CN111431786A

CN111431786A - Steering mode ring protection method of Flexe ring network in SPN

Info

Publication number: CN111431786A
Application number: CN202010186389.9A
Authority: CN
Inventors: 范春泉
Original assignee: Huaxin Saimu Chengdu Technology Co ltd
Current assignee: Huaxin Saimu Chengdu Technology Co ltd
Priority date: 2020-03-17
Filing date: 2020-03-17
Publication date: 2020-07-17
Anticipated expiration: 2040-03-17
Also published as: CN111431786B

Abstract

The invention discloses a ring protection method of a Flexe ring network in an SPN, wherein a working channel and a protection channel are divided by taking a Flexe time slot as a unit in the Flexe ring network, when a switching condition is met, a node which designates or detects a fault is commanded to be used as a guide node to send guide information to a non-fault section on a ring, the guide information is carried in a self-defined protection switching protocol message and a Flexe Call, contains influenced service clients to be protected and a protection channel time slot occupied by the services to be protected, and accordingly, the node turns the guide information of the service of the ring to be protected to indicate the corresponding protection channel time slot, a lower ring service is received from the corresponding protection channel time slot, and the guide information is used as an intermediate node to transmit the time slot occupied by the switching service on a Flexe time slot cross-through protection channel.

Description

Steering mode ring protection method of Flexe ring network in SPN

Technical Field

The invention relates to the field of communication, in particular to a steering mode ring protection method of a Flexe ring network in SPN.

Background

In the white paper of SPN technology released by china mobile, a layered Network model of SPN is defined, including ST L, SC L, and SP L0, where ST L and SC L mainly correspond to OSI Network model L layer, SPN introduces OIF-defined FlexE at L1 layer and extends its application, on the basis of introducing OIF FlexE in ST L, SC L layer is creatively added and proposes SE intersection (SlicingEthernet intersection) and SPN Channel therein, so as to extend from point-to-point application to Network level application of end-to-end Network element SE intersection is the basis of SPN Channel, including intersection of FlexE slots transmitting 66B block code streams and corresponding cooperation of FlexE call, SPN Channel is the Network level application composed of each node on the path and each node on the path, in other words, the sliced Packet Network is composed of several flexel overhead slots, and several SP 5G overhead slots, and the SP 12G overhead Network model includes a number of all existing links spanning OSI Network layers, namely, including escl 3 and 5G overhead Network paths, and SP 462 and SP 12G Network overhead Network layers.

Currently, related protection technologies of the SPN L1 layer mainly include FlexE PHY bonding and 1:1/1+1APS protection of the SC L layer, where the PHY bonding provides a certain degree of protection for a FlexE group link between two adjacent devices, and the 1:1/1+1APS of the SC L layer performs end-to-end linear protection for the SPN channel.

In a transport network, a ring is a commonly deployed network topology. Two main protection modes in the ring protection are wrap (encircling) and Steering (Steering). The surrounding mode is that the service is surrounded to the opposite direction at the fault adjacent node to avoid the fault section. The steering mode is to directly steer the service at the node of the service ring-in and transmit the service from the protection channel to the node of the service ring-down. Among them, the steering system is also called a reducing system because a transmission path is shorter.

For example, as shown in fig. 1, assume that traffic enters from a and normally travels on the working channel B, C to D. (only one direction is used for example, the principle of the other direction is the same, the working channel is in the clockwise direction in the drawing, and the protection channel is in the counterclockwise direction in the drawing.)

In the ring-around mode, when B, C fails (for example, optical fiber is broken) to cause ring protection switching, traffic is bridged and surrounded to a protection channel at a node B after going from a to B, and is transmitted to a node C through a node B-a-F-E-D-C, and is further surrounded to a working channel at the node C, and is transmitted to a node D, and then is looped from the node D, and a transmission path of the traffic sequentially passes through the nodes a-B-a-F-E-D-C-D. After arriving at a network element of a head-end node from a working channel, the service is bridged to a protection channel and is transmitted from the opposite direction; and after reaching the end node network element, the network element is switched back to the working channel and finally transmitted to the destination node network element from the working channel.

In the switching mode, when B, C has fault to cause ring protection switching, the traffic is switched at node A, and is bridged to the protection channel, and is transmitted to the ring below node D via node F and node E. The traffic is transmitted via nodes a-F-E-D as shown in fig. 1. The same traffic and fault conditions, the transmission path in the steering mode is more direct than the transmission path in the surround mode. The prior art lacks a turning mode ring protection technology related to a Flexe ring network in SPN.

Disclosure of Invention

The invention aims to provide a steering mode ring protection method of a Flexe ring network in an SPN (shortest Path bridging) to further perfect and enrich the protection mechanism of the SPN and improve the reliability of the SPN bearing service.

The invention works in L1 layer of OSI model, the ring is composed of multiple sections of Flexe group links, the number of Flexe time slots and bandwidth of each section of link in one ring are the same.

