A scalable system and method for locating a closest server in response to a client
request via an interactive distribution network, such as the Internet, are provided.
A closest content server is defined as having the least round trip time for responding
to a client request. The system including a plurality of content servers; and a
local server in communication with a plurality of clients, the local server acting
as a proxy for communicating client requests from clients to a redirection server.
Client network distance and load information is periodically collected at each
content server in the network from clients communicating with each of the respective
content servers. The redirection server periodically aggregates the network distance
and load information from each content server to create client clusters from both
current and previously aggregated network distance and load information. Each client
cluster represents a division or partition of the total IP address space. Each
client cluster is then mapped (paired) to one or more content servers in the network.
The mapping or pairing is then utilized to respond to client DN requests received
from any client in the network. Another aspect of the invention involves considering
the respective capacities of the content servers in the network. A selection probability
is assigned to each content server/domain index pair to prevent the repeated selection
of the content server having lowest round trip time thereby overloading that server's
service capacity. The selection probabilities assigned to each content server effect
a load balancing to prevent overloading. Another aspect of the invention involves
collecting the distance and load information without incurring any overhead cost
by passively collecting TCP information as it is transmitted from clients in communication
with content servers in the course of normal communications.