Staged CDN Rendezvous Table Deployment
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Solution Overview
Problem
In content delivery networks (CDNs), updating rendezvous tables can lead to invalid or incorrect routing of client requests due to the difficulty in testing the validity and integrity of large, dynamic tables, resulting in potential misdirection of traffic to inappropriate locations.
Innovation Solution
Implement a staged deployment mechanism where the rendezvous system gradually transitions from old ('white') to new ('black') tables using a percentage-based function, allowing for fine-grained control and parallel operation of both sets to ensure smooth transition and rapid rollback if issues arise, with dedicated servers for monitoring new table behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rendezvous tables are updated in CDN, then new routing information is provided, but invalid or incorrect routing may occur due to difficulty in testing table validity
Solution Approach 1:
The patent divides the rendezvous table update process into multiple phases: initial deployment phase where new tables are introduced alongside existing tables, and subsequent phases where the proportion of new tables is gradually increased. This segmentation allows testing of new tables without immediately replacing all existing tables, thereby reducing the risk of incorrect routing while managing the complexity of table validation through controlled incremental changes.
2Reliability
If staged deployment is implemented, then transition stability is improved, but deployment time is extended
Solution Approach 1:
The patent implements dynamic adjustment of the proportion of new versus existing rendezvous tables based on system performance monitoring. The deployment process is not static but adapts in real-time: if issues are detected during the staged rollout, the system can pause or rollback; if successful, the proportion of new tables can be increased more rapidly. This dynamic approach balances transition stability with deployment efficiency.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor the performance and correctness of new rendezvous tables during the staged deployment process. Based on this feedback, the deployment strategy is adjusted - either continuing to increase the proportion of new tables or rolling back to previous versions if problems are detected. This feedback loop optimizes the deployment timeline while maintaining stability.
3Ease of repair
If parallel operation of old and new tables is used, then rollback capability is improved, but system complexity increases
Solution Approach 1:
The patent introduces an intermediary component - the rendezvous system that manages and directs traffic based on the proportion of new versus existing tables. This intermediary layer handles the complexity of parallel operation and rollback logic, shielding the rest of the system from direct exposure to the complexity. The intermediary can seamlessly switch between old and new tables, providing easy rollback capability while containing the architectural complexity within a dedicated management layer.
Data Source
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AI summary
A computer-implemented method in a content delivery network (CDN), wherein the CDN delivers content on behalf of at least one content provider. The CDN includes a rendezvous system that selects CDN servers for clients. In response to a request by a rendezvous mechanism in the rendezvous system, a first given function is evaluated. Based on the outcome of the evaluating, the rendezvous mechanism uses either a first table or a second table. The first table was generated by a first table generation mechanism for use by said rendezvous mechanism to select CDN servers for clients, and the second table was generated by a second table generation mechanism for use by the rendezvous mechanism to select CDN servers for clients.