SharePoint Knowledge Base

Jun 14
SharePoint High Availability via Load Balancing

As SharePoint consultants we often hear "make my mission critical SharePoint highly available". But how to do that simply without expensive F5 devices? There are a variety of ways to do that but many are expensive and require special hardware. This post explains an inexpensive method that achieved the goal.


This post reviews issues you may encounter in specifically in VMWare environments. While Unicast mode does work Unicast mode is not supported in VMWare environments without doing some configuration that breaks vMotion and has some other problems.

Multicast mode is the way to go but you must add static ARP resolution for some network devices (routers/switches). More details about that HERE (link).

NLB Multicast Mode – Static ARP Resolution

  • Since NLB packets are unconventional, meaning the IP address is Unicast while the MAC address of it is Multicast, switches and routers drop NLB packets.
  • NLB Multicast Packets get dropped by routers and switches, causing the ARP tables of switches to not get populated with cluster IP and MAC address.
  • Manual ARP Resolution of NLB cluster address is required on physical switch and router interfaces
  • Cluster IP and MAC static resolution is set on each switch port that connects to ESX/ESXi host
  • Virtual Switch NIC Team Policy > Notify Switches is set to Yes.
  • If CDP (Cisco Discovery Protocol) is enabled on ESX/ESXi and the Cisco Switch - you can determine proper switch ports connecting to ESX/ESXi via the vSphere/Virtual Infrastructure Client.




More resources for NLB in VMWare environments


We love helping with SharePoint and it's all we do so feel free to contact us!

Mention this post and we'll send you a white paper on all of the ways we can help you with optimizing your SharePoint!


There are no comments for this post.