While implementing VMware View 5.1 we came across issue with Microsoft NLB .
We have 2 View Connection Servers for our Bangalore Setup.
We are using Microsoft NLB to load balance between the two in Unicast Mode
Intermittent disconnections when connecting to Virtual Desktops
Post Investigation with help of VMware we have realized that it is the issue related to NLB
The Microsoft NLB cluster masks the cluster's MAC address for all outgoing traffic to prevent the switch from learning the MAC address.
As NLB is configured in Unicast Mode we need to make sure about following
- All members of the NLB cluster must be connected to a single portgroup on the virtual switch.
- All members of the NLB cluster must be running on the same ESXi/ESX host.
- vMotion for unicast NLB virtual machines is not supported (unless you want to migrate all NLB members to a different ESXi/ESX host).
Setup Rule on the VMware to ensure they are on the same hosts all the time. It is called Affinity Rules
Dilemma with workaround is if one of the physical server fails both the View Connection Servers will go down at the same time until it is restarted by VMware Cluster on the other hosts
Setup NLB in Multicast Mode
In Multicast mode servers can communicate with each other via the original addresses of their NLB network cards.
- http://kb.vmware.com/kb/1556 (Microsoft NLB not working properly in Unicast Mode)
- http://kb.vmware.com/kb/1006558 (Sample Configuration - Network Load Balancing (NLB) Multicast Mode Configuration)
- http://www.borgcube.com/blogs/2012/02/vshpere-multicast-support/ (3rd Party Link, with Valid information)