CN1371201A - Asynchronous transferring virtual channel self-healing ring - Google Patents

Asynchronous transferring virtual channel self-healing ring Download PDF

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Publication number
CN1371201A
CN1371201A CN 01104157 CN01104157A CN1371201A CN 1371201 A CN1371201 A CN 1371201A CN 01104157 CN01104157 CN 01104157 CN 01104157 A CN01104157 A CN 01104157A CN 1371201 A CN1371201 A CN 1371201A
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CN
China
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onu
self
atm
node
healing
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CN 01104157
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Chinese (zh)
Inventor
杨震
徐永军
刘格晓
谭德海
程平
张科
姚永鹏
孙庆虎
方海滨
Original Assignee
杨震
徐永军
刘格晓
谭德海
程平
张科
姚永鹏
孙庆虎
方海滨
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Application filed by 杨震, 徐永军, 刘格晓, 谭德海, 程平, 张科, 姚永鹏, 孙庆虎, 方海滨 filed Critical 杨震
Priority to CN 01104157 priority Critical patent/CN1371201A/en
Publication of CN1371201A publication Critical patent/CN1371201A/en

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Abstract

This invention relates to an Asynchronous Transfer Mode Virtual Path self-curing ring technology, using ATM multicast and SDH management path with an algorithm to provide a quick diagnose of the fault and a quick inform capability to realize the quick self-curing fault of the ring net, so as to guarantee to finish the self-curing within 250N microseconds when fault accurse, N is the number of points on the ring. When fault expelled, ring net will be self-recover or undercontrol order.

Description

Asynchronous transferring virtual channel self-healing ring
The present invention relates to a kind of ATM VP (asynchronous transferring virtual channel) Self-healing Rings technology.ATM VP Self-healing Rings is joined end to end by the SDH link by an optical line terminal OLT and a plurality of optical network unit ONU and forms a closed-loop.When the communication node on optical fiber link or the looped network broke down, each relevant each ONU can realize state exchange according to the work at present state on the ATM VP Self-healing Rings in 250 * N microsecond time, thereby guaranteed the upward normal operation of each ONU business of ring.ATM VP Self-healing Rings technology has improved the reliability of network, has strengthened the survival ability at networking.
Looped network is a kind of important networking model, under certain condition, looped network presents very high economy, in addition, for sudden very strong data communication, if adopt suitable technique, as the token ring bussing technique, the looped network bandwidth resources can be utilized better, obtain the statistical gain higher than other topological structure.But there is no hiding it, compares with other topological structure, and looped network reliability is poor.For example, for Single-ring network, when certain communication node breaks down on last a certain section link occurs fault of ring or the ring, will cause all the communication node service disconnection on the whole ring.
Improving effective way of looped network reliability is to adopt the looped network self Healing Technology.Utilize the looped network self Healing Technology can increase substantially reliability, the availability of looped network.In self-healing looped network, though certain node or certain section link occurs fault on the ring, also can by self Healing Technology to malfunctioning node and or faulty link realize bypass, thereby ensure normally carrying out of (other) each node traffic.
The looped network self Healing Technology is perfect substantially in traditional SDH technical system, as two fine UPSRs, two-fibre two-way multi-section rotating loop, four-fiber bidirectional multiplex section rearrangement ring and two-fibre two-way multi-section rotating loop etc., these technology are through years of development and constantly perfect, comparatively ripe, the self-healing time is satisfied the requirement less than 50ms, so the SDH self-healing looped network is widely used in communication network.
For the SDH technology, ATM is a brand-new technology, be mainly used in the backbone network at present, and how backbone network does not adopt ring topology and adopt fully connected topology, so it is not enough for attention of ATM looped network self Healing Technology and research before this, but along with the continuous maturation of atm technology and declining to a great extent of price, atm technology just progressively extends to local network and Access Network, and ring topology is used more and more.Therefore the self Healing Technology of ATMVP loop network progressively comes into one's own with regard to coming on the referred agenda.
Because ATM provides multicast functionality, so the self-healing of ATM looped network is simpler than the self-healing of SDH looped network in theory, as long as, just can set up an ATM VP looped network with one group of ATM switch with self-healing function by suitable connection configuration.There is the self-healing overlong time in this self-healing scheme that realizes by software merely, can not satisfies the communication network 50ms restriction of self-healing time, so this self-healing scheme there is no too big meaning in practice but regrettably.
