CN106301540B

CN106301540B - Method and device for implementing protection switching in optical transmission network

Info

Publication number: CN106301540B
Application number: CN201510293368.6A
Authority: CN
Inventors: 唐世庆; 黄蕾
Original assignee: Alcatel Lucent SAS
Current assignee: Alcatel Lucent SAS
Priority date: 2015-06-01
Filing date: 2015-06-01
Publication date: 2020-02-14
Anticipated expiration: 2035-06-01
Also published as: CN106301540A

Abstract

The invention discloses a method for protection switching implemented in protection switching equipment of an optical transmission network, wherein the protection switching equipment comprises a plurality of changeable main cards, and the method comprises the following steps: A. setting one changeable main card of the plurality of changeable main cards as a core main card and setting other changeable main cards of the plurality of changeable main cards as auxiliary cards; B. providing protection switching for the optical transmission network through the core main card and the auxiliary card; when the core main card fails, one auxiliary card is selected as the core main card according to a predefined arbitration rule to replace the function of the original core main card. The invention also discloses a protection switching device of the optical transmission network. The invention improves the survivability and reliability of the transmission network.

Description

Method and device for implementing protection switching in optical transmission network

Technical Field

The present invention relates to the field of communications, and in particular, to a method and an apparatus for protection switching implemented in an optical transmission network.

Background

With the rapid growth of internet services and the increase in mobility and network dependency, the development of wireless broadband networks to support mission-critical applications has required that they not only support the increasing bandwidth requirements of mobile users, but also provide reliable connectivity to these users.

As is well known, since a radio access network is connected into a fixed network, research and development on survivability of the network have been focused among the fixed network and the radio access network. To improve the survivability of the network, the network may consist of a linear protection scheme for the optical transport network on the optical channel data unit (ODUk) layer. From the access device (working side and protection side) to the ODU core device are all covered in the end-to-end subnetwork working domain. Connecting the domains via redundant (1+1or 1: N) interconnects provides great flexibility to the network when there are a large number of error conditions. In protection switching, especially in a large number of switching devices, when a fixed APS (automatic protection switching) main core main card fails and a distributed auxiliary slot card (slave slot card) cannot be managed in time, an access node is liable to lose a traffic packet.

When a working path fails, protection switching is a way to create a protection path for an ODUK. The protection switching includes linear (1: N and 1+1) protection switching. As shown in fig. 1, generally, the protection switching function is centralized in a core main card composed of an APS FSM processor, a protection switching table, a data path switching, a control management, an OAM processor, and a main CPU. When a path signal failure (TSF) or Signal Degradation (SD) is detected or a remote switch request is received from an APS packet, the APS FSM processor will switch the path for transmitting data from the working path to the protection path. Of course, this protection switching is performed automatically or manually by the main CPU. At the same time, the APS FSM state will be reported to the master CPU.

However, as the number of protection switch groups increases, this implementation architecture will exhibit problems such as the need to consume more Field Programmable Gate Array (FPGA) or hardware resources, increased CPU load, and reduced system reliability due to the lack of suitable redundant backups. These all will cause damage to the telecommunication service.

In contrast to implementing protection switching in one core board, patent 201210378853.X proposes an APS distributed implementation. An APS distributed implementation consists of one ASP master component on the core board and a number of secondary components on the IO cards. The recommended method increases the capacity of the protection group of the IO card, simplifies network management, releases the load of the main CPU and increases the reliability of the equipment. The IO card, however, relies on APS motherboard components on the core host card. Once an APS motherboard component (e.g., APS FSM processor) in the core host card fails, the device will fail in the automatic protection switching mechanism and will cause loss of traffic packets.

Fig. 2 shows an architecture of a conventional dual-core master card implementing protection switching, in which 2 APS master units are respectively concentrated in a core board a and a core board B. Although the survivability of the network is improved by the two core boards, the power consumption in the devices is almost doubled.

Therefore, there is a need for a solution that can reduce the power consumption in the device while improving the survivability of the original network.

