UCS Native VLAN and ESXi mangement network

[Big Vern]

Hi,

We have a UCS Chassis with b200 M4s, connected to 6248 Fi's.

We have ESXi 5.5 Installed, during install we specified a management VLAN on 999 (so in the KVM service console page for ESXi on the ESXi host you can see 'VLAN (optional) 999', this VLAN ID also appears on vSwitch 0 for in the esxi gui client. 

We have created the vNIC temapltes and assigned multiple VLANs inlcuding the ESXi management (vmkernel) VLAN of 999.

I have been told by a cisco pre sales guy that the best practice is to have the ESXi untagged and tag it at the UCS level. But when we untag (so remove the 999 VLAN ID) at the ESXi we loose IP connectivity.

If we leave it untagged the only way to regain IP connectivity is to set the 999 Management VLAN as the 'native VLAN' on the UCS

What is the reason for this? 

What do other people do and what is best practice?

Do we tag at the ESXi level and set the native valn to something else on the UCS vNIC template

Or do we untag at ESXi level and set the native vlan to the 999 Management VLAN on UCS vNIC template.

I understand for windows bare metal we would just setup a single native vlan.

any explanations gratefully accepted, I want to try and understand why as well as get best practice.

[Walter Dey]

https://keepingitclassless.net/2012/05/management-vlan-best-practices-in-esxi-and-cisco-ucs/

Has a complete explanantion.

After you install ESXi, and then configure management IP in the GUI, you essentially have 2 options:

1) you specify a optional Vlan, which means your traffic is tagged, and therefore no need to be native

2) you don't specify a optional Vlan, which means ESXi expects untagged frames, therefore the management Vlan has to be native

[Big Vern]

Manhy thanks I saw that, but wasn't convinced as he corrected himself in the article and I was also looking for some definative BP from cisco on which way to go.