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USITS 2001 Abstract
Fine-Grained Failover Using Connection Migration
Alex C. Snoeren, David G. Andersen, and Hari Balakrishnan, MIT Laboratory for Computer Science
Abstract
This paper presents a set of techniques for providing fine-grained
failover of long-running connections across a distributed collection
of replica servers, and is especially useful for fault-tolerant and
load-balanced delivery of streaming media and telephony sessions. Our
system achieves connection-level failover across both local- and
wide-area server replication, without requiring a front-end transport-
or application-layer switch. Our approach uses recently proposed
end-to-end ``connection migration'' mechanisms for transport protocols
such as TCP, combined with a soft-state session synchronization
protocol between replica servers.
The end result is a robust, fast, and fine-grained connection failover
mechanism that is transparent to client applications, and largely
transparent to the server applications. We describe the details of
our design and Linux implementation, as well as experimental data that
suggests this approach is an attractive way to engineer robust systems
for distributing long-running streams; connections suffer relatively
small performance degradation even when migration occurs every few
seconds, and the associated server overhead is small.
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