Methods and associated hub arrangements are described for use in diagnosis
and recovery in high performance digital loops such as, for example, those seen
in Fiber Channel systems. In one system having a hub configured for interconnection
of a plurality of stations as part of a digital system such that digital data flows
between the stations based on operational status of the system, an arrangement
forms part of the hub which arrangement is connectable at points within the hub
and between at least two different pairs of the stations for, monitoring certain
characteristics of the data in a way which provides for non-invasive identification
of one or more conditions related to the operational status of the system.
