WO2003107565A1

WO2003107565A1 - A virtual protection method and means for the fiber path

Info

Publication number: WO2003107565A1
Application number: PCT/CN2002/000420
Authority: WO
Inventors: Jixiong Dong
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2001-02-05
Filing date: 2002-06-14
Publication date: 2003-12-24
Also published as: CN1184752C; CN1368803A

Abstract

The invention involves a virtual protection method for the fiber path. The method comprises the steps of: dividing the optical port into a plurality of minimum protection units in physics; then dividing the system into more than one logic system based on the minimum protection units; In each logic system, every station can work in each of the following modes: normal working mode, passing working mode, bridging working mode and switching working mode; when the station need protection, it can be switched from the normal working mode to the other working modes by means of the protection ways of multiplexed segment, sub-networks connection and channel. The invention also involves a virtual protection means for the fiber path. With the method and means presented above, the invention not only resolves the problems of the present protection ways, but also makes the transmission networking more flexible and makes the protection ways more suitable for the users' demands.

Description

Method and device for virtual protection of optical fiber path

The present invention relates to a virtual protection method and device for optical fiber paths, which are protected by many synchronous digital series (SDH) optical fiber networks, such as current protocol protection, channel protection, and the like! It provides an extended protection mode. Background of the invention

At present, with the continuous increase of people's requirements for network bandwidth and the huge advantages of SDH transmission, the scale of optical fiber networks is constantly expanding, and the self-healing protection of optical fiber networks is becoming more and more important. According to ITU-T recommendations, the protection methods of SDH optical fiber transmission networks mainly include channel protection, multiplex section protection, and subnet connection protection. Among them, multiplex section protection is the most widely used protection method on transmission networks. Including 1 + 1 linear multiplex section protection, 1: N linear multiplex section protection, 2/4 fiber uni / bidirectional multiplex section shared protection.

The basic principle of multiplex segment protection is to transmit switching information through the K1 / K2 bytes in the SDH frame, thereby implementing the protocol switching function. However, because K1 / K2 bytes are in the multiplex section in the SDH frame, in this way, one fiber or one optical port can only transmit a set of K1 / K2 bytes, that is, one fiber can only belong to one The multiplex section system, that is, a general multiplex section is a multiplex section based on an optical port. This kind of protection has a disadvantage: it cannot flexibly implement corresponding protection according to different services, which results in a waste of VC4 resources on the optical interface. There are so many protection methods for SDH because different protection methods are needed in different applications. In the occasions with high requirements on the switching time, for example: The switching time is required to be less than 20ms, and the protection with the multiplex section may not meet the requirements. At this time, channel protection must be used to achieve this. Moreover, the multiplex section switching has its protocol word. The inherent shortcoming of this section is that only 4 bits are used to represent the node number, then a ring can only support a maximum of 16 sites (excluding REG sites, (Ie relay station), when the number of nodes on the ring is greater than 16, other protection methods can only be used. In addition, for the network topology shown in FIG. 1, site A, site B, site C, and site D form a ring 101, and site A, site B, site D, and site E form a ring 102. When site A When ring 101 consisting of B, C, D is protected by multiplex section or channel, the service between site B or site D and site E cannot be protected. Similarly, when the ring consisting of sites A, B, D, and E is protected 102 When multiplex segment protection or channel protection is used, services between site B or site D and site C cannot be protected.

In fact, under the situation that the current SDH network is becoming more and more complicated, the above phenomenon is very common. Summary of the Invention

The purpose of the present invention is to solve this kind of protection defect, and propose a virtual protection method and device for optical fiber paths, which not only protects more comprehensive and comprehensive, but also makes the transmission network more flexible, and the protection method more meets the needs of users.

To achieve the above objective, the solution of the present invention is implemented as follows:

A virtual protection method for a fiber path provided by the present invention includes the following steps: a. Physically dividing an optical port into one or more minimum protection units;

b. Divide the minimum protection unit of more than one protection channel in each optical port into different logical systems, respectively, to form more than one logical system;

c In each logical system, each station works in one of four working modes: normal working mode, punch-through working mode, bridge working mode, and switching working mode;

d. When protection is needed, each site is switched from the normal working mode to the other three working modes through a switching action. Wherein, the switching action is multiplex segment protection, or subnet connection protection, or channel protection, or other protection methods capable of performing equivalent functions.

