The link round trip delay between two switches in a Fibre Channel network
may be determined by sending a particular timing signal value from an
originating switch to a responding switch. The responding switch may
store the timing signal value in an "echo" register for comparison to
subsequently received timing signals. The originating switch may then
send the pre-selected timing signal to the responding switch while
simultaneously starting a timer. When the responding switch receives the
timing signal, it may compare the value of the received signal to that
stored in its echo register. If the value, is the same, the responding
switch may retransmit--i.e., echo--the timing signal to the originating
switch. When the originating switch receives the echoed timing signal, it
may stop its timer and compute the link round trip delay time. The
computed link round trip delay time between the originating switch and
the responding switch may be advantageously used in fabric routing
algorithms.