CN100414918C - Method and device for transmitting ATM service based on IP switching - Google Patents

Abstract

The invention relates to a method and device for transmitting ATM services based on IP switching. The core of the present invention is to identify the ATM service that needs to be transparently transmitted in the IP access device; and carry out the encapsulation process based on the Ethernet protocol on the ATM service, and send it, thereby ensuring the integrity of the corresponding ATM service information . That is to say, the present invention is that the ATM cell of the ATM uplink interface or the ATM service application user interface is directly carried on the Ethernet, and after passing through the IP switching system, the Ethernet encapsulation is stripped off at the exit or the entrance of the ATM service device and directly restored to the ATM cell In this way, the application of downlink ATM and ATM uplink interface can be achieved simply and conveniently, and there is no need to understand the internal bearer format of the cell, and the scalability is good.

Description

Method and device for transmitting ATM service based on IP switching

technical field

The invention relates to the technical field of network communication, in particular to a method and device for transmitting ATM services based on IP switching.

Background technique

The evolution from ATM (Asynchronous Transfer Mode) to IP transmission mode is the current development trend of access equipment. During the development process, it is necessary to take into account the protection of the existing investment of operators, that is, to enable IP access equipment to access the original ATM access equipment. For this reason, how to support the uplink to the ATM network, and how to support the TDM (Time Division Multiplexing) service supported by the original ATM on the IP DSLAM (IP Digital Subscriber Line Access Multiplexer) are the needs of current IP access equipment. The main problem solved.

When considering the ATM interface, the frame structure of the IP access device is usually based on the IP architecture, as shown in Figure 1, the form of the IP access device is gradually becoming more and more widely used, and the ATM interface on the network side is added to the interface form , the ATM interface can access ATM access equipment or ATM private line services, but because the switching system in the IP access equipment is implemented based on IP, it is relatively difficult to support the ATM interface.

ADSL (Asymmetric Digital Subscriber Line) and ATM E1/E3 interfaces transmit ATM cell data, while the uplink port of IP access equipment may be FE (Fast Ethernet)/GE (Gigabit Ethernet) port IP uplink may also be the ATM uplink of ATM E1/E3. Through the switching system, the connection support from ATM to ATM needs to go through the complicated process of ATM-IP-ATM, and each user needs a MAC ( Media Access Control) address, there is a great demand for the MAC address of the switching system; the entire process of ATM-IP-ATM needs to be processed by SAR (fragmentation and reassembly), and it is difficult to completely transmit ATM information, and it is necessary to support AAL1 and AAL2 The SAR function is more complicated, which increases the difficulty of processing.

In addition to the ATM interface requirements on the network side, as shown in Figure 2, because ATM technology was a mainstream application technology in the early days of DSL access, many current operators use ATM-based equipment at the network aggregation layer or services. At this time, if the ATM access equipment ATM DSLSM (ATM digital subscriber line access multiplexer) or the ADSL terminal is to access the ATM service equipment application, the current IP access equipment cannot support this application. Therefore, when IP access equipment is put into use, support for the above situations needs to be considered.

In order to adapt to the above application environment, IP access equipment needs to be able to support ATM service transmission. For this reason, the industry currently adopts various implementation methods in the application process to achieve the above-mentioned purpose.

One method adopted at present is: multi-bus-based IP access equipment, that is, by providing ATM and IP buses on the IP access equipment at the same time to support the downlink ATM access equipment and the ATM uplink interface. Uplink ATM services go through the ATM bus, so that cells can go directly from the user interface to the network interface.

It can be seen that the multi-bus technology can well solve the ATM uplink problem, but it does not improve the ATM service application support for IP uplink (the ATM service application refers to the ATM service needs to be accessed via IP access equipment and IP The metropolitan area network reaches the ATM service equipment), and for the mixed application of IP and ATM services, especially when there are some ATM services and some IP services on the ATM equipment connected below, because the ATM bus and the IP bus are physically isolated, At this time, the multi-bus solution cannot be realized through a flexible bus allocation mechanism, and the common disadvantages are obvious.

