Wired Intelligent Edge

What would be the correct and recommended way to configure redundant stack links with only two switches? Can ring topology be used with two switches for redundancy and added bandwidth? Or is another method required/possible? Manuals seem to only mention ring starting from three members.

 

This would be for VSF stacking in 2930F series and also for backplane stacking in 2930M series.

Technically speaking a two members stack (backplane/frontplane, it doesn't matter) can't be deployed with a ring interconnection topology...but you could "see" the chain interconnection topology as a sort of a ring (even if it isn't really a ring).

 

With three members, when you reconnect back the third member with the first one...you are going to create - de facto - a ring.

 

In both case (backplane/frontplane stacking) plan to use more than one physical member for the logical interconnection ports to enhance inter-switch resiliency and bandwidth (this translates into frontplane VSF port made with more than one physical member interface and with backplane stacking deployed using a pair of stacking cables between your two switches).

Thanks parnassus. Do you have a link to an example how this should be done with 2930F and 2930M? Or is it identical to a chain configuration, just with added ports?

To help in ring versus chain choice, you may consider future extension of the stack (3 or more). If you already set-up a ring model, this would be less disruptive and  easier to extend.

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@vincent.giles wrote:

To help in ring versus chain choice, you may consider future extension of the stack (3 or more). If you already set-up a ring model, this would be less disruptive and  easier to extend.

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There probably won't be a need to extend in the future in this case. I'm just trying to decide whether to use more than one link for a two node stack and how to configure it.

@vincent.giles: correct.

Consider that, from that standpoint, the Aruba 2930M will let you few choices because it provides just one stacking slot and so stacking can be deployed by using just one Aruba 2930M 2-port Stacking Module (JL325A) per stack member...that mean that ring topology can't be deployed concurrently with stacking port enhanced resiliency (due to the two ports limitation on stacking module)...with VSF there is a little bit room for alternate deployments...it will be more easy to achieve (a) ring topology (future stack expansions proof) concurrently with (b) enhanced VSF ports resiliency.

Well, let me provide two links...but, first, you have to understand that Aruba 2930M uses backplane stacking while Aruba 2930F uses frontplane stacking (VSF)...although both are technology approaches aimed at reaching virtual switching stack...their implementations aren't identical so there are specific tips, tricks, caveats, requirements and restrictions.

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@SpreadSpectrum wrote:

Thanks parnassus. Do you have a link to an example how this should be done with 2930F and 2930M? Or is it identical to a chain configuration, just with added ports?

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With regards to VSF this is worth a read, it should be able to clarify you anything about VSF.

 

With regards to Aruba 2930M (backplane) stacking, start with reading its Aruba 2930M Switches Installation and Getting Started Guide (Chapter 3, "Stacking information and topologies" paragraph) for an overview of stacking topologies then read the Chapter 9 "Stack Management" of Aruba 2930F/2930M Advanced Traffic Management Guide for ArubaOS-Switch 16.08. 

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@parnassus wrote:

 

With regards to VSF this is worth a read, it should be able to clarify you anything about VSF.

 

With regards to Aruba 2930M (backplane) stacking, start with reading its Aruba 2930M Switches Installation and Getting Started Guide (Chapter 3, "Stacking information and topologies" paragraph) for an overview of stacking topologies then read the Chapter 9 "Stack Management" of Aruba 2930F/2930M Advanced Traffic Management Guide for ArubaOS-Switch 16.08. 

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Thank you for the resources. I have to dig into the manuals more, but seems that with 2930M it's mostly plug & play when using two stack cables and with 2930F I can just create the VSF links/ports with several interfaces.