CN1126331C

CN1126331C - Automatically protected switching method and device in high rate SDH loop

Info

Publication number: CN1126331C
Application number: CN99121279A
Authority: CN
Inventors: 杨军
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 1999-11-04
Filing date: 1999-11-04
Publication date: 2003-10-29
Anticipated expiration: 2019-11-04
Also published as: CN1295397A

Abstract

The present invention relates to an automatically protected switching method and a device in a high rate SDH loop. The work flow comprises that group network is allocated, multiplex section level warning messages are detected, K bytes are extracted, and whether switching or recovery is needed or not is judged; if the switching or the recovery is needed, then new K bytes are inserted into overhead bytes after the switching or the recovery is executed, and finally, report is carried out; if the switching or the recovery is needed, the K bytes are directly inserted into the overhead bytes. The present invention uses APS standard signalling proposed by ITU-TG. 841 to response signalling, which is an APS proposal of double-end protection mechanism. Protecting channels used for all nodes on an entire ring are allocated beforehand, and the channel allocation is more reasonable; signalling using specifications are followed strictly, and compatibility exists; original hardware resource is fully used, and the cost is reduced.

Description

Automatic protection switching method on the high rate SDH loop and device

The present invention relates to APS (Automatic Protection Switching is called for short APS) method and the device of SDH (Synchronous Digital Hierarchy SDH) optical transport network; more particularly, be that two-fibre two-way multi-section on a kind of high rate SDH loop is shared automatic protection switching method and device.

At present; the SDH optical transport network is widely used at communication field; progress along with demand and the technical merit of society; the speed of SDH optical transport network is more and more higher; particularly mostly adopted 2.5G bit/s even SDH equipment more at a high speed in trunk cable, this is just so that " self-healing function " of one of two large advantages of SDH optical transport network is the APS function seem all the more important. The ITU-T of International Telecommunication Association (branch of the relevant telecommunication standard of International Telecommunication Union Telecommunication Standardization Sector International Telecommunications Union) G.841 number suggestion " type and the characteristic of SDH network protection architecture " has been made concrete suggestion to the APS function of SDH network. But this standard has just been made regulation in logic at APS algorithm and communications protocol, does not relate to the realization of device level. (application number: 96195023.4) " self-healing network " proposed the solution of oneself to the APS function of SDH optical transport network in the patent application that Sweden Ellison Telephone Co., Ltd submitted to Patent Office of the People's Republic of China on June 18th, 1996. The measuring ability of this patent utilization network node, detect the failure condition (such as the fiber cut between two nodes) with this section spot correlation, when breaking down situation, need not network management, reselecting route sends professional, and when fault restoration, automatically will send business recovery on original route, to reach self-healing function. But find that by analyzing it has following deficiency: 1, owing to there is not to use the signaling technology that is specifically designed to self-healing function; so that this technical scheme is a kind of single-ended protection scheme; in the bad situation of fibre circuit stability; can be because the chain reaction that switching appears in the signal fault of different light directions increases extra work burden and complicated amount of calculation for the defencive function control module. 2, guard channel and working channel unreasonable distribution, poor operability. When the alarm triggered defencive function occurring, need to carry out redistributing of guard channel. 3, this scheme can only be carried out fiber-optic signal and is being in switching under the failure conditions fully, and when network element node two side optical fibers all signal fault occurs, can't assess and preferred according to the quality of both sides optical signal. 4, poor compatibility. Because this scheme is the technical scheme of Ericsson Inc independent development development, therefore when networking, will be incompatible because of the SDH optical transmission device of the difference of protection mechanism and other manufacturers produce.

It is strong to an object of the present invention is to propose a kind of compatibility; channel allocation rationally has also assessing and preferred automatic protection switching method the both sides optical signal of two end protection mechanism, and another object of the present invention is the device that proposes to realize said method.

