White Papers

Figure 125. Four Stacked S5000 Switches
Stack Management Roles
The stack elects the management units for the stack management.
● Stack master — primary management unit, also called the master unit.
● Standby — secondary management unit.
The master holds the control plane and the other units maintain a local copy of the forwarding databases. From the stack
master you can configure:
● System-level features that apply to all stack members.
● Interface-level features for each stack member.
The master synchronizes the following information with the standby unit:
● Stack unit topology
● Stack running configuration (which includes ACL, LACP, STP, SPAN, and so on.)
● Logs
The master switch maintains stack operation with minimal impact in the event of:
● Switch failure
● Inter-switch stacking link failure
● Switch insertion
● Switch removal
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: An S5000 switch stack has only one management IP address.
Stack Master Election
By default, the stack determines a master and standby unit at bootup time by electing the units with the highest MAC
addresses.
You can preconfigure the units which are elected master and standby by assigning higher priorities to these units. (By default,
all stack units have priority 0. Valid priority values are from 0 to 14. A higher value means a higher priority. To remove the
stack-unit priority and set the priority back to the default value of zero, use the no stack-unit priority command.)
If you add a standalone unit, which has the same priority as the master stack unit, the standalone unit joins the stack as a
member unit.
Stacking
827