When multiplex segment switching occurs, step d further includes: dl. Create a logical system for protection switching;

d2. Analyze the four sets of work, switch, bridge, and pass-through pages according to the current configuration; d3. After determining the pass-through site, bridge site, and switch site, issue the pass-through page at the pass-through site, issue the bridge page at the bridge site, and switch-over site Issue a switch page.

Step d3 further includes: if the current site issues a pass-through page, the in-protection bus is directly passed through to the egress protection bus; if the current site issues a bridge page, the in-protection bus is used to replace the working bus; if the current site delivers When the page is switched, the protection bus is replaced with the working bus.

In the above solution, the minimum protection unit is a fourth-order virtual container (VC4) or a third-order virtual container (VC3), and one or more of the more than one fourth-order virtual container or the third-order virtual container are mapped to different ones. In a logic system, more than one logic system is formed.

In this method, when protection switching occurs in a certain logical system, only services on the logical system that meet the trigger conditions of the current logical system protection switching participate in the protection switching process.

The method further includes: the time division crossover unit in the transmission system uniformly cross-connects the services from different minimum protection units to the same minimum protection unit to the same minimum protection unit.

The present invention also provides a virtual protection device for a fiber path, which at least includes:

A page analyzer for analyzing the configuration of the logic system, generating a corresponding work page, and storing the work page in a switching controller;

The switching controller is configured to issue a corresponding work page to the cross-connect board according to the switching status; the cross-connect board is used to complete a corresponding bus connection according to the work page issued.

The work page is a normal work page, or a through page, a bridge page, or a switch page.

The cross-board completes the bus connection by directly connecting the in-work bus and the out-work bus of the current station, or directly connecting the in-protection bus and the out-protection bus of the current station, or The ingress protection bus of the station is connected to the egress protection bus, or the ingress protection bus of the current station is connected to the egress protection bus.

Since the above scheme is adopted, it divides the logic system based on the minimum protection unit, which can be VC4, VC3, and so on. Because an optical port can have multiple minimum protection units, an optical port can be divided into multiple logical systems. It can flexibly choose different protection methods according to different services. In addition, different logical systems (different services, different networks) can use different switching conditions. In this way, the transmission network is more flexible and the protection method is more in line with user needs. Because the same system can be divided into multiple logical systems, each logical system can adopt different protection methods, breaking through the existing technology's one-of-a-kind model, so that more sites can be contained under the protection system. For the situations shown in FIG. 1, the site E that cannot be protected by the traditional method can also be protected here. It can be seen that the protection of the present invention is more thorough, comprehensive, and flexible. Brief description of the drawings

Figure 1 is a schematic diagram showing that two rings cannot be protected at the same time.

Figure 2 is a schematic diagram of different protection methods used by different services.

FIG. 3 is a schematic diagram of an embodiment of a bus crossing method according to the present invention.

FIG. 4 is a schematic diagram of an embodiment of unidirectional multiplex segment switching implementation in the present invention.

FIG. 5 is a schematic diagram of a multiplex segment switching algorithm according to the present invention.

Figure 6 is a schematic diagram of an existing network.

FIG. 7 is a schematic diagram of logical system division under virtual path protection;

FIG. 8 is a schematic structural diagram of a virtual protection device for an optical fiber path according to the present invention. Mode of Carrying Out the Invention

The present invention will be further described in detail below through specific embodiments in combination with the accompanying drawings. As shown in FIG. 2, the present invention can protect multiple services such as image services, voice services, signaling services, and cross-sea services. Different services can adopt different protection methods. The core idea of its technical solution is this:

1. The concept of minimum protection unit. This design idea is based on the fact that the optical port can be physically divided into 4th-order virtual containers (VC4), and the minimum protection unit is a VC4. For example, a 622Mbit / s optical port can be regarded as four independent VC4s because its payload is 4 VC4s.