Specifically, the invention is realized by the following technical scheme:

in the FlexE ring, a working channel and a protection channel are divided by taking a FlexE time slot as a unit, and the FlexE time slots contained in the working channel and the protection channel are equal in number and opposite in direction; and, predefining a one-to-one correspondence between the time slots of one working channel and the time slots of the protection channel.

And when the failure in the Flexe ring network meets the switching condition, the node which detects the failure is used as a guide node to send guide information, and the sending direction is the direction far away from the failure. The guiding information contains the service client number which is interrupted and transmitted by the fault and the protection channel time slot which is occupied for protecting the interrupted service. The above-mentioned steering information is transmitted on the ring until the adjacent failed node at the other end of the failure.

According to the guiding information, if a client number of the service of the ring-in on a certain node belongs to the client number of the service indicated in the guiding information, the service is diverted and transmitted in the time slot of the protection channel corresponding to the client number of the service indicated by the guiding information; and the Flexe Call changing the link is consistent with the transmission of protected services in the protection channel.

If a node has a client number of the service of the lower ring belonging to the client number of the service indicated in the guidance information and the service has been diverted to the protection channel, the service is received from the corresponding time slot corresponding to the client number of the service in the protection channel.

The intermediate node crosses and penetrates through the protection channel time slot which is needed to be occupied by the steering service transmitted on the protection channel by using a Flexe time slot; and the Flexe Call changing the link is consistent with the transmission of protected services in the protection channel.

Further, not only may a failure cause protection switching, but an external command may also be a condition for causing protection switching. In the protection switching initiated by the external command, the node determined by the command is used as a guide node.

The protection switching process is supported by the protection switching protocol defined by the invention, for the reason of the fact that the protection switching protocol is APS protocol for short and the protocol message is APS message for short in the invention, the protection switching protocol uses the APS message and FlexeCalendar thereof to exchange necessary information between nodes so as to coordinate the protection switching process. The above-mentioned navigation information is included in the APS message and the FlexE call.

Furthermore, in order to realize the invention more flexibly, each actual Flexe time slot number (called as physical Flexe time slot number in the invention) in each segment of Flexe group link corresponds to a logical time slot number to form a one-to-one correspondence, and the size sequence of the logical time slot numbers is kept consistent with the arrangement sequence of the corresponding physical Flexe time slot numbers; the one-to-one correspondence between the physical Flexe time slot numbers and the logical time slot numbers is predetermined in the stage of protection group creation or configuration and is independent on each segment of Flexegroup link; the division of the working channel time slot and the protection channel time slot of the ring is carried out according to the logical time slot, and the Flexe time slot involved in the APS protocol is represented by a logical time slot number.

The technical scheme provided by the application at least has the following technical effects or advantages:

the protection is directed to a Flexe layer, has lower hierarchy and higher efficiency compared with the protection of SPN Channel APS, L2 and L3 layers, and can be used cooperatively.

The method of the invention realizes the ring protection in a near reading mode, and the transmission path of the protected service in the protection channel is shorter.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention;

fig. 1 is a schematic diagram of protection switching in a steering manner in ring protection;

fig. 2 is a schematic diagram of an example service in embodiment 1 of the present application;

fig. 3 is a schematic diagram of a service path after protection switching in embodiment 1 of the present application;

fig. 4 is a schematic diagram of node state transition in the protection switching process in the present application.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflicting with each other.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described and thus the scope of the present invention is not limited by the specific embodiments disclosed below.

The invention works in L1 layer of OSI model, the ring is formed by multiple sections of Flexe group links, the number of Flexe time slots and bandwidth of each section of link in one ring are the same, a ring protection group is created on the ring.

In the FlexE ring network, the FlexE time slots are used as units to divide a working channel and a protection channel, and the FlexE time slots contained in the working channel and the protection channel are equal in number and opposite in direction. The working channel bears the ordinary protected service; the protection channel is reserved for protecting the working channel. (wherein: besides, a part of bandwidth can be selected to be reserved on the ring as a non-protection service channel, which is not related to the protection group, and the carried service is not affected by protection or protection switching).

As shown in fig. 2, the counter-clockwise protection channel provides protection for the clockwise working channel, while the clockwise protection channel protects the counter-clockwise working channel.

Since the partitioning is based on the FlexE slots, the ring protection scheme of the present invention can be applied even if the link FlexE group constituting the ring has only one PHY. While PHY bonding based link protection necessarily requires multiple PHYs.

When there is no protection switching, the protection channel can also carry extra service, but once the protection switching occurs, the related protection channel will be preempted by normal service, and the extra service is discarded. And whether to configure additional services on the protection channel can be selected during specific application.

A protection group maintains a one-to-one correspondence between the timeslots of one working channel and the timeslots of a protection channel, which may be user configuration or system default definition. When protection switching occurs, the predefined timeslot correspondence is used to determine which timeslots in the protection channel are used to transmit the protected service.

