Reference Guide

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Virtual IP
You can manage the stack using a single IP, known as a virtual IP, that is retained in the stack even after a
failover.
The virtual IP address is used to log in to the current master unit of the stack. Both IPv4 and IPv6
addresses are supported as virtual IPs.
Use the following command to configure a virtual IP: Dell(conf)#virtual-ip {ip-address |
ipv6–address | dhcp}
Failover Roles
If the stack master fails (for example, is powered off), it is removed from the stack topology.
The standby unit detects the loss of peering communication and takes ownership of the stack
management, switching from the standby role to the master role. The distributed forwarding tables are
retained during the failover, as is the stack MAC address. The lack of a standby unit triggers an election
within the remaining units for a standby role.
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.
MAC Addressing
All port interfaces in the stack use the MAC address of the management interface on the master switch.
The MAC address of the chassis in which you use the master switch as the stack MAC address.
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 different unit becomes the stack master.
NOTE: If the removed management unit is brought up as a standalone unit or as part of a different
stack, there is a possibility of MAC address collisions. 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 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
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.
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
configuration of redundancy in the stack.
Stacking
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