What is Stack Bandwidth ?

[prashanma]

Hi Team,

Stack member	Stack bandwidth	Stack limit	Cisco IOS feature set
2960-XR IP Lite	80 Gbps	8	IP Lite

What is stack bandwidth and how it calculate ? 

[Mark Malone · Accepted solution]

Hi
Its the complete ring bandwidth in a stack when all the switches are connected together in a full ring
the bandwidth is a set amount as per the data sheets , so the full ring bandwidth with 8 switches is 80gb , it varies from platform to platform

so as example of another model the newer 3650 can do up to 160gb ring bw

3650 offers a stacking bandwidth of only 160 Gbps non-blocking.

[prashanma]

Thank you Mark

[Joseph W. Doherty]

What Mark notes is a good example of how Cisco can market stack bandwidths.

I recall (?) the stack links bandwidth on a 2960 stack is for the whole stack while on the 3650 its between stack members. If I remember that correctly, the 2960 whole stack bandwidth is to "inflate" its stack bandwidth.

[Joseph W. Doherty]

As Mark notes, how stack bandwidth is calculated can vary across various platforms. I suspect, Cisco Sales looks for a calculation method to provide the best possible numbers.

If you really want to understand a particular series of stackable switches' stack bandwidth, you really need to dig deep into Cisco documentation for how a particular stack architecture works. (BTW, Cisco often doesn't provide the level of detail that you can fully understand how a particular stack architecture works.)

[prashanma]

Thank you Joseph

[sbhadrav@cisco.com]

Layer 3 redundancy. Some stackable architectures allow for continued Layer 3 routing if there is a “down” switch in a stack. ... For example, some stacking allows for the mixing 10/100 and Gigabit switches in a stack. Dedicated stacking bandwidth.

[prashanma]

Thank you Drav