RU2284662C2 - Method and device for virtual protection of fiber-optic duct - Google Patents

Abstract

FIELD: optical communications engineering, possible use for protecting communication line.

SUBSTANCE: optical port is physically divided on several modules with minimal protection. On basis of modules with minimal protection system is divided on several logical systems. Each node of logical system may operate in one of four modes: normal mode, transfer mode, connection mode and switching mode. When protection is necessary, node is transferred from normal working mode to one of other three working mode by means of either protection of multiplex section, or network connection protection, or channel protection, etc.

EFFECT: increased protection of communication lines and flexible configuration of network.

2 cl, 8 dwg

Description

Technical field

The present invention relates to a method and apparatus for virtual protection of an optical fiber path and provides an improved protection method based on known methods for protecting an optical fiber SDH network (Synchronous Digital Hierarchy), such as protocol protection, channel protection, and the like.

State of the art

At present, fiber-optic communication systems are undergoing a period of continuous and rapid development, which is due to an increase in network bandwidth requirements and the obvious advantages of SDH technology. Moreover, the issue of self-healing of such networks is becoming increasingly important. According to the recommendations of the ITU-T committee, the main methods of protecting fiber-optic SDH networks are ways to protect the channel, protect the multiplex section, protect the connection through the subnet, etc. The most popular among them at present is the protection of the multiplex section, including the protection of the “1 + 1” type of the linear multiplex section, the protection of the “1: N” type of the linear multiplex section, as well as the joint protection of the “2/4” type of unidirectional / bidirectional fiber optic multiplex sections.

The principle of protecting the multiplex section is to transmit switching information by K1 / K2 bytes in the SDH frame to implement the protocol switching function. However, since the K1 / K2 bytes are located in the multiplex section of the SDH frame, only one group of K1 / K2 bytes can be transmitted through one optical fiber line or one optical port. This means that one optical fiber line can belong to only one multiplex section system, namely a common multiplex section connected to the optical port. The disadvantage of this method of protection is that it does not provide the flexibility to select the optimal type of protection for various services, which leads to inefficient use of the resources of the virtual container VC4 (Virtual Container) of the optical port. The reason for the existing variety of protection methods is that different applications require the use of different protection methods. In particular, where the permissible switching time is limited (for example, it should not exceed 20 ms), the protection of the multiplex section may not be sufficient, so channel protection will be required. In addition, the switching process of the multiplex section has a drawback caused by the byte of its protocol, in which only four bits are allocated for information about the node number, and the ring can have no more than 16 nodes (except for REG nodes). If the number of nodes in the ring exceeds 16, you have to use other methods of protection. In addition, in the network with the topology shown in FIG. 1, in which the nodes A, B, C and D constitute the ring 101, and the nodes A, B, D and E comprise the ring 102 if the protection of the multiplex section or protection of the channel, the services between nodes B and E or between nodes D and E cannot be protected. Similarly, if multiplex section protection or channel protection is used in ring 102, services between nodes B and C or between nodes D and C cannot be protected.

In practice, as the complexity of SDH networks increases, the constraint mentioned above is increasingly encountered.

SUMMARY OF THE INVENTION

The aim of the invention is the creation of a method and device for virtual protection of the optical fiber path, devoid of the above disadvantages. The present invention allows not only to provide complete protection of the network and the possibility of its flexible configuration, but also offers a security method that makes it possible to fully satisfy the requirements of users.

The proposed virtual protection method includes the following steps:

a) physical separation of the optical port into several modules with minimal protection;

b) separation of modules with minimal protection of more than one protection channel in each optical port into different logical systems with the creation of more than one logical system;

c) the functioning of each node of each logical system in one of four operating modes: normal mode, transmission mode, connection mode and switching mode;

d) in the event of a need for protection, the switching of each node from the normal mode to one of the three other modes.

The switch can be a switch either to the protection mode of the multiplex section or to the protection mode of the connection via the subnet, or to the protection mode of the channel, or to another mode that provides the same functions.

