Anycast Routing Map Using Segmented IP Space Scanning
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Solution Overview
Problem
Anycast traffic routing on the Internet is complex due to incomplete knowledge of the network graph and varying policies implemented by autonomous systems, making it difficult to determine precisely where an IP address will be routed, leading to operational complexity in production anycast services.
Innovation Solution
A novel approach using passive measurements from deployed anycast services to create an Internet map that partitions IP-space into consistently routed areas, allowing for the selection of representative landmarks for active measurements, thereby reducing the complexity of anycast catchment analysis and improving routing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full ICMP scanning of IPv4 space is performed to identify anycast catchments, then complete routing information is obtained, but the scanning process is onerous and does not scale well
Solution Approach 1:
The patent segments the IPv4 address space into /24 blocks and selects a single representative IP address from each block for scanning. This segmentation approach reduces the scanning scope from all individual IP addresses to one representative address per block, making the scanning process scalable while still capturing routing information for the entire block through passive measurement of deployed anycast services
Solution Approach 2:
The patent leverages existing deployed anycast services to perform passive measurements that automatically reveal routing information. Instead of actively probing every IP address, the system uses the self-service capability of existing anycast infrastructure to provide routing data, eliminating the need for exhaustive active scanning
2Productivity
If scanning is performed on one IP address per /24 block to reduce scanning overhead, then scanning complexity is reduced, but accuracy decreases when IP addresses within the same block are routed to different PoPs
Solution Approach 1:
The patent introduces a two-stage measurement process where initial passive measurements from deployed anycast services identify routing patterns, and then active ICMP scanning is performed only on blocks where routing variation is detected. This intermediary approach allows the system to efficiently identify blocks that require detailed scanning while avoiding unnecessary scanning of homogeneous blocks
Solution Approach 2:
The patent performs partial scanning by selectively applying detailed active scanning only to specific /24 blocks where routing variation is suspected or detected, rather than uniformly scanning all blocks. This partial action approach maintains scanning efficiency while improving accuracy for blocks that actually contain routing diversity
3Measurement precision
If passive measurement from deployed anycast services is used instead of active scanning, then the number of samples and error in estimated catchments is reduced, but reliance on existing service deployment is required
Solution Approach 1:
The patent merges two measurement approaches by combining passive measurement from deployed anycast services with selective active ICMP scanning. The passive measurements provide broad coverage and identify routing patterns, while active scanning provides detailed verification for specific blocks, creating a hybrid methodology that leverages the strengths of both approaches
Data Source
AI summary
Generally, aspects of the invention involve creating a data structure (a map) that reflects routing of Internet traffic to Anycast prefixes. Assume, for example, that each Anycast prefix is associated with two or more deployments (Points of Presence or PoPs) that can provide a service such as DNS, content delivery (e.g., via proxy servers, as in a CDN), distributed network storage, compute, or otherwise. The map is built in such a way as to identify portions of the Internet (e.g., in IP address space) that are consistently routed with one another, i.e., always to the same PoP as one another, regardless of how the Anycast prefixes are deployed. Aspects of the invention also involve the use of this map, once created. The map can be applied in a variety of ways to assist and/or improve the operation of Anycast deployments and thus represents an improvement to computer networking technology.