Another implementation method currently adopted is: equipment based on the IP switching system, for the user interface, whether it is an ADSL or ATM interface, unified reorganization into Ethernet frames, after passing through the IP switching system, it is processed according to the network interface form at the exit , the FE/GE interface directly sends the Ethernet, and the ATM interface needs to be fragmented again. The same applies to the processing returned from the network side.

In this solution, complex reassembly and fragmentation of packets may be required at both the ingress and egress of the IP access device, and the processing cost and complexity are relatively high. Configure the forwarding table for each user on the Internet, which wastes system resources and increases the burden on the system. And considering the diversity of ATM business formats, ATM information is easily lost in recombination and slicing. In addition, for the mixed service application of IP and ATM, and when the uplink port is an FE/GE interface, it is impossible to completely transmit ATM information to the ATM service application equipment.

Another problem obviously existing in the above-mentioned second implementation scheme is that the scalability is not strong. Once the internal format of the cell changes, reorganization or slicing cannot be supported, the ATM service will not be able to be carried out.

Contents of the invention

In view of the existing problems in the above-mentioned prior art, the purpose of the present invention is to provide a method and device for transmitting ATM services based on IP switching, so that the transmission of ATM services can be supported flexibly and conveniently on the IP access equipment, and realize Simple, at the same time, the present invention can also be applied to the mixed application of IP and ATM services.

The purpose of the present invention is achieved through the following technical solutions:

The invention provides a method for transmitting ATM services based on IP switching, including:

In the network where the IP service and the ATM service coexist, the ATM service that needs to be processed through the IP exchange is first encapsulated and processed based on the Ethernet protocol, and then processed and sent through the IP exchange. The method specifically includes:

A, identify the asynchronous transfer mode ATM service that needs to be transparently transmitted in the business that needs to be processed by IP exchange;

B. Encapsulate the ATM service based on the Ethernet protocol, and then send it through IP switching.

In the present invention, when the IP exchange process is performed through the IP access device, the step A includes:

In the uplink direction of the IP access device, judge whether it is an ATM service that needs to be transparently transmitted according to the uplink interface and/or connection information of the received ATM service, and if the uplink interface is an ATM interface or a permanent virtual channel PVC connection, It is an ATM service that requires transparent transmission.

In the present invention, when the IP exchange process is performed through the IP access device, the step A includes:

In the downlink direction of the IP access device, judge whether it is an ATM service that needs to be transparently transmitted according to the interface receiving the service, and if the service is received by an ATM network interface, then the service is an ATM service that needs to be transparently transmitted.

Described step B comprises:

The ATM service to be transparently transmitted is encapsulated with Ethernet header information, connection information, packet type information and/or standard Ethernet checksum information, and sent.

Described step B also includes:

The frames that have undergone Ethernet-based encapsulation processing and IP switching processing are decapsulated based on the Ethernet protocol and sent.

In the present invention, when performing IP exchange processing through the IP access device, the step B also includes:

In the uplink direction of the IP access device, the services that do not need to be transparently transmitted are reorganized into packets, encapsulated into Ethernet frames, and then sent;

After the IP access device exchanges the message to be sent, it judges whether it needs to go up through the ATM interface. If so, it strips and encapsulates the Ethernet-based ATM frame to obtain the ATM The network frame is fragmented into ATM cells and then sent, otherwise, the corresponding message is directly forwarded.

In the present invention, when performing IP exchange processing through the IP access device, the step B also includes:

In the downlink direction of the IP access device, the services that do not require transparent transmission are directly sent for processing;

After the message to be sent is exchanged and processed in the IP access device, it is judged whether it is an Ethernet-based ATM frame, and if so, the encapsulation process is stripped to obtain the ATM cell and then sent, otherwise, the Ethernet frame is fragmented into Sent after ATM cells.

The present invention also provides a device for transmitting ATM services based on IP switching, including:

Identification processing module: used to identify the services that need to be encapsulated or decapsulated based on the Ethernet protocol in the uplink or downlink services that need to be processed by IP switching, and handed over to the Ethernet encapsulation module or the Ethernet Network decapsulation module;

Ethernet encapsulation module: encapsulate the corresponding business based on the Ethernet protocol, and send it to the module responsible for IP exchange processing;

Ethernet decapsulation module: decapsulate the corresponding business based on the Ethernet protocol, strip the Ethernet encapsulation, and send it.

