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Demystifying Migrations Strategies from Lync to Skype for Business

I was tweeted the other day from a follower about how to migrate to Skype for Business from Lync 2013 and further searching social media it seems that us Skype for Business consultants / experts or enthusiasts have blogged with all excitement about the new in place upgrade method and somehow, other migration strategies have perhaps been lost in all the hype. Therefore, I thought I would write a quick post on the other migration strategies you can adopt and not talk about in place upgrade at all from this point on.

If you are considering migrating from your existing Lync deployment to Skype for Business then you must consider the precursor environmental requirements before committing yourself.

It should be with no surprise that Microsoft have indeed allowed N -2 native compatibility with Skype for Business. This means you can perform a migration to Skype for Business if you are currently running  Lync 2010 or Lync 2013 within your domain. Native means, that you must not have a mixture of OCS 2007 servers in your OCS 2007 R2 topology, no OCS 2007 R2 servers in your Lync 2010 topology and no Lync 2010 servers in your Lync 2013 topology. All servers in your topology must be running the same version of Lync throughout.

If you have a mixed topology of legacy OCS or Lync servers, then you must migrate these servers to the required version that your topology supports. How do you do this? Traditionally, OCS and Lync migrations have been what we call Side-by-Side migrations. By this we mean you must stand up new physical or virtual hardware alongside your current deployment, add this to your topology as a Lync 2010 or 2013 Lync role and install the service using the deployment wizard. Once this server is up and running in your topology, you migrate the services over from your legacy server. Once complete, you must remove the legacy server from the topology and remove all components from that legacy server

UPDATE: If you have OCS 2007 R2, you have two upgrade options available. Option 1 is preferred, and is to upgrade to Lync 2013 and then perform an in-place upgrade to Skype for Business. Option 2, is to install a new Skype for Business pool and perform a hard cut over between OCS and Skype for Business. This option is less preferred as it involves users being disabled on OCS and enabled on Skype for Business. The effects of this are that users lose their contact groups, relationships, and future / re-occurring meetings.

Once you have done that and have your Lync topology all native in 2010 or 2013, you can now consider planning for migration to Skype for Business.

Migrating from Lync 2010 or 2013 native topologies to Skype for Business, follows the same side-by-side migration strategy you performed in decommissioning your legacy servers.

Some Skype for Business caveats and requirements:

  • You must* use new physical or virtual hardware that meets the Microsoft supported hardware specification for Skype for Business Server 2015. (reference: https://technet.microsoft.com/en-gb/library/dn951388.aspx)
  • I recommend that you use at least Microsoft Windows Server 2012 for your Skype for Business Servers in order to take advantage of the latest Windows Fabric v3 for high availability. Server 2008 R2 is still supported, but not recommended and will surely be deprecated in future releases.
  • You must be use SQL 2012 SP2 CU2 or newer for your central management store database but SQL 2014 is recommended and preferred for AlwaysOn. Note that while you can still use SQL mirroring, this is now deprecated and you should as a minimum use SQL clustering. For that you will need SQL Enterprise Edition.
  • Important point, do not ignore! You can install the central management database to the same SQL cluster you have for your legacy Lync, as long as it is a separate instance. If you install Skype for Business CMS to the same instance you have Lync CMS installed on, you will overwrite the Lync databases with Skype for Business ones and break your deployment.
  • If you have Lync 2010, installing Skype for Business will require Active Directory Schema updates. If you have Lync 2013, there are no schema updates
  • Skype for Business does not support single-labelled domains. If you have a domain called domain.local, you will be fine. If you have a domain called just local, Skype for Business will not install. (nothing new)
  • Skype for Business does not support renaming of domains either. Therefore once installed you cannot rename your internal Active Directory Domain – Ever! (nothing new)
  • And, of course, all servers must be fully updated with the latest Windows Update patches.

So now that you have your new hardware setup, you can now proceed to perform your side-by-side migration, high level steps are:

  1. Install Skype for Business Front End and Edge Pools with other optional roles such as persistent chat, CQD etc
  2. Publish External URLs for the new topology
  3. Obtain trusted certificates
  4. Migrate users and user’s data from legacy pool to Skype for Business Pool
  5. Migrate conference data to Skype for Business
  6. Migrate CMS to Skype for Business
  7. Decommission legacy Lync pool and hardware
  8. Enjoy Skype for Business!


