Summary: ApplicationLayer Anycasting: A Server Selection
Architecture and Use in a Replicated Web Service
Ellen Zegura and Mostafa Ammar and Zongming Fei and Samrat Bhattacharjee
Abstract --- Server replication improves the ability of a ser
vice to handle a large number of clients. One of the impor
tant factors in the efficient utilization of replicated servers
is the ability to direct client requests to the ``best'' server,
according to some optimality criteria. In the anycasting
communication paradigm, a sender communicates with a re
ceiver chosen from an anycast group of equivalent receivers.
As such, anycasting is well suited to the problem of directing
clients to replicated servers.
This paper examines the definition and support of the
anycasting paradigm at the application layer, providing a
service that uses an anycast resolver to map an anycast do
main name and a selection criteria into an IP address. By
realizing anycasting in the application layer, we achieve flex
ibility in the optimization criteria and ease the deployment
of the service.
As a case study, we examine the performance of our sys