an example in which a failure occurs in a path from a root node to a leaf node in a network to which a protection switching is applied in a rooted multi-point connection path.
3B is a block diagram of a node, such as a root node or a leaf node, according to one embodiment.
FIGS. 4A and 4B are diagrams illustrating a protection switching process according to an embodiment of the present invention in a 1: 1 retry mode when a failure occurs as shown in FIG. 3A.
FIGS. 5A and 5B are diagrams illustrating a protection switching process according to an embodiment in a non-return mode.

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms including ordinal, such as second, first, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

Various embodiments relate to a rooted multi-point connection protection switch, and may be implemented in a multi-point network, such as OTN, Ethernet, Carrier Ethernet, Ethernet Passive Optical Network (E-PON), Gigabit Passive Optical Network (G-PON), Provider Backbone Bridge Traffic Engineering, MPLS, MPLS-TP, and access points between wireless terminals and access points. Those skilled in the art will readily understand that the scope of the rights under this disclosure is not limited by the communication scheme.

Various embodiments are directed to a network having a point-to-multipoint connection that connects one root node with a plurality of leaf nodes, and performs unicast traffic from the root node to one particular leaf node, Multicast traffic from the root node to multiple leaf nodes in a particular set, broadcast traffic from the root node to all leaf nodes, and unicast traffic from the leaf node to the root load. Purpose logical network.

The above-mentioned networks are referred to as E-Tree (MEF) or rooted multipoint connection (IEEE, ITU-T) in the international standard. Meanwhile, a service composed of the above types of traffic is called an E-Tree service or a rooted multipoint connection service.

The operation path and the protection path according to various embodiments may include a path to be transferred from a source to a destination of a packet in an optical transmission network, an Ethernet network, a packet network, and a packet transmission network, a virtual tunnel, a dedicated network, ), And the like, and may be referred to as a path for the convenience of explanation hereinafter.

The messages referred to in various embodiments may be collectively referred to as information delivery messages used for protection switching purposes.

FIG. 2 shows an example of a network configuration to which leaf-based protection switching is applied in a rooted multi-point connection path according to an embodiment. The Unidirectional Working Tree and the Unidirectional Protection Tree represent unidirectional operation trees and protection trees from the root node to each leaf node (Leaf 1, Leaf 2, ..., Leaf M).

The root node can be connected to a plurality of leaf nodes in a tree form, and can perform data transmission / reception. For example, the root node and the leaf node may send and receive traffic based on either the operation tree or the protection tree.

When a single tree-like operation tree becomes a point-to-multipoint connection, unicast, multicast, and broadcast traffic can be transmitted from the root node to each leaf node. Each node on the tree path can perform data copy for multicast and broadcast communications. And assigns one asymmetric VLAN to the unidirectional point-to-multipoint path of the connected tree form. For protection switching, two trees are required. One is a unidirectional working tree, the other is a unidirectional protection tree, and one asymmetric VLAN is assigned to each tree. In FIG. 2, the asymmetric VLANs allocated to the operation tree and the protection tree are denoted by Wr and Pr, respectively.

In FIG. 2, the unidirectional working path and the unidirectional protection path represent unidirectional operation paths W1, W2, Wm and protection paths P1, P2, and Pm from one leaf node to the root node.

One asymmetric VLAN may be assigned for a point-to-point connection path from one leaf node to the root node. For protection switching, two paths are required for each leaf node, one is a unidirectional working path and the other is a unidirectional protection path, and one asymmetric VLAN is assigned to each path. In a rooted multipoint connection network consisting of one root node and M leaf nodes, all (2 + 2M) asymmetric VLANs are required for protection switching per leaf. In FIG. 2, the VLANs allocated to the operation paths and the protection paths for the M leaf nodes are W1, W2, ... Wm and P1, P2, ... Pm.

As described above, a rooted multipoint connection protection switch composed of asymmetric VLANs manages the state between the point-to-point operation tree (or operating path) and the protection tree (or protection path) between the root node and one leaf node (Per-Leaf) protection switching that performs protection switching.