After a failure occurs on the ring and protection switching is caused, the protected service originally transmitted through the working channel of the failure section is transmitted in the protection channel in the opposite direction. Specifically, each protected traffic is diverted at its ring-in node, and transmitted in the opposite direction by a specific timeslot sent by its ring-in node to the protection channel. These time slots of the protection channel are referred to herein as protection time slots for convenience. The protection time slot of the service is the working channel time slot used by the service to enter the next neighbor node of the fault section from the fault section originally, and the protection channel time slot corresponds to the predefined one-to-one correspondence relationship between the working channel time slot and the protection channel time slot. When the protected service is transmitted in the protection channel, the protected service passes through the intermediate node to the node of the service lower ring, and the protection time slots on all sections of FlexeE Group links are the same. For convenience, the next neighbor node of the fault section on the working channel is called a guidance node in the present invention (for it sends information to other nodes to guide switching in the protection switching process, see the description of the protection switching protocol section specifically).

The protection switching can also be triggered by a command issued by the management and control plane, which is only different in triggering conditions, and the guidance node of the protection switching is determined by the switching command rather than the failure, and the protection principle is the same as that of the failure triggering. The protection time slot of the protected service between the ring-entering node and the lower ring node is the working channel time slot originally used by the protected service entering the guide node, and the corresponding protection channel time slot is according to the predefined one-to-one correspondence between the working channel time slot and the protection channel time slot.

Example 1:

for example, as shown in fig. 2, the ring is a ring composed of FlexE group links of 100G single FlexE instance; the first 10 time slots are divided into working channels and the last 10 time slots are divided into protection channels, and the one-to-one correspondence relationship between the predefined protection channel time slots and the working channel time slots is as follows: the protection channel corresponds to the time slot number which is the time slot number of the working channel plus 10; three services A-B, A-D, B-C are arranged on the ring. The service client number of A-B is 1, the normal path passes through the node A-B, and the time slot occupation configuration of the link section is shown in Table 1.

TABLE 1

The number of the service client of A-D is 2, the normal path passes through the nodes A-B-C-D, and the configuration of each segment of time slot is shown in Table 2.

TABLE 2

The traffic client number of B-C is 3, the normal path goes through node B-C, and the slot configuration is shown in table 3.

TABLE 3

Client#	B-C segment time slot
		3	3

If the link of B-C fails (e.g., is broken), which results in protection switching, as shown in fig. 3, the protection timeslot occupied by the protection service is the timeslot (13, 14, 15, 16) of the protection channel corresponding to the timeslot (3, 4, 5, 6) from the original working channel transmitting the service to the guidance node C, and the path of each service after switching and the protection timeslot occupied by each link are as follows:

the A-B service is not affected by the fault, and the original normal path and time slot occupation are kept unchanged;

the a-D traffic will be diverted from node a to the D node down-ring via F-E, and the FlexE time slots occupied by the links on the path are shown in table 4.

TABLE 4

The B-C traffic will be diverted from the node B to the lower ring of the node C via a-F-E-D, and the FlexE time slots occupied by the links on the path are shown in table 5.

TABLE 5

Client#	B-A segment time slot	A-F segment time slot	F-E segment time slot	E-D segment time slot	D-C segment time slot
						3	13	13	13	13	13

The protection switching process is supported by a protection switching protocol. The protection switching protocol uses the self-defined APS message and FlexeCalendar to exchange necessary information between nodes so as to coordinate the protection switching process.

The APS message includes the following contents:

APS condition of highest level switching on ring

APS condition node, the node on which the highest level switching condition is located on the ring

-APS state: protection switching state

-potential protection slots: available guard channel time slot

-used protection slots: guard channel time slot used

-target node: APS target node

Where the highest level condition (APS condition) includes a fault and a command, the priority levels are shown in table 6 in order from high to low.

TABLE 6

	Shorthand writing	Note
			Locking protection	LP	Lockout of protection
Forced switching	FS	Force switch
			Signal failure	SF	Signal Failure
Degradation of signal	SD	Signal Degrade
			Manual switching	MS	Manual Switch
Waiting for recovery	WTR	Wait to restore
			Without faults or commands	NC	No condition

The reported fault is a fault detected along the message transmission direction, that is, the node (APS condition node) of the highest level condition in the ring in the message is the adjacent downstream node of the fault. For example, in the ring shown in fig. 2, if there is no other condition, if the optical fiber between B and C is cut off, the highest level condition in the APS packet ring sent by the node C in the clockwise direction is a signal failure, and the node where the highest level condition in the ring is located is the node C itself; after receiving the APS message, the node D sends an APS message to the node E, wherein the highest level condition in the APS message is signal failure, and the node in which the highest level condition in the APS message is located is the node C; the rest nodes are processed in the same way.

If the protection group has configured WTR time, after the fault disappears, the highest level condition of the node is not directly connected to NC (no fault or command), but is changed into WTR, and a WTR timer is started, and is changed into NC after the WTR timer expires. Once a new fault is detected in the process, the new condition level is changed, and the WTR timer is stopped.