In self Healing Technology, topmost constrained parameters are the time, promptly for the restriction of self-healing time, in communication network, be 50ms for the restriction of self-healing time, switch if can in 50ms, finish self-healing, then to not exerting an influence substantially at line service, if the self-healing time is oversize, then can should avoid producing bigger influence in line service especially real-time interactive service such as voice service as far as possible.
Because the restriction of self-healing time, merely depended software realizes that self-healing is unworkable, merely relies on hardware and realizes then causing the increase of hardware complexity and the increase of hardware cost, and is also improper.
The objective of the invention is to solve the rapidly self-healing problem of ATM VP looped network with the cost of minimum, guarantee when communication node breaks down on optical fiber link or the ring, ATM VP looped network (50ms) in an official hour is finished the self-healing reversed process, thereby drops to minimum to the influence of business fault.
Above-mentioned purpose of the present invention cooperates the translation with VPI simultaneously by comprehensive utilization ATM multicast functionality (Multicast) and SDH management channels, and is auxiliary with the hardware switching and realize.
Superiority of the present invention has been to make full use of the abundant administration overhead passage that the multicast functionality that atm technology possessed (Multicast), routing iinformation interpretative function and SDH are provided, by the perfect and careful algorithm of a cover, the quick diagnosis of fault and quick notification capabilities are provided, with the cost of minimum, realized the rapidly self-healing of looped network under fault condition with the fastest speed.In ATM VP Self-healing Rings, can guarantee to occur to and finish the self-healing switching time and do not surpass at interval 250 * N microsecond from fault, wherein N is the ONU node number on the ring.Utilize ATM VP Self-healing Rings technology, can improve the survival ability of network, strengthened the reliabilty and availability of network, for Virtual network operator provides high quality services that basic material guarantee is provided to the client.
Fig. 1 is the physical topological structure figure of ATM VP self-healing looped network structure;
Fig. 2 is ATM VP Self-healing Rings logic star network figure;
Fig. 3 is the structural map of ATM VP self-healing looped network;
Fig. 4 is the more ordinary construction of ATM VP Self-healing Rings;
Fig. 5 shows the self-healing of OLT single board default;
Fig. 6 shows single fiber or the two fine fracture defect self-healing between OLT and the ONU;
Fig. 7 shows the self-healing of ONU node failure and handles;
Fig. 8 shows self-healing recovery.
Below in conjunction with accompanying drawing the present invention is described in more detail.
The physical topological structure of ATM VP self-healing looped network joins end to end by two opposite ATM/SDH links of direction between OLT and each ONU and forms the sealing looped network shown in figure one.Being connected between OLT and the ONU is that Virtual Channel (VP) connects, and usually, in Access Network or local network, OLT is connected the permanent virtual connections (PVC) of adopting with this VP between the ONU more.Logically, the star topology of formation shown in figure two between OLT and the ONU.Be connected by two two-way VP links between OLT and each ONU, when two-way VP link occurs fault wherein, just can communicate by an other two-way VP link, avoided communication disruption, thereby improved the survival ability of network, this is the basic functional principle of ATM VP self-healing looped network.
In the present invention, OLT is the starting point of looped network, also is the terminal point of looped network.OLT is responsible for the management and the configuration of looped network, is responsible for outer cell importing of ring and the interior cell of ring simultaneously and derives.
In the present invention, ONU is responsible for the importing and the derivation of this node cell, and the ATM cell that will not belong to this node simultaneously is pellucidly to this ring downstream node relaying.
In the present invention, for going into to encircle cell, OLT sends these cells from two rightabouts (figure one, clockwise with counterclockwise) by two ports simultaneously to target ONU node.In OLT, because the ATM switching network provides the support to multicast (Multicast) function, only need just can realize that advancing 2 into ring cell 1 goes out function by the appropriate software setting, finish the task of sending cell simultaneously from two rightabouts to target ONU.
