WO2008011776A1

WO2008011776A1 - An address assignment realizing method and the system, the relay agent, the server thereof

Info

Publication number: WO2008011776A1
Application number: PCT/CN2007/001128
Authority: WO
Inventors: Hongguang Guan
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-07-21
Filing date: 2007-04-09
Publication date: 2008-01-31
Also published as: CN101110817A; CN101110817B

Abstract

An address assignment realizing method is applied to a system including relay agents, client-ends and servers, which includes: a relay agent determines a prefix or prefix identifier after receiving an address request message from a client-end, and transmits the prefix or prefix identifier to a server; the address corresponding to the prefix or prefix identifier is received, and the address is the one which is assigned by the server for the prefix or prefix identifier; the address is transferred to the client-end. Also an address assignment realizing system, a relay agent and a server are provided. According to the invention, the server is clued on that it assigns multiple addresses belonging to the special prefix or prefix identifier to the client-end, and also clued on that it assigns multiple addresses belonging to the multiple prefixes or prefix identifiers to the client-end, so the problem that the selectivity is bad during the server assigning addresses through the relay agents is solved.

Description

Method, system, relay agent and server for implementing address allocation

Technical field

The present invention relates to the field of network communications, and in particular, to a method, system, relay agent, and server for implementing address allocation. Background of the invention

The Dynamic Host Configuration Protocol (IPv6) of IP version 6 is a mechanism for dynamically allocating IPv6 addresses and configuration parameters.

DHCPv6 adopts the client/server mode. The client sends a configuration request to the server. The application includes the following parameters: the assigned IP address, the subnet mask, and the default gateway. The server returns the configuration information according to the policy. The DHCPv6 message adopts the user. The Datagram Protocol (UDP) is encapsulated.

Referring to Figure 1, the working process of DHCPv6 is as follows:

1. The DHCPv6 client looks for the DHCPv6 server: The DHCPv6 client sends a Solicit message to find the DHCPv6 server.

2. The DHCPv6 server provides the IP address: The DHCPv6 server that receives the Solicit message on the network responds, selects the available address and assigns it to the DHCPv6 client, and sends a notification containing the assigned IP address and other configuration parameters to the DHCPv6 client.

(Advertise) message;

3. The DHCPv6 client selects the IP address provided by a DHCPv6 server: If multiple DHCPv6 servers send Advertise messages to the DHCPv6 client, the DHCPv6 client selects one of the received Advertises, that is, selects a DHCPv6 server. The DHCPv6 client then responds with a Request message containing DHCPv6 The IP address of the DHCPv6 server selected by the client and the IP address provided by the DHCPv6 server.

4. The DHCPv6 server confirms the provided IP address: When the DHCPv6 server receives the Request message from the DHCPv6 client, it sends a reply (Reply) message to the DHCPv6 client for the IP address and other configuration parameters provided by the DHCPv6 client. Tell the DHCPv6 client to use the EP address it provides.

The DHCPv6 relay agent is located between the DHCPv6 client and the DHCPv6 server. Its role is to:

1. It can relay messages sent by DHCPv6 clients and Relay-fonvard messages sent by other relay agents. When the relay agent receives a legitimate message that needs to be relayed, it will construct a new Relay-forward message. Fill in the link-address field with a global or local site address, which is used to prompt the server what address to assign to the client. Then fill in the source IP address of the received packet in the peer-address field of the Relay-forward message, and put the received DHCPv6 message (excluding the IP header and UDP header) in the Relay Message option, and add according to the configuration. Some other options are used, and the constructed Relay-forward message is sent to other relay agents or servers.

Referring to Figure 2, the Relay-forward message format is:

Link-address: A global or local site address that the server uses to determine the link where the client is located.

Peer-address: The address of the last hop of the message (may be a client or other relay agent);

Options: Must contain "Railup Message Option".

2. You can relay the Relay-reply message sent by the DHCPv6 server or other relay agent, and process all the options except the Relay Message option in the Relay-reply message, and discard them after processing. Then forward the inbound and outbound messages in the Relay Message option to Other. Relay agent or client.

Referring to Figure 3, the DHCPv6 client requests the address from the DHCPv6 server through the DHCPv6 relay agent as follows:

1. The DHCPv6 client sends a request for a request address to the DHCPv6 relay agent. 2. After receiving the request from the DHCPv6 client, the DHCPv6 relay agent creates a relay-forward message and sends it to the DHCPv6 server. The value of the link-address in the message is IP-Y.

3. After receiving the Relay-forward message from the DHCPv6 relay agent, the DHCPv6 server assigns an address to the DHCPv6 client according to the link-address in the message, and sends the address to the DHCPv6 relay agent. The Relay-forward message at this time. As shown below: msg-type: RELAY-FORW;

Hop-count: 0;

Link-address: IP—Y;

Peer-address: Address of the DHCPv6 client.

