[ASR9K nvEdge]How to decide who will be primary DSC after cluster rebuild?

[hsien-ping tang]

Hi

I have a question about ASR9K nvEdge cluster.

Normally,when the EOBC & IRL link are disconnected, the cluster will enter into "split node" status.

each rack will think itself is primary DSC.

My question is that after the EOBC & IRL are reconneted(cluster rebuild), whick one (rack0 or rack1) will be the primary DSC? and why?

Thanks,

Tom

[Hemachander Janardhan]

Hi Tom,

By design Rack0 will be preferred as primary DSC.

~Chander

[hsien-ping tang]

Hi Chander

Thanks for response,
I have tried that scenario at lab, YES, Rack0 will win the primary DSC as you say.
But I tried another scenario, and it make me confuse.
I reload the Rack0 BEFORE rebuilding nVEdge cluster, Rack1 win the primary DSC.
Is it correct?
How does Rack1 detect that Rack0 is reloaded while EOBC & IRL are disconnected at the given time?

Tom



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[Eddie Chami]

Walk me through the steps from the beginning and we will be able to explain the reason.

Eddie.

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[hsien-ping tang]

Hi Eddie

1. Check cluster status(Rack0 is primary DSC, Rack1 is backup DSC)
2.separate cluster by disconnect EOBC & IRL
3. Rack0 & Rack1 think itself is primary DSC
4. Reload Rack0
5. Re-connect EOBC
6. Rack0 reload again
7. Rack0 join cluster successfully
8. Re-connect IRL
9. Now Rack1 is primary DSC , Rack0 becomes backup DSC.

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[Eddie Chami · Accepted solution]

Yes that's perfect thanks for the details. This is the expected behavior. In fact this is how we will be achieving nv ssu. Which is a new feature on the roadmap. What happens here is rack0 goes down and it sends out beacons while booting on eobc(your step 5) finds that there is a responding DSC (Rack1) gets the sw from rack 1 and reboots and joins the cluster as nonDSC.

Have you had a chance to review the nv edge deployment guide? It has these details.

Eddie.

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