In the present invention, on OLT → ONU direction, need to set up unidirectional VP along clockwise direction with counter clockwise direction respectively in advance and be connected; On ONU → OLT direction, need too to be connected along setting up unidirectional VP with counter clockwise direction clockwise respectively in advance.Need for the self-healing algorithm, the vpi value that different directions VP connects must be different.For example in ATM VP Self-healing Rings, the vpi value that connects for different directions VP can adopt following corresponding relation:
VPI ONU→OLT=VPI OLT→ONU+2 n-1?????????(1)
Wherein, VPI OLT → ONU<2 N-1, n is the effective length of vpi field, when n was 8, equation 1 just became:
VPI ONU→OLT=VPI OLT→ONU+128??????????(2)
Can be as required between each ONU and the OLT, set up many VP and connect, but in the ordinary course of things, only need set up a VP between each ONU and the OLT and be connected and get final product.Among the figure three between OLT and the ONU VP be connected vpi value and see Table one.
In the present invention, deliver correct destination in order to go into to encircle cell, in OLT, need carry out the VPI translation to going into to encircle cell according to the pairing vpi value of purpose ONU node, translation process is referring to table two.When ATM cell goes out to encircle in the same ring, also need ring cell VPI translation, translation process is referring to table three and table two.
In the present invention, go into to encircle cell through after going into to encircle the VPI translation, arrive target ONU node along clockwise direction and counter clockwise direction respectively simultaneously, target ONU node receives these cells simultaneously from two receiving ports respectively.
In the present invention,, reduce design complexity, will guarantee under normal circumstances in the design that all business boards on each ONU are are all only received and dispatched on a ring for simplified design.For example in figure four, all business boards on the ONU1 receive only the ATM cell of receiving from interior articulating that belongs to ONU1, all business boards on the ONU1 are all from the interior environment-development unit of delivering letters, and all business boards on the ONU2 receive only the ATM cell that belongs to ONU2 that receives from outer shroud, and all business boards on the ONU2 all send cell from outer shroud.For simplicity, corresponding to figure four, ring is the building ring of ONU1 in claiming, and outer shroud is the standby ring of ONU1, and in contrast, ring is the standby ring of ONU2 in claiming, and outer shroud is the building ring of ONU2.
In the present invention, each ONU can independently select building ring, also can on purpose select building ring under the control of OLT.When several ONU are evenly distributed on the different building rings, system will provide 1.5 times of power system capacities to looped network speed.
In the present invention, be in ONU under the normal operating conditions and receive the cell that belongs to this node from building ring, and pass through the UTOPIA interface and deliver to each business board respectively, receive the professional cell that is produced by each business board of this node by the UTOPIA interface simultaneously, after these cells carry out the VPI translation, from building ring, send to downstream node.On standby ring, after each ONU receives the cell that belongs to this node, deliver to each business board by the UTOPIA interface equally, but do not have business board to be operated on these UTOPIA interfaces, so these cells finally are dropped.For the ATM cell that does not belong to this node, no matter at building ring still on standby ring, all need with its pellucidly (vpi/vci value of cell remains unchanged) transmit downstream.
For example in figure four, OLT is that 1,2,3,4 and 5 cell is respectively along sending in the ring clockwise and counterclockwise with vpi value.In the counterclockwise direction, cell arrives ONU1 by outer shroud, because on encircling in ONU1 is operated in, so, on outer shroud, vpi value will be abandoned by ONU1 by 1 cell, and also not insert new cell, for other cell that does not belong to ONU1 is that vpi value is 2,3,4 and 5 cell, transmits to ONU2 pellucidly.
Along outer shroud, vpi value is 2,3,4 and 5 ATM cell arrival ONU2, because ONU2 is operated on the outer shroud, so ONU2 will be 2 cell from outer shroud reception vpi value, and these cells are delivered on the corresponding service plate by the UTOPIA interface, simultaneously the cell (vpi value after the conversion is 2+128) after carrying out the VPI conversion that each business board produced on this ONU node is sent along outer hoop ONU3, for other vpi value is 3,4 and 5 ATM cell, and ONU2 transmits to ONU3 pellucidly by outer shroud.On outer shroud, other each ONU node working condition is identical, is 130,131 and 133 cell to OLT transmission vpi value up to ONU5.On interior ring, the working condition of each ONU also is like this.
In the present invention, the quick diagnosis of fault and quick announcement are the prerequisites that realizes rapidly self-healing.In the present invention, the quick diagnosis information of fault is by providing by ATM/SDH PHY chip.RALRM (Receive Alarm) output is arranged in the PHY of ATM/SDH chip,, can detect in real time and have or not warning information by this output.Warning information shows that effectively then the optical fiber link of homonymy is unavailable, need carry out self-healing and switch.