The device described in the present invention can be set in IP access equipment.

It can be seen from the above-mentioned technical solution provided by the present invention that the present invention realizes the support of ATM service on the IP access device through a simple AOE (ATM over Ethernet) encapsulation technology. Specifically include: support for ATM service interface, support for ATM network interface, and support for coexistence of ATM service interface, IP and ATM network interface, in addition, it can also support the connection with ATM service equipment after passing through the IP MAN, and support for IP and ATM hybrid application.

The AOE technology is simple to implement, has strong scalability, and protects investment in ATM access equipment and ATM service equipment. In the transformation from ATM to IP network, it can well support the mixed networking of IP and ATM services, and at the same time connect ATM access equipment to the IP metropolitan area network.

Description of drawings

FIG. 1 is a schematic structural diagram of an IP access device;

Fig. 2 is a network diagram of comprehensive application of IP and ATM services based on IP access equipment;

3 is a schematic diagram of an uplink processing process in the method of the present invention;

Fig. 4 is a schematic diagram of the downlink processing process in the method of the present invention;

Fig. 5 is a schematic structural diagram of the device of the present invention.

Detailed ways

Still referring to Figure 2, the IP access device IP DSLAM (IP Digital Subscriber Line Access Multiplexer) can use ATM, Ethernet or MPLS for uplink on the network side. If the ATM access device ATM DSLSM (ATM Digital Subscriber Line Access Multiplexer) or ADSL terminal is connected to the ATM service device application, it is necessary to transparently transmit the PVC (Permanent Virtual Connection) information to the peer ATM device. The same processing is required from the ATM service equipment to the user side.

For this reason, the present invention provides a kind of AOE (ATM based on Ethernet) technology, can realize through this AOE technology to support and hang down ATM access equipment on IP access equipment, ATM uplink, IP and ATM service hybrid application. It can reduce the difficulty and cost of equipment processing, and transmit PVC information to the business peer without loss, providing the possibility for future business expansion.

The AOE technology of the present invention is mainly: the ATM cell of the ATM uplink interface or the user interface of ATM service application is directly carried on the Ethernet and then stripped at the exit or the entrance of the ATM service equipment after passing through the IP switching system of the IP access device The Ethernet encapsulation is directly restored to ATM cells, so that the application of downlink ATM and ATM uplink interfaces can be implemented simply and conveniently, and there is no need to understand the internal bearer format of cells, and the scalability is good. For the IP service application of the IP interface, it is reassembled into an Ethernet frame at the entrance and forwarded from the FE/GE after passing through the IP switching system.

In order to have a further understanding of the present invention, the application based on AOE will be described in detail below.

Described AOE is a kind of technology that directly encapsulates ATM cells into Ethernet frames, and the AOE frame format after encapsulation is as shown in Table 1:

Table 1

data field illustrate Ethernet frame header Standard Ethernet frame header, including DMAC/SMACNLAN, etc. DMAC/SMAC does not need to be subdivided for users during AOE, and one for each board can also be implemented; AOE type field Description is the flag of AOE format, you can customize a value, which is equivalent to the Ethernet type field Inner join index number Mainly carry some connection information, generally PVC connection information and tag information, the length and format can be customized ATM cell It is possible to transmit ATM cells completely or remove parts such as HEC fields filling Can be with or without, and there is no specific limit on the length FCS Standard Ethernet checksum

Based on the AOE frame format shown in Table 1, transparent transmission of ATM cells can be implemented on the IP access device, and the entire processing process is simple to implement.

In the specific application process of the present invention, the processing for ATM services on the IP access equipment mainly includes the processing of the uplink direction from the user side to the network side and the downlink processing from the network side to the user side. This process is described in detail.