Automatic protection switching method on a kind of high rate SDH loop, its workflow is as follows: at first, carry out the networking configuration by webmaster layer APS configuring maintenance module when starting in system; Secondly, after entering normal operating conditions, the warning information of the multiplex section level on two light directions of line signal alarm extraction module detection of dynamic is also notified APS core processor module, and K1, the K2 byte in the MSOH byte on two light directions of while APS signaling byte-extraction insert module Dynamic Extraction also notified APS core processor module; Then, the information that APS core processor module synthesis is received, judge according to the APS algorithm and whether to carry out bridge joint and switch or switch recovery, bridge joint is switched or recovery operation if carry out, then order bridge joint switching action Executive Module execution bridge joint switching operation or switch recovery operation, then APS core processor module will reflect that by APS signaling byte-extraction insert module K1, the K2 byte of this node the present situation are inserted in the MSOH byte on the corresponding light direction, and last bridge joint switching action Executive Module reports webmaster layer APS configuring maintenance module with operation information; Bridge joint is switched or recovery operation if need not carry out, and then only needs will to reflect by APS signaling byte-extraction insert module that K1, the K2 byte of this node the present situation are inserted in the MSOH byte on the corresponding light direction by APS core processor module and gets final product.

Carry out the networking configuration by webmaster layer APS configuring maintenance module when system starts in the above-mentioned workflow and refer to that webmaster layer APS configuring maintenance module provides needed primary data information to APS core processor module, and finish time-slot cross configuration under the normal condition and the distribution of working channel and guard channel. Primary data information comprises the sign ID of Home Network unit node and the sign ID of two network element nodes adjacent with this network element.

Multiplex section level warning information comprises the LOF of multiplex section level in the above-mentioned workflow, the dropout of multiplex section level, the Signal Degrade of Multiplex Section AIS and multiplex section level.

The bridge joint switching operation refers to this node multiplexing professional and sending to guard channel when sending to working channel from the straight-through business of this node from the light Zhi Luxiang light group road, and the business of will be from the light group road telling to this node optical branch road receives from working channel and forwards guard channel to and receive.

Automatic-protecting switching device on a kind of high rate SDH loop, comprise and be responsible for the networking configuration, safeguard and the webmaster layer APS configuring maintenance module of debugging that described webmaster layer APS configuring maintenance module sends to APS core processor module with the Network Management and Maintenance debug command and the process information that receives from this module reports; Be responsible for the line signal alarm extraction module that multiplex section level warning information extracts on the optical link of both sides, described line signal alarm extraction module extracts multiplex section level warning information and it is sent to APS core processor module; Be responsible on the optical link of both sides K1, the extraction of K2 byte and the APS signaling byte-extraction insert module of insertion in the MSOH byte, described APS signaling byte-extraction insert module sends to APS core processor module with the K byte of extracting and receives insertion K byte from this module; Be responsible for the bridge joint switching action Executive Module of working channel and guard channel allotment, described bridge joint switching action Executive Module is responsible for carrying out from the bridge joint of APS core processor module and is switched or switch the recovery order; And synthesise various information, the APS core processor module that makes a policy and control according to the APS algorithm.

Webmaster layer APS configuring maintenance module is positioned at subnet management control centre in the said apparatus; Line signal alarm extraction module is positioned on the Optical Fiber Interface Board; APS signaling byte-extraction insert module and APS core processor module are positioned on the optical link Overhead Processing Board; Bridge joint switching action Executive Module is positioned on the time-slot cross plate.

Communication in the said apparatus between APS core processor module and the webmaster layer APS configuring maintenance module is transmitted by the network element control plate.

Interface between APS core processor module and the network element control plate is dual port RAM.

The present invention is described in further detail below in conjunction with accompanying drawing.

Fig. 1-A is the SDH loop network schematic diagram under the normal condition, and Fig. 1-B is the SDH loop network schematic diagram that carries out after bridge joint is switched;

Fig. 2 is the theory structure schematic diagram of apparatus of the present invention;

Fig. 3 is the hardware configuration schematic diagram of SDH optical transmission device;

Fig. 4 is the flow chart of automatic protection switching method of the present invention;

Fig. 5 is the structural representation of a specific embodiment of the present invention;

Fig. 6 is the flow chart of APS algorithm in the APS core processor module.

As shown in the figure; Fig. 1-A is the SDH loop network schematic diagram under the normal condition; node A is A → B → C to the professional route between the C; if the transmission cable between Node B and the node C breaks down; the APS scheme will make Node B and node C protect simultaneously and switch; shown in Fig. 1-B; at this moment the professional route between node A and the node C becomes A → B → A → D → C; business between the AC is not interrupted because of the transmission fault between Node B and the node C; greatly strengthened the Survival properties of SDH transmission network, this is the meaning of APS scheme just also.

