Introduction to Stacking & Chassis

The argument on Stackable Switch and Chassis switch has been there for long. Prima facie, Stackable switches are understood to be for medium and low end customers which Chassis based state of art switches are considered for high end market customers and service providers. Let’s deep dive into the discussion and understand how both the competitors perform on set of functional parameters which are foundation of inclination for customers.

Stacking Switch Solution

In this type of set up, two or more switches are stacked over each other, hence the name ” stacking” is used. All the switches in a stack behave like “one single device”. Thus a stacking solution provides increased number of ports by increasing the number of switches in a stack, while serving the characteristics and features of a single switch.

Features of Stacking Switch Solution:

• Initial setup cost is less and it is easily scalable.
• It requires less space for set up.
• As each individual switch requires a PSU, more power cabling is required.
• It shows increase in failure rate with increase in the number of power supplies. Mean time between Failure(MTBF) is low.
• Integration of additional services components (like Firewall Service Module, Intrusion Detection) is not supported.
• Management is a challenge as adding or removing switches in a large stack can be problematic.
• It has dedicated modules for Data, Control and Management Plane.

Chassis Switch Solution

Chassis switch set up is formed of a fixed number of slots into which the line cards are inserted. Thus, chassis network switch has a common backplane at the core, in which all line cards are inserted.

Features of Chassis Switch Solution:

• Initial setup cost is high, but they have longer life span as compared to stackable switch.
• The space requirement is more as compared to stacks.
• It offers a common power supply, cooling fan, and control plane/ processing modules. Thus only 1 set of redundant PSU is required.
• The less number of power supplies, considerably reduces the chance of power supply failure. Thus, the Mean time between Failure(MTBF) is high.
• Integration of additional services components (like Firewall Service Module, Intrusion Detection) is supported.
• Management is easier.

Comparison Table: Stacking vs Chassis Switch

Below table summarizes the difference between the two, and will help you to choose the best for you, considering the pros and cons of both the solutions:

PARAMETER	STACKING	CHASSIS
Cost	Less Expensive	More Expensive
Ease of Redeployment	Easier to resize or redeploy	Not easy to resize or redeploy
Placement	Preferably at Access layer	Preferably at Core and Distribution Layer
Cabling for Redundant power supply	1 PSU per switch is required, hence more power cabling.	Only 1 set of redundant PSU per chassis required, hence less power cabling
MTBF (Mean Time Between Failure)	Usually lesser than Chassis	Usually higher than Stack Switches
Failure Rate	Greater failure considering at least as many power supplies at stack members. E.g. – Stack of 6 switches means 6 power supplies to manage hence greater chance of failure.	Lesser power supplies(generally 2) means less chance of power supply failure.
Additional Components	Stacking does not support integration of additional services components like Firewall Service Module, Intrusion Detection.	Supports integration with services components like FWSM module, Intrusion Detection etc.
Physical Space	Less Space consuming	Twice the space of stacks
Pay as you grow model	Supports appropriately	May or mat not apply
Management and Upgrade	Mixing switch models, firmware and software getting all of these variables to match can be quite the task. Adding or removing switches in a large stack can be problematic.	Ease of management and upgrade
Performance	Low on performance	High on performance
Interface Selection	Lesser choice of Interface selection	More choice of Interface selection
Dedicated modules for Data, Control and Management Plane	Yes	No

Continue Reading:

Switch Stacking Basic Setup and Configuration Steps

Switch Stacking vs Clustering

ABOUT THE AUTHOR

Rashmi Bhardwaj

Founder of AAR TECHNOSOLUTIONS, Rashmi is an evangelist for IT and technology. With more than 12 years in the IT ecosystem, she has been supporting multi domain functions across IT & consultancy services, in addition to Technical content making.

You can learn more about her on her linkedin profile – Rashmi Bhardwaj