In the present invention, the self-healing process involves the ONU building ring and switches problem, so will realize rapidly self-healing, just must realize the quick announcement of fault, so that allow each relevant ONU node carry out switching of building ring.
In the present invention, the quick announcement function of fault is to realize by D (D1-D3, the D4-D12) passage that ATM/SDH PHY chip provides.After detecting the fault generation, utilize any one passage such as D1 in the D passage, transmit a 8bit (as 01111110) or one group of 8bit coded message to downstream node.After downstream node receives specific coded message, that this information is to its downstream node relaying, ultimate up to OLT.By aforesaid mode, can realize the quick announcement of fault.Finishing the needed maximum duration of fault notification is 250 * N microsecond, and be 125 * N microsecond average time, and wherein N is the ONU node number on the looped network.When 64 ONU nodes are arranged on the looped network, corresponding worst case, the needed time of fault notification is 16 milliseconds, much smaller than 50 milliseconds time restriction.The time of finishing fault notification is the self-healing switching time just.
In the quick diagnosis that solves fault with after announcing fast, just can realize rapidly self-healing, be example with the optical fiber link fault below, the process of self-healing is described.
For example in figure six, the fibercuts between OLT and the ONU, the last corresponding ATM/SDH PHY chip of ONU1 produces RALRM information, shows that the optical fiber link between ONU1 and the OLT is unavailable.After detecting ATM/SDH PHY chip and producing effective warning information, ONU1 wants:
1) makes loop back processing being;
2) be ONU2 issue fault notification in the counterclockwise direction to downstream node by the D passage;
So-called loopback will be forwarded to outer shroud pellucidly from the ATM cell that does not belong to ONU1 that interior articulating is received exactly.And, after interior articulating receipts, be submitted to each veneer of ONU1 node by UTOPIA for the node that belongs to ONU1, and by the ATM cell that each business board of ONU1 node is produced, will send by outer hoop ONU2 node.
When taking above-mentioned loopback measure, ONU1 also must be by outer hoop by the generation of D passage to ONU2 announcement fault.ONU2 at first will be to ONU3 relaying fault notification behind the fault notification that receives the ONU1 transmission, and interior simultaneously ring is set to the ONU2 building ring.The course of work of ONU3, ONU4 and ONU5 is identical therewith.
Through after the said process, form the looped network of a sealing once more, looped network has following feature:
1) except that ONU1, the building ring of all other ONU is interior ring;
2) ONU1 is operated on interior ring and the outer shroud simultaneously;
Figure seven provides more general troubleshooting structure.Shown in figure seven, after self-healing is switched, form two independently looped networks of sealing.Figure five has provided the self-healing processing that OLT goes up single board default.
In the present invention, after fault is got rid of, need carry out self-healing recovery, promptly return to network state originally.According to the difference of application scenario, self-healing recovery can select carry out appropriate opportunity under the control of turnkey console, also can be by being decided in its sole discretion by relevant ONU under suitable, as can to avoid the self-healing vibration algorithm prerequisite taking.
After figure eight gets rid of corresponding to fault among the figure seven, the self-healing recovery situation.
The present invention has the following characteristics:
One, system reliability height
By self Healing Technology, can carry out bypass to faulty link and/or malfunctioning node, it is isolated, guarantee other node operate as normal on the looped network.The looped network self Healing Technology has strengthened the survival ability of network greatly, has improved the reliability of network.
Two, provide the rapidly self-healing ability
In the present invention, owing to made full use of the administration overhead passage that multicast functionality that atm technology provided and SDH technology are provided, when fault takes place, need not high layer software participates in, utilize the VP that builds up in advance to connect, the administration overhead passage that provides by SDH is finished fault and is announced fast, can be implemented in to finish self-healing within 250 * N microsecond and switch, and has satisfied the requirement of communication network for the 50ms self-healing time.
