Unified communication is becoming business critical application for all size of organizations. Enterprises are adopting Lync beyond as an instant communication application and finding it as a replacement of traditional telephony solution. The deployment can be done for various sizes and different modalities.

This reference architecture for Lync provides high level design and implementation scenario for 5000 users with all workloads while considering deployment best practices. These workloads include Instance Messaging, Presence, Audio-Video-Web Conferencing, Enterprise Voice and group/persistent chat to end users with the ability to manage all communications from a single application interface.

This solution provides real time communication solution for organizations with 5,000 users built on a central site with one or more branch office locations. This integrated solution leverages wide range of Dell product portfolio, including Dell servers, wired/wireless networking and client devices along with third party gateways. The solution is designed to leverage server virtualization offered by Microsoft Windows Server 2012 R2 Hyper-V. Leveraging this configuration to run Microsoft Lync provides benefits that include consolidation and availability. Entire Lync infrastructure is deployed in virtual machines, reducing physical server count and making the above configuration a well-suited design for organizations looking to save on hardware and maintenance costs.

As shown in Figure, the reference architecture depicts a customer scenario that consists of one central site and one or more branch sites with all workloads. For voice connectivity, the site may have either ISDN (T1/PRI) or SIP trunk connections provided by Internet Telephony Service Provide/Public Switched Telephone Network ITSP/PSTN providers. In this reference architecture Lync infrastructure connects to ITSP via SIP trunk using SBC.

The primary component of this architecture is a Lync Server 2013 Enterprise Edition server pool with collocated Mediation, Archiving and Monitoring Sever Components that serve different workloads. The Enterprise Edition pool consists of three Lync Enterprise Edition servers that are identically configured to provide communication services for a group of users. This pool also provides scalability as well as availability in the event of a server failure. In addition, a SQL Server mirror is deployed to host the Lync Back End, archiving, monitoring and Persistent Chat server databases.

Apart from the Lync primary Component, the architecture uses other components which includes Persistent Chat Server, Office Web App Server, Edge Server, Reverse Proxy, Load Balancer and Enterprise Voice connectivity using third party SBC. 

To verify the implementation, the Lync Stress and Performance Tool was run with instant messaging, audio conferencing, video conferencing using multi-view, application sharing, and other workloads. The performance of the Lync Front End was verified as being within recommended thresholds. A thorough investigation was conducted and the design frame work as mentioned in the Reference Architecture with respect to design principles, such as high availability, application performance and resource consolidation are verified.