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How VSF management module works in VSF ???

Hi All,

 

Appreciate if anyone suggest how VSF works when two swithes have two management modules each and if the Active MM of commander switch fails  then the failover happens within commander standby MM or Standby switch's Active MM??? 

 

Thanks in advance

MVP Expert
MVP Expert

Re: How VSF management module works in VSF ???

Hi,

 

second management module is not supported if using VSF. Compare Documentation/Guides, VSF section, operational notes/restrictions.

 

The second module in a switch will be deaktivated, if VSF is configured.

 

Out of the top of my head: No failover to second MM if primary dies. Instead of this failover to VSF secondary.

But I did my last test for this a long time ago at the time VSF got available for 5400 first time.

 

Maybe a reboot brings second MM of the switch into active state..

But thats not a "fast" failover.

 

Regards, Jö

 

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MVP Expert

Re: How VSF management module works in VSF ???

Hi !

 

It's a little bit more complex than we all (me included) used to think since very first VSF implementations (we learned that standby MM should be removed to let VSF to work safely) ...actually, as reported on the thread linked below, 2nd MM (Offlined) is supported on a VSF node, this doesn't disrupt VSF function (clearly here we're speaking about VSF on Aruba 5400R zl2): read this thread, in case of Active MM fault on a dual equipped MMs VSF node, the VSF node will reboot bringing the offlined MM finally in operation (yes, that's a disruptive process compared to working with NonStop Switching or Warm Standby chassis redudancy methods but this limitation is due to VSF)...at least this is what I learned on the linked thread.

 

I personally still have two unanswered questions...we have an update scenario in which we are trying to decide if coupling an existing Aruba 5412R zl2 with dual MMs in NonStop Switching with another similar switch and then create the VSF, loosing two MMs, or coupling it with another Aruba 5412R zl2 without any MM and using the one we have on the first one...in both cases VSF in mutually exclusive with chassis redudancy.

MVP Expert
MVP Expert

Re: How VSF management module works in VSF ???

Hi Davide,

 

ah, missed that threat.

Talked to a collegue. Behaved like this from the beginning. But now its oficially supported.

 

It is not what our customers expect to gain of a second MM. So we stopped selling it.

 

Regarding your questions: Since secondary MMs are shutown in VSF, I'd expect, they will not get updated. Another "burdon" to that design. One would have to update after failure or perform a failover while updating to do a consistent update. I asume failover can only be done by removing primary MM...

 

Not the nicest solution.

Mybe better to store a cold standby MM for a couple of 5400Rs insted of buing one for every chassis...

 

Regards, Jö

 

 

 

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Re: How VSF management module works in VSF ???

Hi Jo, I'm still trying to understand if my doubts are legitimates... I suspect that having a secondary MM sitting offlined on a VSF node is not worth the potential troubles that can arise in case it kicks in with a non homogeneous software version if compared to faulted MM and, in the long term, the complication of trying to keep offline MM synchronized with online one.

 

On the other hand keeping a spare MM could be problematic too in case of hotswapping with diverged software versions.

 

The optimum would be that VSF will be able to support dual MMs (Active+Standby) letting customers to finally benefit from Chassis Redudancy available modes (NonStop Switching mode or Warm-Standby Switching mode).

MVP Expert
MVP Expert

Re: How VSF management module works in VSF ???

Hi Davide,

 

I think yes, your doubts are legitimates.

 

If you have a cold spare, at least you have to replace and think about that. Good chances to remember to update the cold MM.

 

Support for secondary MMs, like available in Comware, would be perfect. But only developers can say, if this is doable...

 

Regards, Jö

 

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Re: How VSF management module works in VSF ???


@Jö wrote: If you have a cold spare, at least you have to replace and think about that. Good chances to remember to update the cold MM.

Yes, having a spare MM "sleeping on a shelf" will probably be better but trying to keep it aligned with regards to software will be problematic too (when you are concurrently dealing with a VSF node failure due to the broken Active MM)...but, at least, you can prepare a procedure to deal with.

 


@Jö wrote: Support for secondary MMs, like available in Comware, would be perfect. But only developers can say, if this is doable...

Yes it would.

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