Three, realize simple and fast
When fault took place, the self-healing process need not high layer software fully and participates in, and turnkey console need not to change any parameter in the recovery process of in the self-healing process and fault eliminating back except changing the register corresponding to network state after fault takes place.Appendix: ATM:Asynchronous Transfer Mode, asynchronous transfer mode VP:Virtual Path, Virtual Channel SDH:Synchronous Digital Hierarchy, Synchronous Digital Hierarchy OLT:Optical Line Terninal, optical line terminal ONU:Optical Network Unit, optical network unit VPI:Virtual Path Identifier, Virtual Path Identifier PVC:Permanent Virtual Connection, permanent virtual connects UTOPIA:VCI:Virtual Connection Identifier, virtual connections identifier ATM PHY:ATM Physics Layer, the ATM physical layer
Among table one: the figure three between OLT and the ONU VP be connected vpi value
????OLT ????ONU1 ?????ONU2 ?????ONU3 ?????ONU4 ????ONU5
????→ ??← ????→ ??← ????→ ??← ????→ ??← ????→ ??←
Port x ????1 ??129 ????2 ??130 ????3 ??131 ????4 ??132 ????5 ??133
Port y ????1 ??129 ????2 ??130 ????3 ??131 ????4 ??132 ????5 ??133
Annotate: → expression OLT is to the connection of ONU direction, and ← expression ONU is to the connection of OLT direction;
Table two: corresponding with figure three go into to encircle the VPI translation
Target ONU node Original vpi value Vpi value after the translation
????ONU1 ????X1∈[0..2 n-1] ????1
????ONU2 ????X2∈[0..2 n-1] ????2
????ONU3 ????X3∈[0..2 n-1] ????3
????ONU4 ????X4∈[0..2 n-1] ????4
????ONU5 ????X5∈[0..2 n-1] ????5
Annotate: upward X1, X2, X3, X4 and X5 are unequal mutually in the table.
Table three, corresponding with figure three go out to encircle the VPI translation
Source ONU node Original vpi value Vpi value after the translation
????ONU1 ????1 ????X1∈[0..2 n-1]
????ONU2 ????2 ????X2∈[0..2 n-1]
????ONU3 ????3 ????X3∈[0..2 n-1]
????ONU4 ????4 ????X4∈[0..2 n-1]
????ONU5 ????5 ????X5∈[0..2 n-1]
Annotate: upward X1, X2, X3, X4 and X5 are unequal mutually in the table.

Claims (11)

1. ATM VP Self-healing Rings, being joined end to end by the SDH link by two kinds of different functional units of optical line terminal OLT and optical network unit ONU forms the ring of a sealing.An OLT and a plurality of ONU are arranged on the ring.OLT is responsible for the management and the configuration of ATM VP self-healing looped network, is responsible for the importing of the outer cell of ring and the derivation of the interior cell of ring simultaneously.Each ONU is responsible for derivation, the importing of this node cell on the ring, is responsible for simultaneously all cells that does not belong to this node relaying to downstream node.It is characterized in that said ATM VP Self-healing Rings comprises:
VP connection strategy between a kind of OLT and the ONU;
VP is connected the VPI allocation strategy between a kind of OLT and the ONU;
A kind ofly go into to encircle the cell forwarding algorithm;
A kind of ONU mode of operation;
A kind of hard fault detection algorithm;
A kind of hard fault notifying mechanism;
Algorithm is switched in a kind of self-healing;
A kind of detection algorithm of soft fault;
A kind of soft fault processing policy;
A kind of fault recovery algorithm;
2. according to the ATM VP Self-healing Rings of claim 1, it is characterized in that, VP method of attachment between said OLT and the ONU is, OLT sets up two-way VP with target ONU respectively by two ports simultaneously and is connected, and these two two-way VP connect all parameters (as vpi/vci value and various flow parameters etc.) and have consistency completely.
3. according to the ATM VP Self-healing Rings of claim 1 or claim 2, it is characterized in that VP is connected the VPI allocation strategy and is VPI between said OLT and the ONU OLT → ONU≠ VPI ONU → OLT, VPI wherein OLT → ONUThe VP connection identifier (CID of expression OLT on the ONU direction, VPI ONU → OLTThe VP connection identifier (CID of expression ONU on the OLT direction.
4. according to the ATM VP Self-healing Rings of claim 1, it is characterized in that, saidly go into to encircle the cell forwarding algorithm and be, when cell enters OLT outside the ring, OLT utilizes ATM multicast (Multicast) function, sets up the port that two-way VP is connected with target ONU node from two simultaneously after these cells are duplicated and mails to same target ONU node.
