Native VLAN on NX-OS 9.2.2

[martin.chauchet]

Hello there!

I am quite new to the Nexus switch and OS world, but am familiar to the Catalyst and IOS family.

However, during the configuration of the Nexus 3024X we ordered for a mobile virtualization environment I have some trouble with the native VLAN configuration of my trunk ports. The ESXi hosts (currently only one) attached to those trunk ports may not communicate with the gateway. If I change the port type to access mode, communication is possible. The VMKernel port is not using VLAN tags, so using the native VLAN he should be able to talk to his gateway sitting on the same VLAN.

Here's a config example of what the switchports look like:

interface Ethernet1/9
description "esxi-host-1 vmnic2"
switchport mode trunk
switchport trunk native vlan 136
switchport trunk allowed vlan 135,2000-4000

interface Ethernet1/10
description "esxi-host-1 vmnic3"
switchport mode trunk
switchport trunk native vlan 136
switchport trunk allowed vlan 135,2000-4000

interface Ethernet1/11
description "esxi-host-2 vmnic2"
switchport mode trunk
switchport trunk native vlan 136
switchport trunk allowed vlan 135,2000-4000

interface Ethernet1/12
description "esxi-host-2 vmnic3"
switchport mode trunk
switchport trunk native vlan 136
switchport trunk allowed vlan 135,2000-4000

VLAN 136 is the management VLAN, including the ESXi management interface, iDRACs, UPS management and infrastructure services (such as DHCP, DNS, ...).

Does anyone have an idea where my mistake is? Any help will be appreciated!

Thank you in advance and best regards,

Martin

[Remi Astruc]

Hi Martin,

That sounds too easy, but e1/10 and 11 miss the statement:

switchport mode trunk

It should work after that.

*EDIT*: The user corrected his initial message with that statement

Remi Astruc

[Deepak Kumar]

Hi,

I think you are missing something :

interface Ethernet1/10
description "esxi-host-1 vmnic3"
switchport trunk native vlan 136
switchport mode trunk
switchport trunk allowed vlan 135,2000-4000

interface Ethernet1/11
description "esxi-host-2 vmnic2"
switchport trunk native vlan 136
switchport mode trunk
switchport trunk allowed vlan 135,2000-4000

 https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/layer2/b_Cisco_Nexus_5000_Series_NX-OS_/Cisco_Nexus_5000_Series_NX-OS__chapter6.html#con_1206629

Regards,

Deepak Kumar

[martin.chauchet]

Hi, sorry, might have deleted the "switchport mode trunk" statement while stripping out confidential information.

It is included in the original running config on the switch. I'll update my original post.

[Remi Astruc]

Hi,

Then ensure you have not the global command vlan dot1Q tag native configured somewhere:

# show vlan dot1q tag native

vlan dot1q native tag is disabled

Remi Astruc

[martin.chauchet]

Hi,

thank you, I have checked that. Issuing that command shows that "dot1q native tag" is disabled as desired.

My next step will be to use a regular laptop on these ports instead of the ESXi host. Will update this thread with the results.

Best regards,

Martin

[Jon Marshall · Accepted solution]

Not used Nexus switches but as I understand it your ESXi host is in the native vlan but you are not allowing the native vlan on the trunk port. 

Jon

[martin.chauchet]

Thank you very much, that was just the hint I needed.

I thought I had configured the interfaces like this before, but somehow it didn't work.

Took a deep breath and slowly reconfigured the interfaces, and - tada - now it is working.

It was not totally clear to me that I would need to explicitly allow the native VLAN on the trunk port.

Here's my final configuration:

interface Ethernet1/9
description "esxi-host vmnic2"
switchport mode trunk
switchport trunk native vlan 136
switchport trunk allowed vlan 135-136,2000-4000

Best wishes!

Martin