vmware and NLB (unicast vs multicast)

Fri, 10 Dec 2010 00:00:00 +1300

Thought I’d get a bit of clarification around this one. VMWare states –

VMware recommends that you use multicast mode, because unicast mode forces the physical switches on the LAN to broadcast all Network Load Balancing traffic to every machine on the LAN.

There are some issues which come to the surface if you are using unicast. Where possible we should always try to use a Multicast NLB as Unicast can cause some complications around vSwitch configurations. (requirement to change switch notifications to “No” – and seemingly break port id teaming). Detail below;

Nlb on sigtar.com

vmware and NLB (unicast vs multicast)