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The first operational benefit is fewer devices to manage. Multiple physical switches in a stack appear as a single
logical switch. This eases management overhead because there are fewer devices in the network to manage. A
single IP address is used to manage the logical switch. All manageable entities (for example, Ethernet interfaces
and VLANs) on all physical switches can be configured and managed from the logical switch. The logical switch will
appear as a single entity in the network. In a Layer 2 network, the logical switch will appear as a single spanning-
tree entity.
The second operational benefit that stacking provides is built-in redundancy and increased availability. Data path
redundancy is built into the stacking architecture as there are two physical paths between any two stack members.
Connecting stack members with the stacking cables provides data path redundancy for all stack members.
Stacking increases Ethernet switch availability by providing redundancy for both the physical switch and the uplink.
Because different physical switches will connect to the upstream network, losing one switch or one uplink interface
does not prevent connectivity to the network. Since the logical switch has multiple uplinks, the logical switch still
has network connectivity because at least one uplink is still active.
In a logical switch, a single physical switch is acting as the stack master. The stack master manages all physical
switches, including itself. If the master fails, another member automatically becomes the stack master following a
well-documented election process (covered later). The configuration of the stack is preserved through a single
switch failure or a reboot of all stack members. FlexStack provides 1:N redundancy for the stack master, with the
ability for any physical switch to back up the acting master. (See Figure 2.)
Figure 2. FlexStack with Redundant Links
Flexibility of FlexStack allows for modular stacking capability. Cisco Catalyst 2960 switches can be added to a
stack at any time by adding the optional FlexStack module. As the demand for Ethernet access ports increases,
Cisco Catalyst 2960 switches can be stacked together either to create a new stack or to add new Cisco Catalyst
2960 switches to an existing stack. This flexibility provides investment protection for the network administrator, who
can add additional stack members as needed.