You can use external systems to make transports between domains.
External systems are like virtual systems. This means that they are accessed using a communications system. However, for this type of system, an separate transport directory is also defined. This directory can either be located on a disk partition that can be accessed by an SAP System in the other domain, or it is on a replaceable data medium.
To transport between two transport domains using an external system, proceed as follows:
You can now route transports to the external system. All necessary files are stored in the external transport directory.
Using the queue display of the external system, you can check which transport requests have already been created there.
To do this, define another external system in the target domain with the name of the original target system. From the queue display of this system, you can route the transport requests to the SAP System you have chosen.