Preparing
Network
Connections
FDDI
Fault
Management
The
dual rings in an
FDDI
network
provide
fault
tolerance
If
station
on
dual ring shuts
down
or
fails such
as
Station
in Figure
2-25
the ring automatically
wraps
doubles back
on
itself
to
form
single
contiguous
ring
This
removes
the
failed
station
from
the
ring
but
allows
the other
stations
to
continue
operation
In Figure
2-25
the ring
wraps
to
eliminate
Station
and
forms
smaller
ring
that
includes
only
Stations
and
Figure
2-25
DAS
Station
Failure
and
Ring
Recovery
Example
Ring wrap
Note
Each
station
in
ring
refers
to
its
neighbor
stations
as
upstream
or
downstream
neighbors
The
stream
is
based on
the signal flow
on
the primary ring
station
receives
the primary
signal
from
its
upstream
neighbor
and
transmits
the primary
signal
to
its
downstream
neighbor For example
Figure
2-25
shows
the primary
signal
flow
being
transmitted
from
PHY
on
Station
to
PHY
on
Station
and from
PHY
on
Station
to
PHY
on
Station
Using
Station
as
reference
Station
is
the
upstream
neighbor
of Station
and
Station
is
the
downstream
neighbor
of
Station
second
failure
could
cause
the ring
to
wrap
in both
directions
from
the point
of failure
which
would
segment
the ring
into
two
separate
rings
that
could
not
communicate
with
each
other
For
example
if
Station
in Figure 2-25
fails
after
Station
fails Stations
and
will
each
be
isolated
because
no
path
for
communication
exists
between
them
Subsequent
failures
cause
additional
segmentation
Station
Station
Failed
station
Station
Preparing
for Installation
2-37
Summary of Contents for 7513 Series
Page 1: ......
Page 11: ...Cisco 7513 Hardware Installation and Maintenance ...
Page 121: ...Site Log 2 56 Cisco 7513 Hardware Installation and Maintenance ...
Page 162: ...Troubleshooting the Processor Subsystem 4 10 Cisco 7513 Hardware Installation and Maintenance ...
Page 266: ...Interface Processor LEDs B 16 Cisco 7513 Hardware Installation and Maintenance ...
Page 270: ...C 4 Cisco 7513 Hardware Installation and Maintenance ...
Page 288: ...18 Cisco 7513 Hardware Installation and Maintenance ...