| 摘要 |
A number of techniques permit a plurality of servers to provide access to information replicated on the servers and accessed by connecting to a well published address. One approach involves an extension of multicasting in which source specifics joins and leaves are utilized to partition the address space to be serviced by a particular server. When a different address space allocation is desired in accordance with the load balancing policy, a plurality of techniques are utilized to ensure that a connected user obtains the needed information. A second approach involves an extension to the TCP protocol to enable dynamic TCP designations. With this option, a sender provides a tag and a cookie which a server can use. A server replies with a tag, a cookie and destination information. A security mechanism can be utilized to prevent the connection from being hijacked when a "change destination" message is sent. The third approach utilizes tag switching. A pool of servers is supported behind at least one virtual IP address. The servers servicing that IP address set up a family of tag switch trees, one for each server. When a virtual IP machine receives a tag-less packet, it directs one or more upstream routers to either an actual IP address to which subsequent packets should be directed or to a tag switched tree to which the connection should be directed. In this manner, dynamic load balancing among servers handling connection requests to a well published network address can be achieved. |
