WO2004114594A1

WO2004114594A1 - A method on device service backup in synchronous transfer mode(atm) group net

Info

Publication number: WO2004114594A1
Application number: PCT/CN2004/000159
Authority: WO
Inventors: Shanfeng Ke; Ke Li; Xifeng Wan
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2003-06-23
Filing date: 2004-03-01
Publication date: 2004-12-29
Also published as: WO2004114594A8; HK1072670A1; CN1567890A; CN1306769C

Abstract

The invention provides a method on device service backup in asynchronous transfer mode(ATM) group net system, which has excellence about realizing easy but protect function strongly. In the method the invention applied, providing redundant virtual channel internet to realize service backup by configuring multicast connect properly or unilateralism singlecast connect for carry services, at one time, by using physice layer alarming and ATM layer alarming, to realize that the service detect fail fast and switch. Particularly, in order to protect destination terminal of unilateralism virtual connect, it configure source terminal leaf node of multicast virtual channel connect root node. But, in order to protect source node of unilateralism virtual connect, it creates unilateralism singlecast virtual channel connect from each source terminal (including job and including two terminal) to destination terminal, each unilateralism singlecast virtual channel connect has the same virtual path identifier(VPI)/virtual channel identifier(VCI) and flow parameter, and configure one of the unilateralism singlecast virtual channel connect with the state of the active, the other unilateralism singlecast virtual channel connect with the state of the non-active as reservation connect.

Description

04 000159 A service in a heterogeneous transmission mode network ^^ method

Technical field

The present invention relates to a method for distributing services in an asynchronous transmission mode (ATM) device network, and in particular, to a method for implementing service backup by using ATM multicast function and quickly detecting a failure of a service channel. Background technique

Asynchronous Transfer Mode (ATM) is a fast packet switching technology that uses fixed-length data packets called cells. ATM cells need bandwidth only when there is data transmission, but can provide time slots equivalent to time division multiplexers for continuous transmission. Each ATM connection is identified by a label in the cell header. The labels include a virtual channel identifier (Virtual Channel Identifier (hereinafter referred to as VCI)) and a virtual path identifier (Virtual Path Identifier (hereinafter referred to as VPI)) VPI _P —a virtual channel (Virtual Channel (hereinafter referred to as VC)) Or a communication path between two or more endpoints to transmit ATM cells, and a virtual path (hereinafter referred to as VP) is a group of VCs with the same endpoint. On a given interface, many different VPs multiplexed on a transmission payload are identified by their VPI, and different VCs multiplexed in a VP are identified by their VCI.

In data communication networks, ATM technology plays an extremely important role and is widely used in access, aggregation, and core switching equipment. All ATM technology-based devices are hereinafter referred to as ATM switching equipment. ATM equipment generally supports a variety of interfaces, such as El, E3, STM-1, STM-4, and so on. ATM equipment interconnects through these interfaces to realize an ad hoc network, thereby carrying various services such as video, voice, data, and Internet access.

In order to ensure the safety and reliability of these services, the main control unit and switching network board of the ATM equipment generally need to adopt the Chinese backup design to ensure that when one of the paths carrying services fails, the other one is replaced.

An existing service backup method is to implement service protection or interface backup through route switching. Specifically, in this method, it is implemented between the upper and lower ATM devices. 9

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The ATM Forum and related ITU-T protocols (such as PNNI1.1 and IISP) manage the link status between ATM devices, support dynamic routing protocols, and assign addresses to all ATM users to support dynamic calling protocols between users. . When data needs to be transmitted, the source initiates a call to dynamically apply for a virtual connection, and the system selects a normal interface and sends a virtual connection request to the destination device based on the current routing information. Therefore, after negotiation between the two ATM devices, End-to-end connections can be established between them similar to ordinary ATM interfaces. When the interface fails, the routing status will change. The system releases the current virtual connection between the two ATM devices and re-establishes a new connection between them based on the new routing information.

The disadvantage of the above method is that all the devices participating in the networking need to support the relevant protocols of the ATM Forum or ITU-T, resulting in a complicated implementation method. In the digital subscriber line access mode (DSLAM), in order to reduce costs, it is rarely necessary to The SVC / SPVC software protocol provides support, so this method is not suitable for DSLAM. In addition, because the switching is implemented through software negotiation, the switching time is long and cannot meet the switching requirements of some bearer services. For example, in the V5 voice service, failures such as call disconnection may occur.