First, when the business is transferred from the user side to the network side, the corresponding processing process is shown in Figure 3, which specifically includes the following processing steps:

Step 31: Determine whether the service type coming from the user interface needs to be AOE-encapsulated, if yes, perform step 32, otherwise, perform step 33;

Specifically: for the application processing from the user interface to the network interface, judge the user service type at the user interface according to the PVC or the port, if it is an uplink ATM interface or an ATM service application, that is, the destination of the service is an ATM network or an ATM device, then It is determined that the business coming from the user interface is the business that needs to be encapsulated by AOE;

Step 32: adopt the AOE message format shown in Table 1 to encapsulate the ATM cell, and perform step 35;

The connection information uses the PVC connection number or the connection number obtained from table lookup, the DMAC (destination MAC) address is the MAC address of the uplink port, and the SMAC (source MAC) address can be distinguished based on the user, or one for each board;

Step 33: if it is other business applications, i.e. non-ATM business applications, then recombine the corresponding cells such as ATM into messages;

Step 34: Convert the reassembled message into a common Ethernet frame according to the ATM encapsulation type;

Step 35: On the IP access device, pass the corresponding Ethernet frame or AOE frame to the network side interface through the IP switching system, and the IP switching system can be considered as an Ethernet switching device;

Step 36: judging whether it is uplink through the ATM network interface, if yes, then perform step 37, otherwise, perform step 38;

That is to say whether the whereabouts of the business is judged to be the ATM service equipment directly connected with the IP access equipment, if yes, then perform step 37, otherwise, perform step 38;

Step 37: If it is determined that it needs to be forwarded through the ATM uplink interface, then further judge whether it is an AOE frame, if yes, then perform step 39, otherwise, perform step 310;

Step 39: directly stripping the Ethernet encapsulation of the AOE, and sending directly after taking the ATM cell data;

Step 310: Fragment the Ethernet frame into ATM cells and send them. The purpose of this processing is to be compatible with the existing processing.

Step 38: If it is determined that the data needs to be forwarded through the FE/GE IP uplink interface, then directly forward the message, the only difference is that the ATM service application transmits the AOE frame, and the IP service transmits the ordinary Ethernet frame;

The AOE frame applied by the ATM service will be processed by stripping its Ethernet encapsulation on the corresponding equipment at the opposite end receiving the service, so as to obtain the original ATM cell.

Next, the service processing process from the network side to the user interface side will be described, as shown in Figure 4, which specifically includes the following processing steps:

Step 41: judging in the process from the network side to the user interface, whether the network side input interface is an ATM network interface, if so, then perform step 42, otherwise, directly perform step 43;

Step 42: If the network side input interface is an ATM network interface, then the cell is encapsulated into an Ethernet frame according to the AOE format, and step 43 is performed;

Step 43: Exchanging and forwarding the data input by the network side, specifically performing IP or network exchange processing on the data message;

That is, if it is the data imported by the FE/GE IP interface, it will directly carry out IP exchange and forwarding, and if it is the data imported by the ATM network interface, it will need to perform Ethernet frame exchange and forwarding after step 42 is processed;

Step 44: when the user interface is processed through the IP exchange, then judge whether the message is an AOE frame, specifically judge whether it is an AOE frame according to the Ethernet type field, if yes, then perform step 45, otherwise, perform step 44: 46;

Step 45: If the message switched to the user interface is an AOE frame, then strip the Ethernet header and take out the connection number and the ATM cell to directly forward;

After this step, the AOE frame encapsulated at the local end and the AOE frame transmitted through the IP network interface can be processed into original ATM cells and sent to the user side;

Step 46: If it is an Ethernet frame, perform fragmentation processing and then send it to the user side, specifically, fragment the Ethernet frame into ATM cells and then send it.

In a word, the processing process of AOE implementation on the IP access device of the present invention includes the judgment of AOE or common Ethernet frame processing. The specific frame format and bit field field can be customized or processed according to the standard. The present invention does not make specific limitations . Moreover, in the actual processing process, the AOE technology used in the present invention may no longer be the name of AOE, but its main processing is to directly encapsulate the cells into independent Ethernet frames one by one without reorganizing them. The processing method to realize that the IP access equipment supports the ATM service shall be within the protection scope of the present invention.

