WO2006034614A1 - Procede de protection rapide de reseau boucle optique - Google Patents

Procede de protection rapide de reseau boucle optique Download PDF

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Publication number
WO2006034614A1
WO2006034614A1 PCT/CN2005/000321 CN2005000321W WO2006034614A1 WO 2006034614 A1 WO2006034614 A1 WO 2006034614A1 CN 2005000321 W CN2005000321 W CN 2005000321W WO 2006034614 A1 WO2006034614 A1 WO 2006034614A1
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Prior art keywords
signaling
transparent channel
overhead
network element
byte
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PCT/CN2005/000321
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English (en)
French (fr)
Inventor
Desheng Sun
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Zte Corporation
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Priority to EP05729106.4A priority Critical patent/EP1796296A4/en
Publication of WO2006034614A1 publication Critical patent/WO2006034614A1/zh

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0278—WDM optical network architectures
    • H04J14/0283—WDM ring architectures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/03—Arrangements for fault recovery
    • H04B10/032—Arrangements for fault recovery using working and protection systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/27—Arrangements for networking
    • H04B10/275—Ring-type networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0254—Optical medium access
    • H04J14/0272—Transmission of OAMP information
    • H04J14/0273—Transmission of OAMP information using optical overhead, e.g. overhead processing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/08—Intermediate station arrangements, e.g. for branching, for tapping-off
    • H04J3/085—Intermediate station arrangements, e.g. for branching, for tapping-off for ring networks, e.g. SDH/SONET rings, self-healing rings, meashed SDH/SONET networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/06—Management of faults, events, alarms or notifications
    • H04L41/0654—Management of faults, events, alarms or notifications using network fault recovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation

Definitions

  • the present invention relates to the field of optical transmission, and in particular to a protection switching method for an optical transmission ring network. Background technique
  • ITU Recommendation ITU-T.841 “Classification and Characteristics of SDH Network Protection Structures” provides a detailed description of the SDH/SONET optical transmission ring network self-healing function. Among them, the two-fiber or four-fiber bidirectional multiplex section shared protection ring (abbreviated as BLSR in English) is the most important self-healing mode.
  • Recommendation ITU-T X.841 specifies that SDH I SONE carries signaling information in the multiplex section overhead K1 and K2 bytes of its transmitted frame.
  • Recommendation ITU-TG.841 also specifies that the protection switching start-to-protection switching completion interval should be less than 50 ms to minimize service impairments.
  • FIG. 1 is a structural diagram of processing protection switching of an optical transmission network element according to the recommendation of G.841.
  • the units involved in the transmission network element protection switching process include an east and west signaling receiving or alarm detecting unit, an east and west signaling sending unit, a protocol processing unit, and a service cross unit.
  • the signaling receiving or alarm detecting unit detects the new alarm or the new signaling
  • the alarm or signaling information is transmitted to the protocol processing unit, and the protocol processing unit generates signaling according to the protocol principle, and transmits the signaling to the signaling sending unit, and finally Signaling is sent out from the optical port.
  • the protocol processing unit generates signaling according to the protocol principle, and also generates a corresponding service cross relationship, and sends it to the service cross unit to perform service crossover.
  • the protection switching process is divided into an alarm detection or signaling reception process, a protocol processing process, a signaling transmission process, and a cross-unit processing process.
  • the signaling receiving and alarm detecting unit of the network element 1 detects the alarm and notifies the protocol processing unit that the protocol processing unit generates new signaling and The signaling unit sends the next network element.
  • the process of protection switching can be simplified to the process shown in Figure 2B.
  • the transmission time of the signalling in the fiber section in equation (1) is the signalling processing time.
  • detecting the alarm time which is the protocol processing time
  • ⁇ is the signaling processing time
  • the protocol signaling is processed from the receiving protocol processing unit, and finally sent through the sending unit, and the whole process is sequentially completed.
  • the entire processing time is ⁇ / in equation (1).
  • the Chinese patent No. 98113149.2 proposes a method to speed up protection switching.
  • the basic principle of the method is to shorten the processing time of the cross unit, that is, in the formula (1). It can be seen from Fig. 2 ⁇ and formula (1) that only the processing time of the intersecting unit of the last network element affects the protection switching time of the entire ring network, so the method improves the effectiveness. It is very limited.
  • the patent artificially strips the protection switching protocol processing unit into two parts, the signaling comparison unit and the protocol processing unit, which is complicated to handle and introduces a large risk.