When switching to the protection mode of the multiplex section, the step "d", in turn, includes the following steps:

d1) the creation of logical systems for protective switching;

d2) the formation of four groups of pages: work pages, switch pages, connection pages and transfer pages;

d3) after determining the type of node, i.e. whether it is a transmission node, a connection node, or a switching node, sending a transmission page by a transmission node, sending a connection page by a connection node, and sending a switching page by a switching node.

Stage d3, in turn, includes the following actions: if the current node sends a transmission page, then the direct transmission of the input protective bus node to the output protective bus node; if the node sends a connection page, then replacing the output working bus of the node with the input protective bus of the node; if the node sends a switching page, then replacing the node’s output protective bus with the node’s input working bus.

In the method described above, the module with minimum protection is VC4 or VC3, and step b is a mapping of at least one VC4 or VC3 in different logical systems to create more than one logical system.

In the method described above, when implementing protective switching in a certain logical system, only the services of the logical system that satisfy the switching condition of the current logical system are involved in the protective switching.

In addition, the method includes setting up and switching services sent to the same module with minimal protection from different modules with minimal protection through a time-sharing cross-switching module available in the communication system.

The proposed device virtual protection of the optical fiber path includes at least:

a page analyzer for analyzing the configuration of the logical system, creating corresponding working pages and storing the working pages in the switching controller mentioned below;

a switching controller for sending respective work pages to the cross-connect circuit board mentioned below in accordance with the switching state;

and a cross-connection board for switching the bus in accordance with the sent work page.

These work pages can be either normal work pages or transfer pages, or connection pages, or switch pages.

A bus connection is either a connection of the input and output working buses of the current node, or a connection of the input and output protective buses of the current node, or a connection of the input protective bus and the output working bus of the current node, or a connection of the input working bus and the output protective bus of the current node.

In the framework of the system described above, where the separation of logical systems is performed on the basis of a module with minimal protection, such as VC4, VC3, etc., and the optical port can have several modules with minimal protection, the optical port can be divided into several logical systems . This makes it possible to flexibly select different protection methods for different services, and different switching conditions can be used in different logical systems (i.e., in different services, in different networks). Thereby, great flexibility is achieved in organizing network communications and it is possible to select the optimal type of protection in accordance with user requirements. The possibility of dividing the system into several logical systems capable of operating in various protective modes eliminates the drawback of existing systems, which is that each of them can use only one type of protection, without giving a choice. So, for example, the node E shown in FIG. 1 cannot be protected by any known method, but it can be protected by the proposed method. It is obvious that the proposed method of protection is more flexible, versatile and effective.

Brief Description of the Drawings

Figure 1 depicts a diagram illustrating the inability to simultaneously protect two rings.

Figure 2 depicts a diagram illustrating the use of various types of protection by various services.

Figure 3 illustrates a method of cross-switching buses in the proposed device.

Figure 4 illustrates the organization of unidirectional switching of the multiplex section of the proposed device.

Figure 5 depicts a diagram of the switching algorithm of the multiplex section of the proposed device.

6 depicts a diagram of an existing network.

7 depicts a logical separation scheme for virtual path protection.

Fig depicts a structural diagram of the proposed device virtual protection of the optical fiber path.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in more detail with reference to the accompanying drawings.

From figure 2 it follows that the invention allows the protection of various services, such as image transmission, voice messaging, signaling, long-distance communication, etc. For different services, you can use different types of protection. The following are the main ideas of the present invention.

The first such idea is the concept of a module with minimal protection. It is based on the fact that the optical port can be divided into several VC4, which are modules with minimal protection. For example, an optical port with a speed of 622 Mbps can be considered as four independent VC4, since its payload is equal to four VC4.