Compared with the above method, another service backup method mainly depends on the design of the hardware. It provides a backup interface board for each interface board. Under normal circumstances, data is transmitted and received only on the interface of the active interface board. The backup interface The board does not process data. When the main interface board fails or the interface on the main interface board fails, the main board stops processing data and sets it as the standby board, and the previous standby board is upgraded to the main board to start sending and receiving data. There is also a hardware design that considers providing two active-standby interfaces in a single board. Only one interface is sending and receiving data at a time. When one interface fails, data processing is transferred to another interface.

The above method requires special design of the hardware, which leads to an increase in cost, and it is difficult to support both the active and standby interfaces and the active and standby boards at the same time, and is not conducive to the upgrade of the built-in network switching function. In addition, this method can only handle the switching guarantee when the interface between two levels of ATM equipment fails. In a multi-level ATM equipment network, protection switching cannot be performed for the failure of intermediate links and nodes.

Another interface backup method is to abandon the self-organizing network function between ATM devices. 04 000159

A 3—

Transmission equipment is networked. Since this requires a new set of transmission equipment, it is costly and the networking is not flexible. SUMMARY OF THE INVENTION The object of the present invention is to provide a service backup method in an asynchronous transfer mode (ATM) device networking, which has the advantages of simple implementation but strong protection function.

The above object of the present invention is achieved by the following service backup method:

A service backup method in an asynchronous transfer mode (ATM) networking system, the system implements service backup by providing a redundant virtual channel connection for a virtual channel connection carrying a service, wherein the system establishes a Permanent virtual connections from source endpoints to several destination endpoints:

Set the source endpoint as the root node of the multicast connection;

Each destination endpoint is set as a leaf node of the root node of the multicast connection.

In the above-mentioned service backup method in the ATM networking system, the source endpoint and the destination endpoint are connected to a cell bus to complete the exchange of ATM cells in a bus manner.

In the above-mentioned service backup method in the ATM networking system, the source endpoint and the destination endpoint are connected to a centralized ATM switching network to complete the exchange of ATM cells through it.

The above object of the present invention is also achieved by the following service backup method:

A service backup method in an asynchronous transfer mode (ATM) networking system, the system implements service backup by providing redundant virtual channel connections for virtual channel connections that carry services, wherein the system establishes Permanent virtual connections from source endpoints to several destination endpoints:

Set each source endpoint as the root node of a multicast connection, set each destination endpoint as the leaf node of each multicast connection root node, and all multicast connections have the same virtual path identifier (VPI) / virtual Channel identifier (VCI) configuration and traffic parameter configuration;

One of the multicast connections is set as the active connection in the active state, and the remaining multicast connection is set as the standby connection in the inactive state,

And, the system changes the state of the permanent virtual connection in the following manner:

If the current active connection is not available, by setting it to inactive and One of the remaining multicast connections is set to the active state to implement the switching of the active connection. In the above-mentioned service backup method in the ATM networking system, the source endpoint and the destination endpoint are connected to a cell bus to complete the exchange of ATM cells in a bus manner.

In the above-mentioned service backup method in the ATM networking system, the source endpoint and the destination endpoint are connected to a centralized switching network to complete the exchange of ATM cells through it.

A service backup method in an asynchronous transfer mode (ATM) networking system, the system implements service backup by providing redundant virtual channel connections for virtual channel connections that carry services, wherein the system establishes A permanent virtual connection from a source endpoint to a destination endpoint:

Establish a unidirectional unicast connection from each source endpoint to the destination endpoint, each unidirectional unicast connection has the same virtual path identifier (VPI) / virtual channel identifier (VCI) and traffic parameters; one of them is unidirectional Unicast connections are set as the active connection in the active state, and the remaining unidirectional unicast connections are set as the standby connection in the inactive state.

And, the system changes the status of the permanent virtual connection in the following manner: If the current primary connection is unavailable, it is achieved by setting it to an inactive state and setting one of the remaining unidirectional unicast connections to the active state Switching of the active connection.

In the above-mentioned service backup method in the ATM networking system, for virtual connections with the same working / protection interface, it is determined whether the virtual connection carrying the main connection service is connected according to the physical layer alarm reported by the ATM interface. The virtual connection of the virtual channel is to determine whether the virtual connection carrying the main connection service is connected according to the OAM layer alarm reported by the virtual channel.

