Monday, January 21, 2013

VMware View with Microsoft NLB

While implementing VMware View 5.1 we came across issue with Microsoft NLB .

Current Setup

We have 2 View Connection Servers for our Bangalore Setup.
We are using Microsoft NLB to load balance between the two in Unicast Mode

Issue

Intermittent disconnections when connecting to Virtual Desktops

Root Cause

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).

Work around

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

VMware Recommendation

Setup NLB in Multicast Mode
In Multicast mode servers can communicate with each other via the original addresses of their NLB network cards.

References

  • 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)

2 comments:

  1. Hi Sir,
    now,I have problem with MS NLB Exchange CAS,i implementation with vmware ESXi5.1. and 2 CAS on the same host ESXi. I Configured NLB on the CAS with mode : Multicas. NLB still converged but it cann't load balance when the outlook connect to VIP . Only host handle the session.

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  2. So you are saying that you have the NLB configured in Multicast mode and still it is not load balancing. Am i right ?

    ReplyDelete