In the existing point-to-point linear protection scheme, both nodes of the linear protection switch copy the traffic to be transmitted and send it to the operation path and the protection path regardless of the failure, and when there is no obstacle in the operation path, There is a 1: 1 way to send to. In the 1: 1 scheme, if a failure occurs in the operational path, a selective bridge (only a protection path) is used. In case of a failure in the operational path, a broadcast bridge (Broadcast Bridge). In the conventional point-to-point linear protection switching method, both nodes must operate in either 1 + 1 or 1: 1 manner. In addition, both nodes must use selective bridges or broadcast bridges Do not mix two types of bridges.

According to the protection switching method in the point-to-multipoint connection network shown in the various embodiments, if there is no obstacle in the operation tree or operation path, both the root node and the leaf node are transmitted to the operation tree or operation path, The root node copies the traffic and transmits it simultaneously through the operation tree and the protection tree. The leaf node can simultaneously transmit through the operation path and the protection path, or transmit only through the protection path. That is, according to the embodiment, the root node uses the broadcast bridge, but the leaf node can use the selective bridge or the broadcast bridge. That is, according to the embodiment, the root node and the leaf node can mix two kinds of bridges. Due to the operation of transmitting the traffic from the root node to all leaf nodes including the leaf node in the failed state to the operation tree and the protection tree in case of failure, it is necessary to change the protection switching protocol message, Modification of the point linear protection switching operation is necessary.

For protection switching by leaf, an independent and individual message exchange is performed between the root node and the leaf nodes to perform a message exchange between the root node and the specific leaf node and the operation command.

The protection switching structure of a point-to-multipoint network includes per-leaf protection switching and per-tree protection switching. Protection-by-leaf protection transfers only the traffic corresponding to the leaf whose traffic is stopped when a failure occurs in the operation tree of the point-to-multipoint network through the protection tree. On the other hand, protection switching by tree transfers traffic of all leafs through the protection tree at once if the operation tree of the point-to-multipoint network fails.

The leaf-by-leaf protection switch typically has a structure in which there is an individual point-to-point connection between the root node and the leaf nodes, so that there are the same number of point-to-point connections as the total number of leaf nodes. In the case of an Ethernet network, one virtual node (VLAN) for the operational path and one VLAN for the protection path are allocated for protection switching of a point-to-point connection between one leaf node and the root node, In the multi-point network, the operation tree is created with M VLANs as a whole, and the protection tree is formed by another M VLANs, and linear protection switching is applied to each leaf.

In various embodiments, a method of forming asymmetric VLAN and a method of expanding existing point-to-point linear protection switching protocol such as ITU-T G.8031 are proposed for leaf-based protection switching method for a multi-point routed network.

FIG. 3A shows an example in which a failure (SF) occurs in an operation tree from a root node to a leaf node in a network to which leaf-based protection switching is applied according to an embodiment of the present invention in a rooted multi-point connection path. It is assumed that the leaf node 1 (Leaf 1) detects the failure due to the illustrated failure.

3B is a block diagram of a node, such as a root node or a leaf node, according to one embodiment.

As shown in FIG. 3B, the node 300 may include a control unit 310 and a communication unit 320.

The control unit 310 may control the communication unit 320 to perform communication with another node using any one of an operation path and a protection path. The controller 310 may be implemented as an IC chip, a microprocessor, a minicomputer, or the like, and may operate based on the APS protocol including, for example, a bridge / selector or a selector / bridge as described above. The control unit 310 may control the switching process by analyzing the message received from the communication unit 320 and may generate a message required in the switching process. In addition, the control unit 310 may control the communication unit 320 to transmit the generated message to another node.

The communication unit 320 can perform communication with another node. For example, the communication unit 320 may transmit a message input from the control unit 310 to another node, or may output a message received from another node to the control unit 310. The communication unit 320 may include various communication modules such as an antenna, a duplexer / modulator, a frequency processing unit, and a filter unit. The communication unit 320 can perform communication with another node through one of a path of an operation path or a protection path and can perform communication while switching between an operation path and a protection path in a protection switching process.

4A and 4B are diagrams illustrating a protection switching process according to an embodiment of the present invention in a revertive mode of a 1: 1 scheme when a failure occurs as shown in FIG. 3A.

