ESXi LAG to Stacked Cisco SG switches Assign all VLANs or not?

[NickDaGeek]

Hi everyone, 

I have inherited an existing 2 host setup and have been troubleshooting the network performance since I arrived. I have noticed that not all the VLANs in use by the VMs have been assigned to the LAG group connecting the ESXi hosts to the SG Stacked switches. The question I have is this:  is that a problem or not?

I am reading that ESXi vSwitches are VLAN agnostic i.e. they don't handle them internally or tag the packets. i.e. it only matters to the Cisco Switch when routing packets from the switch to the ESXi host. In which case I am confused. The VLAN used by our wired and wireless clients is not assigned to the LAG group that feeds the hosts and yet it seems to work most of the time. It is more a throughput performance issue that I am seeing with very intermittent reports of drops.

I am a little out of my depth here, I know how to set up the LAGs and vSwitches as per the existing ones and copying the current setup works when I added the third host not so long ago. What I don't know is if this is optimal or not. I have found various internal network configuration issues on the virtual servers and inside the ESXi configuration that were causing problems so I am a bit suspicious. 

Any pointers to further information or suggestions for network configurations like this gratefully recieved.

[KJK99]

"the VLANs in use by the VMs"

How have you determined that?

"I have noticed that not all the VLANs in use by the VMs have been assigned to the LAG group connecting the ESXi hosts to the SG Stacked switches. The question I have is this:  is that a problem or not?"

It depends on the physical switch, VM applications and ESXi Port Groups. In ESXi, Port Groups are where you can set VLAN IDs. Port Groups are mapped to VM application NICs. If VLAN ID is set to anything from 1 to 4094, the ESXi host will tag outgoing frames with the given VLAN ID. If VLAN ID is set to 0, the ESXi host will send untagged frames so tagging for it needs to be done on the switch. If VLAN ID is set to 4095, it means that VM applications themselves do tagging and the ESXi host will let those tagged frames go through. 

https://knowledge.broadcom.com/external/article/311764/vlan-configuration-on-virtual-switches-p.html