Initial Stack Installation; Stack Mac Address; Overview - System Configuration; Nortel Ethernet Routing Switch 2500 Series - Nortel 2500 Series System Configuration Manual

1. Base Unit
2. Cascade Cable
3. Cascade Cable (used for return)

Initial stack installation

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 8 units) 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.

Stack MAC address

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 unit in the stack is assigned
as the base unit, the new stack MAC address is the MAC address of the
new base unit plus 1. The original stack IP address still applies to the new
base unit.
Stack configurations
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 system automatically numbers the physical units based on the
designated base unit (Unit 1). In a cascade down configuration, the base
unit is physically located as the top unit in the stack. The cable connected to
the Cascade Down connector of the base unit terminates in the Cascade Up
connector on the next unit in the stack which is physically located below the
base unit. This next unit is designated Unit 2. The stack is wired downward
through the units and the system continues to number in this manner
throughout the stack. In this configuration, the base unit discovers the
stack in a cascade down (stack down) direction. The following illustration
demonstrates a cascade down (stack down) configuration.
Copyright © 2007, Nortel Networks
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Nortel Ethernet Routing Switch 2500 Series

Overview — System Configuration
NN47215-500 (323162-B) 02.02 Standard
4.1 19 November 2007
Stack configuration 49