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When turning up a new port on a 2248 FEX, when the "private-vlan host association primary secondary" command is put on an interface BEFORE the server is cabled up, the interface goes into an "inactive" state and will not come up by bouncing the port. However, when the pvlan host association command is removed and re-added, the interface then comes up right away.

I haven't found any Cisco documentation describing the issue. Does anyone know if this is a bug? Has anyone else seen this issue?

I don't understand why the port must be cabled up before adding pvlan configuration.

  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 8 '17 at 14:42
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Whenever you're configuring a FEX switchport, you must ensure that the configuration is consistent across both parent switches (i.e. Nexus 5K). You can do this manually or use the config-sync feature to simplify your configuration.

For instance:

N5K-A(config)# interface e100/1/40
N5K-A(config-int)# switchport mode trunk

HOWEVER - you must repeat this configuration on the same port on the other control plane (other Nexus parent switch) because the configurations are not sync'd automatically by default.

N5K-B(config)# interface e100/1/40
N5K-B(config-int)# switchport mode trunk

If the configuration for a FEX switchport doesn't match on both parent switches, it will place it into "inactive" state as you describe.

| improve this answer | |
  • You're right but in this case it was for a private-vlan host. It wasn't for an interface going to a 5K. The interface didn't have any Port-channel or VPC config. It was just a host port to an end device where I saw the issue. – packetwrassler Jun 27 '13 at 17:52
  • This applies for downstream-facing ports. Let's assume you have the port-channel/vPC configuration to connect the FEX to the upstream Nexus switches correct. You'll have two control planes (one for each parent nexus switch) that need to be in sync for the host ports on the FEX to get out of that "inactive" state. So for that host-facing port on the FEX, you'll need to make sure the config is the same on both parent switches. – Mierdin Jun 27 '13 at 18:44

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