CN1306770C - A method for bearing IP message protocol on ATM network supported by broadband access equipment - Google Patents

Abstract

The present invention discloses a method for bearing an IP message protocol on an ATM network supported by a broadband access device, which comprises the steps that a broadband access device arranges received messages and converts packed protocol types in the up direction from a user side to a network side, i.e. messages packed by an IPOA protocol are converted into messages packed by an Ethernet protocol, and then the messages are sent to an IP metropolitan area network. The broadband access device converts the packed protocol of received messages in the down direction from the network side to the user side, i.e. messages packed by the Ethernet protocol are converted into messages packed by the IPOA protocol, and then the messages are under the process of route enquiry to obtain relevant PVC information and finally are sent to the user side. The method solves the problem that additional final devices need adding when an ATM network is communicated with the IP metropolitan area network, simplifies network structure, lowers operating cost, and enhances the functions of multicast and cascade connection of the ATM network.

Description

A method for broadband access equipment to support ATM network carrying IP message protocol

technical field

The invention relates to a protocol conversion technology, in particular to a method for a broadband access device to support an IP message protocol (IPOA) carried by an ATM network through protocol conversion.

Background technique

At present, most digital subscriber line (DSL) technologies, including asymmetric digital subscriber line (ADSL), very high-speed digital subscriber line (VDSL), G.shdsl and other DSL technologies are based on ATM cell technology. The residential equipment (CPE) is transmitted to the DSLAM equipment through the subscriber line in the form of ATM cells.

Existing broadband access equipment Digital Subscriber Line Access Multiplexer (DSLAM) does not terminate the ATM cell, after processing at the ATM layer, it goes out from the uplink ATM interface of the DSLAM, and then passes through the ATM network to the BAS (broadband access server) device or to a router. The termination of ATM cell is handled on BAS equipment or router.

In the following description, the forwarding process from the user side to the network side is defined as uplink; the forwarding process from the network side to the user side is defined as downlink.

In the present network, IPOA agreement is suitable for the DSLAM apparatus of ATM network. Through this agreement, DSLAM can directly connect with the BAS equipment of the ATM interface, and can also be forwarded in the ATM network, and then connected with the BAS equipment. If the existing network is an IP network, in order to provide IPOA access in the IP network, the existing equipment cannot directly support the access of the IPOA protocol, and an additional ATM termination device is required to perform IPOA termination and convert it to IP uplink. This increases the operator's investment and complicates the network.

Contents of the invention

The purpose of the present invention is to provide a scheme for supporting IPOA in existing broadband access equipment DSLAM equipment, thereby realizing direct intercommunication between ATM network and IP metropolitan area network.

The present invention includes two parts of uplink processing and downlink processing. In the uplink direction, the transmission process of the message from the user side to the network side includes the following steps:

a1. Receive user messages from the user side;

b1. according to the ATM cell header information in the received message, extract and combine the information in each ATM cell information domain in the message, then encapsulate the combined message according to the IPOA protocol;

c1. convert the message encapsulated by the IPOA protocol into the message encapsulated by the Ethernet protocol in the step b1, and send the encapsulated message to the IP metropolitan area network;

In the downlink direction, the transmission process of the message from the network side to the user side includes the following steps:

a2. receiving the message sent by the IP MAN;

B2. carry out routing inquiry and encapsulation type conversion to the received message, convert the message encapsulated by the Ethernet protocol into the message encapsulated by the IPOA protocol;

c2. Splitting the message encapsulated according to the IPOA protocol in step b2 according to the ATM cell format, and sending the split message to the user side.

Wherein, described in step c1 is converted into by Ethernet protocol encapsulation message and further comprises: first delete the logical link control (LLC) in the IPOA agreement encapsulation message and organization unique identifier (OUI) field, then delete LLC and OUI Before the packet, add the pre-negotiated media access control (MAC) address of the gateway as the destination media access control (DMAC) address, and the MAC address set by the broadband access device as the source media access control (SMAC) address .

Wherein, the routing query described in step b2 refers to searching for PVC information according to the virtual local area network identifier (VLANID) in the message.

Wherein, the routing query described in step b2 refers to searching PVC information according to the IP address of the user in the message.

The present invention terminates the IPOA protocol in the existing DSLAM equipment, specifically, converts the IPOA protocol encapsulated message into the Ethernet format encapsulated message in the DSLAM, and realizes the direct connection between the DSLAM equipment and the IP network. Additional network equipment is used to terminate the IPOA protocol, thereby reducing the cost of network construction and simplifying the network structure; using Ethernet switching technology to increase the switching capacity, because Ethernet has powerful multicast and cascading functions, thus overcoming the inadequacy of ATM networks Supports multicast and implements cascading complex defects.