It can be seen from the above that in the service backup method of the present invention, the ATM networking system can provide redundant virtual channels for bearer services by properly configuring a multicast connection or a unidirectional unicast connection. Connect for business backup. BRIEF DESCRIPTION OF THE DRAWINGS

The objectives, features, and advantages of the present invention can be further understood through the following description of the preferred embodiments of the present invention with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagram of an embodiment of the method according to the present invention.

Fig. 2 is a schematic view of another embodiment of the method according to the present invention. DETAILED DESCRIPTION The core idea of the method of the present invention is to implement service backup by providing redundant virtual channel connections for bearer services, which will be further explained below.

In case 1, if a service is carried by a permanent virtual connection from a source endpoint to a destination endpoint, in order to provide service backup capability to the destination endpoint, according to the present invention, in addition to the destination endpoint, multiple destination endpoints can be added and A virtual channel connection carrying the service is established between the source endpoint and each additional destination endpoint. The multicast function of the ATM technology can establish a starting point-multipoint virtual channel connection, so it can be used to implement the above service backup capability. That is, the source endpoint is first set as the root node of the multicast connection, and then each destination endpoint is set. A leaf node of a root node for the multicast connection.

In case 2, if a service is a multicast service itself, that is, the source endpoint serves as the root node to transmit services to multiple destination endpoints as its leaf nodes. In order to provide service backup capabilities to the source endpoint, according to the present invention, in addition to the Multiple source endpoints can be added in addition to the source endpoint, and each source endpoint is set as the root node of a multicast connection, each destination endpoint is set as the leaf node of each multicast connection root node, and all multicast Connections have the same Virtual Path Identifier (VPI) / Virtual Channel Identifier (VCI) configuration and traffic parameter configuration. In order to ensure that only one multicast connection is transmitting services at a time, one of the multicast connections should be set as the active connection in the active state, and the rest should be set as the standby connection in the inactive state. If the current active connection is unavailable, the active connection is switched by setting it to the inactive state and setting one of the remaining multicast connections to the active state.

In case 3, if a service is permanent from a source endpoint to a destination endpoint N2004 / 000159

A 6-

The virtual connection bearer, in order to provide service backup capability to the source endpoint, according to the present invention, in addition to the source endpoint, multiple source endpoints can be added, and a unidirectional unicast connection from each source endpoint to the destination endpoint is established. A unicast connection has the same virtual path identifier (VPI) / virtual channel identifier (VCI) and traffic parameters. In order to ensure that only one unicast unidirectional connection is transmitting services at any time, one of the unidirectional unicast connections should be set as the active primary connection, and the remaining unidirectional unicast connections should be set as inactive. Backup connection. If the current active connection is unavailable, the active connection is switched by setting it to the inactive state and setting one of the remaining unidirectional unicast connections to the active state.

The above situations 1 to 3 are the basic connection types. The service backup of other connection types can be realized by combining the above methods. For example, for a point-multipoint two-way unicast connection, the method of case 1 can be used to implement service backup of a point-to-multipoint virtual connection, and the method of case 3 can be used to implement service backup of a multipoint-to-point virtual connection.

The following describes two preferred embodiments for implementing protection switching of a bidirectional unicast connection by using the embodiments. The first embodiment is used for an ATM device of a bus-type switching structure, and the second embodiment is used for centralized switching. ATM equipment of the type structure. First embodiment

In the ATM equipment at the access layer, a bus-type switching structure as shown in FIG. 1 is generally used for connection. For simplicity, it is assumed here that three interface boards A, B, and C implement ATM cell exchange based on the bus-type switching structure. The interface board B and the interface board C provide uplink interfaces and are respectively connected to the first device and the second device, that is, they are connected to the upper-layer network through the two uplink interfaces.

In order to enable the services accessed through interface board A to be reliably and reliably transmitted to the upper-layer network (that is, devices 1 and 2) through the two uplink interfaces on interface board B and interface board C, it is necessary to provide the service between the two interfaces. Choose a path. The specific implementation method is as follows:

When a permanent virtual connection is established, in the direction of interface board A to interface board B and interface board C, a multicast connection root with interface board A as the root node and interface board B as the leaf node is first established, and then A leaf is added to the interface board C on this connection, that is, the interface board C is also set as a leaf node of the multicast connection. And on interface board B and interface board C In the direction to interface board A, establish a unidirectional unicast connection from interface board B to interface board A and from interface board C to interface board A, respectively. These two connections use the same VPI / VCI and have the same flow parameters. In addition, in order to ensure that only one connection is available at any one time, only one of the two connections should be activated. For example, it is assumed here that a unicast connection from interface board B to interface board A is activated.

