Patent ID: 8769092

Claim:
A method of providing spillover between Global Server Load Balancing (GSLB) virtual servers executing on an intermediary device, the method comprising: establishing, by a global intermediary device executing a first virtual server to provide global server load balancing of a plurality of local intermediary devices at a plurality of remote sites and in communication with and deployed between a plurality of clients and the plurality of local intermediary devices, a metric exchange connection to each of the plurality of local intermediary devices to receive spillover related statistics from each local intermediary device of the plurality of local intermediary devices for services executing on a plurality of servers at the plurality of remote sites load balanced by each local intermediary device and identified as up, each of the local intermediary devices deployed between the global intermediary device and one or more servers at a remote site of the plurality of remote sites; establishing by the global intermediary device, a spillover threshold for the first virtual server of the global intermediary device, the first virtual server resolving DNS requests to a remote site of the plurality of remote sites; aggregating into an aggregate spillover statistic, by the global intermediary device, each of the spillover related statistics received from each of the plurality of local intermediary devices for services identified as up at the plurality of remote sites by each of the plurality of local intermediary devices; determining that the aggregate spillover statistic for services identified as up exceeds the spillover threshold for the first virtual server; and using, by the global intermediary device responsive to determining that the aggregate spillover statistic for services identified as up exceeds the spillover threshold for the first virtual server, a second virtual server of the global intermediary device to resolve DNS requests across the plurality of remote sites.