The second idea is the tire concept. The SDH system essentially consists of branching modules, linear modules and signal switching modules. The separation of logical systems in accordance with the present invention relates to branching and linear modules. As a result of this separation, the switch page described below is created, with each switch configuration having its own switch page. Switching is mainly carried out by signal switching modules. For I / O multiplexers, there are a large number of services that can be entered or output, for example, services at 2 Mbit / s, 34 Mbit / s, 155 Mbit / s, etc .; the line throughput can be 155 Mbit / s, 622 Mbit / s, 2.5 Gbit / s, etc. It is not possible to select different signal switching modules for different values of line capacity or for different input and output services. When a low priority service is introduced into the line, it will be multiplexed in VC4; for crossover, you can use the time-division signal switching module, which uniquely adjusts and switches the services coming from different VC4 to the expected VC4. In this case, VC4 can be considered as the main speed of the bus module. Crossover tires shown in Fig.3. To the left of the arrow are three different VC4s: VC4 # 1, VC4 # 2 and VC4 # 3, as well as the second module of the first VC4 (1, 2), the third module of the second VC4 (2,3) and the first module, shown as shaded blocks, respectively third VC4 (3, 1). The location of the modules to the right of the arrow shows that after switching the bus with time sharing, the SDH system multiplexes services coming from three different VC4s to one VC4, which sequentially transfers the downloaded services to (3, 1), (1, 2) and (2, 3 )

The third idea is the concept of a logical system. Since the node can belong to networks of different topologies, and each network can have a different type of protection, a physical environment with one standard topology, of the same level and having the same type of protection can be considered as a single entity, called a logical system. The logical system is characterized by the following parameters: throughput level, for example 155M, 622M, 2500M, etc .; the type of network element, for example, an input / output multiplexer (ADM), a terminal multiplexer (TM), and a regenerator (REG); service direction, for example, unidirectional or bidirectional; type of protection, for example, channel protection, multiplexer section protection, 1 + 1 protection, 1: N protection, connection protection via subnet, etc .; the number of optical fibers, for example, 2 fibers, 4 fibers; as well as network topology such as ring, point-to-point, etc. The ADM of the logical system includes the eastern and western signal propagation paths, as well as selectable branches. The logical system TM includes east / west signal propagation paths, as well as selectable branches. The work page and the protection page with the specified characteristics are generated as a result of the analysis of the input / output service or the transfer service. The concept of a logical system facilitates the configuration of services and allows for more flexible protection.

When a protective switching of a logical system occurs, if other logical systems do not satisfy the switching conditions, then only the services of this logical system are involved in the switching process, i.e. logical independence takes place.

The fourth idea is a tire replacement concept. Switching the multiplex section can be performed as follows: one end node of the path goes into connection mode, the other end node of the path goes into switching mode, and the middle node goes into transmission mode, as shown in figure 4, illustrating unidirectional switching of the multiplex section. To the left of the arrow in Fig. 4 shows the topology of the network, consisting of two fiber optic rings, one working channel, one protection channel and four nodes of the ring A, B, C and D. To the right of the arrow in Fig. 4 shows the functional states of the working channel and channel protection for three types of nodes: transmission unit, connection unit and switching unit; however, a block without filling indicates a working channel, and a shaded block indicates a protection channel. In the event of a problem with fiber 401 between nodes B and C, the working channel and the protection channel cease to function. Communication services between nodes B and C or communication services passing through nodes B and C will be transmitted to the destination node through protection channels between BA, AD and DC. At this moment, the node B is connected, the node C is switched, and the nodes A and D become the transfer nodes, in other words, the node B becomes the connection node, the node C becomes the switch node, and the nodes A and D become the transfer nodes. Now suppose that for each node of this embodiment of the invention, 1 ~ 4 are the input busbars of the working channel, 1 '~ 4' are the output buses of the working channel, 5 ~ 8 are the input buses of the protection channel, and 5 '~ 8' is the output buses of the protection channel. As can be seen from figure 4, for the transfer node (which are the nodes A and D), the signals supplied to the input buses (5, 6, 7, 8) of the protection channel are cross-linked to the output buses (5 ', 6', 7 ', 8 ') protection channel; for the connection node (which is node B), the signals originally received from the output buses (1 ', 2', 3 ', 4') of the working channel are transmitted to the output buses (5 ', 6', 7 ', 8') of the channel protection; for the switching node (which is node C), the signals initially supplied to the input buses (1, 2, 3, 4) of the working channel are transmitted to the input buses (5, 6, 7, 8) of the protection channel.

