CN101605090B - Method for realizing two-layer middle agent of dynamic host configuration protocol in passive optical network - Google Patents

Abstract

The present invention provides a method for implementing the DHCP layer-2 intermediate agent of the dynamic host configuration protocol in a passive optical network: the optical line terminal or the optical network unit analyzes the uplink DHCP message sent by the DHCP client, as described in the judgment The uplink message adopts the broadcast mode, then it is converted into the unicast mode and then sent to the DHCP server, and the optical network unit records the same identification information as the corresponding downlink message in the uplink message; the DHCP server according to the received The uplink DHCP message returns the corresponding downlink message. After the optical network unit receives the downlink message, if the recorded identification information can be matched and the identification information corresponds to the uplink message in the broadcast mode, the downlink message is converted It is sent to the DHCP client after it is in broadcast mode. The method can effectively avoid the duplication and forwarding of a large number of DHCP downlink broadcast messages in the passive optical network.

Description

Realization Method of Layer 2 Intermediate Agent of Dynamic Host Configuration Protocol in Passive Optical Network

technical field

The invention relates to the communication field, in particular to a method for realizing a DHCP layer-2 intermediate agent (L2intermediate Agent) in a passive optical network. the

Background technique

At present, passive optical networks including EPON (Ethernet Passive Optical Network, Ethernet Passive Optical Network) and GPON (Gigabit Passive Optical Network, Gigabit Passive Optical Network) systems are gradually and widely deployed. From the downlink direction, different from DSL (Digtal Subscriber Loop, Digital Subscriber Line), the most important access technology at present, the passive optical network is a point-to-multipoint broadcasting system, and the downlink bandwidth of the network is shared by all optical network units. , all business data packets will be multiplexed into the passive optical network downlink frame, so that a large number of broadcast packets downlink in the network will swallow up the downlink service bandwidth of the passive optical network. With the improvement of the application of multi-resident unit mode (Multi-Dwell Unit, MDU), the number of system access users is increasing, so the broadcast efficiency requirements of the passive optical network system are getting higher and higher. How can the downlink broadcast bandwidth be saved? It has become an important functional requirement of passive optical network system. the

And DHCP (Dynamic Host Configuration Protocol, Dynamic Host Configuration Protocol) is the current and future dominant passive optical network service application scenario. The DHCP protocol works at the application layer of OSI (Open System Interconnect, Open System Interconnect), and is a bootstrap protocol that helps hosts obtain their configuration information from a designated DHCP server. DHCP uses the client/server model. The computer that requests configuration information is called a DHCP client, and the computer that provides information is called a DHCP server. Please refer to Figure 1 below, which shows the format of the DHCP protocol, and the important fields are explained as follows:

OP: The operation type of the DHCP message, which is divided into a request message and a response message; if its value is 1, it means a request message; if its value is 2, it means a response message. the

Htype, Hlen: the hardware address type and length of the DHCP client. the

Flags: The first bit is the broadcast response flag, which is used to identify whether the DHCP server response message is sent by unicast or broadcast. The rest of the bits are reserved. the

If the sending mode of the response message identified by the Flags is broadcast, a large number of broadcast messages will be generated in the downlink direction of the application of the DHCP protocol. the

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for realizing the second-layer intermediate agent of the dynamic host configuration protocol in the passive optical network, to realize the conversion of the downlink DHCP message from the broadcast mode to the unicast mode, thereby reducing the N:1 Under the VLAN (Virtual LAN, virtual local area network) architecture, a large number of broadcast packets are copied and forwarded with a huge load. The technology of the invention is applicable to the application of all passive optical network systems in the DHCP scene. the

In order to solve the above-mentioned technical problems, the present invention provides a method for implementing a dynamic host configuration protocol DHCP layer-2 intermediate agent in a passive optical network, wherein:

After the optical line terminal or the optical network unit receives the uplink DHCP message sent by the DHCP client, it analyzes it. If it is judged that the uplink DHCP message adopts the broadcast mode, it converts it into an uplink DHCP message in the unicast mode and sends it to DHCP server. the

Further, the above method can also have the following characteristics:

The optical network unit records the same identification information in the uplink DHCP message as that in the corresponding downlink DHCP message. the

Further, the above method can also have the following characteristics:

The DHCP server returns a corresponding unicast mode downlink DHCP message according to the received uplink DHCP message;

After the optical network unit receives the downlink DHCP message, if it can match the recorded identification information and the identification information corresponds to the uplink DHCP message in the broadcast mode, convert the downlink DHCP message into the broadcast mode The downlink DHCP message is sent to the DHCP client. the

