Comparison of FlexStack, FlexStack-Plus, and FlexStack-Extended
Cisco 2960-X Series support FlexStack-Plus and FlexStack-Extended technologies. What are these two stacking solutions that are supported by Catalyst 2960-X Series? And what are differences between them? The following part will list the main features and differences of FlexStack, FlexStack-Plus, and FlexStack-Extended.

Cisco FlexStack-Plus is a hot-swappable, modular stacking solution that provides a true stacking capability, with all switches acting as a single switching unit with a unified data plane, using a single IP address. Cisco FlexStack-Plus is supported by the Cisco Catalyst 2960-X Series and allows the stacking of up to eight switches, with a throughput of 80 gigabits per second.
Cisco FlexStack-Extended enables long-distance out-of-the-wiring-closet stacking. FlexStack-Extended allows back-panel stacking of up to eight Cisco Catalyst 2960-X or 2960-XR Series Switches. FlexStack-Extended can be added to the Cisco Catalyst 2960-X or 2960-XR Series with a back stacking slot.
FlexStack-Extended is available in two module configurations: Fiber module (C2960X-FIBER-STK) and Hybrid module (C2960X-HYBRID-STK).
And the FlexStack-Plus and FlexStack-Extended technologies are similar to FlexStack technology with the differences listed in the Table below.
Table. Comparison of FlexStack, FlexStack-Plus, and FlexStack-Extended
Platform | Members | Bandwidth | Convergence |
FlexStack | 4 | 40 Gbps | 1–2 sec |
FlexStack-Plus | 8 | 80 Gbps | 100 msec |
FlexStack-Extended | 8 | 40 Gbps | 100 msec |
STACKING Comparison of Cisco Catalyst 2960 Series Switches
Feature | 2960-S | 2960 | ||
CPU | Dual core at 600 MHz | Dual core at 600 MHz | Single core | Single core |
Stacking | FlexStack-Plus, FlexStack-Extended | FlexStack-Plus, FlexStack-Extended | FlexStack | No |
Stack bandwidth | 80 Gbps (FlexStack-Plus); 40 Gbps (FlexStack-Extended) | 80 Gbps (FlexStack-Plus); 40 Gbps (FlexStack-Extended) | 40 Gbps | – |
Stack members | 8 | 8 | 4 | – |
More Q and A tell you about FlexStack combinations, Possible mixed-stack combinations
Q. What are the FlexStack-Plus high-availability features?
A. The following features enhance high availability and manageability across a stack:
● Cross-stack EtherChannel
● SPAN
● FlexLink technology
● Hitless voice calls
Q. What is the difference between the Hybrid (C2960X-HYBRID-STK) and Fiber (C2960X-FIBER-STK) modules of FlexStack-Extended?
A. The Hybrid module has one copper port that enables short-reach connectivity across a local stack of switches and one SFP+ port for long-range connectivity. The Hybrid module provides investment protection and compatibility with FlexStack-Plus.
The Fiber module has two SFP+ ports supporting long-reach out-of-the-wiring-closet stacking.
Q. What optics are supported on the FlexStack-Extended modules?
A. For information about supported SFP+ modules, refer to the transceiver compatibility matrix at cisco.com/en/US/products/hw/modules/ps5455/products_device_support_tables_list.html.
Q. Which cables are supported with the copper port of the Hybrid module (C2960X-HYBRID-STK) in Cisco FlexStack-Extended?
A. CAB-STK-E-0.5M stacking cable with a 0.5 m length .
CAB-STK-E-1M stacking cable with a 1.0 m length .
CAB-STK-E-3M stacking cable with a 3.0 m length.
Q. What is the minimum Cisco IOS Software version required for FlexStack-Extended?
A. FlexStack-Extended is supported from version 15.2(6)E onward.
Q. What are the stackable models of the Cisco Catalyst 2960-X Series?
A. The LAN Base and IP Lite feature set models are stackable models in the Cisco Catalyst 2960-X Series. The LAN Lite feature set model is a standalone model.
Note: The fanless SKU (WS-C2960X-24PSQ-L with Lan Base) does not support stacking.
Q. Can LAN Base and IP Lite feature set models stack together in the Cisco Catalyst 2960-X Series?
A. No, LAN Base and IP Lite feature set models cannot be stacked together. LAN Base feature set models can stack with LAN Base feature set models only. Similarly, IP Lite feature set models can stack with IP Lite feature set models only.
