A task obtained by a communications processor is decomposed into one or more requests that form a request group. The requests of the request group are sent to main memory and responses to those requests are expected. There may be requests for a plurality of request groups being processed concurrently. However, responses to the request groups are to be returned to the communications processor in the order in which the request groups were sent from the communications processor. To ensure this ordering, dependencies between the request groups are tracked by hardware coupled to the communications processor.