Further, the above method can also have the following characteristics:

Whether the uplink DHCP message adopts the broadcast mode is determined by whether the value of the broadcast response identification bit included in the uplink DHCP message is equal to the value representing the broadcast mode or equal to the value representing the unicast mode. the

Further, the above method can also have the following characteristics:

When converting the uplink DHCP message in the broadcast mode to the uplink DHCP message in the unicast mode, the assignment of the broadcast response identification bit is modified to represent the assignment of the unicast mode, and the uplink DHCP message is recalculated. The verification data of the document and update the original verification data. the

Further, the above method can also have the following characteristics:

When the downlink DHCP message of the unicast mode is converted into the downlink DHCP message of the broadcast mode, the assignment of the broadcast response identification bit contained in the downlink DHCP message is modified to represent the assignment of the broadcast mode, and the The MAC address and the IP address included in the downlink DHCP message are changed to the broadcast address, and the verification data of the downlink DHCP message is recalculated and the original verification data is updated. the

Further, the above method can also have the following characteristics:

The optical line terminal or optical network unit parses the uplink DHCP message sent by the DHCP client after receiving it, and if it is judged that the uplink DHCP message adopts the unicast mode, transparently upload it to the DHCP server directly. the

Further, the above method can also have the following characteristics:

After the optical network unit receives the uplink DHCP message and analyzes and learns that it adopts unicast mode or broadcast mode, it records the identification information in the uplink DHCP message and the mode it adopts;

After the optical network unit receives the downlink DHCP message, it extracts the identification information and matches it with the recorded identification information. If the mode corresponding to the matched identification information is broadcast mode, it is determined that the identification information corresponds to Uplink DHCP packets in broadcast mode. the

Further, the above method can also have the following characteristics:

If the optical network unit judges that the mode corresponding to the identification information in the downlink DHCP message is a unicast mode, it will directly and transparently send it to the DHCP client. the

Further, the above method can also have the following characteristics:

The identification information is user port information. the

Further, the above method can also have the following characteristics:

The check data is a frame check sequence value. the

Further, the above method can also have the following characteristics:

The uplink DHCP message refers to a DHCP request message or a DHCP discovery message; the downlink DHCP message refers to a DHCP allocation message or a DHCP confirmation message. the

A method for realizing the second-layer intermediate agent of the dynamic host configuration protocol in the passive optical network described in the present invention can effectively avoid the duplication and forwarding of a large number of DHCP downlink broadcast messages in the passive optical network, thereby effectively saving downlink Service bandwidth improves system security and achieves good forward compatibility, which is a useful supplement and extension to the standard technology of passive optical network systems. the

Description of drawings

FIG. 1 is a schematic diagram of a DHCP message format. the

Fig. 2 is a system structure diagram for realizing the DHCP layer 2 intermediate agent. the

Fig. 3 is a flowchart of a method for performing DHCP Layer 2 intermediate agent processing on a message. the

Detailed ways

The present invention proposes a method for realizing the second-layer intermediate agent of the dynamic host configuration protocol in the passive optical network, which can effectively avoid the duplication and forwarding of a large number of DHCP downlink broadcast messages, thereby effectively saving the downlink service bandwidth and improving the system efficiency. safety. The basic concept is: Optical Line Terminal (OLT) or Optical Network Unit (ONU) listens to the upstream DHCP message of the passive optical network system, and modifies the broadcast/unicast request mode identification , so as to realize the downlink transmission of DHCP messages from the OLT to the optical network unit in unicast mode, and at the same time, considering the compatibility of the DHCP client on the user side, the original broadcast/unicast request mode identifier is reversely converted and restored on the optical network unit. the

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. the

The implementation method of the second-layer intermediate agent of the dynamic host configuration protocol in the passive optical network described in the embodiment of the present invention, its business system structure is shown in Figure 2, including:

DHCP client: resides on the user side and is used to initiate a DHCP request. For DHCP clients under different platforms such as Windows, Unix, and Linux, the original value of the broadcast/unicast request identifier (the first bit of the flags field) may be different, that is, it may be the broadcast request mode (the first bit of the flags field) A bit value is 1), and it may also be a unicast request mode (the first bit value of the flags field is 0). In the following, flag represents the first bit of the flags field. the

DHCP server: Residing on the upstream gateway side, it is used to respond to the request sent by the DHCP client and assign an IP address; the mode of its response packet will be absolutely based on the request mode of the DHCP client according to the protocol requirements, that is, according to the flag value of the upstream DHCP packet To perform unicast or broadcast downlink transmission. the