Disclosure of Invention

In order to achieve the object of the present invention, a first aspect of the present invention provides a method for protection switching implemented in a protection switching device of an optical transmission network, wherein the protection switching device includes a plurality of changeable master cards, including the steps of: A. setting one changeable main card of the plurality of changeable main cards as a core main card and setting other changeable main cards of the plurality of changeable main cards as auxiliary cards; B. providing protection switching for the optical transmission network through the core main card and the auxiliary card; when the core main card fails, one auxiliary card is selected as the core main card according to a predefined arbitration rule to replace the function of the original core main card.

Specifically, the optical transmission network has a plurality of protection switching groups, and each variable master card controls a corresponding plurality of protection switching groups.

Specifically, the step B specifically includes: B1. the variable main card detects signal degradation or signal failure from the working paths of the protection switching groups corresponding to the variable main cards respectively; B2. the variable master card receives a first APS data packet from a working path of a protection switching group corresponding to each variable master card; B3. the alterable master card sending the signal degradation or signal failure and the first APS packet into an APS FSM processor of the core master card; B4. the APS FSM processor of the core main card generates a protection switching instruction and a second APS data packet; B5. the core main card respectively sends the protection switching indication and the second APS data packet to corresponding variable main cards; B6. the variable main card switches the working path based on the corresponding protection switching indication; B7. and transmitting the second APS data packet through the switched working path.

In particular, the predetermined arbitration rules are: the priority of the secondary card set as the core primary card is determined according to the size of the identification number of the secondary card.

Specifically, the step B3 further includes: activating an APS FSM processor in the core master card through the signal degradation or signal failure and the first APS data packet.

A second aspect of the present invention provides a protection switching apparatus for an optical transmission network, characterized in that: the protection switching equipment comprises a plurality of changeable main cards, one changeable main card in the changeable main cards is a core main card, and other changeable main cards in the changeable main cards are auxiliary cards; wherein the changeable master card includes: -an APS auxiliary module configured to communicate with an APS FSM processor of the core master card to assist the core master card in performing protection switching on a protection switching group corresponding to the changeable master card; -an APS FSM processor configured to generate a protection switching indication and a second APS packet when the changeable master card is a core master card; -an APS proxy module configured to manage the reception and transmission of data on the inline side of said changeable master card; wherein an APS FSM processor of a secondary card is activated and becomes the core primary card when the core primary card fails.

In particular, the optical transmission network has a plurality of protection switching groups, and each variable master card manages a plurality of protection switching groups respectively.

In particular, the protection switching device further comprises a distributed protection link module through which the plurality of changeable master cards transmit information.

In particular, the APS auxiliary module comprises: a defect mapping unit configured to detect a defect from a working path of a protection switching group corresponding to each variable master card and map the defect as a signal degradation or a signal failure; an APS receiving unit configured to receive a first APS packet from the working path; an APS transmitting unit configured to transmit the second APS packet via the switched active path; a path switching unit configured to perform switching on the working path.

In particular, the APS proxy module includes: a transmitting unit configured to broadcast protection information to a plurality of changeable master cards; a receiving unit configured to receive protection information from a plurality of changeable master cards.

In particular, the effective data bandwidth of the distributed protection link module is 20 MHz.

The invention improves the survivability of the original network and reduces the power energy consumption in the equipment.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:

FIG. 1 illustrates an existing architecture of a core host card implementing protection switching;

FIG. 2 illustrates an existing architecture of a dual core master card implementing protection switching;

fig. 3 illustrates a protection switching device of an optical transmission network according to the present disclosure;

FIG. 4 is a flow chart illustrating steps for implementing protection switching in the disclosed protection switching device;

FIG. 5 illustrates a detailed block diagram of a variable APS master card according to the present disclosure; and

fig. 6 shows an architectural diagram of the variable APS master card concept disclosed in the present invention being used in SNC protection.

Detailed Description

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof. The accompanying drawings illustrate, by way of example, specific embodiments in which the invention may be practiced. The illustrated embodiments are not intended to be exhaustive of all embodiments according to the invention. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. Moreover, although the steps of a method are described in a particular order in the specification, this does not require or imply that all of the illustrated operations must be performed in the particular order in which the desired results are achieved, but rather that the steps described may be performed in an order different. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step execution, and/or one step broken down into multiple step executions.

