Avaya 5900 Series Installing Manual page 47

a. Base Unit switch
b. Cascade Down connector
c. Cascade Up connector
Figure 22: ERS 5900 stack connectors
a. Base Unit switch
b. Cascade Down connector
c. Cascade Up connector
Figure 23: ERS 59100 stack connectors
Understanding stack types
This section describes the different stack types.
Due to stack parameters being associated with the base unit, the physical stack order depends on
the base unit position and whether the stack is configured cascade up (stack up) or cascade down
(stack down). This designation depends on the stack cabling arrangement.
The Unit Select switch is used to designate a switch in the stack as a base or non-base unit. Sliding
the switch down designates that switch as the base unit. Only one switch in a stack can have the
Unit Select switch in the base unit position. All other switches in the stack must have the Unit Select
switch in the up position which designates them as non-base units.
During the initial installation of the stack, the software automatically determines the physical order of
all units in the stack according to the position of the base unit within the stack. Thereafter, the
individual units maintain their original unit numbering, even if the position of one or more units in the
stack is changed.
For example, when the stack is initially powered, the base unit becomes unit 1 and the unit that the
base unit connects to (via the Cascade Down cable) becomes unit 2 (and the next unit is unit 3 and
so on), until the maximum stack configuration (up to eight units for an ERS 5900 Series stack and
up to four units for an ERS 59100 stack) is reached. If the base unit is changed to another unit in the
stack, the new base unit keeps its original unit number in the stack.
When a switch participates in a stack configuration, a stack MAC address is automatically assigned
during stack initialization. The stack MAC address is the base unit MAC address plus 1. If another
September 2017 Installing Avaya ERS 5900 Series
Comments on this document? infodev@avaya.com
Single and multiple switch arrangements
47