  • the signaling t: ⁇ must add a lot of logical judgments to the unit, and the increase of the logical judgment will inevitably weaken the improvement effect. Summary of the invention
  • the method for quickly protecting an optical transmission ring network includes the following steps: Step 1: construct a transparent channel through the network management layer;
  • Step 2 Each network element alarm detection module detects the line condition in real time, and the signaling detection unit detects the change of the ill signaling byte and the transparent channel overhead byte in real time;
  • Step 3 If an alarm or a network management switchover command is detected, perform step 4; if a change of the transparent channel overhead byte is detected, perform step 5; if a change of the signaling byte is detected, perform step 6; 4.
  • the overhead byte is sent; or, according to the protocol signaling information to be sent, the simplified signaling is generated and sent in the overhead byte corresponding to the transparent channel. Perform step seven;
  • Step 5 The network element that detects the change of the transparent channel credit byte is not processed if the current state is the switching state; if the current state is the idle state or the punch-through state, the overhead byte is used as the corresponding
  • the signaling bytes received by the direction signaling detecting unit are sent to the protocol processing module for processing; or, if the received compact signaling, the related received signaling information is generated and sent to the protocol processing module for processing according to the reduced signaling.
  • Step 6 If the received signaling indication is that the destination is a short-path request of the network element, the network element is opposite to receiving the short-path request after the protocol processing is completed and the east-west transparent channel is disconnected.
  • the interleaving unit copies the signaling byte to be sent to the overhead byte corresponding to the transparent channel and sends it; or generates the reduced signaling according to the information to be sent and writes the overhead byte corresponding to the transparent channel. Sent in. Otherwise, according to the G.841 protocol, if the alarm disappears or the network management switchover command is revoked, the two switching NEs automatically write the default signaling pattern of the protection switching protocol to the transparent channel, and re-orientate the east-west direction. After the transparent channel is turned on, return to step 2; otherwise, return directly to step 2.
  • the method of creating a transparent channel in the above step 1 is: according to the multiplexing section of each network element segment
  • two available overhead bytes are specified in the eastbound segment and the westbound segment of the network element, and the east-west segment is turned on by the overhead crossover unit.
  • the method for constructing the transparent channel may also be: according to the multiplex section overhead usage of each network element segment, sequentially designating an available overhead byte in the eastbound segment and the westbound segment of the network element, and The east-west is turned on to the channel where the overhead byte is located.
  • the optical transmission ring network fast protection method includes the following steps:
  • Step 1 Construct a transparent channel through the network management layer
  • Step 2 Each network element alarm detection module detects the line condition in real time, and the signaling detection unit detects the change of the signaling byte and the transparent channel ⁇ pin byte in real time;
  • Step 3 If an alarm or a network management switchover command is detected, step 4 is performed; if a change of the transparent channel overhead byte is detected, step 5 is performed; if a change of the signaling byte is detected, step 6 is performed;
  • Step 4 The network element that detects the alarm or the network management switchover command, after the protocol processing is completed, the overhead cross unit disconnects the east-west transparent channel, generates the thinned signaling according to the signaling information to be sent, and writes the overhead word corresponding to the transparent channel. Sent in the section;
  • Step 5 The network element that detects the change of the JP pin of the transparent channel is not processed if the current state is the switching state; if the current state is the idle state or the punch-through state, according to the thin signaling, The signaling information received by the t-direction is sent to the protocol processing module for processing.
  • Step 6 If the received signaling indication is a short-path request of the destination network element, the network element requests and receives the short-path request after the protocol processing is completed and the east-west transparent channel is disconnected. In another direction, the overhead cross unit generates the reduced signaling according to the information to be sent and writes the overhead byte corresponding to the transparent channel;
  • Step 7 If the alarm disappears or the network management switchover command is revoked, the two switching network elements automatically write the default signaling pattern of the protection switching protocol to the transparent channel, and then re-turn the east-west transparent channel to return to step 2; No Belle returns directly to step two.
  • the method proposed by the present invention can be used for the optical transmission ring network, and other network elements except the fault detection network element can receive the transparent transmission channel after the faulty network element sends out several optical transmission delays after the agriculture is requested. Request information passed. After the transparent channel is established, the network element that monitors the alarm writes the information to the transparent channel. Since the transparent channel is basically a ring type, the information written by the network element monitoring the alarm will be transmitted according to the optical catch. Therefore, after monitoring other network elements downstream of the alarm network element, the information can be detected after several optical transmission delays. Therefore, the final calculation switching time of the protection method proposed by the present invention will be:
  • Equation (2) is the number of network elements of the optical transmission ring network, t 0 , , t 2 , t 3 , t 4 , and the description are the same as in equation (1).