The 1: 1 scheme refers to the way in which traffic is delivered to either the operating tree path or the protection tree path. FIG. 4A shows a procedure of exchanging messages between a leaf node Leaf 1 and a root node that detects a failure, and FIG. 4B shows a procedure of a message exchange between leaf nodes Leaf 2, Leaf M, And a root node (Root), and a procedure of operation according to the message exchange. FIG. 4B is a representative example of a leaf node M as an example of a node having no fault, and message exchanges and operations between other nodes having no fault and the root node are the same.

In FIGS. 4A and 4B, the message exchange is displayed only when a new message having a different value from the previously generated message occurs. When a new message other than the previous message is generated, three messages are prepared The message transmission rule of the existing linear protection switching system which transmits the message within 5 msec after the transmission within 3.3 msec can be followed. On the other hand, the above-mentioned time interval is merely an example, and it is easily understood by those skilled in the art that the time interval is changeable.

As an example, there are r / b information (r, b) related to the main status information and the Bridge / Selector information, and r / b is the operation / And information for selecting a traffic according to the protection state of each node by transmitting a Bridge and a Selector selection information to the protection route.

r is the Requested Signal, which informs the second node, which is the message sending node, of the message to be sent through the protection path. If the value is null signal (0), it sends the traffic to the protection path (1), it is requested to send the traffic to the protection path. When the second node sends a message to the first node, the second node transmits the traffic specified by the r value

B is a bridged signal that informs traffic that the first node, which is a message transmitting node, transmits traffic to the protection path. If the value is a null signal (0), it indicates that traffic is not sent to the protection path. Traffic signal (1) indicates that traffic is being sent to the protected path.

The main status information exchanged through the protection switching message includes a Lockout of Protection (LO) state in which traffic is transmitted and received only in the operational path, a Signal Failed Protection (SF-P) status in which the failure is detected in the protection path, (FS) state that forcibly transmits and receives traffic to the protection path, a signal failure on working state that recognizes a failure in the operation path, an SD (signal degrade) state in which the signal is attenuated on the path, (MS) state in which a manual transfer request is acknowledged, a Wait to Restore (WTR) state in which a timer is operated for a certain period of time until recovery is recovered, an EXER (Exercise) state in a test, and an RR Reverse request status), a Do Not Revert (DNR) state for transmitting / receiving traffic to / from a protected path by non-return, and an NR (No Request) without a specific request or command.

In this specification, a protection-switching message may be in the form of NR (r, b), NR r, b, SF r, b, SF r, b, WTR . ≪ / RTI >

Referring to FIGS. 4A and 4B, the per-leaf protection switching according to the embodiment of the present invention can perform the protection operation for the entire tree path when a failure occurs in the tree path as follows.

The root node and the leaf nodes Leaf 1, ..., and Leaf M are in a normal state and transmits and receives a NR (r / b = null) message (NR 0,0) (S400). NR is the no-request state in which the current node is in the No-Request state, that is, there is no valid command or request to the current node. Bridges and selectors are choosing the operating tree path.

The leaf node 1 recognizing the failure may transmit a SF (r / b = normal traffic signal) message to the root node (S410). The SF message may be mixed with SF (1,1), SF 1,1, a message requesting switching to a protected path, and the like. SF may indicate a state in which the current node is aware of a signal failure state, that is, an operational path failure. SF message and the traffic receiver (Selector) can select the protection tree.

The traffic sender can send the traffic only to the protected path, or copy the traffic and send it simultaneously to the operating path and the protection path. Here, the method of copying the traffic and sending it to both paths is a method of transmitting source address learning in the Ethernet packet transmission method when the bandwidth of the link connected to the leaf node is less than the bandwidth of the link connected to the root node in the point- Can be used to avoid congestion of the network due to failure to do so. In the case where there is no congestion of the network even if the source address learning is not performed because the bandwidth of the link connected to the leaf node is equal to the bandwidth connected to the root node, the traffic can be transmitted only to the protection path.

Referring to FIG. 4B, the leaf node M that has not recognized the failure has no change in status.

