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New Member

Nexus 5k Failover

I'm working on a customer's network and have two 5k's setup for
redundancy via HSRP. We are having an issue testing the VoIP vlan (vlan 110) failover.
When we test failover on VoIP phones (Siemens VoIP system) we go through the following
1. On 5k-1, I shut down the Layer 3 SVI for vlan 110. It fails over properly to 5k-2 via
HSRP(one to two missed pings), however, phones cannot dial out. They keep their IP, but we
cannot ping it. 
2. When I also shut down the physical port (int e1/31) on 5k-1 that connects the layer 2
switch upon which phones reside, then I can ping the phones and phones dial out. Were
essentially going through 5k-2 now.
3. If we bring up the physical port again on 5k-1, we lose phones again...until we also
bring up vlan 110 SVI again.

Since I can ping the gateway for that vlan via HSRP, shouldn't phones be able to work if
interface e1/31 is up and SVI vlan 110 on 5k-1 is down?

Everything is working fine now, however if 5k-1 were to go down, we'd have issues until he
could also shut down the physical port.

I've been told that this is not a valid test of the 5k's and that to properly test I should completely shut down the primary 5k.

Is this not a valid test for the 5k's?
Is this what is called a "black-hole"?

Anyone have a link on VPC Peer's and them having to be symmetric?

Thank you,
Bobby Grewal
Cisco Employee

Nexus 5k Failover

Hi Bobby,

Please could you attach the toplogy diagram and explain it a bit more. You have VPC configured between the 5K's? Which is the access layer switch that is conneceted to 5K's?

Please could you paste the configs as well?


-amit singh

New Member

Re: Nexus 5k Failover


Please see attached. Thanks in advance.

Bobby Grewal

On Fri, Nov 18, 2011 at 5:05 PM, asingh2 <

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