L P (L ockout of protection) is a special external command from the network management system, under which protection switching is not performed, even if there is a fault affecting the traffic transmission, other commands or fault conditions (FS, SF, SD, MS) may cause protection switching.

The protection Switching state (APS state) includes a Switching state, a bridge state and a Selected state flag, where the Switching state indicates that protection Switching is in progress, the bridge state indicates that traffic has been diverted to a protection channel, and the Selected state indicates that traffic has been switched to the protection channel to receive protected traffic.

The Potential protection slots are protection channel time slots determined by the guide node and possibly bearing the affected protected services, and are used as a part of the guide information to guide the node receiving the APS message to divert the relevant protected services to the protection time slots for transmission through the protection channels.

Used protection slots represent the protection channel time slots actually occupied, and are sent to the downstream neighbor nodes by the upstream nodes on the protection channel, which represent that the protection time slots indicated by the field are occupied on the section of link.

The target node (target node) is contained in an APS message sent by the leader node; in the protection switching caused by the fault, the field is the neighbor node of the other end of the highest level fault considered by the guide node, namely the upstream neighbor node of the guide node in the protection group Ring Map; in command switching, the field is determined by a command, and the default is also the upstream neighbor node of the guide node; in other scenarios this field is meaningless.

The APS message is generated by each node network element of the protection ring and is sent to the adjacent node.

APS message transmission has periodicity, and has a fast period and a slow period. Once the highest level condition of the node changes, the node becomes the node of the highest level condition, or the node of the highest level condition of the receiving ring changes, a new APS message is generated immediately, a certain amount of APS messages are sent in a fast period, and then the APS messages are converted back to a slow period.

According to the received APS message and the fault or received command detected by the node, each node judges the highest level condition on the ring and the node where the highest level condition is located, and issues the highest level condition in the APS message sent by the node. For convenience, a failure detected by a node or an external command received is referred to as the node condition. The deduction logic of the highest level condition on the judgment ring and the node where the highest level condition is located is as follows: if the condition level of the node is lower than (known by the node according to the received APS message) the highest level condition (APScondition) on the ring, and the node where the highest level condition (APS condition node) on the ring is known not to be the node, keeping the original known highest level condition on the ring and the node where the highest level condition is located; otherwise, judging that the highest level condition (APS condition) on the ring is the condition of the node, and judging that the node (APS condition node) where the highest level condition on the ring is located is the node.

The judgment is only the judgment of the node according to the known information and the condition of the node, and is not necessarily the actual situation of the ring; however, as each node continuously propagates APS messages, each node will know exactly the highest level condition within its reach and the node where it is located after stabilization.

Based on the highest level condition and the judgment of the node where the highest level condition is located, the APS protocol starts the protection switching process when the protection switching condition is satisfied. The APS messages of the same node in different directions on the ring carry the protection switching conditions, states and other information in different directions. In the protection switching process for a fault in one direction, information needs to be exchanged between nodes except for a fault section through APS messages in two directions. To describe the protocol more specifically, the direction from the leading node to the target node away from the failure is labeled as direction a, and the other direction is labeled as direction G. Or more generally speaking, the direction in which the direction switch condition (including a fault or an external command) is communicated is denoted as the a direction, and the opposite direction is denoted as the G direction. For example, as in example 1, the A direction is the direction of node C- > D- > E- > F- > A- > B, and the G direction is the direction of node B- > A- > F- > E- > D- > C.

Meanwhile, the direction a is also the normal protected service transmission direction, i.e. the working channel transmission direction, and the direction G is the corresponding protection channel transmission direction.

Obviously, the a direction/G direction is for one direction switching condition or traffic transmission. For example, for a bidirectional failure, the a direction of the APS message of the protection switching protocol caused by a failure in one direction is the G direction of the APS message of the protection switching protocol caused by a failure in the other direction, and vice versa.

If the node judges that the highest level condition is not L P or NC and the node is the node where the highest level condition is located, it will immediately generate and send a new APS message (A direction), and besides updating APS condition and APScondition node, it will also take on the role of guide node, in the A direction APS message sent by it, the potential protection slots are the time slot of the protection channel corresponding to the time slot of the original working channel transmission service to the node, the Switching position of APS state, in the Flexe overhead, the client number of each time slot corresponding to the potential protection slots in the Standby call is filled with the client number corresponding to the working channel time slot of the node, and after confirming that the role of the guide node is unchanged in a certain number of fast periods, it will suppress the extra service.

If the node receives the message (a direction message) of the APS state Switching setting and determines that the node is not the node where the ring highest level is located, the node keeps the potential protection slots, APS state and target node to continue transmitting the APS message and Standby call until the target node indicated by the APS message. If the nodes continuously receive a certain number of APS messages in the direction, the APS messages and the APS condition nodes are consistent, Flexe related to time slots indicated by the potential protection slots in the APS messages is cancelled in a cross mode, and extra services are suppressed.