For each of the nodes, it may be necessary to work in any of the mentioned switching modes, so each node must prepare four pages: a normal page, a transfer page, a connection page, and a switching page. A normal page is formed as a result of the analysis of logical systems, and the remaining pages are based on a normal page with a bus replacement. In the context of the present invention, the terms “replacement” and “switching” have different meanings. The replacement has a numerical expression, for example, the input bus 1 is replaced by the input bus 9, while the switching refers to a network element and represents the action of a logical system. For example, we can say that the logical system has a switching multiplex section, but we can not say that the logical system has a replacement multiplex section. Switching is the process of moving from a work item to a security item.

According to the above concepts, the proposed method of virtual protection of the optical fiber path includes the following steps;

but; the optical port is physically divided into several modules with minimal protection;

b; depending on the requirements of the service, modules with minimal protection of the protection channels of each optical port are divided into different logical systems in such a way that more than one logical system is formed, while the optical port is divided into several different logical systems;

from; each node in each of the logical systems can be in one of four operating modes: normal operating mode, operating transmission mode, operating connection mode and switching operation mode;

d; when there is a need for protection, the normal operating mode is replaced by one of the three remaining operating modes by switching the multiplex section.

The fifth idea is the concept of independence of defense. Different protection characteristics correspond to different protection conditions. Channel protection is triggered by a signal (TU-AIS) of a tributary channel module failure, etc. Multiplex section protection is activated by a signal (MS-AIS) of the multiplex section failure, etc. Different types of protections logically belong to different network topologies and, in the general case, are realized through different physical channels, as a result of which the action of protections cannot occur simultaneously. Therefore, it is necessary that the protection of the logical system does not affect the other operating modes of the logical system.

Figure 5 shows a simplified diagram of the implementation of the switching algorithm of the multiplex section. First create a logical system to protect the multiplex section. Then, according to the configuration, four working pages should be analyzed: a normal working page, a switching page, a connection page and a transfer page. A normal work page is a page from the input work bus to the output work bus. The switch page is the page from the output protective bus to the input working bus. The connection page is the page from the output working bus to the input protective bus. The transfer page is the page from the input protection bus to the output protection bus. Site type analysis is performed by the protective switching controller. If the node is a connection node, then the connection page is sent further, and the output working bus is replaced by the input protective bus. If the node is a switching node, then the switching page is sent further, and the output protective bus is replaced by the input working bus. If the assembly is a transmission assembly, then the transmission page is sent further, and the input protection bus is directly transmitted to the output protection bus. As shown in FIG. 4, if there are problems with the fiber between nodes B and C, when there is a need to switch the multiplex section, the system must determine what changes are required for nodes AD, analyzing the current normal working pages of each node and the location of the problem. During the analysis, it was found that the nodes A and D are the transfer nodes, the node B is the connection node, and the node C is the switching node; then nodes A and D send further the transfer page, node B sends further the connection page, and node C sends further the switch page. As can be seen from the switching algorithm, the bus switching mode in this case differs from the usual one (when all VC4s of one port take part in switching) in that VC4 belonging to the logical system takes part in the switching. Therefore, the number of VC4s that take part in the switching can be configured on a case-by-case basis, and the rest of the VC4s can be used for other types of protection.

6 shows the topology used in some existing networks. Based on the counterclockwise direction, the network elements A, B, C, D, E, F and G form a ring 601; network elements H, I, J, K, L, M, N and O form a ring 602; and both of these rings are connected through G, H and F, I. Services in ring 601 and in ring 602 can be protected by protecting the multiplex section or another type of protection, but services between the rings cannot be protected.

