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Hot Socket Failover of Queued Work

IP.com Disclosure Number: IPCOM000169214D
Original Publication Date: 2008-Apr-10
Included in the Prior Art Database: 2008-Apr-10
Document File: 2 page(s) / 149K

Publishing Venue



Outlines a system to make a network tier highly available by transferring work and active sockets to another server in the event of a failure.

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Hot Socket Failover of Queued Work

This article outlines a system which allows a tier in an enterprise network to be highly available by transferring work and active sockets off to another server in the event of a failure. A common network topology has a load balancer spraying a tier or proxy server that fronts a tier of content servers. Also, technology exists today to quiesce work at the proxy server tier until there is capacity on the back-end tiers (see Figure 1 below).

Problems exist if a proxy server fails and has sockets with work outstanding. Some of these sockets are still connected and may have been waiting for capacity to open up on the back-end server to which the proxy is routing. A common way to recover from a proxy server process crash is for the tier in front of the proxy server to retry the connection. With common server implementations, the server would reset the connection in the event of a failure and begin a new one, losing any socket data that had been queued on the proxy server tier.

A system can be made more highly available by replicating session information across nodes in the proxy server tier and having an intelligent, stateful load balancer in front of the proxy tier that can push fail-over state to an available server. For example, the load balancer maintains a connection record with socket state which can be forwarded to the proxy server. When the primary proxy server is not available, the load balancer pushes state to an available proxy server along with any init data required...