  • the protection switching time processed according to the method described in G.841 is 82 milliseconds. . If the service cross-unit of a network element is removed, t4 is processed, and the method for the application number is 98113149.2, and the switching time is 79 milliseconds. The protocol processing time t2 of the middle 6 network elements is removed, and the patent method switching time of patent number 5,636,205 is 64 milliseconds. With this patented method, according to formula (2), the protection switching time is only 28 milliseconds. It can be seen that the method proposed by the invention has better technical effects.
  • FIG. 1 is a schematic diagram of a processing protection switching structure of an optical transmission network element according to G.841;
  • FIG. 2A is a schematic diagram of a two-fiber bidirectional multiplex section shared protection ring for protecting eight network elements;
  • FIG. 2B is a network of FIG. 2A according to G. 841 suggests a schematic diagram for calculating the protection switching time;
  • FIG. 3A is a schematic diagram of a protection switching structure of an optical transmission network element adopting the method of the present invention
  • FIG. 3B is a schematic diagram of the network configuration transparent channel of FIG. 2A;
  • FIG. 4 is a schematic diagram of a ring network including N network elements calculating a protection switching time according to the method of the present invention
  • FIG. 5 is a flow chart of the method proposed by the present invention. detailed description
  • FIG. 4 is a schematic diagram of the protection switching time calculation of the protection method proposed by the present invention.
  • FIG. 3A is a diagram of a protection switching structure of an optical transmission network element using the method of the present invention.
  • a credit cross processing unit is added, and the overhead cross unit turns on or off the transparent channel of the frozen west according to the instruction of the protocol processing unit, according to the information notified by the protocol processing unit.
  • the transparent channel writes specific information and the like.
  • FIG. 3B is a schematic diagram of the network of FIG. 2A after the transparent channel is configured. As shown in FIG. 3B, on the basis of FIG. 2A, two transparent channels that surround the entire transport ring network are disposed. And, through the overhead cross unit, the overhead bytes transmitted by the transparent channel in the idle state are guaranteed. To protect the default signaling pattern of the switching protocol.
  • Figure 5 is a flow chart of the method proposed by the present invention.
  • the following is an example in which the network between the network elements 1 and 8 in the network shown in FIG. 3B is faulty and the fault disappears.
  • the two overhead byte transparent channels of the solution of the present invention are described in detail with reference to FIG. 3A, FIG. 4 and FIG.
  • Step 1 at the network management layer, determine the available overhead of the fiber segments such as network elements 1-8, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8. . Then, through the overhead cross unit, the network element 1 turns on the available overhead of the 1-8 and 1-2 fiber sections. In the same way, NEs 2, 3, 4, 5, 6, 7, 8 will be 1-2 and 2-3, 2-3 and 3-4, 3-4 and 4-5, 4-5 and The available overhead of fiber sections such as 5-6, 5-6 and 6-7, 6-7 and 7-8 is turned on. Finally, a transparent channel surrounding the entire transmission ring network shown in Fig. 3B is constructed. In addition, in the process of being turned on, the network element sets the overhead byte transmitted by the transparent channel through the overhead cross unit to the default signaling pattern of the protection switching protocol, for example, 0x0ff0.
  • the network element sets the overhead byte transmitted by the transparent channel through the overhead cross unit to the default signaling pattern of the protection switching protocol, for example, 0x0ff0.
  • the network element 1 detects the alarm between the network element 1-8 segments, and notifies the protocol processing unit of the alarm, and the protocol processing unit generates a signaling request, where the K1 word sent to the network element 1-2 fiber direction is sent.
  • the request type indicated by the section is a invalidation request, and the destination network element is 8. Go to the next step.
  • the network element 2 detects that the 1-2 direction transparent channel overhead byte changes.
  • the network element 3 detects that the 2-3 transparent channel overhead byte has changed.
  • the same network element 4, 5, 6, 7 and other network elements have also detected such changes. Go to the next step.
  • step 5 the network element 2 is currently in a non-switching state.
  • the transparent channel overhead bytes received in the 1-2 direction are sent to the protocol processing module as the K1 and ⁇ 2 signaling bytes received in the 1-2 direction, and the protection channel is punched through.
  • network elements 3, 4, 5, 6, and 7 are handled in the same way.
  • the network element 8 detects the protocol signaling in the direction of 7-8 (the signaling sent by the network element 7 after the processing in step 5) changes.
  • the signaling byte K1 indicates that the destination is a network element, and the request type is a failure request, so the network element 8 immediately performs bridge switching.
