The Effectiveness of Request Redirection on CDN Robustness
It is becoming increasingly common to construct network services using
redundant resources geographically distributed across the Internet.
Content Distribution Networks are a prime example. Such systems
distribute client requests to an appropriate server based on a variety
of factors---e.g., server load, network proximity, cache locality---in
an effort to reduce response time and increase the system capacity
under load. This paper explores the design space of strategies
employed to redirect requests, and defines a class of new algorithms
that carefully balance load, locality, and proximity. We use
large-scale detailed simulations to evaluate the various strategies.
These simulations clearly demonstrate the effectiveness of our new
algorithms, which yield a 60-91% improvement in system capacity when
compared with published state-of-the-art CDN technology, yet
user-perceived response latency remains low and the system scales well
with the number of servers.