MS Network Load Balancer and VMWare

I have a client with two VMW hosts with local disks (so think no HA). Each host has a front end application server on them and both connect to the same back end box. The goal is to load balance the two front end servers.

I added the NLB feature to both MS 2008r2 VMs. When I enable it on VM1 and add VM1 to the cluster (thus creating the VIP and adding it to the VM1), VM1 loses all network connectivity. It cannot even ping the gateway at this point.

I figured/assumed something may be blocking it within the vswitch. There is NO port security on the physical switch.

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Schuyler DorseyAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
You must use Multicast Mode.

and what the articles do not mention is Static ARP Entries on your switches!

and make sure you also allocate Static ARP Entries to ALL your physical switch ports, against mac address and IP Address for your cluster.

e.g. if using Cisco see example from our switches

arp 03bf.c0a8.0107 ARPA
arp 03bf.ac10.f104 ARPA
arp 03bf.c0a8.0100 ARPA
arp 03bf.ac10.f10b ARPA
arp 03bf.ac10.f007 ARPA
arp 03bf.ac10.f108 ARPA
arp 03bf.ac10.f107 ARPA
arp 03bf.ac10.f005 ARPA
arp 03bf.c0a8.0100 ARPA

the above IP Addresses are the IP Address of the Cluster IP, and MAC Address of the Multicast Address
Schuyler DorseyAuthor Commented:
Thanks for the info all!

I opted to configure it for unicast mode because I didn't really want to configure static arp entries in my switches.

I had 2 vnics for each VM and dedicated one on each as the nlb nic. Then on the vswitch in each host, you have to ACCEPT forged transmits.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Multicast is the recommended option for VMware vSphere.
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