As for the fiber optic rings shown in Fig. 7, although they have the same network topology as in Fig. 6, they use the logical system separation, which is the subject of the present invention, which allows to protect any part of the fiber-optic network. 7, based on the counterclockwise direction, the network elements A, B, C, D, E, F and G form a virtual ring 701; network elements H, I, J, K, L, 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 and G form a large virtual ring 703. In virtual rings 701 and 702 to protect services inside these rings protection of the multiplex section can be used, and channel protection in ring 703 can be used to protect services between the rings. In this embodiment, each node is configured in the form of two logical systems; depending on the requirements of the service, all VC4s of each fiber can be mapped to the logical system of the multiplex section, or part of the VC4s of each fiber can be mapped to the logical system of the multiplexed section. As for the logical system that makes up the virtual ring 703, since this logical system has more nodes and channel protection requires more resources, in general, one or more VC4s of each of the optical ports are mapped to the logical system depending on the number of services and levels of optical ports .

On Fig shows the structure of a virtual security device that implements the above-described proposed method of virtual security. The fiber optic virtual security device includes at least three components: a 801 page analyzer, a switch controller 802, and a cross-connect circuit board 803. Each node sends work pages, the type of which depends on its current state, and switches the corresponding bus. To analyze the configuration of the logical system, an 801 page analyzer is used, which creates four working pages: a normal working page, a transfer page, a connection page, and a switching page, and stores them in the switching controller 802. Since each node has many logical systems, there are many pages, each of which refers to the logical system. A switch controller 802 is used to send a work page to the cross-connect circuit board 803, depending on the state of the connections. The cross-connect circuit board 803 carries out the switching of the respective buses. Thus, the switching process occurs.

The most preferred embodiment of the present invention is described above, which should not be understood as limiting the scope of the claims of this invention.

Claims (10)

1. The method of virtual protection of the optical fiber path, including but. physical separation of the optical port into several modules with minimal protection, b. separation of modules with minimal protection of more than one protection channel in each optical port into different logical systems with the creation of more than one logical system, from. the functioning of each node of each logical system in one of four operating modes: normal mode, transmission mode, connection mode and switching mode, d. if there is a need for protection, switching each node from the normal mode to one of the other three modes. 2. The method according to claim 1, in which the switch is a switch to the protection mode of the multiplex section, or to the protection mode of the connection via the subnet, or to the protection mode of the channel. 3. The method according to claim 2, in which switching to the protection mode of the multiplex section includes the following steps: d1. creation of logical systems for protective switching, d2. the formation of four groups of pages: work pages, switch pages, connection pages and transfer pages, d3. after determining whether the node is a transmission node, a connection node or a switching node, sending a transmission page to a transmission node, sending a connection page to a connection node and sending a switching page to a switching node. 4. The method according to claim 3, in which step d3 includes the following steps: if the current node sends a transfer page, then direct transmission through the input protective bus of the node to the output protective bus of the node, if the node sends a connection page, then replace the output working bus of the node with the input protective bus of the node, if the node sends a switching page, then replace the output protective bus node to the input working bus node. 5. The method according to claim 1, in which the module with minimal protection is VC4 or VC3, and step b is a display of at least one of many VC4 or VC3 in different logical systems to create more than one logical system. 6. The method according to claim 1, in which, when implementing protective switching in a certain logical system, only the services of the logical system that satisfy the switching condition of the current logical system are involved in the protective switching. 7. The method according to claim 1, which further includes configuring and switching services sent to the same module with minimal protection from different modules with minimal protection through a time-sharing cross-switching module available in the communication system. 8. A fiber optic virtual protection device, including at least a page analyzer for analyzing the logical system configuration, creating corresponding working pages and storing working pages in the switching controller mentioned below, a switching controller for sending the corresponding working pages to the cross-switching board mentioned below in accordance with the switching state and the cross-switching board for switching the bus in accordance with the sent work page. 9. The device of claim 8, in which the working pages are either normal working pages, or transmission pages, or connection pages, or switching pages. 10. The device according to claim 8 or 9, in which the bus connection is either a connection of the input and output working buses of the current node, or a connection of the input and output protective buses of the current node, or a connection of the input protective bus and the output working bus of the current node, or input working bus and output protective bus of the current node.

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