In this configuration of a two-leaf multicast connection + two unidirectional unicast connections, the data connected to interface board A is sent to the connections on interface boards B and C at the same time, but interface board A only sends from interface board B Receiving data, thereby achieving data transmission with the uplink device through the "dual transmission selective reception" mode. When switching is required (for example, when the connection between interface board B is abnormal or data cannot be received), the multicast connection from interface board A to interface board B and interface board C does not change. You only need to control interface board B and The state of the two unidirectional unicast connections from interface board C to interface board A is sufficient. Specifically, deactivate the unicast connection from interface board B to interface board A and activate the unicast connection from interface board C to interface board A. .

In order to achieve fast switching, the system needs to know the fault conditions of each virtual connection in time. Therefore, it is necessary to support the physical layer alarm and the operation and management (OAM) alarm capability between the device and the upper-level device, according to the OAM on the interface link and the connection. Alarms switch unicast connections in a timely manner.

Because an interface supports many virtual channel (VC) connections, if the F5 alarm cell is used to detect the status of data transmission and reception on each VC connection, more system resources will be consumed. In order to save system resources, VC connections with the same path and the same service are assigned the same VPI, so only F4 alarm cells can be used in the device, that is, only alarms at the VP layer are detected. Once a fault is found, all VCs on the VP are performed. Switch. For example, virtual connections with the same working port / protected port can be grouped into the same protection group, and a VP can be arbitrarily selected as a channel for establishing F4 OAM, and then periodically (for example, 0.5 seconds) in the OAM channel. Send CC cells (or receive cells). If CC cells are not received within three consecutive CC cell sending cycles, the protection group is considered to be faulty, and the services of the entire protection group are switched from the working path to the protection path.

In addition, related protection protocols such as 1.610 and 1.630 can also be used to detect RLOS / ROF / SD alarms at the physical layer, AIS / RDI alarms at the ATM layer, interfaces on the device, and board failure alarms to initiate service protection switching. T N2004 / 000159

1 8 1 Second Embodiment

In the backbone layer and convergence layer equipment, due to the high demand for switching capacity, the centralized switching structure shown in Figure 2 is generally used for connection. For the sake of simplicity, it is assumed that the three ATM business processing units are respectively connected to the interface boards A and B. , C and the switching network board access the switching network to realize the exchange of ATM cells, and the interface boards B and C provide working ports and protection ports respectively.

In order for the service accessed by the interface board A to be transmitted stably and reliably through the two ports on the interface boards B and C, two selection paths need to be provided for the service. The specific implementation method can also adopt the configuration of a two-leaf multicast connection + two unidirectional unicast connections, which will be further described below.

When establishing a permanent virtual connection, in the direction of interface board A to interface boards B and C, first establish a root of a multicast connection with interface board A as the root node and interface board B as the leaf node, and then in this section A leaf is added to the interface board C on the connection, that is, the interface board C is also set as a leaf node of the multicast connection. In the direction of interface boards B and C to interface board A, one unidirectional unicast connection is established from interface board B to interface board A and interface board C to interface board A, and these two connections are at the source and destination. Points use the same VPI / VCI and have the same flow parameters. In addition, in order to ensure that only one connection is available at any time, only one of the two connections should be activated. For example, it is assumed here that the interface board is activated.

Unicast connection from B to interface board A.

Similarly, during the operation, the data connected to interface board A is sent to the connections on interface boards B and C at the same time, but interface board A only receives data from interface board B, thus implementing the mode of "dual transmission and selective reception". The reliable transmission of data. When switching is required (for example, when the connection of interface board B is abnormal or data cannot be received), the multicast connection from interface board A to interface boards B and C does not change. You only need to control interface board B and interface board The state of the two unidirectional unicast connections from C to interface board A is sufficient. Specifically, the unicast connection from interface board B to interface board A is deactivated and the unicast connection from interface board C to interface board A is activated.

Compared with the first embodiment, the second embodiment should also support the physical layer alarm and the operation and management (OAM) alarm capability between the device and the superior device to switch the order in time according to the OAM alarm on the interface link and connection Broadcast connection. And to save system resources, the same 004 000159

-9- You can also assign the same VPI to VC connections with the same path and the same service, so you can use only F4 alarm cells in the device.

