Dell Force10 MXL Blade MXL 10/40GbE Switch IO Module Configuration Guide - Page 549

Stack Master Election, Adding a Stack Unit, Merging Two Stacks

Page 549 highlights

If the master switch goes off line, the standby replaces it as the new master and the switch with the next highest priority or MAC address becomes standby. Note: For the MXL Switch, the entire stack has only one management IP address. Stack Master Election The stack elects a master and standby unit at bootup time based on two criteria: • Unit priority: This is user-configurable. Valid values are from 1 to 14. A higher value means a higher priority. The default is 0. To remove the stack-unit priority and set the priority back to the default value of zero, use the no stack-unit priority command. • MAC address (in case of priority tie): The unit with the higher MAC value becomes master. To view which switch is the stack master, use the show system command. Figure 31-2 shows sample output from an established stack. A change in the stack master occurs when: • You power down the stack master or bring the master switch offline. • A failover of the master switch occurs. • You disconnect the master switch from the stack. Note: When a stack reloads and all the units come up at the same time; for example, when all units boot up from flash, all units participate in the election and the master and standby are chosen based on the priority or MAC address. When the units do not boot up at the same time; for example, some units are powered down just after reloading and powered up later to join the stack, they do not participate in the election process, even though the units that boot up late may have a higher priority configured. This happens because the master and standby have already been elected; therefore, the unit that boots up late joins only as a member. Also, when an up and running standalone unit or stack is merged with another stack, based on election, the losing stack reloads and the master unit of the winning stack becomes the master of the merged stack. For more information, refer to "Adding a Stack Unit" and "Merging Two Stacks". To ensure a fully synchronised bootup, it is possible to reset individual units to force them to give up the management role; or reload the whole stack from the command line interface (CLI). Stacking | 547

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Stacking
|
547
If the master switch goes off line, the standby replaces it as the new master and the switch with the next
highest priority or MAC address becomes standby.
Stack Master Election
The stack elects a master and standby unit at bootup time based on two criteria:
Unit priority: This is user-configurable. Valid values are from 1 to 14. A higher value means a higher
priority. The default is 0. To remove the stack-unit priority and set the priority back to the default value
of zero, use the
no stack-unit priority
command.
MAC address (in case of priority tie): The unit with the higher MAC value becomes master.
To view which switch is the stack master, use the
show system
command.
Figure 31-2
shows sample output
from an established stack.
A change in the stack master occurs when:
You power down the stack master or bring the master switch offline.
A failover of the master switch occurs.
You disconnect the master switch from the stack.
Note:
For the MXL Switch, the entire stack has only one management IP address.
Note:
When a stack reloads and all the units come up at the same time; for example, when all units boot up
from flash, all units participate in the election and the master and standby are chosen based on the priority
or MAC address. When the units do not boot up at the same time; for example, some units are powered
down just after reloading and powered up later to join the stack, they do not participate in the election
process, even though the units that boot up late may have a higher priority configured. This happens
because the master and standby have already been elected; therefore, the unit that boots up late joins only
as a member. Also, when an up and running standalone unit or stack is merged with another stack, based
on election, the losing stack reloads and the master unit of the winning stack becomes the master of the
merged stack.
For more information, refer to “
Adding a Stack Unit
” and “
Merging Two Stacks
”.
To ensure a fully
synchronised bootup, it is possible to reset individual units to force them to give up the management role;
or reload the whole stack from the command line interface (CLI).