  • step 7 while the network element 1 detects the alarm, the network element 8 also detects the alarm of the 1-8 sector. Therefore, the network element 8 and the network element 1 perform the above processing at almost the same time.
  • the processing mode of the network element 8 is the same as that of the network element 1. The only difference is the signaling transmission direction of the network element 8, and the transparent channel overhead byte is transmitted along the direction 8 The direction of -7-6-5-4-3-2-1 is opposite to the direction of the network element 1.
  • the network element 1 detects the signaling of the 1-1 direction (the signaling sent by the network element 2), and the signaling byte K1 indicates the purpose.
  • the request type is a invalidation request, so the network element 1 immediately performs bridge switching.
  • step 9 after the 1-8 segment alarm disappears, the network elements 1 and 8 automatically go to 1-2-3-4-5-6-7-8 and 8-7-6-5-4-3-2- Write the default signaling pattern of the protection switching protocol, such as OxOffO, in the transparent channel in the 1 direction, and re-energize the transparent channel between 1-2 and 1-8, 1-8 and 7-8.
  • Other treatments were performed in full compliance with G.841.
  • the specific implementation process of the present invention adopting an overhead byte transparent channel is different from the transparent channel adopting two overhead bytes in that the transparent channel information is transmitted.
  • the element needs to generate reduced signaling information according to the signaling information to be sent.
  • the network element that receives the transparent channel information needs to be restored to the protocol signaling information according to the received reduced signaling.
  • the combination of the source network element ID and the destination network element ID indicated by the network element 1 and the destination network element ID transmitted by the network element 1 in the 1-2 direction is the overhead corresponding to the transparent channel of the 1-byte protocol 1-2 direction.
  • Bytes are sent. For example, if the source network element of the signaling request is 1 and the destination network element is 8, the content of the byte is 0x18.
  • the network element 2 restores the corresponding K1 and ⁇ 2 according to the transparent channel overhead byte received in the 1-2 direction, and the request type defaults to the signal failure. And the K1 and ⁇ 2 signaling bytes received as 1-2 directions are sent to the protocol processing module for processing.
