Method and apparatus for routing between fibre channel fabrics

An interfabric link between two separate Fibre Channel fabrics so that devices in one fabric can communicate with devices in another fabric without requiring the merger of the two fabrics. The interfabric switch performs a conversion or a translation of device addresses in each fabric so that they are accessible to the other fabric. This translation is preferably done using a private to public loop address translation. In a first embodiment the external ports of the interfabric switch are configured as E_ports. A series of internal ports in each interfabric switch are joined together forming a series of virtual or logical switches. The virtual switches are then interconnected using private loops. The use of the private loop is enabled by the presence of translation logic which converts fabric addresses to loop addresses and back so that loop and fabric devices can communicate. Because each port can do this translation and the private loop addressing does not include domain or area information, the change in addresses between the fabrics is simplified. In a second embodiment the external ports are configured as NL_ports and the connections between the virtual switches are E_ports. Thus the private to public and public to private translations are done at the external ports rather than the internal ports as in the prior embodiment. The virtual switches in the interfabric switch match domains with their external counterparts so that the virtual switches effectively form their own fabric, connected to the other fabrics by the private loops.