Referring again to FIG. 4A, when the root node receives a SF (r / b = normal traffic signal) message from the failed leaf node 1, the root node copies all the traffic to the leaf nodes, And it may be that the broadcast bridge chooses both an operation tree and a protection tree.

The root node transmits a NR (r / b = normal traffic signal) message (may be mixed with NR (1,1), NR 1,1, etc.) to the leaf node 1 (S420) Select the path. The root node transmits NR (r = null signal, b = normal traffic signal) message (NR (0,1), NR 0,1, etc.) to the leaf node M in which no failure has occurred (S430) The selector that receives the traffic maintains the operating path. That is, the root node can switch only the path to the failed leaf node from the operational path to the protection path. The root node can maintain traffic transmissions to and from the leaf node that has not failed.

When the failed leaf node 1 receives the NR (r / b = normal traffic signal) message from the root node, it verifies that the protection switching process is completed. Thereafter, leaf node 1 can send and receive NR messages again with the root node.

When the leaf node M receives the NR (0,1) message from the root node, the leaf node M recognizes that the root node is sending the traffic to the operation tree and the protection tree. The leaf node M sends the traffic to the operation path, Copy the traffic and simultaneously transmit it to the operational path and the protection path. Here, the method of copying the traffic and sending it to both paths is a method of transmitting source address learning in the Ethernet packet transmission method when the bandwidth of the link connected to the leaf node is less than the bandwidth of the link connected to the root node in the point- Can be used to avoid congestion of the network due to failure to do so. If the network bandwidth is not equal to the bandwidth of the link connected to the leaf node and the source address learning is not performed, the traffic can be transmitted only to the operation path when the network is not congested.

If leaf nodes that do not have a failure send only traffic to the operational path, send NR (0,0) message to the root node, and when copying the traffic to the operational path and protection path, send NR (0,1) (S440).

On the other hand, when receiving NR (0,1) message, the selector that receives the traffic from the leaf node where the failure does not occur maintains the operation tree.

In FIGS. 4A and 4B, if the failure is eliminated in the leaf node Leaf 1 that detected the failure, the following operation is performed.

The leaf node 1 recognizing the failure clearance state (Clear SF) enters a Wait to Restore (WTR) state for return and drives the WTR timer and transmits a r / b = normal traffic signal (WTR) message , 1), WTR 1,1 message, etc.) (S450).

When the WTR status is in the return mode, when the path is recovered from the protection path to the operation path in the process of recovering after the failure occurs in the operation path, the system waits for a certain period of time until recovery. A wait timer (WTR Timer) is in operation.

When there is no further failure or request and the WTR timer expires, leaf node 1 enters the NR state and transmits a NR (r / b = null signal) message (NR 0,0) (S460) Select the tree.

The root node receiving the NR (0,0) message receives the traffic from the operational path of the leaf node 1 and transmits the NR (0,0) message to the leaf node 1 (S470).

In addition, if there is no failure or operator request on the operation tree and operation path for all the leaf nodes in the network, the root node will only bridge the traffic to the operation tree and send an NR (0,0) message to all the leaf nodes (S480).

The leaf node receiving the NR (0, 0) message receives traffic from the operation tree and transmits traffic only to the operational path (S490).

At this point, the process of returning traffic to the operation tree and the operational path is completed.

An embodiment of the non-return mode will be described with reference to Figs. 5A and 5B. Per-Leaf protection switching according to an exemplary embodiment may be performed in the same manner as in FIGS. 4A and 4B when a failure occurs in the tree path.

Before the failure occurs, the root node and the leaf nodes Leaf 1, ..., and Leaf M are in a normal state and transmit and receive the NR (r / b = null) message NR 0,0 (S500). NR is the no-request state in which the current node is in the No-Request state, that is, there is no valid command or request to the current node. Bridges and selectors are choosing the operating tree path.

The leaf node 1 recognizing the failure may transmit a SF (r / b = normal traffic signal) message to the root node (S510). The SF message may be mixed with SF (1,1), SF 1,1, a message requesting switching to a protected path, and the like. SF may indicate a state in which the current node is aware of a signal failure state, that is, an operational path failure. SF message and the traffic receiver (Selector) can select the protection tree.

