Setup Guide
After the former master switch recovers, despite having a higher priority or MAC address, it does not recover its master role but instead
takes the next available role.
To view failover details, use the show redundancy command.
MAC Addressing on Stacks
The stack has three MAC addresses: the chassis MAC, interface MAC, and null interface MAC.
All interfaces in the stack use the interface MAC address of the management unit, and the chassis MAC for the stack is the master’s
chassis MAC. The stack continues to use the master’s chassis MAC address even after a failover. The MAC address is not refreshed until
the stack is reloaded and a dierent unit becomes the stack master.
NOTE: If the removed management unit is brought up as a standalone unit or as part of a dierent stack, there is a possibility of
MAC address collisions.
A standalone is added to a stack. The standalone and the master unit have the same priority, but the standalone has a lower MAC address,
so the standalone reboots. In the second example, a standalone is added to a stack. The standalone has a higher priority than the stack, so
the stack (excluding the new unit) reloads.
Example of Adding a Standalone with a Lower MAC Address to a Stack
Example of Adding a Standalone with a Lower MAC Address and Equal Priority to a Stack
Stacking LAG
When multiple links are used between stack units, Dell EMC Networking OS automatically bundles them in a stacking LAG to provide
aggregated throughput and redundancy.
The stacking LAG is established automatically and transparently by Dell EMC Networking OS (without user conguration) after peering is
detected and behaves as follows:
• The stacking LAG dynamically aggregates; it can lose link members or gain new links.
• Shortest path selection inside the stack: If multiple paths exist between two units in the stack, the shortest path is used.
Supported Stacking Topologies
The device supports stacking in a ring or a daisy chain topology.
Dell EMC Networking recommends the ring topology when stacking the switches to provide redundant connectivity.
High Availability on Stacks
Stacks have master and standby management units analogous to Dell EMC Networking route processor modules (RPM).
The master unit synchronizes the running conguration and protocol states so that the system fails over in the event of a hardware or
software fault on the master unit. In such an event, or when the master unit is removed, the standby unit becomes the stack manager and
Dell EMC Networking OS elects a new standby unit. Dell EMC Networking OS resets the failed master unit: after online, it becomes a
member unit; the remaining members remain online.
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Stacking