Abstract: Method, apparatus and program products are provided for persistent cache synchronization for a first communication session and a concurrent second communication session over an external communication link between a client protocol conversion application executing on a first computer and a server protocol conversion application executing on a second computer located remote from the first computer. An active cache is established independently for each session with a corresponding cache for each session at the other computer for use with the first and the second communication session respectively. A checkpoint request is transmitted to the server application indicating one of the active protocol caches from either the first session or the second session to be used to provide a checkpoint. On receipt of the request from the server application, the active protocol cache for the indicated session is copied to provide a checkpoint cache of the second computer.