2. Bus concept. The SDH transmission system can be roughly divided into branch units, line units, and crossover units. The division of the logical system of the present invention is the division of the line unit and the tributary unit. The generation of the following switching pages is generated by this division. Different divisions have different switching pages, and the execution of the switching is mainly This is done by a cross unit. For an add / drop multiplexing device, there are many types of services, such as 2M bit / s, 34M bit / s, 155M bit / s, etc., and the capacity on the line can be 155M bit / s, 622M bit / s, 2.5 G bit / s, etc., it is impossible to select different crossover units according to the line capacity or the different services. Because low-order services are multiplexed into VC4 when they are connected to the line, time-division crossover units can be used on the cross. Services from different VC4 to the same VC4 are uniformly adjusted to the VC4 by the time-division crossover unit. . Here, VC4 can be used as the basic rate of the bus unit. The meaning of this kind of bus crossing can be seen in Figure 3. The left part of the arrow in Figure 3 indicates that there are three different VC4--VC4 # 1, VC4 # 2 and VC4 # 3, where the ones filled with oblique lines are the first The second unit of the VC4 (1,2), the third unit of the second VC4 (2,3), and the first unit of the third VC4 (3,1). The SDH system multiplexes services from three VC4s onto the same VC4 for unified adjustment. The multiplexed VC4 sequentially transmits services carried on (3,1), (1,2,) and (2,3). .

3. Logical system concept. Since the same site can belong to multiple basic network topologies, and the protection method on each network may be different, the same base can be The physical medium under the same level and the same protection method of the topology is considered as a whole, which is called a logical system. The attributes of the logic system are: level, such as 155M, 622M, 2500M, etc .; network element types, such as add / drop multiplexer (ADM), terminal network element (TM), relay station (REG); service direction, one-way or Bidirectional; protection type, channel protection, multiplex segment protection, 1 + 1, l: n protection, subnet connection protection, etc .; number of fibers, 2 or 4 fibers; basic network topology type, ring or chain, etc. The logic system of ADM includes eastbound line, westbound line and optional branch, and the logic system of TM includes eastbound / westbound line and optional branch. Through these attributes, the business that goes up and down or through this logic system is analyzed to generate work pages and protection pages. The concept of a logical system simplifies business configuration while providing the possibility for flexible implementation of protection.

When protection switching occurs in a logical system, if other logical systems do not meet the triggering conditions for protection switching of the logical system, only the services on the logical system participate in the protection switching process, that is, logic independence exists.

4. Bus replacement concept. The switching of the multiplex section can be completed by the idea of "one end bridge, one end switch, and intermediate site pass-through". This idea can be implemented in the manner shown in Figure 4. FIG. 4 is a schematic diagram of an embodiment of unidirectional multiplex segment switching implementation. In FIG. 4, the left part of the arrow is a network topology in actual application, and the network includes a fiber ring and four sites AD on the ring. Each ring represents the working channel and protection channel in the fiber, and the right part of the arrow indicates the working status of the three types of sites-through-site, bridge site, and switching site. The white box represents the working channel. The diagonally striped box represents the protection channel. When the optical fiber 401 between B and C fails, the working channel and the protection channel between B and C are unavailable. The transmission service between B and C or the transmission service passing through B and C It will be transmitted to the destination site through the protection channel between BA, AD, and DC. At this time, site B will be bridged, site C will be switched, and sites A and D will pass through, that is, sites A and D are pass-through sites. Site B is a bridging site, and site C is a switching site. In this embodiment, it is determined that 1 to 4 in each station are the incoming buses of the working channel, and 1, 4 are the working channels. 5 ~ 8 are the incoming buses of the protection channel, and 5 ~ 8 are the outgoing buses of the protection channel. Then, it can be seen from the figure that for the pass-through stations (sites A and D), it is actually The signal from the incoming bus (5, 6, 7, 8) on the protection channel crosses to the outgoing bus (5, 6, 6, 7 ', 8,) on the protection channel, and for the bridging site (site B), the The signal originally outputted to the working channel (Γ, 2, 3, 4, 4,) is converted to the protection channel (5 ,, 6 ', 7, 8, 8). For the switching site (site C), it is Change the signal from the working channel (1, 2, 3, 4) to the protection channel (5, 6, 7, 8).

