Topology-Aware Cache Cooperation for CDN Bandwidth Reduction
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Solution Overview
Problem
Content distribution networks (CDNs) face inefficiencies in managing content distribution and storage, as existing systems lack coordinated global and local cache management, leading to suboptimal content placement and increased bandwidth costs due to asymmetric network traffic and underutilized upstream bandwidth.
Innovation Solution
A system that allocates local and federated cache space based on content popularity, utilizing reverse channel capacity for efficient content migration between caches, allowing peer-to-peer content migration and leveraging underutilized upstream bandwidth to create a virtual federated cache, thereby reducing transit bandwidth costs and improving content availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If caches at the same hierarchical level store the same content and forward requests to parent caches, then cache hit rate is improved for popular content, but bandwidth cost increases due to repeated upstream requests for less popular content
Solution Approach 1:
The patent combines federated cache spaces across multiple caches at the same hierarchical level to form a unified virtual federated cache. This merging allows caches to share less popular content through peer-to-peer transfers, reducing repeated upstream requests and bandwidth costs while maintaining high cache hit rates for both popular and less popular content.
Solution Approach 2:
The patent creates virtual copies of federated cache spaces across multiple caches. Each cache maintains a local federated cache space that is a virtual copy of the global federated cache, enabling local content retrieval without upstream requests and reducing bandwidth consumption while preserving content availability.
2Reliability
If local cache space is increased to store more content, then content availability is improved, but storage cost increases
Solution Approach 1:
The patent merges federated cache spaces across multiple caches to create a virtual federated cache with aggregate storage capacity. This allows the system to provide content availability equivalent to large local storage without incurring proportional storage costs, as content is distributed across multiple caches' federated spaces.
Solution Approach 2:
The patent enables federated cache spaces to serve multiple functions: storing less popular content, enabling peer-to-peer content sharing, and providing a cost-effective alternative to expanding local cache capacity. The virtual federated cache acts as a universal storage resource for the entire cache hierarchy.
3Productivity
If upstream bandwidth is utilized for content migration, then content distribution efficiency is improved, but available capacity for user requests decreases
Solution Approach 1:
The patent inverts the traditional content migration direction by utilizing downstream bandwidth (from parent to child caches) for federated cache content transfer instead of relying on upstream bandwidth. This inversion allows content migration to occur during periods when downstream capacity is available, preserving upstream bandwidth for user requests while maintaining efficient content distribution.
Data Source
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AI summary
A content distribution network (CDN) comprising a hierarchy of content storage nodes (CSNs) or caches having storage space that is allocated between local space for storing locally popular content objects and federated space for storing a portion of the less popular content objects. Local space and federated space based upon changes in content object popularity and/or other utility factors. Optionally, parent/child (upstream/downstream) communication paths are used to migrate content between CSNs or caches of the same or different hierarchical levels to avoid utilizing higher price top hierarchical level communications channels.