3850 support for VSS

[Patrick McHenry]

Hey 

searching for documentation on VSS for the 3850 and can't seem to find any that specifically says it is supported.

This technology is similar to the vPC on the Nexus correct? - where both up links from an access switch can forward to 2 different 3850 cores?

Thanks

[Jon Marshall]

Patrick

As far as I know VSS is only supported on 4500, 6500, 6800 switches.

However if you mean a pair of stacked 3850s and you then uplink an access switch using etherchannel and spread the etherchannel over both 3850s then this is supported.

It is called cross-stack etherchannel.

Jon

[Patrick McHenry]

Thanks Jon - my attached paint diagram might explain what I am trying to understand better.

Is the design possible with 3850s?

Thank you

[Jon Marshall]

Patrick

Yes it is as long as the 3850 pair are stacked which it appears they are.

Jon

[Patrick McHenry]

No Jon I was implying that they were not stacked - just uplinked.

So, I guess my diagram is not possible using 3850s?

Thank you, Pat

[Jon Marshall]

Pat

Apologies, I saw stack and assumed the connecting cable was a stack cable.

You mean two stacked pairs connected together by a normal connection either a single link or an etherchannel and then connecting an access layer switch using etherchannel to both stacks.

If so no, that isn't possible as far as I know.

Jon

[vivek srivastava]

Jon is correct, This topology not supported with 3850. need a minimum 4500 or 4500x

vivek

[Joseph W. Doherty]

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Posting

My understanding is like Jon's this isn't possible, at least not yet.  Why "not yet"?  I understand 3850 stacking to be more VSS like, then 3750 stacking, so perhaps, at some point stacking might be supported on regular Ethernet links, in addition to the special stack links (like some other vendors already support; such as brand J).

[Leo Laohoo]

Pat, 

I'm with everyone here.  The 3850 at the top needs to be stacked, as to form a single logical switch unit, to be able to configure an etherchannel like the one at the bottom of the picture.  

If the two switches were, for instance, a 4500, 6500 or a 6800 series chassis with VSS enabled, then yes.  It's supported.  

But if both units on top are totally separate logical units, then it's not possible.  Not even when you use "switch clustering".  

The main difference between VSS and switch stacking is the amount of physical switches to for a single logical unit.  

[Jiann-Ming Su]

The main difference between VSS and switch stacking is the amount of physical switches to for a single logical unit.

I think I would also add that VSS allows you to have geographic diversity whereas the stack does not.  We've been asking very similar questions, so thanks for all the insights.

[weylin.piegorsch]

2 1/2 year-old thread, but still...

Cisco recently released "stackwise virtual."  Is that what you're looking for?

Cisco StackWise Virtual FAQ

weylin

[nanodit1016]

Apparently only one of the available models can support it.
Check this one:
Q: What hardware and software matrix is required to deploy StackWise Virtual?
A: Cisco StackWise Virtual is supported on the hardware and software version shown in Table 1.
Table 1.
Cisco StackWise Virtual Support Matrix
Hardware Software
Cisco Catalyst 3850-48-XS Series 16.3.3

https://www.cisco.com/c/dam/en/us/products/collateral/switches/catalyst-3850-series-switches/q-and-a-c67-738577.pdf