* = Can always do in place upgrade if you have Lync 2013 – Highly recommended (sorry had to mention it again)

Looking towards the future, it is pretty accurate to assume that this will be the last side-by-side migration strategy in the Skype for Business evolution. Microsoft have made it pretty clear they favour IPU over the traditional methods, so rather than a new full Skype for Business Server release, we will see small, continuous improvements and features through cumulative updates and hotfixes.


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  2. N -1 =Lync 2013
    N -2 = Lync 2010
    Surely to migrate from OCS 2007 R2 to Skype4B would be N -3 ? And the diagram following your statement obviously shows no reference to OCS 2007R2

    Struggling to work out how to get from OCS2007 R2 to S4B with a customer who is not willing to go down the ‘interim Lync 2013’ route.
    Any advice most welcome

    • Thanks for bringing this to my attention. Having re-read the post I realise i was talking crap about OCS. Think I must have misread somewhere. The option you have is either swing to Lync 2013 then in place upgrade, or stand up a new SfB topology and perform a hard switch over ( no migration / topology merge). This method would mean user disabling on OCS then enabling on Sfb, but they will lose their contact groups, future meetings etc.

      • Thanks Mark, I appreciate the reply. Would the move-sclegacyuser type commands not work at all? It literally would be a case of creating new CS users, and only enabling them once the OCS User object is disabled? Thanks in advance

      • Hi
        No the legacy command would not work, because you can’t merge the topologies. It would as if OCS was removed and SfB installed in its place.

  3. I appreciate your feedback and am going to let it rest after this post to go off and start lab-ing this scenario. My lingering doubts are based on the following Technet posts
    Which states “Migrates one or more user accounts from Microsoft Office Communications Server 2007 R2 to Skype for Business Server 2015”
    and https://technet.microsoft.com/en-us/library/gg425870.aspx
    Which states “The Merge-CsLegacyTopology cmdlet enables you to migrate topology information from Microsoft Office Communications Server 2007 R2 or Microsoft Office Communications Server 2007 to Skype for Business Server 2015”
    The second link doesn’t worry me too much – I think it merges certain aspects of a topology (dial-plans, policies, etc) rather than merging the entire topology. But the first link seems to indicate that you CAN move a user between OCS R2 and S4B. So my lab work will be to see how seamless this is, and what exactly is moved with the user object, as I doubt this particular customer would want to lose many thousands of contact / buddy lists.

  4. Does anyone know of documentation (or blogs) regarding the intricacies of side-by-side migrations? We’re in the process of Lync2010 –> S4B2015 side-by-side and have some questions we can’t find answers for. For example, “Do the S4B edges need to communicate with the Lync2010 front ends for any reason, such as to receive CMS replication?”

    • Hi

      It is recommended that all edge servers can see all Lync / SfB front ends. Although, you would mark the SfB FE pool as the next hop for the SfB Edges.


      • Thanks for the quick response Mark. (And for all your information in general!) We’re looking for a collection of Q&As to other undocumented requirements/recommendations like this. All of those “ah-ha” things that Microsoft fails to define.

  5. Does Anybody know an easy way to go from OCS R2 to O365 SfB online. I assume the only way is to disable OCS user and recreate SfB user?

  6. FV – as Mark says, that is the way to go. You could do it your way but the users would be starting with a clean client and would lose all buddy / contact lists.

    • Hi

      Its recommended to upgrade the edge to sfb too. In fact to do hybrid this is now a requirement. They will work as long as the next hop pool for them is still lync 2010/13 and pretty sure they will if sfb is the next hop. However, you may not get the full toolset from a hybrid setup.

      If L2013 then you can in place upgrade them with no firewall or dns changes necessary.


      • Thanks Mark for replying. Although it is recommended but still till the time we are upgrading edge to S4B edge, can we use our existing edge servers for successful login (On permises)?

  7. (Step 6 above) Are there any gotcha’s when moving the CMS databases from Lync 2010 to SfB?

  8. Mark, I am migrating from LYNC 2010 to SfB 2015, I have done this a few times before, but this setup the customer wants to use SQL 2016.

    LYNC 2010 one Enterprise pool with SQL 2008
    SfB 2015 one Enterprise pool SQL 2016

    Do you know if there will be any issues with the SQL 2016 under normal replication with the SQL 2008 or any issues when I come to move the CMS, I can’t seem to find a definitive answer on this.


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