The link is nothing more than a definition (where to go find table or view at some remote location). The target database is either able to accept connections or it is not. There is nothing rectified or "re-init" for a link. From a SQL perspective, there is no way the source server knows the remote server is up unless a connection attempt is made via a statement. You could also be constrained by the allowable number of open links. And what does "established db link fails" mean in terms of an error or result?