Extreme Networks ExtremeSwitching 5720 Series Hardware Installation Manual page 41

Build Stacks
Slot Numbers in Stacks
A switch stack can be thought of as a virtual chassis. Each switch (node) operates as if it were
occupying a slot in a chassis and is controlled by the primary. The high-speed stacking links function like
the backplane links of a chassis.
Each switch in the stack is assigned a "slot number" during the initial software configuration of the
stack. Starting at the switch with the console connection, numbers are assigned in numerical order
following the physical path of the connected stacking cables. For example, if you follow the cabling
recommendations presented in
configure a vertical stack from the console on the switch at the top of the physical stack, the switches
will be assigned slot numbers 1 through 8 from the top down.
The Mode button is used to cycle through three display modes for the port LEDs. After two presses of
the Mode button, the port LEDs will enter the STK Display Mode, indicated by the STK LED. STK mode is
used to indicate slot presence and slot number via the first eight port LEDs.
Figure 17: Mode Button with SRK LED Example
The LED is steady green if the link is OK, blinking green if traffic is present, and off if no signal is present.
A quick way to verify that the cable connections match the software configuration is to check the stack
number indicator on each switch. If the slot numbers do not line up in the order you arranged the
switches, this might indicate that the stacking cable setup differs from what you intended when you
configured the software. In this case, reconnect the cables in the correct order and perform the
software configuration again.
Primary/Backup Switch Redundancy
When your stack is operational, one switch is the primary switch, responsible for running network
protocols and managing the stack.
To provide recovery in case of a break in the stack connections, you can configure redundancy by
designating a backup switch to take over as primary if the primary switch fails. When you perform the
initial software configuration of the stack, the "easy setup" configuration option automatically
configures redundancy, with slot 1 as the primary and slot 2 as the backup. You can also configure
additional switches as "primary-capable," meaning they can become a stack primary in case the initial
backup switch fails.
When assigning the primary and backup roles in mixed stacks, consider the feature scalability and the
speed of each switch model. The easy setup configuration process selects primary and backup switches
based on capability and speed. The following list shows the capabilities based on the ability to cross
stack with other switch families. The most capable switches are shown at the top of each list:
1. ExtremeSwitching 5720
2. ExtremeSwitching 5520
For example, in a stack that combines 5720 series switches with 5520 series switches, a 5720 series
switch might provide more memory and more features than the 5520 series switches in the stack.
Connect the Switches to Form the Stack Ring
ExtremeSwitching 5720 Series Hardware Installation Guide
Build Basic Stacks
on page 51 and
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