The theory structure schematic diagram of apparatus of the present invention that Fig. 2 represents. As shown in Figure 2, the present invention comprises with lower module: webmaster layer APS configuring maintenance module, line signal alarm extraction module, APS signaling byte-extraction insert module, bridge joint switching action Executive Module and APS core processor module, the below does detailed introduction to the function of these modules and annexation each other thereof respectively.

Webmaster layer APS configuring maintenance module is responsible for networking configuration, maintenance and debugging work. When system started, webmaster layer APS configuring maintenance module will be carried out initialization operation, comprising: 1, the distribution of each network element ID. Interstitial content can not be above 16 in MS-SPRING (two-fibre two-way multi-section shared protection ring) monocycle; each network element must distribute an ID (Identifier) that sign is unique; span is between 0 to 15; network element ID ID is the first element that this node normally starts the APS function; must along with the network element master database is issued on the APS core processor simultaneously when the node electrifying startup, must also to notify the APS core processor ID of two network elements adjacent with this network element simultaneously. 2, the distribution of working time slot and protection time slot. Design according to MS-SPRING APS; AU4 (Administrative Unit level4 speed grade is 4 administrative unit) time slot capacity on every optical link need to distribute the capacity of half as the professional working time slot of transmission normal operation, in addition the protection time slot of half the transmission failure section of striding Working service when breaking down on the optical link. Under the state of normal operation, webmaster layer APS configuring maintenance module also is responsible for maintenance work, and the APS external command of carrying out attended operation comprises:

1, protection locking LP-R; This order is for preventing working channel at the guard channel of a certain ring switching of the appointment section of striding access, and it can be realized by making node lose any ring protection ability of switching of request. Because this order can't be transmitted, so must be assigned simultaneously by two end nodes of webmaster layer APS configuring maintenance module on the section of striding of protection locking, want the additional directions parameter when requiring simultaneously subnet management control centre to assign the LP-R order in the K byte.

2, Forced Switch FS-R; The ring switching of this command execution from the working channel to the guard channel, unless the bridge joint request of higher level is arranged, otherwise no matter the state of guard channel how, all will carry out bridge joint and switch. Because FS-R can transmit in the K byte, can arrange, the webmaster layer is only assigned at the node that starts Forced Switch, and adds and decide directioin parameter.

3, Manual Switch MS-R; This order is identical with the Forced Switch command convention, and just bridge joint request rank is lower.

4, remove CLR; The external command that former webmaster layer is assigned is removed in this order, same additional directions parameter. When removing the protection lock command, need to assign simultaneously at two nodes of the corresponding section of striding, and the additional directions parameter, and when removing other external commands, only need to assign clear command at the former Nodes of assigning external command, and additional identical directioin parameter.

Webmaster layer APS configuring maintenance module also is responsible for carrying out debugging work, mainly encircles the manoeuvre operation. The ring Exercise Order is EXER-R; This orders the protection of only manoeuvre institute request channels to be switched, but is not to implement bridge joint and switching action, because the ring manoeuvre can be transmitted by the K byte, can arrange equally to be assigned by order starter node webmaster layer, and can arrange direction. The webmaster layer is only assigned this order at the node that starts Forced Switch, and the additional directions parameter.

Line signal alarm extraction module is responsible for extracting the multiplex section level warning information on the optical link of both sides, comprising Signal Fail (being other LOF of multiplex section level (Loss Of Frame LOF), LOS (Loss Of Signal dropout) and MS-AIS (Multiplex Section Alarm Indication Signal Multiplex Section AIS)) and Signal Degrade. Line signal alarm extraction module provides the trigger condition of APS to the APS core processor.

APS signaling byte-extraction insert module is responsible for extracting and insert K1, the K2 byte in the MSOH byte. In the shared APS scheme of two-fibre two-way multi-section, to use two APS signaling bytes: K1 and K2. K1 and K2 transmit in the MSOH byte of the STM-N (Synchronous Transport Module level N speed grade is the synchronous transfer mode of N) of carrying guard channel. Wherein 1～4 bit of K1 is bridge request codes, and descending order according to priority is listed in the table below; 5～8 bits of K1 are destination node ID of the indicated bridge request codes of 1～4 bit of K1. 1～4 bit of byte K2 is the source node ID that sends the bridge joint request, and the 5th bit is length/minor axis sign (wherein 0 represent minor axis, 1 represents major diameter), and 6～8 bits are the current bridge joint solicited status code of source node that sends the bridge joint request.