  • NE 1 and NE 8 do not process the received transparent channel overhead bytes. It can be seen from the above operation steps that the network elements 1 and 8 simultaneously detect alarms and generate protocol signaling and transparent channel overhead information, and the intermediate network elements 2, 3, 4, 5, 6, and 7 before receiving the changed protocol signaling. According to the information carried by the overhead bytes transmitted by the transparent channel in the two directions, the generated signaling is quickly generated and the protection channel is punched through, which is fast and efficient.
  • the main feature of the method of the present invention is to construct a transparent channel to quickly transmit request information without changing the original protection switching protocol processing unit, and the reliability is good.
  • the SDH/SONET network has a large amount of overhead available in its multiplex section layer. Compared with other methods described in the background art, this patented method has a low cost.

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Description

技术领域
本发明涉及光传输领域， 具体涉及光传输环网的保护倒换方法。 背景技术
光传输环网在电信领域已经得到广泛应用。国际电联 ITU-TG.841 号建议《SDH网络保护结构的分类和特性》对 SDH / SONET光传输 环型网络自愈功能进行了详细的描述。其中， 二纤或四纤双向复用段 共享保护环 （英文简称为 BLSR)是最主要的自愈方式。 ITU-TG.841 号建议规定 SDH I SONE 在其传送帧的复用段开销 K1和 K2字节承 载信令信息。 ITU-TG.841 号建议同时规定保护倒换启动到保护倒换 完成的时间间隔应该小于 50毫秒， 最大限度减少业务损伤。
一般说来， 当业务受损时间小于 50毫秒时， 可以满足绝大多数 业务质量要求。但是， 当光传输环网规模较大， 传输网元较多时， 保 护倒换时间很难保证 50毫秒。
图 1是光传输网元按照 G.841建议进行处理保护倒换结构图。如 图 Γ所示，传输网元保护倒换处理所涉及的单元包括东、西向信令接 收或告警检测单元、 东、西向信令发送单元、协议处理单元以及业务 交叉单元。 信令接收或告警检测单元检测到新告警或新的信令之后， 将告警或信令信息传送至协议处理单元，协议处理单元根据协议原理 生成信令， 并传送至信令发送单元， 最终将信令从光端口发送出去。 协议处理单元根据协议原理生成信令的同时，还将生成相应的业务交 叉关系， 并发送至业务交叉单元执行业务交叉。这样， 从一个传输网 元的角度看，保护倒换的处理过程分为告警检测或信令接收过程、协 议处理过程、 信令发送过程和交叉单元处理过程。 以图 2A所示的 8 网元传输环网为例说明按照 G.841建议进行处理的保护倒换时间计算 方法。 当附图 2A中的网元 1和网元 8之间区段发生故障， 网元 1的 信令接收和告警检测单元检测到告警，并通知协议处理单元，协议处 理单元产生新的信令并经信令发送单元向下一个网元发送。由于网元 1和网元 8同时检测到告警， 因此网元 1和网元 8的处理过程是总是 同时进行的。 这样， 保护倒换的过程可以简化为图 2B所示的过程。 如图 2B所示， 总的保护倒换时间为- T =∑T i0+ t4
Ti= i0+ ii + t3 + t3 (i = l，2",.，8) (1) 公式 （1 ) 中的 为信令在光纤区段的传输时间， 是收信令处理时 间或检测告警时间， 是协议处理时间， ^是发信令处理时间， 是 交叉单元处理时间。协议信令从接收到协议处理单元完成处理，最后 再经发送单元发送出去，整个过程是顺序完成的，整个处理时间就是 公式 （1 ) 中的 Γ/。
申请号为 98113149.2的中国专利提出了一种加快保护倒换的方 法。 该方法的基本原理在于縮短交叉单元的处理时间， 即公式 （1 ) 中的 。 结合图 2Α和公式 （1 )可以看出， 只有最后一个网元的交 叉单元处理时间影响整个环网的保护倒换时间，因此该方法的改进效 果非常有限。
