IPv6 Source Address Extrapolation for Multi-Homed Networks
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Solution Overview
Problem
In multi-homed end customer networks with IPv6 addressing, there is no standardized solution for additional service providers to learn and propagate the globally valid IPv6 prefix used by the customer network, which is assigned by the Internet access provider, especially when there are multiple logical or physical WAN connections to different service providers.
Innovation Solution
The method involves monitoring the source addresses of IPv6 packets from end systems in the customer network to extrapolate the IPv6 customer prefix, generating and propagating corresponding forwarding entries in the edge router of the additional service provider, allowing downstream traffic to correctly route packets back to the customer network without relying on permanent communication between the Internet access provider and the additional service provider.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the additional service provider uses a standardized solution with permanent communication between providers to learn and propagate the IPv6 prefix, then the routing accuracy and reliability are improved, but the device complexity and implementation overhead increase significantly
Solution Approach 1:
The additional service provider's edge router autonomously learns the customer's IPv6 prefix by monitoring source addresses of incoming IPv6 packets from the customer network. The router independently extrapolates the prefix without requiring communication with the Internet access provider or other external systems, thereby achieving reliable routing while maintaining simplicity.
Solution Approach 2:
The incoming IPv6 packets from the customer network serve as an intermediary carrier that conveys the customer's IPv6 prefix information to the additional service provider's edge router. By examining the source addresses of these packets, the router can infer the prefix without needing direct communication channels between providers.
2Device complexity
If the additional service provider monitors and extrapolates the IPv6 prefix from incoming packets, then the configuration complexity is reduced and service provider independence is improved, but the risk of incorrect prefix identification and security vulnerabilities increases
Solution Approach 1:
The edge router is pre-configured with the customer's MAC address binding to a specific interface before prefix learning begins. This preliminary configuration establishes a trusted foundation that prevents unauthorized or incorrect prefix extrapolation, as the router only learns prefixes from packets sourced by the authenticated customer network.
Solution Approach 2:
The system continuously monitors incoming IPv6 packets and dynamically adjusts the learned prefix based on actual traffic patterns. This feedback mechanism ensures that the extrapolated prefix accurately reflects the customer's actual address space while providing ongoing validation to prevent security issues.
3Reliability
If multiple edge routers are used in the additional service provider's network, then the network redundancy and fault tolerance are improved, but the propagation of forwarding entries and synchronization effort increase
Solution Approach 1:
Each edge router in the additional service provider's network independently performs prefix learning and extrapolation by monitoring its own incoming packets. This eliminates the need for centralized prefix distribution and synchronization between multiple routers, as each router autonomously maintains its own forwarding entries based on local observations.
Data Source
Figure 1
AI summary
A method for controlling a multi-homed end-customer network with a home gateway (#3) which has a connection via a first interface to an internet access service provider (#1) which propagates an IPv6 prefix to the home gateway (#3) and the end-customer network, wherein the end-customer network has at least one further connection to another service network (#6) via a second interface, which is established via an edge router of the service network (#2), comprising the steps: - Analyzing the IPv6 packet from the end-customer network by the edge router (#2); - Determining the possible IPv6 prefix of the end-customer network, preferably by extrapolation, by the edge router (#2); - Entering the IPv6 prefix into the table of the edge router so that the response packets from the service network are transported via the second interface.