Relay Message option: <Request for DHCPv6 Client>.

4. After receiving the address sent by the DHCPv6 server, the DHCPv6 relay agent forwards it to the DHCPv6 client.

Referring to Figure 4, assume that the prefix corresponding to Internet Service Provider_1 (ISP_1) is prefix_l, the prefix corresponding to ISP-2 is prefix-2, the prefix corresponding to ISP is prefix_3, and the client wants to obtain ISP-1, ISP. 2, the address of ISP-3, but the client does not know the specific prefix. In this case, if the DHCPv6 server is prompted according to the link-address (ie interface IP-Y), the DHCPv6 server (DHCP v6 Server) Only one address associated with the interface IP_Y can be assigned to the client, and addresses belonging to ISP-1, ISP_2, and ISP-3 cannot be provided.

Therefore, in the prior art, the DHCPv6 relay agent cannot prompt the DHCPv6 server. To provide customers with an address with a specific prefix, only one address associated with the DHCPv6 relay agent address can be assigned, and the customer has poor selectivity when applying for an address. In addition, when there are multiple DHCPv6 relay agents, except for the DHCPv6 relay agent closest to the client, the link-address inserted by the other DHCPv6 relay agent in the Relay-forward message cannot be used by the DHCPv6 server to determine the client. Link. Summary of the invention

Embodiments of the present invention provide a method, system, pants agent, and server for implementing address allocation, which can effectively solve the problem of poor address selectivity when a server allocates an address through a relay agent.

A method for implementing address allocation is applied to a system including a relay agent, a client, and a server; when the relay agent receives an address request message from the client, the method includes:

Determining a prefix or prefix identifier and transmitting the prefix or prefix identifier to the server;

Receiving an address corresponding to the prefix or prefix identifier, where the address is an address allocated by the server for the prefix or prefix identifier;

The relay agent forwards the address to the client.

A system for implementing address allocation, comprising:

a client, configured to send an address request message;

a relay agent, configured to: when receiving an address request message sent by the client, determine a prefix or a prefix identifier, and send the prefix or a prefix identifier; receive an address corresponding to the prefix or the prefix identifier, and forward the address The address to the client;

a server, configured to determine, according to the prefix or the prefix identifier sent by the relay agent, an address corresponding to the prefix or the prefix identifier, and corresponding to the prefix or the prefix identifier The address is sent to the relay agent.

A relay agent that implements address allocation, including:

a first module, configured to determine a prefix or a prefix identifier after receiving an address request message from the client;

The second module is configured to send the prefix or prefix identifier to the server.

A server that implements address allocation, including:

a first module, configured to determine an address corresponding to the prefix or prefix identifier according to a prefix or a prefix identifier from a relay agent;

And a second module, configured to send the address corresponding to the prefix or the prefix identifier to the relay agent.

It can be seen that the prefix selection option can be inserted in the Relay-forward message sent by the relay agent to the server, and the prefix or prefix identifier is stored in the prefix selection option, or the relay agent directly deposits the prefix or prefix identifier into the prefix selection option. In the Link-addres field of the Relay-forward message, the server is prompted to assign an address to the client that belongs to a specific prefix or prefix identifier, or the server may be prompted to assign multiple addresses belonging to multiple specific prefixes or prefix identifiers to the client. BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic diagram of a working process of a DHCPv6 in the prior art;

2 is a schematic diagram of a Relay-forward message format of a DHCPv6 relay agent in the prior art;

3 is a schematic diagram of a DHCPv6 client performing address selection process through a DHCPv6 relay agent in the prior art;

4 is a schematic diagram of address allocation by a DHCPv6 relay agent in the prior art; FIG. 5 is a flowchart of an address allocation method according to an embodiment of the present invention; 6 is a schematic diagram of a format of a prefix selection option according to an embodiment of the present invention; FIG. 7 is a schematic diagram of a specific prefix format in a prefix selection option according to an embodiment of the present invention; and FIG. 8 is a schematic diagram of an address allocation system according to an embodiment of the present invention. Mode for carrying out the invention

The invention will be further described with reference to the accompanying drawings and specific embodiments, but not to be construed as limiting.

An embodiment of the present invention is described by using IPv6 as an example. In the relay-forward message of the original DHCPv6 relay agent, a prefix selection option is inserted, so that the DHCPv6 server can be prompted to perform address allocation according to the option. '

FIG. 5 is a flowchart of an address allocation method according to an embodiment of the present invention. In the method, the client is a DHCPv6 client, the relay agent is a DHCPv6 relay agent, and the server is a DHCPv6 server.