The traffic sender can send the traffic only to the protected path, or copy the traffic and send it simultaneously to the operating path and the protection path. Here, the method of copying the traffic and sending it to both paths is a method of transmitting source address learning in the Ethernet packet transmission method when the bandwidth of the link connected to the leaf node is less than the bandwidth of the link connected to the root node in the point- Can be used to avoid congestion of the network due to failure to do so. In the case where there is no congestion of the network even if the source address learning is not performed because the bandwidth of the link connected to the leaf node is equal to the bandwidth connected to the root node, the traffic can be transmitted only to the protection path.

Referring to FIG. 5B, the leaf node M, which has not recognized the failure, has no state change.

Referring again to FIG. 5A, when the root node receives a SF (r / b = normal traffic signal) message from the failed leaf node 1, the root node copies all the traffic to the leaf nodes, And it may be that the broadcast bridge chooses both an operation tree and a protection tree.

The root node transmits a NR (r / b = normal traffic signal) message (NR (1,1), NR 1,1, etc.) to the leaf node 1 (S520) Select the path. The root node transmits NR (r = null signal, b = normal traffic signal) message (may be mixed with NR (0,1), NR 0,1, etc.) to the leaf node M in which no failure has occurred (S530) The selector that receives the traffic maintains the operating path. That is, the root node can switch only the path to the failed leaf node from the operational path to the protection path. The root node can maintain traffic transmissions to and from the leaf node that has not failed.

When the failed leaf node 1 receives the NR (r / b = normal traffic signal) message from the root node, it verifies that the protection switching process is completed. Thereafter, leaf node 1 can send and receive NR messages again with the root node.

When the leaf node M receives the NR (0,1) message from the root node, the leaf node M recognizes that the root node is sending the traffic to the operation tree and the protection tree. The leaf node M sends the traffic to the operation path, Copy the traffic and simultaneously transmit it to the operational path and the protection path. Here, the method of copying the traffic and sending it to both paths is a method of transmitting source address learning in the Ethernet packet transmission method when the bandwidth of the link connected to the leaf node is less than the bandwidth of the link connected to the root node in the point- Can be used to avoid congestion of the network due to failure to do so. If the network bandwidth is not equal to the bandwidth of the link connected to the leaf node and the source address learning is not performed, the traffic can be transmitted only to the operation path when the network is not congested.

If leaf nodes that do not have a failure send only traffic to the operational path, send NR (0,0) message to the root node, and when copying the traffic to the operational path and protection path, send NR (0,1) (S540).

On the other hand, when receiving NR (0,1) message, the selector that receives the traffic from the leaf node where the failure does not occur maintains the operation tree.

5A and 5B, if the failure is eliminated in the leaf node Leaf 1, the operation is as follows, and the operation is different from the case of the return mode using the WTR timer.

The leaf node 1 recognizing the failure clearance state (Clear SF) enters the Do not Revert (DNR) state indicating that the leaf node 1 does not return and transmits a DNR (r / b = normal traffic signal) message (DNR , DNR 1,1 message, etc.) (S550).

The DNR state indicates that the path has not returned from the protection path to the operational path after the failure has been resolved after the failure has occurred in the operational path in the non-return mode. This is because, unlike the automatic return using the WTR timer, (For example, when the amount of traffic is small), it is possible to return the path to the operating path.

The root node receiving the DNR (1,1) message converts the status to DNR without changing the selector and the bridge position, sends the DNR (1,1) message to the leaf node 1, and DNR (0, 1) message (S560).

Upon receiving the DNR (0,1) message, the leaf node M changes its status to DNR without changing the selector and bridge positions, and transmits a DNR (0,0) or DNR (0,1) message (S570).

The traffic and messages then remain in the same state unless there is a separate fault or operator command.

If an operator removes this non-return status and makes it in the normal state, it may use the operator command provided by the existing linear protection switch (for example, the Clear command after the Manual Switch to Working command).

