Link up/up on vIOS even after peer link is down

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Aninda
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Joined: Mon Mar 04, 2019 4:45 pm

Link up/up on vIOS even after peer link is down

Post by Aninda » Mon Apr 22, 2019 6:40 am

Pretty simple question and I think this is how vIOS is built (I'm assuming) - I have two routers connected back to back via gig0/0. If I shutdown one side, the other router's gig0/0 stays up/up. I would expect it to go down but it doesn't. I've seen this before with Cumulus VX as well and this happens because there is a small "switch" that emulates the link and it is not really a direct connection to the peer.

Does anyone know if this is the case with vIOS as well? Anyway around this if I want to test protocol convergence scenarios with link down events?

Cheers!

Uldis (UD)
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Re: Link up/up on vIOS even after peer link is down

Post by Uldis (UD) » Mon Apr 22, 2019 3:39 pm

you forgot that virtual nodes have not option of L1 !!
so it always will be up/up or down/down
no option up/operational down

Simply such not exist on any virtual node

Aninda
Posts: 9
Joined: Mon Mar 04, 2019 4:45 pm

Re: Link up/up on vIOS even after peer link is down

Post by Aninda » Tue Apr 23, 2019 6:01 am

Thanks for the reply, Uldis. I understand up/down is not a possibility. But when I admin shut one side, the peer link should at least go into down/down state? With 156-1T vIOS image (and probably older ones as well), the peer link will be up/up even when the other side is admin down.

Uldis (UD)
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Re: Link up/up on vIOS even after peer link is down

Post by Uldis (UD) » Tue Apr 23, 2019 6:45 am

No,
thats exactly what happens on virtual nodes. as ythey don't have Layer1, if you will shutdown Node A, node B does not receive any L2 signal to be in down.

so if one end is dow/down, other ened can stay on up/up.
Such isvirtual nodes behave and we must accept it.
If you want somehow simulate interface state, then best is shut interface which is involved in configuration like IP SLA...

We have in roadmap, then probably qemu nodes will be ebale to get link state up/down

Aninda
Posts: 9
Joined: Mon Mar 04, 2019 4:45 pm

Re: Link up/up on vIOS even after peer link is down

Post by Aninda » Thu Apr 25, 2019 1:38 am

Thanks for clarifying, Uldis! :)

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