Administrator Guide

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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 configuration) 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.
Figure 115. Supported Stacking Topologies
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 configuration 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.
Example of Stack Manager Redundancy
DellEMC#show redundancy
-- Stack-unit Status --
------------------------------------------------
774
Stacking