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (20)

A plurality of leaf nodes transmitting and receiving at least one of a transmission traffic and a reception traffic through each of a plurality of operation routes, a first leaf node, a first leaf node, and a second leaf node, Receiving a SF message (Signal Fail on Working message);
Transferring the first operational path to a first protection path to receive traffic received from the first leaf node; And
Receiving received traffic from each of the leaf nodes other than the first leaf node through each of the operational paths other than the first operational path;
Gt; a < / RTI > root node. The method according to claim 1,
Transmitting a first NR message (No Request message) to each of the plurality of leaf nodes; And
Receiving a second NR message from each of the plurality of leaf nodes
Gt; a < / RTI > root node. The method according to claim 1,
Receiving the SF message and transmitting the same through the first operation path and the first protection path by copying the transmission traffic
Further comprising the step of: The method according to claim 1,
Transmitting to the first leaf node a third NR message indicating that the transfer is completed
Further comprising the step of: 5. The method of claim 4,
Transmitting a fourth NR message to the leaf node other than the first leaf node to maintain transmission and reception of transmission traffic and reception traffic to the operational path;
Further comprising the step of: The method according to claim 1,
Receiving a return-waiting message indicating that the fault has been removed from the first leaf node
Further comprising the step of: The method according to claim 6,
Determining that the fault at the first leaf node is eliminated; And
Receiving a fifth NR message indicating that the return waiting timer from the first leaf node is to be terminated
Further comprising the step of: 8. The method of claim 7,
When receiving the fifth NR message, switching from the first protection path to the first operation path and receiving reception traffic
Further comprising the step of: Transmitting and receiving at least one of a transmission traffic and a reception traffic through a root node and an operation path;
Detecting that a failure has occurred in the operation path;
Receiving the received traffic by switching the operational path to a protection path;
Transmitting a SF message (Signal Fail on Working Message) indicating that a failure occurs in the operation path; And
Receiving a first NR message (No Request message) indicating that the root node has switched
Gt; a < / RTI > leaf node. 10. The method of claim 9,
Transmitting a second NR message to the root node; And
Receiving a third NR message from the root node
Further comprising the step of: 10. The method of claim 9,
Copying the transmission traffic and simultaneously transmitting through the operation path and the protection path or transmitting the transmission traffic through the protection path
Further comprising the step of: 10. The method of claim 9,
Transmitting the fourth NR message to the root node after the switching;
Further comprising the step of: 10. The method of claim 9,
Detecting that the fault has been resolved
Further comprising the step of: 14. The method of claim 13,
And transmitting a return waiting message indicating that the fault has been resolved to the root node
Further comprising the step of: 15. The method of claim 14,
Transmitting the return waiting message and initiating a return waiting timer; And
And when the return waiting timer expires, transmitting a fifth NR message to the root node
Further comprising the step of: 16. The method of claim 15,
Wherein the fifth NR message is a message that causes the root node to switch from the protection path to the operational path to receive received traffic. 16. The method of claim 15,
Transmitting and receiving at least one of transmission traffic and reception traffic by switching from the protection path to the operational path when the return waiting timer is terminated
Further comprising the step of: A plurality of leaf nodes transmitting and receiving at least one of a transmission traffic and a reception traffic through each of a plurality of operation routes, a first leaf node, a first leaf node, and a second leaf node, A communication unit receiving the SF message (Signal Fail on Working message); And
Receiving the received traffic from the first leaf node, receiving from the leaf node other than the first leaf node through each of the operating paths other than the first operating path, receiving the received traffic from the first leaf node, A control unit for controlling the communication unit
Root node. A communication unit for transmitting and receiving at least one of a transmission traffic and a reception traffic through a root node and an operation path; And
And a control unit for controlling the communication unit to receive the received traffic by switching the operation path to the protection path when it is detected that the failure occurs in the operation path,
Lt; / RTI >
The communication unit transmits a SF (Message Fail on Working) message indicating that a failure has occurred to the operation path, and transmits a first NR message (No Request message) indicating that the root node has switched . 20. The method of claim 19,
Wherein the communication unit transmits the transmission traffic through the protection path by simultaneously transmitting the traffic through the operation path and the protection path by copying the transmission traffic.

Images