专禾 U号为 5,636,205的美国专利提出一种加快保护倒换的方法， 该方法通过一个信令比较单元判断网元接收的信令字节，根据信令字 节中的目的标识决定是否旁路信令。该方法的主要目的是缩短协议处 理时间， 即公式 （1 ) 中的 t2。 相对申请号为 98113149.2的中国专利 而言， 该方法改进效果比较明显。但是， 改进效果取决于信令比较单 元的实现方法。如果该单元通过硬件方式实现， 则改进效果明显， 但 增加了成本。 如果通过软件实现， 则改进效果较小。不论采用何种实 现方式， 该专利人为地将保护倒换的协议处理单元剥离为信令比较单 元和协议处理单元两个部分，处理复杂且引入较大风险。要降低风险， 则信令 t:匕较单元必须增加许多逻辑判断，而逻辑判断的增加必然减弱 改进效果。 发明内容
本发明的目的在于提出简单、 可靠的光传输环网快速保护方法。 本发明的核心思想是：利用传输网络的可用复用段开销构建一透 明通道，各网元在接收信令请求之前通过透明通道判断网络的故障区 段， 并申艮据故障区段完成协议处理实现快速处理。
本发明提出的光传输环网快速保护方法， 包括下列步骤： 步骤一、 通过网管层构建透明通道；
步骤二、各网元告警检测模块实时检测线路状况，信令检测单元 实时检 ill信令字节和透明通道开销字节的变化； 步骤三、 如果检测到告警或网管倒换命令， 则执行步骤四； 如果 检测到透明通道开销字节的变化， 则执行步骤五； 如果检测到信令字 节的变化， 则执行歩骤六； 步骤四、检测到告警或网管倒换命令的网元，在协议处理完成后， 开销交叉单元断开东西向透明通道， 并将非故障方向的，待发送的信 令字节复制一份到透明通道对应的开销字节中发送； 或者，根据待发 送协议信令信息生成精简信令并写入透明通道对应的开销字节中发 送。 执行步骤七；
步骤五、检测到透明通道幵销字节变化情况的网元，如果当前状 态是倒换状态， 则不处理该开销字节；如果当前状态是空闲态或穿通 状态，则将该开销字节作为相应方向信令检测单元接收到的信令字节 送交协议处理模块处理； 或者， 如果接收的是精简信令， 则根据精简 信令，生成相关接收的信令信息送交协议处理模块处理。返回步骤二； 步骤六、如果接收到的信令指示是目的为本网元的短径请求，则 该网元在协议处理完成并断开东西向透明通道后，在与接收短径请求 相对的另一方向，开 肖交叉单元将待发送的信令字节复制一份到透明 通道对应的开销字节并发送； 或者，根据待发送信息生成精简信令并 写入透明通道对应的开销字节中发送。否则按照 G.841协议进行处理； 步骤七、如果告警消失或网管倒换命令撤销， 则两个倒换网元自 动向透明通道中写入保护倒换协议的缺省信令码型，并重新将东西向 透明通道导通后返回步骤二； 否则直接返回步骤二。
~ 上述步骤一中抅建透明通道的方法为：根据各网元区段的复用段 开销使用情况，依次在网元东向区段和西向区段指定两个可用开销字 节， 并通过开销交叉单元将东西向该开销字节所在通道导通。
另外，构建透明通道的方法也可以是： 根据各网元区段的复用段 开销使用情况，依次在网元东向区段和西向区段指定一个可用开销字 节， 并通过开销交叉单元将东西向该开销字节所在通道导通。
当上述透明通道为一个开考肖字节的透明通道时，光传输环网快速 保护方法包括下列步骤：
步骤一： 通过网管层构建透明通道；
步骤二：各网元告警检测模块实时检测线路状况，信令检测单元 实时检测信令字节和透明通道^销字节的变化；
步骤三： 如果检测到告警或网管倒换命令， 则执行步骤四； 如果 检测到透明通道开销字节的变化， 则执行步骤五； 如果检测到信令字 节的变化， 则执行步骤六；
步骤四：检测到告警或网管倒换命令的网元，在协议处理完成后， 开销交叉单元断开东西向透明通道，根据待发送协议信令信息生成精 简信令并写入透明通道对应的开销字节中发送；
步骤五：捡测到透明通道 JP销字节变化情况的网元，如果当前状 态是倒换状态， 则不处理该幵 肖字节； 如果当前状态是空闲态或穿通 状态，则根据精简信令， 生成 t目关接收的信令信息送交协议处理模块 处理。
步骤六：如果接收到的信令指示是目的为本网元的短径请求，则 该网元在协议处理完成并断开东西向透明通道后，在与接收短径请求 相对的另一方向，开销交叉单元†艮据待发送信息生成精简信令并写入 透明通道对应的开销字节中发送；
步骤七、如果告警消失或网管倒换命令撤销， 则两个倒换网元自 动向透明通道中写入保护倒换协议的缺省信令码型，并重新将东西向 透明通道导通后返回步骤二； 否贝 ϋ直接返回步骤二。
本发明提出的方法对于光传输环网而言，除故障检测网元之外的 其它网元都能在故障网元发出请农后的几个光传输时延 之后，就能 收到透明通道中传递的请求信息。 建立了透明通道之后， 监测告警的 网元将信息写到透明通道， 由于透明通道基本是一个环型，这样监测 告警的网元写入的信息会按照光逮传递。因此在监测告警网元的下游 其它网元， 经过几个光传输延迟之后， 都可以检测到该信息。 因此， 本发明提出的保护方法最终计算的倒换时间将是:
T= (N-l)^to + 2x(tj + t2+ t3)+ t4 (2) 其中公式 （2) 中的 N为光传输环网的网元个数， t0、 、 t2、 t3、 t4、 说明与公式 （1 ) 中相同。
如果假设网元总数 N为 8， tO为 1毫秒， tl、 t2、 t3和 t4都是 3毫秒， 则根据公式（1 )可以计算出按照 G.841所述方法处理的保护 倒换时间为 82毫秒。 去掉一个网元的业务交叉单元处理 t4, 则申请 号为 98113149.2的方法倒换时间为 79毫秒。 去掉中间 6个网元的协 议处理时间 t2,则专利号为 5,636,205的专利方法倒换时间为 64毫秒。 而采用本专利方法，根据公式（2) 可知，保护倒换时间仅为 28毫秒。 由此可见本发明提出的方法具有更好的技术效果。 附图说明
图 1是光传输网元按照 G.841建议进行处理保护倒换结构图； 图 2A是一个保护八网元的二纤双向复用段共享保护环示意图； 图 2B是图 2A中的网络按照 G.841建议计算保护倒换时间的示意 图；