Since each site is likely to handle all switching situations, for each site, four sets of pages need to be prepared: normal pages, pass-through pages, bridge pages, and switch pages. The normal page is based on the analysis of the logical system, and the other pages are replaced by the bus on the basis of the normal page. In the present invention, the "replacement" and "switching" mentioned are different concepts. The substitution refers to the digital meaning. For example, the inbound bus 1 is replaced by the inbound bus 9, and the inversion refers to a network element. Specifically, It is an action taken by the logic system, for example, the logic system 1 undergoes a multiplex segment switch, and it is not said that the logic system 1 undergoes a multiplex segment replacement; the switch is the switching from the working part to the protection part.

According to the above concept, the virtual protection method of the optical fiber path of the present invention includes the following steps: a. Physically dividing the optical port into multiple minimum protection units;

b. #According to the needs of the business, the minimum protection units of multiple protection channels in each optical port are divided into different logical systems, so as to form more than one logical system; thus, the optical port is divided into multiple In different logic systems;

c In each logical system, each site can work in one of four working modes: normal working mode, punch-through working mode, bridge working mode and switching working mode;

d. When protection is required, switch from the normal working mode to the other three working modes through multiplex segment switching.

5. The concept of protection of independence. Different protection attributes have different protection conditions: channel The protection is based on the tributary unit-alarm indication signal (TU-AIS) on the channel, and the multiplex segment protection is based on the multiplex segment-alarm indication signal (MS-AIS) on the multiplex segment. Different protections are subordinate to logic Different network topologies usually take different physical paths, so protection does not occur at the same time. Therefore, the protection of one logical system will not affect the working mode of other logical systems.

FIG. 5 is a schematic diagram of a simple process for implementing a multiplex segment switching algorithm. First, a logic system for multiplex segment protection must be created, and then four sets of working pages are analyzed according to the configuration, that is, the normal working page, the switching page, the bridge page, and the pass-through page. The normal work page is from the incoming work bus to the outgoing work bus, the pass-through page is from the incoming work bus to the outgoing work bus, the bridge page is from the outgoing work bus to the incoming work bus, and the switching page is from the outgoing work bus to the incoming work bus. Whether the site is a bridging site, a protection site, or a pass-through site is analyzed by the protection switching controller. If it is analyzed that the site is a bridge site, issue a bridge page, and replace the work bus with the protection bus; if it is analyzed that the site is a switch site, issue a switch page, and replace the protection bus with the work bus; The exit site is a pass-through site, and a pass-through page is issued to pass the incoming protection bus directly to the outgoing protection bus. As shown in Figure 4, a fiber optic ring network includes sites A to D. When the fiber between sites B and C fails and multiplex segment switching is required, the system needs to use the normal working pages of each site and At the location of the fault, analyze what changes should occur in the working status of sites A to D. After analysis, confirm that site people and D are pass-through sites, site B is a bridging site, and site C is a switching site. D issues a pass-through page, site B delivers a bridge page, and site C delivers a switch page. It can be seen from this switching algorithm that bus switching is used here, which is different from the traditional switching method (all the VC4 on the optical port is involved in the switching), and the VC4 to which the logical system belongs is involved in the switching. Therefore, you can configure the number of VC4s participating in switching according to your own needs, and use other VC4s for other protections.

FIG. 6 is a topology diagram of a certain network in the prior art. In the counterclockwise direction, the network elements A, B, and 0

C, D, E, F, and G form ring 601; network elements H, I, J, K, L, M, N, and O form ring 602, and the two rings are connected through GH and FI. For ring 601 and ring 602, The multiplex segment protection method or other protection methods may be adopted to protect the services in the ring, but the services between the rings cannot be protected.

