Topic Last Modified: 2010-11-16
In Microsoft Lync Server 2010 communications software, you define sites on your network that contain Lync Server 2010 components. A site is a set of computers that are well-connected by a high-speed, low-latency network, such as a single local area network (LAN) or two networks connected by a high-speed fiber optic network. Note that Lync Server sites are a separate concept from Active Directory Domain Services (AD DS) sites and Microsoft Exchange Server sites. Your Lync Server 2010 sites do not have to correspond to your Active Directory sites.
Each site is either a central site, which contains at least one Front End pool or Standard Edition server, or a branch site. Each branch site is associated with exactly one central site, and the users at the branch site get most of their Lync Server functionality from the servers at the associated central site.
Each branch site contains one of the following:
A Survivable Branch Appliance, which is a new device introduced in Lync Server 2010. The Survivable Branch Appliance is an industry-standard blade server with a Microsoft Lync Server 2010 Registrar and Mediation Server running on Windows Server 2008 R2. The Survivable Branch Appliance also contains a PSTN gateway. The Survivable Branch Appliance is designed for branch sites with between 25 and 1000 users.
A Survivable Branch Server, which is another new device introduced in Lync Server 2010. The Survivable Branch Server is a server running Windows Server that meets specified hardware requirements, and that has Lync Server 2010 Registrar and Mediation Server software installed on it. It must connect to either a PSTN gateway or a SIP trunk to a telephone service provider. The Survivable Branch Server is designed for branch sites with between 1000 and 5000 users.
A PSTN gateway and, optionally, a Mediation Server.
A branch office with a resilient wide area network (WAN) link to a central site can use the third option, a PSTN gateway and optionally a Mediation Server. Branch office sites with less-resilient links should use a Survivable Branch Appliance or Survivable Branch Server, which provide resiliency in times of wide-area network failures. For example, in a site with a Survivable Branch Appliance or Survivable Branch Server deployed, users can still make and receive Enterprise Voice calls if the WAN connecting the branch site to the central site is down. For details about the Survivable Branch Appliance, Survivable Branch Server, and resiliency, see Planning for Enterprise Voice Resiliency in the Planning documentation.
Your deployment must include at least one central site, and can include zero to many branch sites. Each branch site is affiliated with one central site. The central site provides the Lync Server 2010 services to the branch site that are not located locally at the branch site, such as presence and conferencing.