KEMP LoadMaster: Skype For Business Server 2015 load balancing configuration

The purpose of this post is to cover the steps I used when configuring the free version of the popular KEMP LoadMaster to load balance a Skype for Business 2015 Server deployment in my lab. The free version has some limitations obviously but none that affect me using it in my lab, give it a try yourself by downloading from here http://freeloadbalancer.com/

My lab consists of two servers configured in an enterprise edition front-end pool and I’m using the LoadMaster as my hardware load balancer for the web services used by Skype for Business. To start with I am only using the Conferencing role internally with no Edge deployment so this will be a simple setup. Once I’ve done this I will expand and there will be follow up posts to cover those.

Disclaimer: the steps below are how I configured the Kemp LoadMaster in my lab environment and may not necessarily be exactly the same in your environment so I would always encourage you to read the product documentation from Microsoft and KEMP to ensure you understand what your doing and if your not sure test in a lab first.

General KEMP LoadMaster settings

These settings are general settings within the LoadMaster configuration which are recommended to be set when using it with a Skype for Business 2015 deployment.

1. Disable SNAT Globally

By default, global Server Network Address Translation (SNAT) is enabled in the LoadMaster settings. KEMP recommends disabling SNAT globally when using the LoadMaster with a Skype for Business 2015 environment. To disable SNAT globally, follow the steps below:

  1. In the main menu, select System Configuration.
  2. Select Miscellaneous Options.
  3. Select Network Options.
  4. Remove the check from the Enable Server NAT checkbox

KEMP LoadMaster Disable SNAT

2. Change Drop Connections Settings

The LoadMaster must be configured to drop connections on Real Server Failure in order to have fast failover for clients to another Real Server.

  1. To configure dropping connections, click System Configuration.
  2. Click Miscellaneous Options.
  3. Click L7 Configuration.
  4. Select the Drop Connections on RS failure checkbox.

KEMP LoadMaster Drop Connections On RS Failure

3. Increase the Connection Timeout

The LoadMaster Connection Timeout must be set to one day. The reason why this value can be set so high is because the LoadMaster monitors client connection to Real Servers and if a server fails then the LoadMaster can drop the associated client connections to that Real Server. Clients are disconnected from the LoadMaster and then reconnected to the LoadMaster to connect to another Real Server. One day is the maximum value for this setting and it must be used in conjunction with the Drop
Connections on RS failure option.

  1. To configure the Connection Timeout, click System Configuration.
  2. Click Miscellaneous Options.
  3. Click L7 Configuration.
  4. Enter 86400 (1 day) in the L7 Connection Drain Time (secs) field and click Set Time.

KEMP LoadMaster Increase Connection Timeout

Front End Pool Configuration

For this one I used one of the templates provided by KEMP and I would advise you to do the same when configuring load balancing for any of the products they provide templates for, you can view and download them from here https://kemptechnologies.com/uk/loadmaster-documentation/

I used the Front End HLB Only template which contains four virtual services pre-configured:

  • Skype Front End HLB Only – WebSvc HTTP
  • Skype Front EndHLB Only – WebSvc HTTPS
  • Skype Front End HLB Only – SIP
  • Skype Front End HLB Only – DCOM

To add the Virtual Services for Skype Front End with the template, follow the steps below:

  1. Click the Add New button.
  2. Enter a Virtual Address.
  3. Select SkypeFront EndHLB Only in theUse Template drop-down list.
  4. Click Add This Virtual Service.

KEMP LoadMaster Add new virtual service

Once the four new services have been added it will take you into the configuration page for the first of those services, on this page you need to scroll down to the Real Servers section and click on Add New … to add each of your Front End pool server

KEMP LoadMaster add real server

Once you have added in each of your real servers click Back until you get back to the Virtual Services screen and then modify each of the remaining three services and add the real servers into there too. Once done you should get a nice green dot and Up in the status column like below.

KEMP LoadMaster Virtual Services

DNS

Once you have configured your load balancer you should then update your Skype for Business DNS records to point to the VIP you have used as part of the configuration of your load balancer.

Testing

At this point you should be able to sign into the Skype for Business client providing you have enabled a user for Skype for Business.

If you are struggling to get a user signed in then I recommend you start by checking out the steps in this article https://support.office.com/en-us/article/Turn-on-error-logs-in-Skype-for-Business-Lync-eaf6602b-95e0-4c27-869f-36017475806c