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Are your AX 2012 AOS servers load balancing?

If you’re familiar with how AX 2009 load balancing works, you might get caught off guard when you find out that standard AX 2012 AOS clustering only load balances some of the communication to your AOS servers. The rest may only be going to a single server without you knowing about it. If that’s the case, you could find yourself causing a major system outage when you thought you were just doing some routine maintenance on a fully redundant part of your AX environment.

With previous versions of AX, the only way to communicate with an AOS instances is via Remote Procedure Calls (RPCs) which are hosted on tcp port 2712 by default. AX 2012 added a second way for clients to communicate directly with an AOS instance when it introduced Windows Communication Foundation (WCF) services into the mix. An AOS instance listens for WCF traffic on tcp ports 8101 (WSDL) and 8201 (services endpoint). Inbound services connections are not load balanced based on the AOS cluster settings in the application (System administration > Setup > System > Cluster configuration). This is for RPC communication only. If you’re wondering when services are used instead of RPC calls, here’s a quick reference for you.



AX client

RPC and WCF services

Enterprise Portal

RPC and WCF services

IIS (Web services)

WCF services

IIS (Help server)

WCF services

Office Add-ins (Word, Excel)

WCF services

Report Server

WCF services


If you want to load balance AX services, you’ll have to look outside the AX client to configure it because there is no AX user interface for that setup. You can load balance services on an AOS using the Network Load Balancing (NLB) Windows component or a hardware load balancer the same way you would for a web server farm.


Load Balancing Solution


AOS clustering

WCF services

Network Load Balancing (NLB)


Check out the following MSDN article for details on how to configure network load balancing for AX 2012 services.

Comments (2)
  1. What about the business connector? Is this done like the ax client?

  2. Donna says:

    Thanks for garnering all those information.

    I am doing some research about AX 2012 AOS servers load balancing.



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