A shared I/O subsystem for a plurality of computer systems. The shared I/O
subsystem includes a plurality of physical I/O interfaces and a plurality
of virtual I/O interfaces where each of the computer systems is
communicatively coupled to one or more of the virtual I/O interfaces. The
shared I/O subsystem also includes a forwarding function having a
forwarding table that logically arranges the shared I/O subsystem into
one or more logical LAN switches. Each of the logical LAN switches
communicatively couples one or more of the virtual I/O interfaces to at
least one of the physical I/O interfaces. For each of the logical LAN
switches, the forwarding function receives a data packet from any one
from the group of the physical I/O interfaces and the virtual I/O
interfaces, and directs the data packet to at least one from the group of
the physical I/O interfaces and the virtual I/O interfaces. Two or more
of the physical I/O interfaces may be aggregated to form a logical I/O
interface by selectively altering entries in the forwarding table without
reconfiguring the computer systems.