Mac Address on th wrong VIF

[fr_fiocre]

Good morning every one,

A little post to discuss about a weird situation i found on two UCS domain i installed recently.

On each UCS domain I created a service profile with two VNIC (VNIC0 and VNIC1) each VNIC is configured to be connected to a different Fabric Interconnect. VNIC0 on FIA and VNIC1 on FIB. for each VNIC i created a MAC pool with the name of the Fabric Interconnect in to help for the troubleshooting.

On this Service Profile I installed a Cisco version ESXi 5.5 U2. when I boot my server everything is ok my VNI0 is pinned to Fabric A with VIF 787 and my VNI1 is pinned to Fabric B with VIF788.

After the boot of my ESXi i used the two VNIC on the management vSwitch for my vmKernel. i look at my vmKernel and it has the MAC address of the VNIC0. But when i go in CLI to my Fabric A and look in the MAC table, no MAC address present. When i go in CLI to my Fabric B I see the MAC Address of my vmKernel (so my VNIC0) connected to my VIF788 and i can join my ESXI!!

Its pretty weird so i tried to shut down my uplink port on the Fabric Interconnect B and go in my MAC Table to see what happen. Miracle i see my MAC address on Fabric A connected to my VIF 787.

My problem is that i cant explain this weird behavior and i wanted to understand why. Someone has an idea ?

Somme point to precise.

My UCS domain is in 2.2.3d firmware version.

I have no Fabric Failover configured on my VNICs.

I have this problem on both UCS domain.

My UCS domain is connected to a single Nexus 5548

Regards François

[Marcin Latosiewicz]

François, 

Going out on a limb here, but my guess is that particular VLANs are "observed" (in VMWare lingo) on only one of the vmnics. 

It will depend on your configuration obviously. 

M. 

[fr_fiocre]

I know that the vmKernel choose one of the MAC address too communicate but why the MAC address of the VNIC0 is found in the VIF of the VNIC1 ? for me when you configure the VNIC you choose the Fabric that VNIC will use so i suppose that it impossible to find the MAC address on the other Fabric

[fr_fiocre]

Ok i m a complete dumb guy ! at the installation the ESXi take the MAC address of the VNIC you use. in the MAC address Table it is not the VNIC MAC address that you see in the table but the MAC adress of the VMkernel. SO its normal that the MAC adress switch on the different Fabric Interconnect.