NDP Mediation via PE Proxy for IPv6 VLL
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Solution Overview
Problem
In IPv6 networks, existing methods for Virtual Leased Line (VLL) services face inefficiencies due to the need for extensive signaling to communicate multiple IP addresses for Neighbor Discovery Protocol (NDP) mediation, which is not desirable for IP interworking VLLs, as it requires large amounts of signaling across the LDP control link.
Innovation Solution
The method intercepts and modifies NDP and Inverse NDP messages at Provider Edge (PE) devices, learning and forwarding IPv6 interface and link-layer addresses within these messages, thereby eliminating the need to communicate CE device IP addresses over the LDP control link, allowing PE devices to act as proxies and facilitate address discovery between CE devices connected via dissimilar link-layer protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple IP addresses are communicated over the LDP control link for NDP mediation, then address discovery between CE devices is enabled, but signaling overhead increases significantly
Solution Approach 1:
The PE device acts as an intermediary that intercepts NDP messages containing multiple IP addresses and selectively forwards only the necessary address information to the remote PE device. This mediation function reduces the amount of signaling required while maintaining address discovery capability across the VLL.
Solution Approach 2:
The invention extracts only the essential IP address information from the intercepted NDP messages and forwards this extracted data through the LDP control link, rather than transmitting all multiple IP addresses. This extraction approach significantly reduces signaling overhead while preserving the necessary address discovery function.
2Quantity of substance
If PE devices intercept and modify NDP messages to learn CE device addresses, then signaling overhead is reduced, but device complexity increases
Solution Approach 1:
The PE device leverages its existing multi-functional role in the network (routing, pseudowire termination, LDP processing) to incorporate the NDP message interception and modification function. By integrating this address learning capability into the existing PE device architecture, the complexity increase is minimized while achieving reduced signaling overhead.
3Reliability
If ARP mediation methods are adopted for IPv6 NDP mediation, then address resolution is achieved, but large amounts of signaling are required across the LDP control link
Solution Approach 1:
Instead of having CE devices directly exchange multiple IP addresses through extensive signaling (the traditional ARP mediation approach), the invention inverts the approach by having PE devices intercept NDP messages and selectively forward necessary address information. This inversion significantly reduces the signaling volume required for address resolution.
Data Source
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AI summary
The invention is directed to providing NDP mediation over an IP interworking VLL. ICMPvß Neighbor Discovery and Inverse Neighbor Discovery messages are intercepted by provider edge (PE) devices to learn both IPv6 interface addresses and link-layer addresses of customer edge (CE) devices before forwarding the messages to the CE devices, and in some cases after altering the messages to make them more meaningful to the receiving CE devices. In this manner, the CE device interface addresses do not need to be communicated over the LDP control link, as in IPv4 ARP Mediation.