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Stack Switching vs Cisco VSS: Where to use

Today i will discuss the difference between the Cisco VSS and the Stack switching. Many of you know both the concepts but still i have many queries from your side to understand the concept of the Stack switching and the Cisco VSS.

Stack Switching:
Stack Switching is the concept of stacking the various switching via stack cables so that they can act like a single switch with various ports. Lets us suppose we have a requirement of 200 users at access layer, what to do which switch you will recommend here, Let me talk about Cisco 3850 with 48 port switch now with Cisco 3850- 48 port you can't fill your 200 users requirement, so you required 5 quantity of Cisco 3850 switches in a stack and in this way you have 240 user ports which can fill your requirement.

Below is the image showing the stack of 4 switches in the enterprise environment, you can stack the switches with the stack cables that will be come if you order the stack kit 

Fig 1.1- Stack Switching

Some of you have question, how many switches we can stack and how stacking works actually. 

You can stack upto 9 switches if i am talking about Cisco 3750 or Cisco 3850 Switches in the enterprise network.One of the Cisco EtherSwitch service modules or Catalyst 3750 switches controls the operation of the stack and is called the stack master. The master LED in the front panel of the 3750 switch turns green when the switch becomes master in the stack. The stack master and the other Cisco EtherSwitch service modules or Catalyst 3750 switches in the stack are stack members. The stack members use the Cisco StackWise technology to behave and work together as a unified system. Layers 2 and 3 protocols present the entire switch stack as a single entity to the network.

If you want stack switching in detail, i will soon write an article on stack switching with configuration part and will share with you.

Cisco VSS:
The concept of Cisco VSS- Virtual switching systems where a pair of Catalyst 6500 series switches into a single network element. The VSS manages the redundant links which externally act as a single port channel.The VSS simplifies network configuration and operation by reducing the number of Layer 3 routing neighbours and by providing a loop-free Layer 2 topology.

Fig 1.2- Cisco VSS Concept


An access switch connects to both chassis of the VSS using one logical port channel. The VSS manages redundancy and load balancing on the port channel. This capability enables a loop-free Layer 2 network topology. The VSS also simplifies the Layer 3 network topology because the VSS reduces the number of routing peers in the network. I will explain the full concept in detail about the VSS in another article

Lets talk about the difference between both the technology

  • Switch Stacking uses proprietary cabling and is limited in distance while in the case of Cisco VSS, It uses 10 GE interfaces and so it can be geographically separated
  • In the case of stacking, no configuration required if switch supports stacking while in the case of Cisco VSS concept, you need to configure about the VSS and VSL on the switches.
  • You can have stack upto 9 switches via stack cabling, while in the Cisco VSS, only two switches can be the part of VSS.
  • For Cisco portfolio, Cisco switches like 2960 or 3750,3850 will be the part of the cisco stack switching while Cisco 4500 catalysts, Cisco 6500 and Cisco 6800 catalysts are using the concept of Cisco VSS.
  • Another thing like Cisco stack switching generally used at Access layer while Cisco VSS can be used at distribution or core layers.
These ar above main differences in Stacking and VSS while we have many other concepts like vPC or Clustering for which we will come up with another article to deeply understanding about the difference between them.