Stackwise Virtual on C9300X

[Shree Barad]

Hi Friends,

As per my understandings, stackwise virtual was not supported on C9300 series till 2024. Does it provisioned now ?? specifically with C9300X models ?

Regards,

Shriram B

[M02@rt37]

Hello @Shree Barad 

Platorms c9300 are designed for the access layer. So, no StackWise virtual, only StackWise with short cable.

https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9300-series-switches/white-paper-c11-741468.html

[Leo Laohoo]

Only the 9400, 9500 & 9600 support Stackwise Virtual (aka VSS).  9200/9300 support Stackwise (aka stacking).

[Shree Barad]

Noted & Thank you for your inputs. 

[Joseph W. Doherty]

Just curious, why traditional stacking wouldn't be suitable for your use case?

Depending on your network goals/requirements, one approach might be more beneficial.

As noted by @Leo Laohoo , that feature can be found on other Catalyst 9k switch families.

[MHM Cisco World]

Use stackwise instead.

Why you looking for stackwise virtual?

MHM

[slichtblau]

Well, with the 9500's going End of Sale, it would be good to have a non-modular type chassis to support split room aggregation, which the 9300X appears to somewhat target, at least in concept.  It appeared the 9300X was going to fill that gap, as a cost effective aggregation of SFP type connections.  Hopefully stackwise-virtual will come to it with later IOS updates.

But the 9500X appears to be going for the 40/100G market of aggregation where the 9300X is going after the 1/10/25G aggregation area.  Sad that only the 9500 supports the stackwise-virtual.

[Leo Laohoo]

9400, 9500 and 9600 support VSS. 

The 9300/9300L/9300X and 9200/9200L will never support VSS because it will only muddle up the waters between the 9300X and the 9500/9500X.  

VSS with a stack of 9300 will guarantee instability to the stack/network.

[Joseph W. Doherty]

VSS with a stack of 9300 will guarantee instability to the stack/network.

Just being curious, why so?

[Leo Laohoo]

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@Joseph W. Doherty wrote:
Just being curious, why so?

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There is a saying about stacking:  Shared state, shared fate.  

I have used the stacking feature since the GigaStacking GBIC module for the WS-C3500XL-EN (and later to the 2950/3550 switches).  This feature progressed or improved to the 3750 Stacking feature and finally to the stacking in the 3850 and 9300 switch families that run, exclusively, on IOS-XE.  

Since knowing about the stacking feature, I have never known to have any bad experience with the StackWise feature of the classic IOS.  While classic IOS Stackwise is stable (except a few quirks), StackWise in IOS-XE is the complete opposite.  A stand-alone 9300, for example, can (and will) be more stable compared to a stack of 9300.  This is because Cisco has allowed/encouraged bad coding as a whole and this practice has trickled down to affect StackWise.  And StackWise Virual (aka VSS).  

There is currently a growing list of bugs about StackWise and StackWise Virtual where the workaround is to remove the stacking cables and cold-reboot the switches.

Imagine what would happen if Cisco even allowed a 9300 that can/will support both StackWise and StackWise Virtual at the same time?  

And nobody, even Cisco sales, talks about StackWise/StackWise Virtual without talking about another signature Cisco feature:  ISSU.  Well, ISSU is having a bad run.   Cisco cannot seem to fix ISSU in the entire 17.15.X train (CSCws35670 & CSCwr15775) and 17.18.X (CSCwr15775).  This is not about one or two releases in a Train but, rather, the entire train.  

But not to worry, the affected (and buggy) versions are still found to be in the ISSU Compatibility Matrix as "good".  

Circling back to the question:  What's wrong with StackWise/StackWise Virtual?   My answer:  Unreliable and unstable firmware (or code) is what is happening to StackWise/StackWise Virtual and, as an extension, ISSU.

IMPORTANT:  If the switches (or WLC) are in a stack &/or VSS, (always) reboot the switches every 6 months. 

Ignore my warning, but Cisco TAC's current recommended "upgrade to the next buggy code" is (sort of ) a euphemism for "reboot the stack" and the only difference between my recommendation and Cisco TAC 's is that one has the official Cisco logo. 

[Joseph W. Doherty]

This is because Cisco has allowed/encouraged bad coding as a whole and this practice has trickled down to affect StackWise. And StackWise Virual (aka VSS).

I very much doubt "encouraged".

"Allowed", very possibly.  Although, to be fair to Cisco, software feature growth, is often very prone to introducing bugs.  I can not think of any other engineering that's quite the same.

[Leo Laohoo]

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@Joseph W. Doherty wrote:
I very much doubt "encouraged".

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I do believe "encouraged". 

Bad code only pays well.

[Joseph W. Doherty]

Conceptionally, probably, any 9k switch might support SVL, but Cisco marketing decisions may say no, and probably will.

Historically, consider the 6500 "switch" and the 7600 "router".  For a while, they could use identical sups, some identical line cards and even identical IOS images, but each also only supported some line cards unique to each.  Hmm, was there a major technical reason why one platform couldn't support all line cards?

Well, even if not, clearly (wink, wink) there's benefit, to the customer, in needing to purchase both a switch and a router, avoiding the proverbial placing all your eggs in one basket.

BTW, I can say, I've also used Brand "J" stackable switches that didn't make the usage distinction as described in @balaji.bandi personal reference.  But, it was a different approach.  Was it a "better" approach?  That would depend on how you define "better".  I would, though, say it was possibly more "flexible".

[balaji.bandi]

NO - you need to understand the difference Stackwise(traditional) vs Stackwise Virtual (SVL) (aka old VSS)

what i learning from Cisco documentation and deployment:

https://www.balajibandi.com/?p=2907