First, insert the prefix selection option (Relay Prefix Selection Option) in the relay-forward message format of the DHCPv6 relay agent. See Figure 6 for the prefix selection option format:

OPTION—RELAY— PS: Relay prefix selection option;

Option-len: the length of the option;

PS-Prefix option 1, PS-Prefix option 2, , PS- Prefix option n: prefix information, ie prefix or prefix identifier;

The PS-Prefix option option is used to describe each specific prefix or prefix identifier in the relay prefix selection option. For details, see Figure 7:

OPTION— PSPREFIX: prefix option;

Prefix-length: prefix length;

IPv6-prefix: IPv6 prefix or prefix identifier;

Related options: Other options related to this prefix or prefix identifier. The method of the embodiment of the present invention specifically includes the following steps:

Step 101: The DHCPv6 client sends an address request message in multicast mode.

Step 102: After receiving the address request message, the DHCPv6 relay agent determines the prefix information according to the selection policy, and stores the prefix information in a prefix selection option, where the selection policy includes at least one of the following policies:

1) Select the prefix or prefix identifier according to the location of the DHCPv6 client;

2) selecting a prefix or a prefix identifier according to the information in the address request message, where the information in the address request message refers to the hardware address of the client, a network access identifier (NAI), a client identifier, and the like;

3) Select the prefix or prefix identifier based on the current configuration of the DHCPv6 relay agent.

Of course, in addition to the three selection strategies listed above, other selection strategies may be included.

In this embodiment, the DHCPv6 relay agent performs prefix selection according to the current configuration of the DHCPv6 relay agent, and generates prefix information: [prefix-1, prefix-2, ..., prefix_n], and prefixes the prefix. The information is stored in the prefix selection option.

Step 103: The DHCPv6 relay agent sets up a Relay-forward message, and sends a Relay-forward message to the DHCPv6 server, where the Relay-forward message is:

Msg-type: The type of the message, which is Relay-forw;

Hop-count: The number of times the packet has undergone transit from the node to the destination node, which is 0;

Link-address: A global or local site address that the server uses to determine the link where the client is located. This is IP-Y;

Peer-address: Address of the last hop of the message (may be a client or other relay agent), which is the client address;

Relay Message Option: includes [; DHCPv6 client address request message], Is a required option in the Options option;

Prefix selection options: Includes prefix information [prefix 1 , prefix - 2, ..., prefix - n]. Step 104: After receiving the Relay-forward message, the DHCPv6 server obtains the prefix information from the prefix selection option, obtains the address request message from the Relay Message Option option, and then assigns the prefix information to the DHCPv6 client according to the address allocation policy. the address of.

The above address allocation strategy is at least one of the following strategies:

1) performing address allocation according to the obtained prefix information;

2) The allocation of addresses is performed based on the information in the prefix information and the address request message.

Of course, in addition to the two address allocation policies listed above, other address allocation policies may be included.

In this embodiment, the address is allocated according to the information in the prefix information and the address request message. After the address allocation policy is determined, the client is assigned an address corresponding to the prefix information in the prefix selection option, and the assigned address is the address IP with the prefix one. 1. Address IP-2 with prefix - 2, ... IP with address - n.

Step 105: After the DHCPv6 server selects the address corresponding to the prefix information, the address corresponding to the prefix information is carried in the Relay-reply message, and the Relay-reply message is sent to the DHCPv6 relay agent, where the Relay-reply message is The Relay Message Option option is a response message from the DHCPv6 server to the DHCPv6 client. The response message contains the address corresponding to the prefix information assigned by the DHCPv6 server to the DHCPv6 client.

Step 106: After receiving the relay-reply message sent by the DHCPv6 server, the DHCPv6 relay agent extracts the response message from the DHCPv6 server to the DHCPv6 client from the Relay Message Option, and sends the response message to the DHCPv6 client.

Step 107: After receiving the response message, the DHCPv6 client receives the response message. Obtain the assigned address, which is the address IP-1 with the prefix -1, the address IP with the prefix -2, 2, ..., the IP__n with the prefix -n.

In this embodiment, the prefix selection option may not be inserted in the Relay-forward message, but the prefix information determined by the DHCPv6 relay agent is placed in the Link-address field of the Relay-forward message, and the DHCPv6 server receives the Relay-forward. After the message, the DHCPv6 client is assigned an address according to the prefix information in the Link-address field.

