VMware have recommended for quite some time that we stick to multicast when configuring NLB (MS’s Network Load Balancing) where possible:
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.
If you need to use unicast, then to prevent port flooding you should change the Port Group’s “Notify Switches” policy to No – the default being Yes.
Windows 2008 R2 Failover Clustering
According to this white paper from Microsoft,
Multicast functionality has been discontinued in Windows Server 2008 failover clustering, and cluster communications now use User Datagram Protocol (UDP) unicast.
So Microsoft clustering gurus, does this mean for Window 2008 R2 Failover Clusters we should also change the “Notify Switches” policy off? Is the recommended setting for MS NLB clustering now applicable to MS’s latest version of MSCS?