DHCPv6 Server IP Address Retention via Relay Agent Payload
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Solution Overview
Problem
In DHCPv6 communication systems, clients cannot obtain the IP address of the DHCPv6 server due to message header stripping by relay agents, which hinders source address authentication and message protection.
Innovation Solution
The DHCPv6 server includes a method to carry its IP address in the payload of response messages sent through DHCPv6 relay agents, ensuring the IP address is retained and can be obtained by clients, and optionally uses Cryptographically Generated Addresses (CGA) for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the DHCPv6 relay agent strips the message header when forwarding the response message from the DHCPv6 server to the client, then the relay agent can effectively forward messages between the server and client, but the IP address of the DHCPv6 server carried in the message header is discarded, causing the client to be unable to obtain the server's IP address
Solution Approach 1:
The patent introduces a new message type called Router Advertisement (RA) message as an intermediary carrier. Instead of relying on the message header that gets stripped, the DHCPv6 server's IP address is embedded within the payload of the RA message, which is not stripped by the relay agent. This intermediary structure allows the information to be transmitted through the relay process without being lost.
Solution Approach 2:
The patent moves the DHCPv6 server IP address from the message header dimension to the message payload dimension. By placing the server IP address in the payload of the RA message rather than in the header, the information survives the relay agent's header stripping process. This dimensional shift from header to payload resolves the contradiction.
2Device complexity
If the client cannot obtain the IP address of the DHCPv6 server, then the message forwarding process remains simple, but the client cannot perform source address authentication on messages from the DHCPv6 server, compromising security
Solution Approach 1:
The patent implements preliminary action by having the DHCPv6 server include its IP address in the RA message payload during the initial message exchange. This early provision of the server's IP address enables the client to perform source address authentication on subsequent messages, establishing security before potential threats can arise. The authentication capability is prepared in advance rather than being added later.
3Loss of information
If the DHCPv6 server includes its IP address in the message header, then the client can obtain the server's IP address, but the relay agent strips the header causing the IP address to be lost
Solution Approach 1:
The RA message serves as an intermediary container that protects the DHCPv6 server IP address from being stripped by the relay agent. The payload structure of the RA message acts as a shield, allowing the embedded server IP address to pass through the relay process intact while the relay agent continues to strip only the outer headers as usual.
Data Source
AI summary
The present invention relates to the field of communications, and in particular, relates to a method for obtaining an Internet Protocol (IP) address of a Dynamic Host Configuration Protocol version 6 (DHCPv6) server, a DHCPv6 server, and a DHCPv6 communication system. The method is applied in a scenario of communication through a DHCPv6 relay agent, and includes: receiving, by a DHCPv6 server, a message of a DHCPv6 client forwarded by a DHCPv6 relay agent; sending, by the DHCPv6 server, a response message to the DHCPv6 client through the DHCPv6 relay agent, in which a payload of the response message carries an IP address of the DHCPv6 server, so that the DHCPv6 client obtains the IP address of the DHCPv6 server from the response message.