If a node continuously receives APS messages APS condition and APS condition node of a certain number of APS state Switching positions and the target node indicated by the messages is the node, if the node has a service which is the same as the client number of some time slots indicated by the corresponding potential protection slots in the received Flexe status calendar (indicating that the service corresponding to the client numbers needs protection), the service of the client number is diverted and sent to the time slot corresponding to the client number in the potential protection slots, and the Flexecalenar in the direction is correspondingly changed; and, no matter whether the node itself has the traffic to be diverted to the protection channel for protection, the node will immediately send the APS message in the opposite direction (i.e. G direction) and the transmission cycle of the APS message in the opposite direction (i.e. G direction) will be switched to the fast cycle (if the transmission cycle of the APS message in G direction is not the fast cycle), the APSstate bridge in the APS message in the opposite direction (G direction) is set, and if the traffic is diverted, its used protection slots include those protection slots that the traffic is diverted to occupy.

In another case, the target node indicated by the APS packet (a-direction packet) received by the node from the APS state Switching is not the local node but a downstream node in the APS packet direction, but the node does not receive the expected APS packet from the opposite direction (i.e., G direction) for a certain number of fast periods, and determines that the node is a node close to the failure, and executes the operation of the target node described above.

In the opposite direction, if the node receives the packet with the APS state bridged set (G-direction packet), then:

if the ring-entering service on the node is the same as the previously received client numbers of some time slots indicated by corresponding potential protection slots in the standby calendar (indicating that the services corresponding to the client numbers need protection), the service of the client number is diverted and sent to the time slot corresponding to the client number in the potential protection slots;

if the node has a lower ring service which is the same as the previously received client number of some time slots indicated by corresponding potential protection slots in the standby calendar, and in the used protection slots indicated by the received APS state bridged set message (G direction message), receiving the service lower ring from the corresponding protection slot of the service client number;

except the lower ring service, the node carries out Flexe intersection to pass through other protection time slots indicated by the user protection slots in the received APS state bridged set message in the G direction, and the number of the intersected input time slot is consistent with that of the output time slot;

the protection time slots to be actually occupied include the protection channel time slot occupied by the traffic diverted by the node, and the protection channel time slot occupied by the traffic diverted at the upstream node and continuously transmitted to the downstream node through the node on the protection channel; that is, the protection channel timeslot + occupied by the service diverted by the node + used protection slots in the APS state bridged set message (G-direction message) is received to remove the portion occupied by the services of the ring below the node.

The node immediately sends an APS message in the opposite direction (G direction) and converts the APS message sending period in the opposite direction (G direction) into a fast period, and the APS state bridged set and used protection slots in the APS message in the opposite direction (G direction) include the protection slots occupied by the local node forwarding service and the upstream node forwarding service continuing to transmit through the local node;

correspondingly changing the Flexe callback of the direction, and filling the client number of each time slot of the user protection slots corresponding to the client number of each time slot of the user protection slots in the transmission direction Flex callback of the protection channel.

After the node receives the packet with the APS state bridged set in the G direction and processes the packet as above, the node sends an APS state selected set in the APS packet in the other direction (direction a).

The node receives APS messages, the highest level condition (APS condition) of the ring is changed into NC, and the APS messages of a certain number of NC are continuously received to confirm the no-protection switching condition of the ring. After the original guide node continuously receives a certain number of NC APS messages to confirm that no protection switching condition exists on the ring, the original guide node does not select and receive the protected service from the protection channel, the service is selected and received from the normal working channel time slot, APS message APS state selected state clearing and potential protection slots clearing are sent in the same direction (direction A) of the ring, but the APS state switching in the APS message is still set at the moment. After the nodes in the protection state between the other original guide nodes and the fault adjacent nodes or target nodes determined by the switching command receive the APS messages in sequence, the protected service of the node entering the ring is not diverted any more and is sent to the normal time slot of the working channel; simultaneously, the protection time slot punch-through cross on the node is cancelled; the protected service is not selected from the protection channel to be received in the lower ring, and the service is selected from the time slot of the normal working channel; and the APS messages are sent in the same direction (A direction) of the ring with APS stateselected state cleared and switching state set and potential protection slots cleared, and in the opposite direction (G direction) with APS message bridged state cleared and used protection slots cleared. After a fault adjacent node or a target node of a switching command receives the APS message, the protected service of the node entering a ring is not turned but is sent to a normal time slot of a working channel, and the BRIDged state of the APS message is cleared and the usedprotection slots are emptied in the opposite direction (G direction); and the extra service is recovered in the transmission direction of the protection channel, the Calendar in the Flexe overhead is kept consistent, and the Calendar which is normally transmitted without protection switching is correspondingly recovered. In the opposite direction (G direction), after each node receives the APS message with the cleared APS state bridge state, the original guide node recovers the extra service without suppressing, resumes to send the Calendar with the normal Flexe overhead, and sends the APSstate switching state clear in the APS message in the other direction (A direction).