Description of drawings

Fig. 1 is a schematic diagram of the networking applied in the present invention;

FIG. 2 is a schematic diagram of a message format of the IPOA protocol;

Fig. 3 is a schematic diagram of the message format of the Ethernet protocol;

Fig. 4 is the working flow diagram of the DSLAM device for uplink service from the user side to the network side in the present invention;

Fig. 5 is a working flow chart of the DSLAM device for the downlink service from the network side to the user side in the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

FIG. 1 is a network diagram to which the present invention is applied. As shown in Figure 1, CPE is the user's residential equipment, DSLAM is the digital subscriber line access multiplexer, and BAS is the broadband access server. The invention realizes the direct connection between the DSLAM and the IP metropolitan area network by encapsulating the message according to the Ethernet protocol in the DSLAM equipment, and can also access the BAS through the metropolitan area network to realize communication with other ATM equipment.

Figure 2 is the message format of the IPOA protocol. The IPOA encapsulated message format is shown in Figure 2, including logical link control (LLC), organization unique identifier (OUI), Ethernet type (Ether Type), IP message and frame Check Sequence (FCS). Among them, LLC occupies 3 bytes, the value is 0xAA-AA-03, OUI occupies 3 bytes, the value is 0x00-00-00, Ether Type occupies 2 bytes, the value is 0x08-00, and the following The longest IP message can be 2 ¹⁶ -9 bytes, and the last FCS occupies 4 bytes, which saves the CRC check value of the message.

FIG. 3 is a schematic diagram of a message format of the Ethernet protocol. The Ethernet protocol message includes: 6-byte destination medium access control (DMAC) address, 6-byte source medium access control (SMAC) address, 4-byte virtual local area network flag (VLAN Tag), 2-byte length /type, 46 to 1500 bytes of data, and 4 bytes of FCS. Among them, the 4-byte VLAN Tag includes a 2-byte protocol identifier (TPID) and a 2-byte identification control information (TCI), the value of the TPID is fixed at 0x8100, and the identification control information consists of a 3-bit user priority domain ( Priority), a 12-bit virtual local area network identification number (VLAN ID), a 1-bit canonical format indicator (CFI), and a 4-byte FCS to store the cyclic redundancy check (CRC) value of the message.

The process of supporting the IPOA protocol by the broadband access device of the present invention is shown in FIG. 4 and FIG. 5 , which is divided into two types: processing of uplink services and processing of downlink services. Wherein, Fig. 4 is a working flow chart of the DSLAM device for uplink service from the user side to the network side in the present invention, and Fig. 5 is a work flow chart of the DSLAM device for the downlink service from the network side to the user side in the present invention.

As shown in Figure 4, the processing flow of the uplink service by the DSLAM includes the following steps:

Step 401: The DSLAM device receives a message from the user side, that is, receives the user's message through the CPE device, and the message is transmitted in the form of an ATM cell.

Step 402: Packet sorting. According to the information of the cell header in the received ATM cell, extract and combine the information in the 48-byte information field of each ATM cell in the message, and encapsulate it according to the IPOA protocol. The format of the encapsulated message is shown in Figure 2 , where LLC is 0xAA-AA-03, OUI is 0x00-00-00, and Ether Type is 0x08-00.

Step 403: Determine whether the message is legal. Carry out CRC check on the message encapsulated in step 402, and count the message length, if the CRC value, message length value and the CRC value and length value in the message are the same, it means that no error occurred in the message during transmission , go to step 405; if not the same, it means that an error occurred during the transmission of the message, go to step 404, discard the message, and end this process.

Step 405: Determine whether the packet is a forwarded packet. According to the information of the cell header in the ATM cell obtained in step 402, the message type is judged. If it is the Internet Group Management Protocol (IGMP) message or the operation management and maintenance (OAM) signaling or the Dynamic Host Configuration Protocol (DHCP) message, then proceed to step 406, hand over the CPU to process, and end this flow process, otherwise proceed to the step 407;

Step 407: Packet encapsulation. Encapsulate the current packet to be forwarded according to the Ethernet protocol. When encapsulating, the LLC and OUI in the IPOA message are removed, and then the destination media access control (DMAC) address, source media access control (SMAC) address and VLAN Tag are added in front of the message, and then the cyclic redundancy check is recalculated. Check (CRC) is added to the end of the message as the frame check sequence (FCS), thus completing the conversion of the message encapsulation type or protocol type.