For the optical fiber ring network shown in FIG. 7, although the topology structure of the network is the same as that in FIG. 6, but because it uses the idea of dividing the logical system of the present invention, it can be implemented in any part of the optical fiber network. protection. FIG. 7 is a method for logically dividing the network by using the present invention. The ring shown by the dotted line in FIG. 7 is two optical fiber ring networks composed of each network element in practical applications. In the logical division shown in FIG. 7, according to the counterclockwise direction, a virtual ring 701 is composed of network elements A, B, C, D, E, F, and G, and is composed of network elements H, I, J, K, L, and M. , N, and O form a virtual ring 702, and the network elements A, B, C, D, E, F, I, J, K, L, M, N, O, H, G form a large virtual ring 703. In the virtual ring 701 and the virtual ring 702, multiplex segment protection can be used to protect intra-ring services, while the virtual ring 703 can use channel protection to protect inter-ring services. In this solution, two logical systems are configured at each site. According to the needs of the business, all VC4s of each fiber can be mapped into the multiplex segment logical system, and some of the VC4s can be mapped to the complex logical system. In the segment logic system, for the logical system 3 constituting the virtual ring 703, since there are more sites to cross and the channel protection consumes resources, it is generally necessary to select one or all of the optical ports according to the number of services and the level of the optical port. Several VC4s are mapped into this logical system.

FIG. 8 shows a structure of a virtual protection device for realizing the above-mentioned virtual protection method according to the present invention. The virtual protection device of the optical fiber path includes at least a page analyzer 801, a switching controller 802, and a crossbar 803. The corresponding work page is issued in the switched state, and the corresponding bus connection is completed. The page analyzer 801 is used to analyze the configuration of the logic system, generate corresponding four sets of work pages for normal work, punch-through, bridge, and switch, and store the work pages in the switch controller 802. Because each site has a lot of logic System, so there are many sets of pages, so the pages are all related to the logical system. The switching controller 802 is configured to issue a corresponding work page to the cross-connect board 803 according to the switching state, and complete the corresponding bus connection through the cross-connect board 803 to complete the switching action.

The above description is only the preferred embodiments of the present invention, and is not intended to limit the protection scope of the present invention.

Claims

Claim

1. A virtual protection method for an optical fiber path, comprising the following steps: a. Physically dividing the optical port into one or more minimum protection units;

d. When protection is needed, each site is switched from the normal working mode to the other three working modes through a switching action.

2. The virtual protection method according to claim 1, wherein: the switching action is multiplex segment protection, or subnet connection protection, or channel protection.

3. The virtual protection method according to claim 1 or 2, wherein step d when the multiplex segment switching occurs further comprises:

dl. Create a logical system for protection switching;

4. The virtual protection method according to claim 3, wherein step d3 further comprises: if the current site issues a pass-through page, directly passing the in-protection bus to the e-protection bus; if the current site issues a bridge page, then Replace the protection bus with the protection bus. If the current site issues a page change, replace the protection bus with the protection bus.

5. The virtual protection method according to claim 1, wherein: the minimum protection unit is a 4th order virtual container (VC4) or a 3rd order virtual container (VC3), and more than one 4th order virtual container or 3 One or more of the order virtual containers are mapped to different logical systems to form more than one logical system.

6. The virtual protection method according to claim 1, characterized in that: when a protection switching occurs in a logical system, only services on the logical system that satisfy the triggering condition of the protection switching of the current logical system participate in the protection switching process.

7. The virtual protection method according to claim 1, further comprising: the time division crossover unit in the transmission system will uniformly adjust the services from different minimum protection units to the same minimum protection unit through uniform adjustment of the time division crossover unit. , Uniformly cross to the same minimum protection unit.

8. A virtual protection device for an optical fiber path, comprising at least: a page analyzer for analyzing a configuration of a logical system, generating a corresponding work page, and storing the work page in a switching controller;

The switching controller is configured to issue a corresponding work page to the cross-connect board according to the switching state; the cross-connect board is used to complete a corresponding bus connection according to the issued work page.

9. The virtual protection device for the optical fiber path according to claim 8, wherein the working page is a normal working page, a through-page, a bridged page, or a switched page.

10. The virtual protection device for an optical fiber path according to claim 8 or 9, characterized in that: the cross-connect board directly connects the in-work bus and the out-work bus of the current station, or connects the in-protection bus and the out-protection bus of the current station. Connect directly, or connect the in-protection bus of the current station with the out-work bus, or connect the in-operation bus of the current station with the out-work bus.