Optical line terminals and optical network units: can be collectively referred to as access nodes (Access Node). In the present invention, the modification of the uplink DHCP message can be completed at the optical line terminal or at the optical network unit, and the modification of the downlink DHCP message can be completed at the optical network unit. This functional module is referred to as a DHCP Layer 2 intermediate agent in the present invention. Further, the optical network unit also includes: a corresponding table of flag information and ports, the corresponding table is used to record the source information of the DHCP message flag of a specific port, and the reverse conversion of the flag in the downlink DHCP message will be based on the information of this table query to complete. the

The following will introduce the method of implementing the DHCP layer 2 intermediate agent based on the system structure shown in Figure 2. Taking the DHCP layer 2 intermediate agent processing of a message as an example, please refer to Figure 3. The method includes steps:

Step S301: the optical network unit receives the uplink message sent by the DHCP client, and parses the flags field contained in the uplink message. The message can be a discovery message (Discover) or a request message ( Request);

The request message carries the information of the DHCP client, and is used to request dynamic allocation of IP addresses;

The discovery message is the first standard message of the DHCP protocol, which is used to find a DHCP server;

The message formats of the request message and the discovery message all conform to the DHCP protocol format shown in Figure 1, which includes the flags field, and the first bit of this field is a broadcast response identification bit, which is used to identify the DHCP server response message Whether to use unicast mode or broadcast mode to send. the

Step S302: the optical network unit judges the first bit of the parsed flags field, that is, the assignment of the broadcast response identification bit, if the broadcast response identification bit is assigned a value of 0, then enter step S303; if the broadcast response identification bit If the assigned value is 1, enter step S304;

Step S303: directly forward the uplink message to the optical line terminal, and then send it to the DHCP server by the optical line terminal, and end;

The assignment of the broadcast response identification bit to 0 means that the unicast transmission mode is adopted; the uplink message is transparently forwarded to the optical line terminal, and then sent to the DHCP server by the optical line terminal;

Step S304: The optical network unit assigns the broadcast response identification bit in the DHCP uplink message to 0, and recalculates the frame check sequence value (Frame Check Sequence, FCS) of the DHCP message, and updates the original frame check sequence value , to ensure that the DHCP server can correctly receive and process the uplink message;

The calculation of the frame check sequence value adopts the cyclic redundancy check method used by the TCP/IP protocol standard to modify the frame check sequence value of the DHCP message, which will not be repeated here. the

Step S305: the optical network unit writes the source DHCP flag and user port information of the DHCP uplink message into the corresponding table of the source DHCP flag and the user port, and sends the modified uplink message to the optical line terminal, and then the The optical line terminal sends to the DHCP server;

If the corresponding table of source DHCP flag and user port has not been created, create the corresponding table first and then write the above information;

Step S306: The DHCP server receives the uplink message and sends a corresponding downlink message to the optical line terminal according to the information of the uplink message. The downlink message can be an allocation message (offer) or an acknowledgment message (ACK) ;

The allocation message corresponds to the request message, and is used to dynamically allocate an IP address for the DHCP client;

The confirmation message corresponds to the discovery message, and is used to confirm that the DHCP server is found;

The processing flow of the DHCP server receiving the uplink message and sending the corresponding downlink message according to the information of the uplink message can be processed according to the existing standard protocol, and will not be repeated here;

Step S307: the optical network unit obtains a downlink allocation message or confirmation message from the optical line terminal, and parses the flags field contained in the downlink message;

Step S308: the optical network unit checks the corresponding table of the source DHCP flag and the user port, if the first bit of the original flags field of the user port DHCP message is assigned a value of 0, then enter step S309; if the user port DHCP message The first bit of the original flags field of the original flags field is assigned a value of 1, then enter step S310;

Step S309: the optical network unit sends the downlink message to the optical line terminal, and then the optical line terminal sends it to the DHCP client;

Step S310: the optical network unit assigns a value of 1 to the first bit of the flags field contained in the downlink message; changes the MAC address and IP address in the downlink message to a broadcast address, and recalculates the Frame check sequence value and replace the original frame check sequence value;

Assigning a value of 1 to the first bit of the flags field contained in the downlink message represents the broadcast mode, so correspondingly, the MAC address and IP address of the message need to be modified to a broadcast address, that is, the downlink message The 48-bit MAC address contained in the text is filled with 1 and changed to 0xff-ff-ff-ff-ff-ff, and the 32-bit IP address is filled with 1 and changed to 0xff-ff-ff-ff;