图 3A是光传输网元采用本发明所述方法的保护倒换结构图； 图 3B是图 2A网络配置透明通道后的示意图；
图 4是包含 N个网元的环网按照本发明所述方法计算保护倒换时 间的示意图；
图 5是本发明提出的方法的流程图。 具体实施方式
下面结合附图和实施例对本发明作进一步的详细说明。 ' 其中图 1、 图 2A、 图 2B在背景技术中已经进行过说明， 图 4是 本发明提出的保护方法的保护倒换时间计算示意图。
图 3A是光传输网元采用本发明所述方法的保护倒换结构图。 如 图 3A所示， 在图 1的基础上， 增加了一个幵销交叉处理单元， 开销 交叉单元根据协议处理单元的指令导通或断开冻西向的透明通道，根 据协议处理单元通知的信息向透明通道写入特定信息等。
图 3B是图 2A网络配置透明通道后的示意图。如图 3B所示，在 图 2A的基础上，配置了两条环绕整个传送环网的双方向的透明通道。 并且，通过开销交叉单元，保证空闲情况下透明通道传送的开销字节 为保护倒换协议的缺省信令码型。
图 5是本发明提出的方法的流程图。 下面以图 3B所示网络在网 元 1和 8之间的区段发生故障和故障最后消失为例， 结合图 3A、 图 4和图 5详细说明本发明方案的采用两个开销字节透明通道的具体实 施过程：
第 1步， 在网管层， 确定网元 1-8、 1-2、 2-3、 3-4、 4-5、 5-6、 6-7、 7-8等光纤区段的可用开销情况。 然后， 通过开销交叉单元， 网 元 1将 1-8和 1-2光纤区段的可用开销导通。 按照同样的方法， 网元 2、 3、 4、 5、 6、 7、 8分别将 1-2和 2-3、 2-3和 3-4、 3-4和 4-5、 4-5 和 5-6、 5-6和 6-7、 6-7和 7-8等光纤区段的可用开销导通。 最终构 建环绕整个图 3B所示的传输环网的透明通道。 此外， 在导通的过程 中，网元通过开销交叉单元设置透明通道传送的开销字节为保护倒换 协议的缺省信令码型， 例如 0x0ff0。
第 2步， 网元 1检测到网元 1-8区段之间的告警， 并将告警通知 协议处理单元， 协议处理单元生成信令请求， 其中往网元 1-2光纤方 向发送的 K1字节指示的请求类型为失效请求， 目的网元是 8。 转入 下一步。
第 3步， 网元 1的开销交叉单元断开网元 1-8和 1-2光纤区段的 透明通道， 并将 1-2方向传送的 Kl、 Κ2复制一份到 1-2方向的透明 通道对应的开销字节并发送。
第 4步， 网元 2检测到 1-2方向透明通道开销字节发生变化。 网 元 3检测到 2— 3方向透明通道开销字节发生变化。 同样网元 4、 5、 6、 7等网元也检测到这样的变化。 转入下一步。
第 5步， 网元 2当前处于非倒换状态。 将 1-2方向收到的透明通 道开销字节作为 1-2方向收到的 Kl、 Κ2信令字节送交协议处理模块 处理， 并穿通保护通道。 同样， 网元 3、 4、 5、 6、 7也按照同样的方 法处理。
第 6步， 网元 8检测到 7-8方向的协议信令（网元 7按照第 5步 处理之后发送的信令）发生变化。且信令字节 K1指示目的为本网元， 请求类型为失效请求， 因此网元 8立即进行桥接倒换。
第 7步， 在网元 1检测告警的同时， 网元 8也检测到 1-8区段的 告警。因此网元 8和网元 1几乎在同一时刻进行上述处理， 由于网元 8的处理方式与网元 1相同， 唯一区别是网元 8的信令传递方向， 透 明通道开销字节传递方向沿 8-7-6-5-4-3-2-1方向，与网元 1方向相反。
第 8步， 几乎在第 6步网元 8检测信令的同时， 网元 1检测到 1 一 1方向的信令 （网元 2发送的信令） 发生变化， 且信令字节 K1指 示目的为本网元，请求类型为失效请求， 因此网元 1立即进行桥接倒 换。
第 9步， 1-8区段告警消失后， 网元 1和 8自动往 1-2-3-4-5-6-7-8 和 8-7-6-5-4-3-2-1方向的透明通道中写入保护倒换协议的缺省信令码 型， 例如 OxOffO, 并重新将 1-2和 1-8， 1-8和 7-8之间的透明通道导 通。 其它处理完全遵照 G.841进行。
本发明方案的采用一个开销字节透明通道的具体实施过程与采 用两个开销字节的透明通道的不同之处在于发送透明通道信息的网 元， 需要根据待发送协议信令信息生成精简信令信息。接收透明通道 信息的网元， 需要根据接收的精简信令还原为协议信令信息。 艮卩， 第 3步中， 网元 1根据 1-2方向传送的 Kl、 Κ2所指示的源网元 ID和目的网元 ID组合为 1个字节协议 1-2方向的透明通道对应的开 销字节并发送。 例如信令请求的源网元是 1， 目的网元为 8， 则该字 节内容为 0x18。
第 5步中， 网元 2根据 1-2方向收到的透明通道开销字节， 还原 对应的 Kl、 Κ2， 请求类型默认为信号失效。 并作为 1-2方向收到的 Kl、 Κ2信令字节送交协议处理模块处理。
网元 1和网元 8不处理收到的透明通道开销字节。从上面的操作 步骤可知， 网元 1、 8同时检测告警， 同时产生协议信令和透明通道 开销信息， 中间网元 2、 3、 4、 5、 6和 7在接收到变化的协议信令之 前，根据两个方向透明通道传送的开销字节携带的信息， 迅速生成发 送的信令并穿通保护通道， 具备快速、 高效的特点。
此外， 从上述步骤可以看出，本发明方法的主要特征在于构建透 明通道快速传递请求信息， 不改变原保护倒换协议处理单元， 可靠性 较好。 同时， SDH/SONET网络在其复用段层有大量的开销可用， 与 本文背景技术介绍的其它方法相比较， 本专利方法具备成本低的特

Claims

权利要求
1、 一种光传输环网快速保护方法， 其特征在于包括下列步骤- 步骤一、 通过网管层构建透明通道； .