Wherein, the destination MAC address of the message uses the MAC address of the Ethernet switch (gateway) obtained through negotiation, and the source MAC address uses the general MAC address set for the IPOA protocol conversion module. Because one IPOA protocol conversion module can provide access for multiple users, it is also allowed to set multiple general MAC addresses for the IPOA protocol conversion module, that is, to set a different MAC address for each user.

Step 408: Send the message. The DSLAM sends the encapsulated message to the IP MAN.

As shown in Figure 5, the processing flow of the DSLAM to the downlink service includes the following steps:

Step 501: The DSLAM device receives a message from the network side, the message is a message encapsulated according to the Ethernet protocol, and its message format is shown in FIG. 3 .

Step 502: Determine whether the message is legal. Perform CRC check on the received message and count the message length. If the CRC value and message length value are the same as the CRC value and length value in the message, it means that there is no error in the message transmission process. Step 504; if they are not the same, it means that an error occurred during the transmission of the message, go to step 503, discard the message, and end the process.

Step 504: Determine whether the packet is a forwarded packet. Determine the packet type according to the content of the protocol type field stored in the IP packet. If it is an Internet Group Management Protocol (IGMP) message or an operation management and maintenance (OAM) cell or a Dynamic Host Configuration Protocol (DHCP) message, then proceed to step 505, hand it over to the CPU for processing, and end this flow process, otherwise proceed to the step 506;

Step 506: Routing query. According to the VLAN ID information in the message or according to the user IP address information in the message, the permanent virtual connection (PVC) needed when forwarding is searched in the pre-established table for recording user information. This table is established in advance in the device according to the user's needs, and it records the corresponding relationship between VLAN ID, user IP address, virtual channel identifier (VCI), virtual channel identifier (VPI), and PVC.

Step 507: Packet encapsulation. According to the IPOA protocol, the DMAC, SMAC and VLAN Tag in the header of the received message are removed, the LLC and OUI are added, and then the CRC is recalculated and added to the end of the message as the frame check sequence (FCS), thus completing the report Text encapsulation type or protocol type conversion. Among them, LLC is 0xAA-AA-03, OUI is 0x00-00-00, and Ether Type is 0x08-00.

Step 508: packet splitting. The message is divided into 48 bytes as unit cells, according to the VCI, VPI information obtained by step 506 table lookup and the value obtained by checking the segmented cells, the ATM cell header is generated, and then the segmented cells are placed on the ATM Behind the cell header, an ATM cell is formed.

Step 509: Send a message, and send the ATM cell to the user port through the CPE device based on the PVC information obtained in step 506.

Claims (4)

1, a kind of broadband access equipment is supported the method for atm network bearing IP packet protocol IP OA, it is characterized in that this method comprises up processing and two processes of downlink processing:

On up direction, the transmission course of message from the user side to the network side comprises the steps:

A1. receive user's message from user side;

B1. according to receiving ATM cell header in the message, extract and make up the information in each ATM cell information field in the message, the message after should making up according to the IPOA protocol encapsulation then;

C1. the message by the IPOA protocol encapsulation among the step b1 is converted to the message that encapsulates by Ethernet protocol, and the message after will encapsulating sends to the IP metropolitan area network;

On down direction, the transmission course of message from the network side to the user side comprises the steps:

A2. receive the message that the IP metropolitan area network sends;

B2. the message that receives is carried out the conversion of routing inquiry and encapsulated type, will be converted to message by the message of Ethernet protocol encapsulation by the IPOA protocol encapsulation;

C2. according to the message of pressing the IPOA protocol encapsulation among the atm cell format splitting step b2, and the message after will splitting is dealt into user side.

2, method according to claim 1, it is characterized in that, be converted to described in the step c1 by the Ethernet protocol encapsulated message and further comprise: delete the logic link control LLC in the IPOA protocol encapsulation message earlier and organize unique identification OUI field, again before the message of deletion LLC and OUI, order is added the medium access control MAC Address of consulting the gateway determined in advance as purpose medium access control dmac address, and the MAC Address that is provided with as the broadband access equipment of medium access control SMAC address, source.

3, method according to claim 1 is characterized in that, the routing inquiry described in the step b2 is meant that searching permanent virtual according to the VLAN ID VLAN ID from network side to the user side message connects PVC information.

4, method according to claim 1 is characterized in that, the routing inquiry described in the step b2 is meant according to user's IP address from network side to the user side message searches PVC information.

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