60 SunFDDI/P1.0 Adapter User’s Guide—May 1997
6
FDDI Failure Recovery
One of the primary advantages of FDDI is its ability to recover reliably from
failures in stations and cables. The failure mechanism is implemented and
controlled by the Station Management (SMT) entity described in the section
“Station Management (SMT) Layer” on page 52.
A failure could be something as insignificant as someone switching off their
workstation; the ability of FDDI to recover from such an event increases the
reliability of the network significantly.

Station Wrapping

Figure6-8 shows the effect of a single-station failure in an FDDI network that
comprises four dual-attached stations connected in a basic ring configuration.
When a failure occurs, the SMT entities on the stations on either side of the
fault reconfigure the network dynamically to isolate it. In this condition, the
primary and secondary rings are wrapped on to each other to form a single,
one-way ring.
Figure6-8 Isolating a Single Station Failure
Failed FDDI DAS
FDDI DAS FDDI DAS
FDDI DAS
Secondary ring
Primary ring