Proxy Server Failover via Generic IP Announcement in CDNs
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Solution Overview
Problem
Content delivery networks (CDNs) face disruptions due to proxy server failures or overload, leading to temporary unavailability of content to end users, as existing systems lack effective failover and load balancing mechanisms.
Innovation Solution
Implementing a method where proxy servers announce both specific and generic IP addresses using Border Gateway Protocol (BGP) sessions, allowing routers to route requests to alternative servers in case of failures and distribute load across multiple servers based on hash values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single proxy server is used to provide content to end users, then the system structure is simple, but the system reliability deteriorates when the proxy server fails or becomes overwhelmed with traffic
Solution Approach 1:
Multiple proxy servers are merged into a single failover group that shares a common IP address space. The proxy servers work together as a unified system where any server in the group can handle requests for any content, creating a combined resource pool that improves reliability without requiring complex client-side load balancing logic.
Solution Approach 2:
Each proxy server in the failover group is designed to be universal and can provide any content from the CDN, not just a specific subset. This multi-functionality allows any server to take over for any other server, ensuring that content availability is maintained regardless of which specific server is handling the request.
2Reliability
If multiple proxy servers are deployed to improve reliability through failover, then the system reliability improves, but the routing complexity and information management deteriorate
Solution Approach 1:
The system implements continuous feedback through BGP announcements that inform the network of which proxy servers are currently operational and their associated IP address ranges. This feedback mechanism ensures that routing information is always up-to-date, allowing the network to automatically redirect traffic to available servers without losing routing information accuracy.
Solution Approach 2:
IP address ranges are pre-assigned and announced to the network before failover is needed. This preliminary action ensures that routing information is already in place and validated, so when failover occurs, the network can immediately use the pre-announced IP ranges to route traffic to the new active server without information loss or delays.
3Measurement precision
If proxy servers announce specific IP addresses for each content file, then the routing precision is high, but the system cannot provide failover when a proxy server fails
Solution Approach 1:
The IP address space is segmented into specific ranges that are associated with different proxy servers. Each proxy server announces its specific IP range for the content it is currently serving, maintaining precise routing. When failover is needed, the IP ranges are re-segmented and reassigned to the new active server, preserving routing precision while enabling service continuity.
4Productivity
If load balancing is implemented across multiple proxy servers, then the productivity and content delivery speed improve, but the system complexity and coordination overhead increase
Solution Approach 1:
The load balancing mechanism operates autonomously using BGP routing protocols and IP address announcements. Each proxy server independently announces its availability and IP ranges, and the network automatically routes requests to appropriate servers based on current capacity and availability. This self-service approach improves productivity through distributed decision-making while minimizing coordination overhead by eliminating the need for centralized load balancing control.
Data Source
AI summary
Aspects of the present disclosure involve systems, methods, computer program products, and the like, for providing failover and load clustering features to one or more proxy servers of a content delivery network (CDN). In one embodiment, one or more proxy servers may announce a virtual host internet protocol (IP) and, to provide a failover feature, two or more of the proxy servers may also announce a more generic virtual network IP address that includes a broader range of IP addresses associated with the virtual network IP address. In another embodiment, each of the proxy servers in communication with the router may announce a generic IP network address to the router. In response to receiving a request for content from an end user of the CDN, the router may select a proxy server and load balance the received requests among the proxy servers.