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Adding members to a stack and replacing physical units are much easier when multiple switches are combined into

a FlexStack group. Since the stack retains the configuration, there is no need to back up the configuration prior to

removing the switch. Conversely, when a new member is inserted into the stack, the configuration of the stack is

pushed to the new member. The network administrator need not explicitly recover the switch configuration since

the stack took care of it.

Stacking and Clustering

Stacking is not clustering. Clustering is a technology available on Cisco Catalyst fixed Ethernet switches that allows

the network administrator to use a single public IP address to manage multiple physical switches. Clustering was

created to assist network administrators by having a single point of management as well as in preserving valuable

public IP addresses needed to manage the Ethernet switches. Stacking is much more than a single point of

management and IP address preservation because it offers redundancy, availability, and ease of management.

Cisco Catalyst 2960 supports clustering as well as stacking.

What Are FlexStack and FlexStack-Plus?

FlexStack is the name of the stacking technology used by the Cisco Catalyst 2960-S Series of fixed Ethernet

switches. FlexStack is specific to Cisco Catalyst 2960-S switches, and only Cisco Catalyst 2960-S Series Switches

use FlexStack.

FlexStack-Plus is the name of the stacking technology used by the Cisco Catalyst 2960-X and 2960-XR Series of

fixed Ethernet switches. FlexStack-Plus is specific to the 2960-X and 2960-XR Series of switches.

Both FlexStack and FlexStack-Plus require a specific external module in order to stack together. In addition to

the FlexStack and FlexStack-Plus modules (Figure 3), a special FlexStack cable is also required to interconnect

the modules. There are two different modules for FlexStack. The FlexStack module (PID: 2960S-STACK) is for

2960-S, and the FlexStack-Plus module (PID: 2960X-STACK) is for 2960-X and 2960-XR. These two modules are

different sizes and cannot be inserted into the wrong 2960 model. Each FlexStack module supports two FlexStack

ports. The FlexStack module is inserted into the rear of the Cisco Catalyst 2960 switch. Two FlexStack cables,

inserted into the FlexStack module, provide data path redundancy for traffic flowing across the stack. Using

FlexStack cables, the physical members of the stack form a ring, providing the built-in redundant data path for each

member of the stack. FlexStack and FlexStack-Plus share the same stack cable types. You do not need different

FlexStack cable types for FlexStack and FlexStack-Plus.

FlexStack and FlexStack-Plus are optional. In order for a 2960 switch to stack, a separate FlexStack or FlexStack-

Plus module (depending upon your exact 2960 model) must be inserted in the rear of the switch. Without this

module, stacking cannot function. Figure 3 shows a FlexStack-Plus module to be inserted into the rear of a Cisco

Catalyst 2960-X switch. All FlexStack module types are hot swappable.

Cisco Catalyst 2960 switches running FlexStack and FlexStack-Plus use a hop-by-hop method of transferring

Ethernet packets across the stack. Packets traverse the stack by going from one member to another over the

FlexStack links until the packet reaches its destination. This is a behavior similar to that of multiple standalone

Ethernet switches forwarding packets from one switch to another.