Users Guide

Stacking LAG
When multiple links are used between stack units, Dell 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 Networking OS (without user conguration) 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.
High Availability on S5000 Stacks
An S5000 stack has a master and standby management unit that provide redundancy in a similar way to redundant route processor
modules (RPMs).
As shown in the following example, the show redundancy command displays the status and conguration of redundancy in the
stack.
The master unit synchronizes the running conguration 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 Networking OS elects a new standby unit. Dell Networking OS resets the failed master unit: after online, it
becomes a member unit; the remaining members remain online.
Example of S5000 Stack Manager Redundancy
Stack#show redundancy
-- Stack-unit Status --
----------------------------------------
Mgmt ID: 0
Stack-unit ID: 1
Stack-unit Redundancy Role: Primary
Stack-unit State: Active
Stack-unit SW Version: 9.1(1.0)
Link to Peer: Up
-- PEER Stack-unit Status --
---------------------------------------
Stack-unit State: Standby
Peer stack-unit ID: 2
Stack-unit SW Version: 9.1(1.0)
-- Stack-unit Redundancy Configuration --
----------------------------------------
Primary Stack-unit: mgmt-id 0
Auto Data Sync: Full
Failover Type: Hot Failover
Auto reboot Stack-unit: Enabled
Auto failover limit: 3 times in 60 minutes
-- Stack-unit Failover Record --
-----------------------------------------
Failover Count: 0
Last failover timestamp: None
Last failover Reason: None
Last failover type: None
--Last Data Block Sync Record: --
-----------------------------------------
Stack Unit Config: succeeded Mar 24 2013 20:35:14
Start-up Config: failed Mar 24 2013:35:14
Runtime Event Log: succeeded Mar 24 2013 20:35:14
Running Config: succeeded Mar 24 2013 20:35:14
ACL Mgr: succeeded Mar 24 2012 20:35:14
LACP: no block sync done
Stacking
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