In short, no matter whether it is a centralized switching structure or a bus switching structure, the method of the present invention can be used to implement service backup of a bidirectional unicast connection, and the difference lies only in the multicast replication structure. For those of ordinary skill in the art, the same is true for service backups of other connection types, and therefore will not be described again. It can be seen from the above that the method of the present invention can realize the protection switching of the interface without any special design of the interface hardware of the ATM device. As long as the ATM device supports the multicast feature, it can be used in a wide range and has a wide range of supported interface types. Supports various interfaces such as E1 / T1, E3 / T3, STM-1 / STM-4, etc.), with strong portability and low cost.

In addition, the method of the present invention can not only realize board-level and interface-level protection switching, but also can implement VP-level protection switching. Therefore, the method has a wider application range, more flexible modes, and more powerful protection functions.

Finally, compared with a backup solution implemented by other software such as SVC, the technical solution of the present invention is simple in design, has a fast switching speed, and can complete switching within 50ms, so it has almost no impact on various services carried.

Claims

Rights request

1. A service backup method in an asynchronous transfer mode (ATM) networking system, characterized in that the system establishes a permanent virtual connection from one source endpoint to several destination endpoints in the following manner:

Set the source endpoint as the root node of the multicast virtual channel connection;

Each destination endpoint is set as a leaf node connected to the root node of the multicast virtual channel.

The service backup method in an ATM networking system according to claim 1, characterized in that the source endpoint and the destination endpoint are connected to a cell bus to complete the exchange of ATM cells in a bus manner.

3. The service backup method in the ATM networking system according to claim 1, wherein the source endpoint and the destination endpoint are connected to an ATM switching network to complete the exchange of ATM cells in a centralized manner.

4. A service backup method in an asynchronous transfer mode (ATM) networking system, characterized in that the system establishes permanent virtual connections from several source endpoints to several destination endpoints in the following manner:

Set each source endpoint as the root node of a multicast virtual channel connection, set each destination endpoint as the leaf node of each multicast virtual channel connection root node, and all multicast virtual channel connections have the same virtual path identifier (VPI) / Virtual Channel Identifier (VCI) configuration and traffic parameter configuration;

One of the multicast virtual channel connections is set as the active active connection, and the remaining multicast virtual channel connection is set as the inactive standby connection.

In addition, the system changes the status of the permanent virtual connection in the following manner: If the current active connection service is unavailable, it is set to an inactive state and one of the remaining multicast virtual channel connections is set to an active state. To achieve the switchover of the active connection.

5. The service backup method in the ATM networking system according to claim 4, wherein the source endpoint and the destination endpoint are connected to a cell bus to complete the exchange of ATM cells in a bus manner.

6. The service backup method in the ATM networking system according to claim 4, wherein the source endpoint and the destination endpoint are connected to an ATM switching network to complete the exchange of ATM cells in a centralized switching manner.

7. A service backup method in an asynchronous transfer mode (ATM) networking system, characterized in that the system establishes a permanent virtual connection from several source endpoints to a destination endpoint in the following manner:

Establish a unidirectional unicast virtual channel connection from each source endpoint to the destination endpoint, each unidirectional unicast virtual channel connection has the same virtual path identifier (VH) / virtual channel identifier (VCI) and traffic parameters

One of the unidirectional unicast virtual channel connections is set as the active connection in the active state, and the remaining unidirectional unicast virtual channel connection is set as the inactive standby connection, and the system changes the permanent virtual link in the following manner. Connection status: If the current active connection service is unavailable, the active connection is switched by setting it to the inactive state and setting one of the remaining unidirectional unicast virtual channel connections to the active state.

The service backup method in an ATM networking system according to claim 7, characterized in that the source endpoint and the destination endpoint are connected to a cell bus to complete the exchange of ATM cells in a bus manner.

The service backup method in the ATM networking system according to claim 7, characterized in that the source endpoint and the destination endpoint are connected to the ATM network to complete through centralized exchange

ATM cell exchange.

10. The method for backing up services in an ATM system network according to claim 4 or 7, characterized in that, for virtual connections having the same working / protection interface, it is determined that the main connection service is carried according to a physical layer alarm reported by the ATM interface. Whether the virtual link of the virtual link is connected, and for the virtual link with the same working / protection virtual path, determine whether the virtual link carrying the main connection service is connected according to the OAM alarm reported by the virtual path.