Stackwise vs Solo Switches - 3850

[kaetwo1]

This is my first time posting and I'm fairly new to the Cisco world, so I apologize if this is a simple question.

I'm pretty familiar with the pros and cons of stacking, but I had a question that I could not find an answer too online.

I have (6) 3850 switches with 4x 1gig modules, all in the same IDF.  Each one has a pair of 1 gig port-channeled connections back to my Nexus 5K cores.  I was thinking about making these (6) 3850s a stack and port-channeling gig1/1/1 and 6/1/1 back to the cores (which are running VTP).

My question is this;

Would I have better throughput keeping these 6 switches independent (6 - 1gig port-channeled links) vs stacking the 6 switches (2 - 1gig port-channeled links)?  It would seem like I would be over-provisioned.

I know it would be better to get (2) 2x10gig/2x1gig modules and run 10gig back to the cores, but I'm just curious what everyone's thoughts are.

Thanks for all the help.

Brett Thorne

[luis_cordova · Accepted solution]

Hi @kaetwo1 

You currently have 6 switch traffic traveling through 6 different channels. If you do the stack, then you will have the 6 switch traffic traveling through 1 channel. In addition, each switch currently switches its own traffic, but to stack, the master switch will manage the switching of the 6 switches.

I think that if you have no administration problems or shortage of ports on your core switch, it is better to continue with your current topology.

Regards

[Leo Laohoo]

SFP ports and SFP runs are an "estate" by themselves.
I would never go over than an etherchannel made up of >4 physical links.
If you're planning to have 6 links with SFP, then it's better to have 2 or 3 SFP+ in an etherchannel.

[Joseph W. Doherty]

This is an "it depends" answer. The the answer mainly depends on is where does your traffic flow now?

If the bulk of your traffic is between the independent switches, then having those switches in a stack would provide much more bandwidth between those switches.

If the bulk of your traffic is between those switches and else where in your network, your current setup provides much more bandwidth.

That said, another important question is just how much traffic is passing through those switches' uplinks now? I.e. what bandwidth do you need? If you don't need the bandwidth on the uplinks, then the other advantages of a switch stack might determine it's "better" than having the switches as independent switches.

BTW, years ago, we were considering whether it was "better" to have a large number Eitherchannel links of gig ports or a couple of 10g ports, for uplinks. (This was also when 10g was still pretty new and 10g ports were expensive.) We found, for fiber, 10g actually cost less when you considered the cost of the optics of all the additional gig.

[paul driver]

Hello

I agree with @luis_cordova  if you don't have much horizontal traffic and your not restricted in cabling racking etc then your current design would be applicable

[kaetwo1]

I appreciate everyone's advice.

Brett Thorne