In this step, the cyclic redundancy check method used by the TCP/IP protocol standard is also used to recalculate the frame check sequence value of the DHCP message, and replace the original frame check sequence value to ensure that the DHCP client can correctly receive and process said message;

Step S311: the optical network unit sends the modified downlink message;

After this step, the corresponding table of the source DHCP flag and the user port can also be emptied, or not emptied, and there is no limitation here;

In another embodiment, when processing the uplink message, the optical network unit side only records the source DHCP flag and the user port of the uplink message without modifying it, and then sends the uplink message The text is sent to the optical line terminal, and the optical line terminal modifies the broadcast response identification bit and the verification data in the uplink message in the same way as the optical network unit in the above-mentioned embodiment, and the rest of the process steps are the same as the above-mentioned embodiment, here No longer. the

In the above embodiment, the optical network unit records the source DHCPflag and user port information in all uplink DHCP messages. In other embodiments, the optical network unit can also only record the uplink DHCP message whose first bit value of flags is 1. The user port information in the text or other identification information in the uplink DHCP message that is the same as the corresponding downlink DHCP message, when processing the downlink DHCP message, only need to judge whether the user port information has been recorded, if recorded, then It needs to be converted into a downlink DHCP message in broadcast response mode, otherwise it can be forwarded transparently. This is also possible. the

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. the

Claims (12)

1. two layers of middle-agent's of a dynamic host configuration protocol in passive optical network DHCP implementation method is characterized in that:

Optical line terminal or optical network unit are resolved after receiving the up DHCP message that dhcp client sends, as up DHCP message adopts broadcast mode as described in judging, send to Dynamic Host Configuration Protocol server after then being converted into the up DHCP message of unicast mode.

2. the method for claim 1 is characterized in that:

Described optical network unit records the identification information identical with corresponding descending DHCP message in the described up DHCP message.

3. method as claimed in claim 2 is characterized in that:

Described Dynamic Host Configuration Protocol server returns the descending DHCP message of corresponding unicast mode according to the described up DHCP message of receiving;

After described optical network unit is received described descending DHCP message, if match the identification information of record and this identification information corresponding to the up DHCP message of broadcast mode, then described descending DHCP message is converted to the descending DHCP message of broadcast mode, sends to described dhcp client.

4. method as claimed in claim 3 is characterized in that:

Be the assignment that equals to represent broadcast mode by the assignment of the broadcasting response identification position that comprises in the described up DHCP message, still equal to represent the assignment of unicast mode, judge whether described up DHCP message adopts broadcast mode.

5. method as claimed in claim 3 is characterized in that:

When the described up DHCP message of broadcast mode is converted to the up DHCP message of unicast mode, be that the assignment of inciting somebody to action broadcasting response identification position wherein is revised as the assignment that represents unicast mode, and recalculate the checking data of described up DHCP message and upgrade original checking data.

6. method as claimed in claim 3 is characterized in that:

When the described descending DHCP message of unicast mode is converted to the descending DHCP message of broadcast mode, the assignment that is the broadcasting response identification position that will comprise in the described descending DHCP message is revised as the assignment that represents broadcast mode, broadcast address is revised as in the MAC Address and the IP address that comprise in the described descending DHCP message, and recalculates the checking data of described descending DHCP message and upgrade original checking data.

7. method as claimed in claim 3 is characterized in that:

Described optical line terminal or optical network unit are resolved after receiving the up DHCP message that dhcp client sends, as up DHCP message adopts unicast mode as described in judging, then directly it are transparently uploaded to described Dynamic Host Configuration Protocol server.

8. such as the described method of arbitrary claim in the claim 2 to 7, it is characterized in that:

Described optical network unit receive described up DHCP message and resolve learn that it adopts unicast mode or broadcast mode after, all the described identification information in the described up DHCP message and the pattern of employing thereof are carried out record;

After described optical network unit is received described descending DHCP message, extract wherein identification information and with the identification information coupling of record, as pattern corresponding to the identification information that matches be broadcast mode, determines that then described identification information is corresponding to the up DHCP message of broadcast mode.

9. method as claimed in claim 8 is characterized in that:

Described optical network unit is unicast mode such as pattern corresponding to identification information in the descending DHCP message as described in judging, then directly it is transparently sent to described dhcp client.

10. method as claimed in claim 3, it is characterized in that: described identification information is user port information.

11. such as claim 5 or 6 described methods, it is characterized in that: described checking data is the frame check sequence value.

12. method as claimed in claim 3 is characterized in that:

Described up DHCP message refers to that DHCP request message or DHCP find message; Described descending DHCP message refers to DHCP assignment message or DHCP confirmation message.

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