The external command that transmits in the APS signaling has the ring switching of pressure FS-R, artificial ring switching MS-R, Exerciser-Ring EXER-R; Ring signal inefficacy SF-R, the deteriorated SD-R of ring signal, ring reverse request RR-R, Wait-to-Restore WTR are arranged in the auto switching order and without request NR, these instructions transmit in the K1 byte. The signalling coding of each instruction in APS signaling byte is as shown in the table:

Request instruction coding schedule (K1 byte 1～4bit)

Order	Coding	Order	Coding
Order	Coding	Order	Coding	FS-R	1101	SF-R	1011
SD-R	1000	MS-R	0110	FS-R	1101	SF-R	1011
SD-R	1000	MS-R	0110	TR	0101	EXER-R	0011
RR-R	0001	NR	0000	TR	0101	EXER-R	0011

The solicited status code that transmits in the K2 byte has Multiplex Section AIS MS-AIS; the multiplex section far-end detects inefficacy MS-RDI; at guard channel transmission extra traffic Extra traffic on protection channels; bridge joint switch status Bridged and Switched, bridge joint Bridged idle condition Idle.

Solicited status instruction encoding table (K2 byte 6～8bit)

State	Coding
State	Coding	MS-AIS	111
MS-RDI	110	MS-AIS	111
MS-RDI	110	Reserved	101
Reserved	100	Reserved	101
Reserved	100	Extra traffic on protection channels	011
Bridged and Switched	010	Extra traffic on protection channels	011
Bridged and Switched	010	Bridged	001
Idle	000	Bridged	001

Bridge joint switching action Executive Module is responsible for the allotment of working channel and guard channel according to the order of APS core processor. Needs according to instruction encoding, need 4 control signal lines between APS core processor and the bridge joint switching action Executive Module, respectively as east side bridge joint control signal wire, east side switching control holding wire, west side bridge joint control signal wire, west side switching control holding wire. High level represents that order is effective, and low level represents order cancellation, and its command code table is as follows:

Command name	APS3	APS2	APS1	APS0	Describe
Command name	APS3	APS2	APS1	APS0	Describe	East side bridge joint/switch	0	0	1	1	The working time slot that original outer shroud fibre is sent to the east side is bridged to the fine protection time slot that sends to the west side of interior ring and gets on, and is used for receiving the working time slot that comes in the east side and is switched to the fine protection time slot that comes in the west side that receives of outer shroud and gets on ring in original is fine
West side bridge joint/switch	1	1	0	0	The fine working time slot that sends to the west side of ring is bridged to the protection time slot that the outer shroud fibre sends to the east side and gets on originally, and originally outer shroud is fine is used for receiving the working time slot that comes in the west side and is switched to the fine next protection time slot in east side that receives of interior ring and gets on	East side bridge joint/switch	0	0	1	1

Unloading the east side switches	1	The protection time slot that comes from the west side on the outer shroud fibre is now received signal return to the working time slot reception signal next from the fine east side of interior ring.
Unloading the east side switches	1		Unloading the west side switches	0	1	0	0	The protection time slot reception signal that comes from the east side on interior ring fibre is now returned to the working time slot that comes from the fine west side of outer shroud receive signal.
Unloading the east side bridge joint switches	0	Get on returning to the working time slot that sends to the east side at the outer shroud fibre at the fine signal that sends to west side protection time slot of interior ring now; The protection time slot that comes from the west side on the outer shroud fibre is now received signal return to the working time slot reception signal next from the fine east side of interior ring. Be that full recovery is normal	Unloading the west side switches	0	1	0	0
Unloading the east side bridge joint switches	0		Unloading the west side bridge joint switches	0	0	0	0	The signal that sends to east side protection time slot at the outer shroud fibre is now returned at the fine working time slot that sends to the west side of interior ring; The protection time slot reception signal that comes from the east side on interior ring fibre is now returned to the working time slot that comes from the fine west side of outer shroud receive signal. Be that full recovery is normal

