CDN Anycast Prefix Routing for PoP Load Control and Failover
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Solution Overview
Problem
Existing CDN routing techniques, such as unicast and anycast, face challenges in load management and user experience due to DNS TTL pitfalls and lack of control over PoP performance, leading to potential overload and suboptimal path selection.
Innovation Solution
Implementing an improved anycast routing technique that assigns unique IP address subnets to each PoP, allowing the CDN to control load distribution by geography and redirect requests to alternative PoPs using unique anycast prefix announcements, ensuring efficient routing and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If unicast routing with DNS records is used to direct content requests to CDN entry points, then load management control is improved, but geographic proximity routing deteriorates causing requests to be routed to non-closest entry points
Solution Approach 1:
The patent segments the monolithic DNS-based routing approach into a hierarchical system where anycast routing handles geographic proximity at the network layer, while DNS records provide supplemental load management information. This segmentation allows both geographic optimization and load control to function simultaneously without conflict.
Solution Approach 2:
The patent introduces anycast routing as an intermediary layer between end-user devices and DNS-based load management. The anycast routing protocol (BGP) acts as a mediator that automatically routes requests to geographically closest PoPs based on network topology, while DNS records provide additional load balancing guidance when multiple PoPs are equidistant.
2Speed
If anycast routing with common IP addresses is used to route requests to geographically closest PoPs, then routing efficiency is improved, but load management control deteriorates causing PoP overload
Solution Approach 1:
The patent applies local quality by making each PoP unique through assigning distinct IP address subnets to specific geographic regions. Instead of using a common IP address for all PoPs, each PoP announces its own unique anycast prefix to local networks, enabling region-specific load management while maintaining geographic proximity routing efficiency.
Solution Approach 2:
The patent changes the routing parameter from a single common IP address to multiple unique IP address subnets distributed across different PoPs. This parameter change allows the routing system to differentiate between PoPs and implement load management by selecting appropriate subnets based on current PoP capacity and performance metrics.
3Ease of manufacture
If a single common anycast prefix is announced by all PoPs, then operational simplicity is improved, but load distribution capability deteriorates
Solution Approach 1:
The patent segments the single common anycast prefix into multiple unique IP address subnets, each assigned to specific PoPs. This segmentation maintains operational simplicity by using standard anycast routing mechanisms while dramatically improving load distribution capability through subnet-specific routing policies that can direct traffic based on PoP capacity, geographic region, and performance metrics.
4Stability of the object's composition
If DNS records are cached with TTL to maintain routing information, then system stability is improved, but responsiveness to entry point failures deteriorates
Solution Approach 1:
The patent introduces anycast routing as an intermediary that provides real-time failure detection and automatic request redirection. When a PoP fails, the anycast routing infrastructure (BGP) automatically stops announcing its IP address subnet, causing subsequent requests to be routed to alternative PoPs without waiting for DNS TTL expiration, thus maintaining both stability and reliability.
Data Source
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AI summary
The system disclosed herein implements an improved anycast routing technique that enables a content delivery network (CDN) to control the load on various points of presence (PoPs), but that also maintains the ability to have requests that would have been sent to an offline PoP be automatically redirected to another PoP. The CDN is able to control the load on the PoPs by configuring content requests to be routed to a particular PoP. For instance, a CDN is configured to assign a subnet of distinct IP addresses to each PoP in a group of PoPs, so that each PoP can announce a unique anycast prefix. The CDN can control when and how these unique anycast prefix are announced to balance load across the PoPs.