ACI trunk ports - native vlan

[cowser1979]

Hello -

can someone explain (in detail) or point to documentation that explains, if/how the dot1q native vlan works on ACI trunk ports?  Currently, I only use statically mapped ports in my environment (no L2 outs) and I keep seeing the following errors on my downstream UCS FI trunk links:

Critical
Last Transition:
2015-07-08T06:31:06.451+00:00
Lifecycle:
Raised
Affected Object:

topology/pod-1/node-105/sys/lldp/inst/if-[eth1/30]/adj-1
Description:
LLDP neighbor is bridge and its port vlan 1 mismatches with the local port vlan Unspecified

there is no "untagged" vlan tag set on any ports, so not sure where/how there is a native vlan in ACI?

thanks

[Robert Burns]

Cowser,

ACI doesn't have any default native VLANs on Leaf interfaces, as a traditional network switch would. 

Because your downstream switch is advertising a native VLAN (likely VLAN 1) via LLDP, ACI sees this as a mis-match and raises the alert.

In the next major release, we've silenced this alert unless BPDU's are seen.  This is tracked as CSCuq81938.

There are two workarounds if this alarm really bothers you. 

First you could create a dummy EPG and statically map it to the relevant ports and set a dummy native VLAN (matching the other switch). (EPG > Static Path Binding).

Alternately, you can disable the native VLAN advertisement on the downstream which with "no vlan dot1q tag native" or equivalent depending on the platform. 

Regards,

Robert

[cowser1979]

Perfect, thanks for your help! 

so does that also mean that ACI would ignore/discard any untagged frames on that port (traffic sent on the native vlan)?  Correct me if Im wrong, but there are instances where there could be untagged traffic sent along, as untagged/on the native vlan?

thanks

[Robert Burns]

Unless there is a Interface Policy associated to this interface making use of that untagged VLAN, untagged traffic will be discarded.

Robert

[Mark Potter]

Thank you Robert.

Just what I was looking for.

Mark.