APS core processor module is the core of whole APS scheme, its synthesise various information, makes analysis decision and sends control instruction according to the APS algorithm. Most important in the APS core processor is exactly the APS algorithm, and G.841 number suggestion of ITU-T " type and the characteristic of SDH network protection architecture " has been made regulation in logic to the APS algorithm, and Fig. 6 has represented the flow chart of APS algorithm. As shown in Figure 6, in the APS algorithm, at first detect the APS external command that has or not from the webmaster layer, if having, then process by special webmaster layer command process submodule; Then detect the multiplex section level fault warning information that is reported by line signal alarm extraction module, different from original fault if find new fault, then transfer to local troubleshooting submodule and carry out troubleshooting; The APS signaling byte K1, the K2 that at last APS signaling byte-extraction insert module are extracted judge, and determine whether will carry out the bridge joint switching operation or switch recovery operation, then send control instruction such as needs.

Fig. 3 is the hardware configuration schematic diagram of SDH optical transmission device, and Fig. 5 is the structural representation of a specific embodiment of the present invention. From Fig. 3 and Fig. 5, can find out, among the embodiment webmaster layer APS configuring maintenance module is placed in the subnet management control centre, line signal alarm extraction module is placed on the Optical Fiber Interface Board, APS signaling byte-extraction insert module and APS core processor module have been placed on the optical link Overhead Processing Board, bridge joint switching action Executive Module has been arranged on the time-slot cross plate. Take full advantage of like this hardware configuration of existing equipment, and need not newly-increased special APS disposable plates, effectively reduced cost. Communication interface between APS core processor and the network element control plate adopts dual port RAM, and the interface of all the other each several parts is all used the interface of original hardware device as far as possible, but will suitably increase several backboard cablings, is used for the signal connection of offside is come.

Fig. 4 is the flow chart of automatic protection switching method of the present invention. When starting, system carries out the networking configuration by webmaster layer APS configuring maintenance module: provide needed primary data information to APS core processor module; comprising the ID of this network element and adjacent two network elements, finish time-slot cross configuration under the normal condition and the distribution of working channel and guard channel. After entering normal operating conditions, the warning information of the line signal alarm extraction module detection of dynamic multiplex section level on the Optical Fiber Interface Board also reports APS core processor module, and K1, the K2 byte in the APS signaling byte-extraction insert module Dynamic Extraction MSOH byte on the while optical link overhead board also reports APS core processor module; Then, the information that APS core processor module synthesis is received, judge according to the APS algorithm and whether to carry out bridge joint and switch or switch recovery, bridge joint is switched or recovery operation if carry out, then order the bridge joint switching action Executive Module on the time-slot cross plate to carry out the bridge joint switching operation or switch recovery operation, then APS signaling byte-extraction insert module will reflect that K1, the K2 byte of this node the present situation are inserted in the MSOH byte, and last bridge joint switching action Executive Module reports webmaster layer APS configuring maintenance module with operation information; Bridge joint is switched or recovery operation if need not carry out, and then only needs will reflect that by APS signaling byte-extraction insert module the K1 of this node the present situation, K2 byte are inserted in the MSOH byte and get final product.

The automatic protection solution that the present invention proposes has used ITU-T to advise that G.841 the international APS signaling that provides carries out signaling and reply, and is a kind of APS scheme of two end protection mechanism; Pre-configured can be for the guard channel of all nodes on the whole ring so that the distribution of channel be more reasonable; G.841 advise the signaling operating specification stipulated owing to strictly follow ITU-T, therefore have good compatibility; In addition, the automatic protection solution that the present invention proposes takes full advantage of the hardware resource of original transmission equipment, has effectively reduced cost.