Example 2:

as shown in fig. 2, the correspondence between the working channel and the protection channel divided on the ring and the time slot thereof is the same as that in embodiment 1, and the service configuration is the same as that in embodiment 1, for example, the protection switching process is described. The default setting of the system is that the fast period of APS message transmission is 1 FlexE OMF (overhead multiframe) time (about 3.35 milliseconds), the slow period is 100 FlexEOMF time, and the APS message reception in 3 consecutive periods is consistent to confirm the consistent APS message reception.

And no fault and switching command exists on the starting ring, each node sends an APS message in a slow period, wherein APScondition in the APS message is NC, and APS state is clear.

When a link of a B-C fails, for example, is broken, after detecting the failure, a node C generates and sends an APS message to a node D, and the message is sent according to a fast period, wherein the APS condition is SF, the APS condition node is a node C ID, the target node is a node B ID, and if no hold off time is configured (the hold off time is 0), the APS status switching is set, and the potential protection slots are 13, 14, 15 and 16; the client numbers of the 13 th, 14 th, 15 th and 16 th time slots in the Standby Call in the Flexe overhead from the node C to the node D are respectively 3, 2 and 2, namely the client numbers of the B-C service and the A-D service.

Once the D node receives the APS message sent by the C node, the D node immediately sends the APS message to the E node, the message is sent according to a fast period, the APS condition is SF, the APS condition node is C node ID, the target node is B node ID, and the potential protection slots are 13, 14, 15 and 16; the client numbers of the 13 th, 14 th, 15 th and 16 th time slots in the StandbyCalendar in the Flexe overhead from the D node to the E node are respectively 3, 2 and 2.

And similarly, the E node and the A node keep the content in the APS message unchanged, the APS message is transmitted in sequence, and the client numbers of the 13 th time slot, the 14 th time slot, the 15 th time slot and the 16 th time slot which are transmitted by the Standby Call in the Flexe overhead are respectively 3, 2 and 2 until the B node.

After receiving 3 APS messages with the above contents from node a, node B turns the service to be protected (client number 3) entering the ring at the node to the protection channel, occupies time slot 13, sends APS message with APS statebridged set and used protection slots 13 to node a direction, and sends out slot number 13 in the callback overhead on the link in the B-a direction, where the client number of the time slot 13 is 3; and continuously sending APS messages to the node A at a fast period.

After receiving the APS message from the node B, the node a turns the service to be protected (client number 2) entering the ring at the node to a protection channel, occupies time slots 14, 15, 16, and makes a FlexE cross pass through the time slot 13 (i.e. the input time slot in the cross B-a direction is 13, the output time slot in the a-F direction is 13), sends APS message APS state bridged bits and usedprotection slots 13, 14, 15, 16 to the node F, and sends the client numbers of the time slots 13, 14, 15, 16 in the calenar overhead of FlexE in the link in the a-F direction to be 3, 2, respectively; and continuously sending APS messages to the F node direction in a short period. And setting the APS state selected in the APS message sent in the clockwise direction.

Similarly, after receiving the APS message, the F node and the E node in the counterclockwise direction in the figure make FlexE cross-pass through the time slots 13, 14, 15, and 16, the APS state bridged set and the used protection thresholds of the APS message sent in the direction are 13, 14, 15, and 16, the APS message is sent in a fast cycle, and the number of the time slot client 13, 14, 15, and 16 in the callbar in the overhead of sending the FlexE in the direction link is 3, 2, and 2, respectively. And setting APSstate selected in the APS message sent in the clockwise direction.

After receiving the APS message in the counterclockwise direction, the node D receives the service downlink with the client number of 2 from the time slots 14, 15, and 16, and makes a FlexE cross-penetrating time slot 13, the APS state bridged set and the used protection slots of the APS message sent in the direction are 13, the APS message is sent in a fast cycle, and the client number of the time slot 13 in the calltrailer overhead sent in the direction link is 3. And setting the APS stateselected in the APS message sent in the clockwise direction.

And after receiving the APS message in the anticlockwise direction, the node C receives the service downlink with the client number of 3 from the time slot 13. And setting the APS state selected in the APS message sent in the clockwise direction.

Through the above process, the service (client numbers 2 and 3) interrupted by the fault is transmitted through the protection channel, so as to be protected.

If the state machine represents the behavior of the participating node, the protection Switching process is completed in the sub-state transition of the Switching state of the state machine shown in fig. 4.

In fig. 4, the Clear state is a normal working state, there is no failure on the ring or an external command protection switching condition, and the service is normally transmitted on the working channel; the Switched state is a protection switching completion state, and protected services are transmitted in a protection channel; the Switching state from the Clear state to the Switched state is the state in the protection Switching process. The states "Switching-decision", "Switching-Steering leading node", "Switching-Steering target node", "Switching-Steering possible intermediate node", "Switching-Switch neighboring node", "Switching-Switch intermediate node", "Switching-Switching leading node" shown in fig. 4 are sub-states of the Switching state, and the protection Switching process includes these sub-state transitions of the Switching state.

