I understand VLANs to mainly serve two purposes. Security and traffic segregation to cut down on the amount of multicast traffic being sent to ports. I have a physically separate storage network for my ESXi hosts and SAN and currently have 2 VLANs set up but am questioning their benefit in my setup.
One VLAN is set up for iSCSI traffic and the other VLAN is set up for vMotion traffic.
The result of this, as I understand it, is that when we vMotion machines any multicast traffic will not be sent to the switch ports that are not part of that VLAN. Which in our set up means that ports connecting to our ESXi hosts will be excluded, but ports connected to our SAN will be included.
Because our ESXi hosts only have ISCSI connections coming out of them on this network and those go to our SAN, any extra load added to the SAN ports would affect our iSCSI traffic indirectly anyway. The only benefit I see is that the ESXi hosts themselves won't see any multicast traffic produced by a vMotion move.
I could see how in certain environments with a substantial amount of multicast traffic one would want to cut down as much extra overhead as possible. But in our environment of 5 physical hosts and 2-3 vMotion events per day, I don't believe there is enough extra traffic to appear on any radar much less cause any issues.
Any input is appreciated.
I know that the standard network design handbook would say to VLAN things without question as to whether it really provides any benefit, but these VLANs in place now have caused a few headaches and if they aren't producing a tangible benefit then I'd prefer we go without them.
Much like wearing a seatbelt on the public roads but not while moving cars around a car dealer's lot, I have a feeling that using VLANs is a good recommendation, but not actually needed unless the traffic is at a certain level.
Thanks in advance.