5. according to the ATM VP Self-healing Rings of claim 1, it is characterized in that, said ONU mode of operation is, when being in normal operating conditions, ONU receives the ATM cell that upstream node sends, all ATM cell that do not belong to this node (are not promptly changed the vpi/vci value of these cells) pellucidly to be transmitted to downstream node, and the ATM cell that will belong to this node is submitted to the corresponding service plate by the UTOPIA interface, and receive the ATM cell of submitting by this node business board, and it is sent to downstream node by the UTOPIA interface.When being in the loopback operating state, ONU receives cell from a ring, all ATM cell that do not belong to this node are transmitted pellucidly to downstream node by the another one ring, the ATM cell that will belong to this node is submitted to business board by the UTOPIA interface, and is sent by another one hoop downstream node by the cell that business board is submitted.
6. according to the ATM VP Self-healing Rings of claim 1, it is characterized in that, said hard fault inspection algorithm is, by suitable setting, the physical layer alarm signal that directly utilizes the ATM/SDH physical chip to provide is realized the fast detecting of fault, in case alarm signal effectively just illustrates hard fault and takes place that the communication link of homonymy is unavailable, need carry out self-healing treatment.
7. according to the ATM VP Self-healing Rings of claim 1 or claim 6, it is characterized in that, said hard fault notifying mechanism is, when ring is gone up some ONU node detection when fault takes place, generate the hard fault notice message immediately and insert transmission downstream in the heteropleural SDH D passage, ONU node on the same ring need terminate the downstream node relaying of this hard fault notice message on same ring after receiving the hard fault notice message up to the OLT place.
8. according to the ATM VP Self-healing Rings of claim 1, it is characterized in that, algorithm is switched in said self-healing, the ONU node that detects the hard fault generation places this node the loopback operating state immediately, downstream ONU node on same ring sends the hard fault notice message simultaneously, after downstream ONU node is received the hard fault notice message from an articulating, must guarantee that each business board on the ONU is received and dispatched ATM cell from another ring.
9. according to the ATM VP Self-healing Rings of claim 1, it is characterized in that, said soft defect detection mechanism is, receive ATM cell from both direction simultaneously, some performance parameters to physical layer and ATM layer are added up and are compared, if find a parameter or some parameters bigger departing from arranged, then enter the soft fault processing procedure.
10. according to the ATM VP Self-healing Rings of claim 1, it is characterized in that said soft fault processing policy is when detecting the soft fault generation, to the turnkey console announcement, and to carry out building ring and switch.So-called building ring is switched, and just is meant that ONU goes up the transmitting-receiving of business board cell and is switched on another ring from a ring.
11. ATM VP Self-healing Rings according to claim 1, it is characterized in that, said self-healing recovery algorithm is, after fault is got rid of, the ONU node adjacent with former fault point detect corresponding alarm signal invalid after, to open the loopback passage, and select building ring randomly, the operating state of other each ONU node is constant.For fear of the self-healing vibration, self-healing recovery can carry out under software control.For the influence that self-healing recovery is caused drops to minimumly, self-healing recovery can be chosen in traffic carrying capacity to carry out after a little while.
CN 01104157 2001-02-22 2001-02-22 Asynchronous transferring virtual channel self-healing ring CN1371201A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004051934A1 (en) * 2002-12-04 2004-06-17 Huawei Technologies Co., Ltd. A method of realizing protecting switching on packet double-ring network
CN100373866C (en) * 2004-12-24 2008-03-05 中兴通讯股份有限公司 Method of network fault recovery crossing over connections in multiple domains
CN101807950A (en) * 2010-02-25 2010-08-18 福建三元达通讯股份有限公司 Method for realizing loop self-healing function of repeater system
CN101192959B (en) * 2006-11-28 2011-04-20 中兴通讯股份有限公司 A recovery method for multicast service connection in automatic switching optical network

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004051934A1 (en) * 2002-12-04 2004-06-17 Huawei Technologies Co., Ltd. A method of realizing protecting switching on packet double-ring network
CN100373866C (en) * 2004-12-24 2008-03-05 中兴通讯股份有限公司 Method of network fault recovery crossing over connections in multiple domains
CN101192959B (en) * 2006-11-28 2011-04-20 中兴通讯股份有限公司 A recovery method for multicast service connection in automatic switching optical network
CN101807950A (en) * 2010-02-25 2010-08-18 福建三元达通讯股份有限公司 Method for realizing loop self-healing function of repeater system

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