In the Clear state, both the switching state and the selected state in the APS message in the A direction are not set, the condition of the highest level of the ring is NC, the potential protection slots are empty, and the message sending period is a slow period. At this time, if a fault occurs on the ring or an external command is given, the nodes at different positions on the ring will detect the condition or receive the APS message with the highest condition level and the changed node, so that the node enters the Switching-decision sub-state of the Switching state, and the APS message sending period in the a direction is changed into a fast period.

The Switching-decision mainly judges whether the node meets the condition as a guidance node, if the node is judged to be the highest level condition, the node enters a Switching-Steering node, guidance information is sent out in an APS message in the A direction and FlexeCalendar of the node, and the Switching state of the APS message in the A direction is set.

Under several Switching-Steering states, the node mainly functions to transmit guidance information by using an APS message in the A direction and Flexecalendar, and if the APS message is detected to be inconsistent in a certain number of continuous fast periods, extra services are suppressed, and preparation is made for service Switching for migrating to the corresponding next sub-state. During this period, the node determines whether it is a neighboring node of the current protection Switching, specifically, if the node receives a target node indicated in an APS message with the same direction a or does not receive an APS message with a bridged state set in the direction G within a certain amount of fast cycle time, it determines that it is a neighboring node and enters a "Switching-Switch neighboring node".

The nodes in the Switching-Switch state are used for completing protection Switching and transferring and receiving the service to be protected to the protection channel. If a node has a service to be protected which enters a ring under the state of 'Switching-Switch adjacent node' (and the corresponding change of the transmission direction of a protection channel Flexe Call is kept consistent with the service), setting the bridged state in an APS message in the G direction, and indicating that the service actually uses the protection channel time slot by using protection slots; after receiving the APS message with the bridge state set in the G direction, the intermediate node enters a corresponding 'Switching-Switching intermediate node' state, if a lower ring service belongs to a service to be protected, the intermediate node receives a lower ring from a protection channel, the service to be protected (if the service to be protected is present) which is looped into the intermediate node is turned (and the corresponding change of the transmission direction of the protection channel FlexeCalendar is kept consistent with the service), the bridge state set in the G direction APS message and the used protection slots indicate that the turning service actually uses the protection channel time slot, and the selected state set in the A direction APS message; and the guide node enters a corresponding 'Switching-Switch guide node' state after receiving the APS message with the bridge state set in the G direction, and if a lower-ring service belongs to a service to be protected, the lower-ring service is received from the protection channel, and the selected state set is set in the APS message in the A direction. And completing protection Switching through the processing in the Switching-Switch state, and migrating the node state to Switched.

Other parts of this embodiment are the same as embodiment 1, and thus are not described again.

Regarding the bidirectional protection: if the protection mode is configured as bidirectional protection, one method is to treat the fault detected in one direction as the fault in two directions, and then the protection switching can be respectively completed in the two directions according to the technical scheme of the protection switching, thereby completing the bidirectional protection switching. The specific method may be that after receiving the APS packet of the failure in the other direction, the upstream neighboring node of the failure treats it as if it detects the failure. The APS message content can be expanded, reverse direction condition information is added, and the fault can be quickly notified to the upstream adjacent node of the fault in the case of unidirectional fault.

Logical time slot: in order to realize the invention more flexibly, each real Flexe time slot can be corresponding to a logic time slot number, and the mapping relation from the physical time slot to the logic time slot is independent on each segment of Flexe group link and can be different; the order of the size of the logical slot numbers remains consistent with the physical slot number arrangement. The guard slots are then determined according to the logical slots. In this way, on each segment of FlexE group link of a ring, although the bandwidth of the protection channel configuration is the same, the specific composition of FlexE slots may be different, and flexible assignment may be performed.

After introducing the logical time slot number, the protection switching protocol described above involves that the FlexE time slot is represented by a logical time slot. Because both the potential protection slots and the used protection slots in the APS message are represented by logic time slots, the actual input FlexE time slots and the actual output FlexE time slots of the through crossings made on the nodes during protection switching may be different, but the corresponding logic time slot numbers are the same.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A steering mode ring protection method of a Flexe ring network in an SPN is characterized by comprising the following steps:

in a Flexe ring network of the SPN, a working channel and a protection channel are divided by taking a Flexe time slot as a unit, and the number of the Flexe time slots contained in the working channel and the protection channel is equal and the directions are opposite; predefining a one-to-one corresponding relation between the time slot of one working channel and the time slot of the protection channel;

when a fault occurs in the Flexe ring network and meets the switching condition, the node which detects the fault is used as a guide node to send guide information, and the sending direction is a direction far away from the fault; the guiding information contains a service client number which is interrupted and transmitted by the fault and a protection channel time slot which needs to be occupied by the interrupted service; the guiding information is transmitted on the ring until the adjacent fault node at the other end of the fault;