In order to solve the above technical problem, the present invention discloses a protection switching device implemented in an optical transmission network, as shown in fig. 3, the device includes a plurality of changeable APS main cards 301, each of which is installed in a slot (slot), wherein each of the changeable APS main cards includes an FSM APS processor (APS main part) and an APS auxiliary module (APS auxiliary part), so that each of the changeable APS main cards can operate as both a core main card and an auxiliary card of an auxiliary core main card. The main role of the core main card in the device disclosed by the invention is to determine the switching path in each protection switching group according to the switching request, Signal Degradation (SD) or Signal Failure (SF) received from each protection switching group, and the role of the auxiliary card is to assist the core main card to manage the switching of the working path in the protection switching group corresponding to the core main card. It is noted that only one of the plurality of changeable APS master cards 301 may be used as a core master card at the same time.

In the invention, when the core main card has a fault, the equipment selects one auxiliary card from a plurality of auxiliary cards as the core main card according to a predefined arbitration rule so as to replace the function of the original core main card.

In the invention, the optical transmission network is divided into a plurality of protection switching groups, each protection switching group is provided with a working path for transmitting data and a backup protection path, and each variable APS auxiliary module of the APS main card corresponds to a plurality of protection switching groups. In one embodiment, each protection switch group is pre-assigned a group number that corresponds to the card number of the variable APS master card.

In the example shown in fig. 3, the protection switching device has 4 changeable APS master cards, 301a, 301b, 301c, and 301d, respectively. Of course, the number of variable APS master cards in this example is merely exemplary, and may be set to any number according to the number of protection switching groups. Each changeable APS master card has an APS FSM processor, an APS auxiliary module and an APS proxy module, respectively. When data is transmitted between the variable APS master cards, the variable APS master cards manage the data transmitted between the cards through the APS proxy module, for example, select to receive specific data of a certain variable APS master card, or combine data of different variable APS master cards.

As shown, the APS FSM processor in each variant APS master card is connected to the APS auxiliary modules in all variant APS master cards through the master port of the APS proxy module, and likewise, the APS auxiliary modules in each variant APS master card are connected to the APS FSM processors in all variant APS master cards through the auxiliary ports of the APS proxy module, that is: each APS FSM processor may be in operative communication with an APS assist module. The connection mode is such that the signal degradation, signal failure or switching request of its corresponding protection switching group obtained by the APS secondary module in any variant APS main card can be sent to the APS FSM processor in any variant APS main card, and the switching path result determined by the APS FSM processor in any variant APS main card can be sent to the APS secondary module in any variant APS main card. Likewise, a first APS packet (APS _ RX), a second APS packet (APS _ TX), and APS FSM Enable information (APS _ FSM _ Enable) can also be passed between the APSFSM processor and the APS auxiliary module.

The disclosed device further comprises a distributed protection link module 302, said distributed protection link module 302 being configured to transmit information between said plurality of changeable APS master cards 301. In the invention, when an APS main component (APS FSM processor) in an originally set core main card fails, a variable APS main card is selected from variable APS main cards as auxiliary cards as the core main card by using a predefined arbitration rule, wherein the predefined arbitration rule can be used for determining the core main card according to the group number of a protection switching group or the identification number of the card corresponding to each variable APS main card. When the changeable APS main card is an auxiliary card, the APS FSM processor in the changeable APS main card is not triggered and is not in an operating state. The APS FSM processor is triggered to enter the active state only when the changeable APS master card is the master card.

In one particular embodiment, such as in the example of FIG. 3, assume that group number or card number for variable APS master card 301a is 0, group number or card number for variable APS master card 301b is 1, and so on. Then mutable APS master card 301a is set as the core master card and the other mutable APS master cards (301b, 301c, 301d) are set as auxiliary cards, and when the APS FSM processor in 301a fails, 301b is set as the core master card. When the APS FSM processors in 301a, 301b fail, 301c is set as the core master card, and so on. The arbitration rules are easy to implement and low cost.