Referring to FIG. 8, an embodiment of the present invention further provides a system for address allocation, where the system includes a client, a relay agent, and a server;

The client is configured to send an address request message and receive an address allocated by the server. The relay agent is configured to receive an address request message sent by the client, determine prefix information according to the selection policy, and send the prefix information to the server. At the same time, the relay agent is further configured to receive an address corresponding to the prefix information sent by the server;

The server is configured to receive the prefix information sent by the relay agent, and allocate an address corresponding to the prefix information according to the address allocation policy, and send the address corresponding to the prefix information to the relay agent.

The relay agent includes a relay-forward message module and a selection policy module. The relay-forward message module is configured to store an address request message and prefix information sent by the client.

The selection policy module provides for selection of a prefix based on the location of the client, selection of prefix information based on information in the address request message, or selection of prefix information based on the current configuration of the relay agent.

The server includes a relay-reply message module and an address allocation policy module. The relay-reply message module is configured to store an address corresponding to the prefix information. The address allocation policy module performs address allocation according to the obtained prefix information. The information in the prefix information and the address request message is used for address allocation. The client in the system is a DHCPv6 client, the relay agent is a DHCPv6 relay agent, and the server is a DHCPv6 server.

The above-mentioned embodiments are only one of the more preferred embodiments of the present invention, and all the usual changes and substitutions made by those skilled in the art within the scope of the present invention should be included in the scope of the present invention.

Claims

Claim

A method for implementing address allocation, applied to a system including a relay agent, a client, and a server; wherein, when the relay agent receives an address request message from the client, the method includes :

Forwarding the address to the client.

2. The method of claim 1 wherein the relay agent determines the prefix or prefix identifier based on a selection policy.

3. The method of claim 2, wherein the selection strategy comprises at least one of the following strategies:

Selecting a prefix or a prefix identifier according to the location of the client;

Selecting a prefix or a prefix identifier according to the information in the address request message; selecting a prefix or a prefix identifier according to the current configuration of the relay agent.

The method of claim 1, wherein the step of the relay agent sending the prefix or the prefix identifier to the server comprises:

The prefix or prefix identifier is carried in the relay-forward message and sent to the server.

The method of claim 4, wherein the carrying the prefix or prefix identifier in the relay-forward message includes:

A prefix selection option is inserted in the Relay-forward message, and the prefix or prefix identifier is stored in the prefix selection option.

The prefix or prefix identifier is stored in the Link-address field of the Relay-forward message.

7. The method of claim 1, wherein the address is an address assigned by the server to the prefix or prefix identifier according to an address assignment policy.

8. The method of claim 7, wherein the address allocation policy comprises at least one of the following strategies:

Assigning an address according to the prefix or prefix identifier;

The assignment of the address is performed based on the prefix or prefix identifier and the information in the address request message.

The method according to claim 1 or 8, wherein the information in the address request message includes at least one of the following:

The client's hardware address, network access identifier (NAI), and client identifier.

10. The method according to claim 8, wherein the server sends a response message containing an address assigned to the prefix or prefix identifier to the relay agent in a relay-reply message.

The method of claim 10, wherein the relay agent forwarding the address to the client comprises:

The relay agent extracts the response message from the relay-reply message, and sends the response message to the client.

12. A system for implementing address allocation, comprising:

a client, configured to send an address request message;

a relay agent, configured to determine a prefix or a prefix identifier when receiving an address request message from the client, and send the prefix or prefix identifier; receive the prefix or prefix An address corresponding to the identifier and forwarding the address to the client;

a server, configured to determine, according to the prefix or the prefix identifier sent by the relay agent, an address corresponding to the prefix or the prefix identifier, and send the address corresponding to the prefix or the prefix identifier to the middle Following the agent.

13. The system of claim 12, wherein the relay agent is configured to determine the prefix or prefix identifier based on a selection policy.

The system according to claim 12, wherein the relay agent is configured to carry the prefix or prefix identifier in a Reky-forward message and send the message to the server.

The system according to claim 12, wherein the server is configured to assign the client an address corresponding to the prefix or prefix identifier according to an address allocation policy.

A relay agent for implementing address allocation, comprising: a first module, configured to determine a prefix or a prefix identifier after receiving an address request message from a client;

The relay agent according to claim 16, wherein the first module is configured to determine a prefix or a prefix identifier according to a selection policy.

The relay agent according to claim 16, wherein the second module is configured to send the prefix or prefix identifier to a server in a Relay-forward message.

19. A server for implementing address allocation, comprising:

a second module, configured to send an address corresponding to the prefix or the prefix identifier to the middle Following the agent.

The server according to claim 19, wherein the first module is configured to determine an address corresponding to the prefix or prefix identifier according to an address allocation policy.

The server according to claim 19, wherein the second module is configured to carry a response message including an address corresponding to the prefix or the prefix identifier in a Relay-reply message and send the message to the relay. proxy.