The present invention also provides a device for transmitting ATM services at an IP access device, as shown in Figure 5, the device specifically includes:

Identification processing module: used to identify the business that needs to be processed by Ethernet encapsulation or decapsulation in the uplink or downlink services of the IP access device, and hand it over to the Ethernet encapsulation module or Ethernet decapsulation module;

Ethernet encapsulation module: perform Ethernet encapsulation processing on the corresponding services, and send them to the sending module in the IP access device (the sending module is an existing module in the IP access device), which can be used as shown in Table 1 AOE frame format for Ethernet encapsulation processing;

Ethernet decapsulation module: perform Ethernet decapsulation processing on the corresponding business, that is, strip the Ethernet encapsulation of the business, and send it to the sending module for transmission.

To sum up, the present invention supports ATM services on IP access equipment through a simple AOE encapsulation technology. Moreover, the AOE technology is simple to implement, has strong scalability, and can effectively protect investment in ATM access equipment and ATM service equipment. In the transformation from ATM to IP network, it can well support the mixed networking of IP and ATM services, and at the same time connect ATM access equipment to the IP metropolitan area network.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (9)

1. A method for transmitting ATM services based on IP switching, characterized in that, comprising: A, identify the asynchronous transfer mode ATM service that needs to be transparently transmitted in the business that needs to be processed by IP exchange; B. Encapsulate the ATM service based on the Ethernet protocol, and then send it through IP switching. 2. the method for transmitting ATM service based on IP exchange according to claim 1, is characterized in that, when carrying out IP exchange process by IP access equipment, described step A comprises: In the uplink direction of the IP access device, judge whether it is an ATM service that needs to be transparently transmitted according to the uplink interface and/or connection information of the received ATM service, and if the uplink interface is an ATM interface or a permanent virtual channel PVC connection, It is an ATM service that requires transparent transmission. 3. the method for transmitting ATM service based on IP exchange according to claim 1, is characterized in that, when carrying out IP exchange process by IP access equipment, described step A comprises: In the downlink direction of the IP access device, judge whether it is an ATM service that needs to be transparently transmitted according to the interface receiving the service, and if the service is received by an ATM network interface, then the service is an ATM service that needs to be transparently transmitted. 4. according to claim 1,2 or 3 described based on the method for IP exchange transmission ATM service, it is characterized in that, described step B comprises: The ATM service to be transparently transmitted is encapsulated with Ethernet header information, connection information, packet type information and/or standard Ethernet checksum information, and sent. 5. according to claim 1,2 or 3 described based on the method for IP exchange transmission ATM service, it is characterized in that, described step B also comprises: The frames that have undergone Ethernet-based encapsulation processing and IP switching processing are decapsulated based on the Ethernet protocol and sent. 6. according to claim 1,2 or 3 described based on the method for IP exchange transmission ATM service, it is characterized in that, when carrying out IP exchange process by IP access equipment, described step B also comprises: In the uplink direction of the IP access device, the services that do not need to be transparently transmitted are reorganized into packets, encapsulated into Ethernet frames, and then sent; After the IP access device exchanges the message to be sent, it judges whether it needs to go up through the ATM interface. If so, it strips and encapsulates the Ethernet-based ATM frame to obtain the ATM The network frame is fragmented into ATM cells and then sent, otherwise, the corresponding message is directly forwarded. 7. according to the method for claim 1,2 or 3 described based on IP switching transmission ATM service, it is characterized in that, when carrying out IP switching process by IP access equipment, described step B also comprises: In the downlink direction of the IP access device, the services that do not require transparent transmission are directly sent for processing; After the message to be sent is exchanged and processed in the IP access device, it is judged whether it is an Ethernet-based ATM frame, and if so, the encapsulation process is stripped to obtain the ATM cell and then sent, otherwise, the Ethernet frame is fragmented into Sent after ATM cells. 8. A kind of device based on IP switching and transmitting ATM service, is characterized in that, comprises: Identification processing module: used to identify the services that need to be encapsulated or decapsulated based on the Ethernet protocol in the uplink or downlink services that need to be processed by IP switching, and handed over to the Ethernet encapsulation module or the Ethernet Network decapsulation module; Ethernet encapsulation module: encapsulate the corresponding services based on the Ethernet protocol, and send them to the module responsible for IP exchange processing; Ethernet decapsulation module: decapsulate the corresponding business based on the Ethernet protocol, strip the Ethernet encapsulation, and send it. 9. The device for transmitting ATM services based on IP switching according to claim 8, characterized in that, the device can be arranged in the IP access equipment.

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