stack and vss

[Mary]

in stack, we can combine three or switches into one logical switch, but using vss we can only combine two switches, so if both two switches fail, then it cause problem, while in stack, if we can three switches, two fail but remaining one still work, so can i say stack is better than vss?

[Manish Gogna]

Hi,

You can read the following discussions about similar query

https://learningnetwork.cisco.com/thread/78073

https://learningnetwork.cisco.com/thread/52894

Manish

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[Joseph W. Doherty]

If you don't mind losing two thirds of your capacity, yes you might say a stack of thee is better that a VSS pair.

However, also consider, some VSS pairs members support multiple line cards, power supplies and supervisors, so, for those, such members offer more redundancy than a stack of three.

Also consider, if you had a stack of four or more, losing two stack members would partition the stack, having the two stacks "claiming" to be the logical device.

Lastly, consider, some stacks don't require all stack member to have the same feature set installed.  I.e., in you example of losing two of your stack members, this might result in the remaining stack member (of three) being unable to support the features being used when all the stack members were in operation.

To sum it all up, "so can i say stack is better than vss?"  Maybe, maybe not, it's a depends type of answer.