Fig. 4 is a flowchart illustrating steps for implementing protection switching in the protection switching device disclosed in the present invention, fig. 5 is a detailed architecture block diagram of a changeable APS master card, and a process for implementing protection switching by the protection switching device is described below with reference to fig. 3 to 5.

As shown in fig. 5, the APS auxiliary module 510 includes a defect mapping unit 511, an APS receiving unit 512, an APS transmitting unit 513, and a path switching unit 514. The APS proxy module 530 includes a transmitting unit 531 and a receiving unit 532.

In step 401, the Defect mapping unit (Defect _ to _ sfsd _ map)511 detects signal defects from the working paths of the protection switching groups corresponding thereto, and maps the defects to corresponding Signal Degradation (SD) or Signal Failure (SF).

In step 402, the APS receiving unit (APS _ oh _ RX)512 receives a first APS packet (APS _ RX) from the active path of the protection switching group corresponding thereto. In one embodiment, the APS packet includes information about the APS protocol.

It should be noted that the defect mapping unit and the APS receiving unit in

steps

401 and 402 are not only in the auxiliary card, but also in the core main card. In addition, the implementation orders of step 401 and step 402 can be interchanged or implemented simultaneously.

In step 403, the transmitting unit 531 in the APS proxy module transmits the received Signal Degradation (SD), Signal Failure (SF), and first APS packet (APS _ RX) to the receiving unit 532 in the APS proxy module of the core master card.

In step 404, the receiving unit 532 in the APS proxy module of the core main card merges the SF or SD through the SF/SD merging unit and transmits to the APS FSM processor of the core main card. The receiving unit 532 of the core main card further selects and sends the first APS data received by each APS auxiliary module to the APS FSM processor through the APS first selecting unit. The APS FSM processor in the core master card may be configured to be triggered when SF, SD, or first APS data is received to save power. Upon activation, the APS FSM processor generates a protection switch indication and a second APS data packet (APS _ TX) based on the SF, SD or first APS data of the respective protection switch group. The protection switching indication includes switching result information (APS _ switch _ result) indicating an APS switching result and enable information (APS _ FSM _ enable) informing that an APS FSM processor of the core master card is activated.

In step 405, these protection switch indications and the second APS packet will be broadcast by the sending unit 531 in the core master card via the distributed protection link 302 to the respective variant APS master cards.

The distributed protection link module 302 is used for data transmission among multiple changeable APS master cards, the distributed protection link uses 8B/10B coding and has a speed of 25MHz and an effective data bandwidth of 20 MHz. Errors and failures received by the link layer will be detected by the 8B/10B code. The transmitted information will be transmitted in data packets within a cycle. Byte and packet boundaries support K28.5 encoding. check _ sum [15:0] will be added to one end of the packet and packet level reception errors will be detected by the check _ sum and 8B/10B codes. The minimum packet gap is 12 bytes. The size of the information sent by the distributed protection link module is 40960 bits, which can be transmitted in 2.05ms for a 20MHz link.

In step 406, each variable APS master card obtains protection switching indication information corresponding to its own protection switching group through the switching result selecting unit. The path switching unit 514 in the APS auxiliary module then performs switching on the working paths in the protection switching group it manages. Each variable APS master card acquires second APS data corresponding to its own protection switching group through an APS second selection unit, and then an APS transmission unit 513 in the APS auxiliary module transmits a second APS data packet through the switched working path.