Q. Can Cisco Catalyst 2960-X switches stack with Cisco Catalyst 2960-XR switches?
A. No. Cisco Catalyst 2960-X and 2960-XR switches can’t stack together since they don’t share common feature set model.
Q. Is FlexStack-Plus stacking backward compatible with FlexStack?
A. Yes. Unlike competing products, the FlexStack-Plus stacking is backward compatible with FlexStack to preserve customer investment. This allows mixed stacking of Cisco Catalyst 2960-S and Cisco Catalyst 2960-SF LAN Base series with 2960-X LAN Base series for investment protection.
Q. Is FlexStack-Extended supported with FlexStack-Plus?
A. Only the Hybrid module (C2960X-HYBRID-STK) can connect to the FlexStack-Plus module using the copper port.
Q. Is FlexStack-Extended supported with FlexStack?
A. No, FlexStack-Extended is not supported with FlexStack.
Q. What is a mixed stack?
A. The stack is called a mixed stack if it has both the Cisco Catalyst 2960-S Series Switch and Cisco Catalyst 2960-X Series Switches. The mixed stack features are limited to Cisco Catalyst 2960-S Series features. (See Table1.)
Table1. FlexStack combinations
Stack combination | Max stack bandwidth | Stack limit | Cisco IOS license |
2960-XR | 80G | 8 | IP Lite |
2960-X | 80G | 8 | LAN Base |
2960-S/SF | 40G | 4 | LAN Base |
Mixed stack: 2960-X (C2960X-STACK) and 2960-S/SF (C2960S-STACK) | 40G | 4 | LAN Base |
Q. Does mixed stacking require any configuration on Cisco Catalyst 2960-X Series Switches?
A. Yes. The switch stack speed should be set to 40 using configure mode command “switch stack-speed 40” on Cisco Catalyst 2960-X switches to stack with Cisco Catalyst 2960-S switches. While forming a homogenous stack of Cisco Catalyst 2960-X revert back the stack speed to 80 using “no switch stack-speed 40”.
Q. Can Cisco Catalyst 2960-X and 2960-XR Series Switches stack together?
A. No. Cisco Catalyst 2960-X and 2960-XR Series Switches can’t be stacked together. Even though they belong to the same 2960-X Series, they do not share same Cisco IOS license models.
Q. What are the possible mixed-stack combinations?
A. The LAN Base models can only form mixed stacks. The possible mixed-stack combinations are listed in Table2.
Table2. Possible mixed-stack combinations
Mixed-stack combination | 2960-XR IP Lite | 2960-X LAN Base | 2960-S/SF LAN Base |
2960-XR IP Lite | Yes | No | No |
2960-X LAN Base | No | Yes | Yes (C2960X-STACK only) |
2960-S/SF LAN Base | No | Yes (C2960X-STACK only) | Yes |
Q. Which SDM template should be selected on the Cisco Catalyst 2960-X Series with LAN Base to form a mixed stack with Cisco Catalyst 2960-S?
A. If Cisco Catalyst 2960-S is running the “default” SDM template, then Cisco Catalyst 2960-X must use the “default” template. If Cisco Catalyst 2960-S is running the “lanbase-routing” template, then Cisco Catalyst 2960-X must use the same.
Q. Can Cisco Catalyst 2960-S be the stack master in a mixed stack of 2960-S and 2960-X switches?
A. Yes. Cisco Catalyst 2960-S can be stack master in a mixed stack.
Q. In a mixed stack of Cisco Catalyst 2960-S and 2960-X, must all the switches be on the same Cisco IOS Software release?
A. Yes. All the switches in the stack, regardless of model, must be on the same Cisco IOS Software release. This includes the rebuild number. The minimum Cisco IOS Software release that will support both 2960-S and 2960-X is 15.0(2)EX.
Q. Can we use FlexStack stacking modules with Cisco Catalyst 2960-X Series?
A. No. The form factors of FlexStack-Plus and FlexStack modules are different. The FlexStack stacking module cannot be used with the Cisco Catalyst 2960-X Series. Similarly, the FlexStack-Plus module cannot be used with the Cisco Catalyst 2960-S Series.
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