according to the guiding information, if the client number of the service of the ring-in on a certain node belongs to the client number of the service indicated in the guiding information, the service is diverted and transmitted in the time slot of the protection channel corresponding to the client number of the service indicated by the guiding information; and the Flexe Call that changes the link is consistent with the protected service transmitted in the protection channel;

the intermediate node crosses and penetrates through the protection channel time slot which is needed to be occupied by the steering service transmitted on the protection channel by using a Flexe time slot; and the Flexe Call that changes the link is consistent with the protected service transmitted in the protection channel;

if the client number of the service of the lower ring on a certain node belongs to the client number of the service indicated in the guidance information and the service is diverted to the protection channel, the service lower ring is received from the corresponding protection channel time slot corresponding to the service client number in the protection channel.

2. The turning mode ring protection method of the Flexe ring network in the SPN according to claim 1, wherein the condition causing the protection switching comprises an external command, in addition to the protection switching caused by the failure in the Flexe ring network; in protection switching initiated by an external command, the node determined by the external command serves as a leading node.

3. The turning mode ring protection method of the FlexE ring network in SPN according to claim 1, wherein the one-to-one correspondence between the time slots of the predefined working channel and the time slots of the protection channel is defined by user configuration or system default; when protection switching occurs, the protection switching protocol determines which time slots in the protection channel are used for transmitting the protected service according to the corresponding relationship between the time slots of the predefined working channel and the time slots of the protection channel.

4. The turning mode ring protection method of the FlexE ring network in the SPN according to claim 1, characterized in that the protection switching process is supported by the protection switching protocol defined by the present invention, the protection switching protocol uses protocol messages and flexecendar to interact necessary information between nodes to coordinate the protection switching process;

the protection switching protocol message indicates the highest level switching condition on the upper ring and the node thereof in the message transmission direction, the protection switching state of the node, the available protection channel time slot, the actually used protection channel time slot and the target node;

according to the received protection switching protocol message and the fault or external protection switching command detected by the message, when the node judges that the node becomes the highest level condition, the node meets the protection switching condition, and the node is used as a guide node to promote the protection switching process; the guide node sends a protection switching protocol message indicating an available protection channel time slot in a direction away from the detected fault or a direction determined by an external command, wherein the protection switching protocol message indicates that a protection switching process is initiated, and indicates a to-be-protected service client number corresponding to the available protection channel time slot in a standby terminal; wherein, the available protection channel time slot indicated in the protection switching protocol message is the time slot of the protection channel corresponding to the time slot for transmitting the service to the node in the original working channel according to the one-to-one correspondence between the predefined working channel time slot and the protection channel time slot; the above information is used as guiding information to be transmitted on the ring until the other end of the fault is close to the node of the fault or the target node determined by the external command;

after the fault adjacent node or the target node determined by the external command receives the guidance information and confirms that the fault adjacent node or the target node is correct, if the service to be protected of the service on which the ring-in service belongs to the service to be protected indicated in the guidance information, the service is diverted and transmitted in the time slot of the protection channel corresponding to the service client number indicated by the guidance information, in the opposite direction, namely the transmission direction of the protection channel, the corresponding Flexe Call changes accordingly to be consistent with the service transmission, the protection channel time slot actually used by the diverted service is indicated in the protocol message, and the protection switching state in the protocol message indicates that the diversion is performed;

the protocol message is transmitted to the direction of the guide node along the transmission direction of the protection channel, and if the service of the ring-in is the service to be protected indicated in the guide information, the service is turned to the protection channel through each intermediate node, if the service of the lower ring is the service which is already turned, the service lower ring is received from the corresponding protection channel time slot, so that the protection channel time slot which is actually used on the next link is changed, the corresponding Flexe Calendar is changed along with the change of the protection channel time slot which is actually used by the turning service, and the protection switching state in the protocol message is sent in the direction to indicate that the turning service is actually used, and the protection switching state in the protocol message is sent to indicate that the turning is already done; after receiving the protocol message analysis, the guide node receives the corresponding protection channel time slot if the service of the lower ring belongs to the diverted service; thereby completing the protection switching of the service.

5. The turning mode ring protection method for the Flexe ring network in the SPN according to any one of claims 1 to 4, characterized in that, each physical Flexe time slot number in each segment of Flexe group link is corresponding to a logical time slot number to form a one-to-one correspondence, and the size sequence of the logical time slot numbers is kept consistent with the arrangement sequence of the corresponding physical Flexe time slot numbers; the one-to-one correspondence between the physical Flexe time slot numbers and the logical time slot numbers is mutually independent on each segment of Flexe group link; the division of the working channel time slot and the protection channel time slot of the ring is carried out according to the logical time slot, and the protection switching protocol relates to the FlexE time slot which is expressed by the logical time slot number.