步骤二、 各网元告警检测模块实时检测线路状况， 信令检测单元 实时检测信令字节和透明通道开销字节的变化；
步骤三、 如果检测到告警或网管倒换命令， 则执行步骤四； 如果 检测到透明通道开销字节的变化，则执行步骤五； 如果检测到信令字 节的变化， 则执行步骤六；
步骤四、检测到告警或网管倒换命令的网元，在协议处理完成后， 开销交叉单元断开东西向透明通道，并将非故障方向的，待发送的信 令字节复制一份到透明通道对应的开销字节中发送， 执行步骤七； 步骤五、 检测到透明通道开销字节变化情况的网元， 如果当前状 态是倒换状态，则不处理该开销字节；如果当前状态是空闲态或穿通 状态，则将该开销字节作为相应方向信令检测单元接收到的信令字节 送交协议处理模块处理， 返回步骤二；
步骤六、 如果接收到的信令指示是目的为本网元的短径请求， 则 该网元在协议处理完成并断开东西向透明通道后，在与接收短径请求 相对的另一方向，开销交叉单元将待发送的信令字节复制一份到透明. 通道对应的开销字节并发送； 否则按照 G.841协议进行处理；
步骤七、 如果告警消失或网管倒换命令撤销， 则两个倒换网元自 动向透明通道中写入保护倒换协议的缺省信令码型，并重新将东西向 透明通道导通后返回步骤二； 否则直接返回步骤二。
2、 根据权利要求 1所述的方法， 其特征在于所述步骤一中构建透明 通道的方法为： 根据各网元区段的复用段开销使用情况， 依次在网元 东向区段和西向区段指定两个可用开销字节，并通过开销交叉单元将 东西向该开销字节所在通道导通。
3. —种光传输环网快速保护方法， 其特征在于包括下列步骤：
步骤一： 通过网管层构建透明通道；
步骤二： 各网元告警检测模块实时检测线路状况， 信令检测单元 实时检测信令字节和透明通道开销字节的变化；
步骤三： 如果检测到告警或网管倒换命令， 则执行步骤四； 如果 检测到透明通道幵销字节的变化， 则执行步骤五； 如果检测到信令字 节的变化， 则执行步骤六；
步骤四： 检测到告警或网管倒换命令的网元， 在协议处理完成后， 开销交叉单元断开东西向透明通道，根据待发送协议信令信息生成精 简信令并写入透明通道对应的开销字节中发送；
步骤五： 检测到透明通道开销字节变化情况的网元， 如果当前状 态是倒换状态， 则不处理该开销字节； 如果当前状态是空闲态或穿通 状态， 则根据精简信令， 生成相关接收的信令信息送交协议处理模块 处理。
步骤六： 如果接收到的信令指示是目的为本网元的短径请求， 贝 IJ 该网元在协议处理完成并断开东西向透明通道后，在与接收短径请求 相对的另一方向，开销交叉单元根据待发送信息生成精简信令并写入 透明通道对应的开销字节中发送；
步骤七、 如果告警消失或网管倒换命令撤销， 则两个倒换网元自 动向透明通道中写入保护倒换协议的缺省信令码型，并重新将东西向 透明通道导通后返回步骤二； 否则直接返回步骤二。
4、 根据权利要求 3所述的方法， 其特征在于所述步骤一中构建透明 通道的方法为：根据各网元区段的复用段开销使用情况，依次在网元 东向区段和西向区段指定一个可用开销字节，并通过开销交叉单元将 东西向该开销字节所在通道导通。
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CN1756223A (zh) 2006-04-05
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EP1796296A4 (en) 2016-07-06

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