Rampart keeps Token Storage in the Axis2 ConfigurationContext.
TokenStorage storage = (TokenStorage) configurationContext.getProperty(TokenStorage.TOKEN_STORAGE_KEY);
If you use WSAS [which is built on top of Axis2] to enable clustering, it replicates following three session data accross nodes.
-ServiceContext: Data that should only be available to a service.
-ServiceGroupContext: Common data for all the services in a service group.
-ConfigurationContext: Common data for all the service groups
This explains more about how to clustering with WSAS.