Fig. 6 shows an architectural diagram of the variable APS master card concept disclosed in the present invention being used in SNC protection. As shown, there are 2 10G ports (a and B) in the customer card 1, and the customer card 1 has a first priority for the worker card and the protection card. The traffic of 10G in port a is input to an optical path processor (Flex frame) that processes an optical path protocol and connected to the protection card and the work card through a cross configuration (cross configuration). Likewise, the traffic of 10G in port B is also input to an optical path processor (Flex parameter) that processes the optical path protocol and connected to the protection card and the working card through a cross configuration. The 10G traffic in port a and port B is mapped into ODU2 and into 2 line cards, respectively, which are OTU4 interfaces. In the mechanism of the present invention, line cards with working line connections, line cards with protection line connections and customer cards are candidates for implementing the APS master functionality. To avoid conflicts and detuning, we choose the APS master in the client card with the highest priority. When a line fails, the client card may default to operate as an APS master, which may control protection switching and generate egress APS information for the line port. The mechanism is also applicable to the client card 2, and the APS master function in the client card 2 can control protection switching in the client card 2 and can share the load of the protection switching process load in the system.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Furthermore, it will be obvious that the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. Several elements recited in the apparatus claims may also be implemented by one element. The terms first, second, etc. are used to denote names, but not any particular order.

Claims

1. A method for protection switching implemented in a protection switching device of an optical transmission network, wherein the protection switching device includes a plurality of changeable master cards, and each changeable master card controls a corresponding plurality of protection switching groups in the optical transmission network, respectively, the method comprising the steps of:

setting one changeable main card of the plurality of changeable main cards as a core main card and setting other changeable main cards of the plurality of changeable main cards as auxiliary cards;

B. providing protection switching for the optical transport network through the core main card and the auxiliary card, comprising the steps of:

B1. the variable main cards detect signal degradation or signal failure from the working paths of the protection switching groups corresponding to the variable main cards respectively;

B2. the plurality of changeable main cards receive a first APS data packet from the working path of the protection switching group corresponding to each changeable main card;

B3. the plurality of alterable master cards sending the signal degradation or signal failure and the first APS data packet into an APS FSM processor of the core master card;

B4. generating, by an APS FSM processor of the core master card of the plurality of changeable master cards, a protection switch indication and a second APS data packet;

B5. the core main card respectively sends the protection switching indication and the second APS data packet to corresponding variable main cards;

B6. the variable main card switches the working path based on the corresponding protection switching indication;

B7. transmitting the second APS packet via the switched working path;

when the core main card fails, one auxiliary card is selected as the core main card according to a predefined arbitration rule to replace the functions of the original core main card, and the APS FSM processor of the selected auxiliary card is activated.

2. The method of claim 1, wherein the predetermined arbitration rule is: and determining the priority of the auxiliary card as the core main card according to the size of the identification number of the auxiliary card.

3. The method according to claim 2, wherein the step B3 further comprises:

activating an APS FSM processor in the core master card through the signal degradation or signal failure and the first APS data packet.

4. A protection switching device of an optical transmission network, characterized by:

the protection switching device comprises a plurality of changeable main cards, one changeable main card of the changeable main cards is a core main card, other changeable main cards of the changeable main cards are auxiliary cards, and each changeable main card respectively manages a plurality of corresponding protection switching groups in the optical transmission network;

wherein the changeable master card includes:

-an APS auxiliary module configured to communicate with an APS FSM processor of the core master card to assist the core master card in performing protection switching on a protection switching group corresponding to the changeable master card, wherein the APS auxiliary module comprises:

a defect mapping unit configured to detect a defect from a working path of a protection switching group corresponding to each variable master card and map the defect as a signal degradation or a signal failure;

an APS receiving unit configured to receive a first APS packet from the working path;

an APS transmitting unit configured to transmit a second APS packet via the switched active path;

a path switching unit configured to perform switching of the working path;

-an APS FSM processor configured to generate a protection switching indication and the second APS packet when the changeable master card is a core master card;

-an APS proxy module configured to manage the reception and transmission of data on the inline side of said changeable master card; wherein an APS FSM processor of a secondary card is activated and becomes the core primary card when the core primary card fails.

5. The protection switching device of claim 4, further comprising a distributed protection link module through which the plurality of changeable master cards transmit information.

6. The protection switching device of claim 5, wherein the APS proxy module comprises:

a transmitting unit configured to broadcast protection information to a plurality of changeable master cards;

a receiving unit configured to receive protection information from a plurality of changeable master cards.

7. The protection switching device of claim 5, wherein an effective data bandwidth of the distributed protection link module is 20 MHz.