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How to configure vNICs on UCS Blade in Trunk mode

Level 1
Level 1


        We have 6120XP FI's and 2 Chassis with 8 blades each. There is ESXi 4.1 installed on all the blades and multiple customer VMs will be deployed on top of these ESXi hosts. All these customers will be having their separate VLANs configured on ESXi vSwitch Port Groups. This vSwitch is attached to vmnic0 (ie. vNIC1 in UCS) and all customers traffic (Customer VLAN range 100 to 2000) will be passing through this physical NIC. Now when I create a service profile/template I get two options either to connect vNIC1 to default/Native VLAN or manually creat 2000 VLANs and assign them manually to the vNIC1 which will be the worst way to do. So please let me know if there is any way I can set the vNIC to "Trunk" mode or any easier way to allow 2000 VLANs on vNIC1.

5 Replies 5

Cisco Employee
Cisco Employee

By default all UCS NIC interfaces run in trunk mode. Outside of using the CLI there currently is no other way to allow VLANs on an interface other than going through an individually selecting the VLAN for the interface or via a vNIC template which would have the same limitation. I had previously submitted a feature request for an "Allow All" configuration to the vNIC but that has yet to be prioritized by engineering. If you could do trunk allowed all, you would just need

to add the VLAN to the UCS VLAN database and each nic with that option would automatically have it available without modification.

There is also currently a limit of 1024 VLANs supported on the Fabric Interconnect:

I am surprised by this limitation in UCS which allows only 1024 VLANs on vNICs of the blade. I guess UCS engineering team should look into this issue and come up with some practical solution. Attaching thousands of VLANs to vNICs is simply imposible and in our case we have 4 such vNICs on each blade ie. atleast 4000 VLANs to be atached.
Being in cloud business we were planning to use VLANs for tenant isolation and with this limitation we are limited to max around 1000 customers per FI pair. To overcome this limitation we have found that UCS version 1.3 used to support trunk mode on the vNICs hence we are planning to downgrade from version 1.4.1 to version 1.3 but before doing that just wanted to confirm if there are any other issues / limitations related to version 1.3.


In version 1.3 we limited the amount of VLANs to 512 (502 user configurable).  This was doubled in 1.4 to 1024.  The limitation should continue to increase as development scales the software limitations.  I don't have an answer to the "why" the systems is scaled in this manner, but it applies to pretty much all Cisco software.

=> Can you please explain what you mean by "1.3 supports trunk mode on vNICs"?

In both version a vNIC can be configured as a trunk to allow multiple VLANs.  We don't have the concept of an access port in UCS.  Instead the configuration underneath will configure a trunk with your single VLAN as the native VLAN which is operationally the same.

1.4 Release Notes:

1.3 Releaes Notes:



Hi Robert,


This is the issue I was refering to...Does latest version(1.4.1) of UCS supports VTP? 

No.  In version 1.4(1j) VTP support is not yet present.  I haven't heard of any ETA yet either.  All VLANs must be defined within UCSM.

Manish may be able to respond with any roadmaps for VTP.



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