Administrator Guide

• Stacking is supported only with other Aggregators. A maximum of six Aggregators are supported in a single stack. You cannot
stack the Aggregator with MXL 10/40GbE Switches or another type of switch.
• A maximum of four stack groups (40GbE ports) is supported on a stacked Aggregator.
• Interconnect the stack units by following the instructions in Cabling Stacked Switches.
• You cannot stack a Standalone IOA and a PMUX.
Master Selection Criteria
A Master is elected or re-elected based on the following considerations, in order:
1. The switch with the highest priority at boot time.
2. The switch with the highest MAC address at boot time.
3. A unit is selected as Standby by the administrator, and a fail over action is manually initiated or occurs due to a Master unit
failure.
No record of previous stack mastership is kept when a stack loses power. As it reboots, the election process will once again
determine the Master and Standby switches. As long as the priority has not changed on any members, the stack will retain the same
Master and Standby.
NOTE: Each stack members’ role (including the Master and Standby) can be dened by the user at any time by setting
the priority.
If the entire stack is powered OFF and ON again, the unit that was the Master before the reboot will remain the Master after the
stack resumes operation. However, when a stack is powered on, all members are in sleep mode for 5 seconds while waiting on the
previous Master to join the stack. If the previous Master fails to join within 5 seconds, the remaining members (including the
Standby) elect a new Master.
Conguring Priority and stack-group
Perform the following steps to congure the priorities and stack-groups for each of the switches.
1. Set the priorities for the stack-unit.
CONFIGURATION mode
stack-unit unit-number priority 1-14
Dell(conf)# stack-unit 0 priority 12
Setting the priority will determine which switch will become the management (Master) switch. The switch with the highest
priority number is elected Master. The default priority is 0.
NOTE: It is best practice to assign priority values to all switches before stacking them in order to acquire and retain
complete control over each units role in the stack.
2. Congure the stack-group for each stack-unit.
CONFIGURATION mode
stack-unit unit-no stack-group stack-group-id
Dell(conf)# stack-unit 0 stack-group 0
Dell (conf)#02:26:05: %STKUNIT0-M:CP %IFMGR-6-STACK_PORTS_ADDED:
Ports Fo 0/33 have been configured as stacking ports.
Please save and reload for config to take effect
Stack-groups are easier to think of simply as stack ports. For example, using the stack-group 0 command simply turns the
lower port (port 9) into a stacking port. Similarly, stack-group 1, stack-group 2 and stack-group 3 commands
correspond to ports 10, 11 and 12 respectively.
Stacking
189