Claims

1. the automatic protection switching method on the high rate SDH loop is characterized in that:

Carry out the networking configuration by webmaster layer APS configuring maintenance module when (1) at first, starting in system;

(2) secondly, after entering normal operating conditions, the warning information of the multiplex section level on two light directions of line signal alarm extraction module detection of dynamic is also notified APS core processor module, and K1, the K2 byte in the MSOH byte on two light directions of while APS signaling byte-extraction insert module Dynamic Extraction also notified APS core processor module;

(3) then, the information that APS core processor module synthesis is received judges according to the APS algorithm and whether to carry out bridge joint and switch or switch recovery;

(4) bridge joint is switched or recovery operation if carry out, then order bridge joint switching action Executive Module execution bridge joint switching operation or switch recovery operation, then APS core processor module will reflect that by APS signaling byte-extraction insert module K1, the K2 byte of this node the present situation are inserted in the MSOH byte on the corresponding light direction, and last bridge joint switching action Executive Module reports webmaster layer APS configuring maintenance module with operation information;

(5) bridge joint is switched or recovery operation if need not carry out, and then only needs will to reflect by APS signaling byte-extraction insert module that K1, the K2 byte of this node the present situation are inserted in the MSOH byte on the corresponding light direction by APS core processor module and gets final product.

2. the automatic protection switching method on a kind of high rate SDH loop as claimed in claim 1; it is characterized in that: carry out the networking configuration by webmaster layer APS configuring maintenance module when described system starts and refer to that webmaster layer APS configuring maintenance module provides needed primary data information to APS core processor module, and finish time-slot cross configuration under the normal condition and the distribution of working channel and guard channel.

3. the automatic protection switching method on a kind of high rate SDH loop as claimed in claim 2 is characterized in that: described primary data information comprises the sign ID of Home Network unit node and the sign ID of two network element nodes adjacent with this network element.

4. the automatic protection switching method on a kind of high rate SDH loop as claimed in claim 1; it is characterized in that: described multiplex section level warning information comprises the LOF of multiplex section level; the dropout of multiplex section level, the Signal Degrade of Multiplex Section AIS and multiplex section level.

5. the automatic protection switching method on a kind of high rate SDH loop as claimed in claim 1; it is characterized in that: described bridge joint switching operation refers to this node multiplexing professional and sending to guard channel when sending to working channel from the straight-through business of this node from the light Zhi Luxiang light group road, and the business of will be from the light group road telling to this node optical branch road receives from working channel and forwards guard channel to and receive.

6. the automatic-protecting switching device on the high rate SDH loop, it is characterized in that: comprise and be responsible for the networking configuration, safeguard and the webmaster layer APS configuring maintenance module of debugging that described webmaster layer APS configuring maintenance module sends to APS core processor module with the Network Management and Maintenance debug command and the process information that receives from this module reports; Be responsible for the line signal alarm extraction module that multiplex section level warning information extracts on the optical link of both sides, described line signal alarm extraction module extracts multiplex section level warning information and it is sent to APS core processor module; Be responsible on the optical link of both sides K1, the extraction of K2 byte and the APS signaling byte-extraction insert module of insertion in the MSOH byte, described APS signaling byte-extraction insert module sends to APS core processor module with the K byte of extracting and receives insertion K byte from this module; Be responsible for the bridge joint switching action Executive Module of working channel and guard channel allotment, described bridge joint switching action Executive Module is responsible for carrying out from the bridge joint of APS core processor module and is switched or switch the recovery order; And synthesise various information, the APS core processor module that makes a policy and control according to the APS algorithm.

7. the automatic-protecting switching device on a kind of high rate SDH loop as claimed in claim 6, it is characterized in that: described webmaster layer APS configuring maintenance module is in subnet management control centre.

8. the automatic-protecting switching device on a kind of high rate SDH loop as claimed in claim 6, it is characterized in that: described line signal alarm extraction module is positioned on the Optical Fiber Interface Board.

9. the automatic-protecting switching device on a kind of high rate SDH loop as claimed in claim 6, it is characterized in that: described APS signaling byte-extraction insert module and APS core processor module are positioned on the optical link Overhead Processing Board.

10. the automatic-protecting switching device on a kind of high rate SDH loop as claimed in claim 6, it is characterized in that: described bridge joint switching action Executive Module is positioned on the time-slot cross plate.

11. the automatic-protecting switching device on a kind of high rate SDH loop as claimed in claim 6 is characterized in that: the communication between described APS core processor module and the webmaster layer APS configuring maintenance module is transmitted by the network element control plate.

12. the automatic-protecting switching device on a kind of high rate SDH loop as claimed in claim 11 is characterized in that: the interface between described APS core processor module and the network element control plate is dual port RAM.