Avaya 4900 Series Installing page 43

Figure 11: Stack Connector
Unit Select switch
Use the Unit Select switch to designate a switch in the stack as the base unit. Slide the Unit Select
switch DOWN to designate a switch as the base unit. You can designate only one switch in a stack
as the base unit; that is, with the switch in the base unit position. For all other switches in the stack,
the Unit Select switch must be positioned UP.
The base unit designation for a switch appears on the front panel LED display. See
state indicators on page 50.
Cascade Down connector
Use the Cascade Down connector to connect a switch to the next unit in the stack through a
cascade cable. Connect the other end of the Cascade Down cable to the Cascade Up connector of
the next switch in the stack. A return cable from the Cascade Down connector of another unit to the
Cascade Up connector of the first unit completes the stack connection.
Important:
To create a stack connection, order the appropriate switch cascade cables to ensure fail-safe
stacking. A 1.5 foot stacking cable is included with the switch. For stacking three or more units
(maximum eight units per stack), order the cables as applicable.
Cascade Up connector
The Cascade Up connector provides an attachment point that accepts a cascade cable connection
from another unit in the stack. A return cable from the Cascade Down connector of one switch to the
Cascade Up connector of an adjacent switch completes the stack connection. The following figure
illustrates a typical crossover connection configuration. Failure to use this configuration can result in
loss of connectivity.
Important:
In the Unit 1, set the Base unit select switch position to Base.
February 2016 Installing Avaya Ethernet Routing Switch 4900 Series
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Stacking
Switch LED
43