In preparation for the Exam 70-665: PRO: Microsoft Lync Server 2010, Administrator I found this article on TechNet useful: http://technet.microsoft.com/en-us/library/gg398552.aspx. It’ s about need to know basics and numbers when planning your Microsoft supported Lync design. Here is a summary with the numbers you must know before taking the Lync PRO Exam:

Site Types

• Central Site
  • Contains at least one Front End Pool or Standard Edition Server
  • Is mandatory in a Lync Server Deployment
• Branch Site
  • Is connected to exactly one Central Site and contain one of the following
  • A PSTN gateway and, optionally, a Mediation Server.
    • Designed for branch sites with between 1 and 25 users
  • Survivable Branch Appliance (SBA)
    • Is an industry-standard blade server with a Microsoft Lync Server 2010 Registrar and Mediation Server running on Windows Server 2008 R2
    • The SBA also contains a PSTN gateway
    • Designed for branch sites with between 25 and 1000 users
  • Survivable Branch Server (SBS)
    • 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
    • Does not contain a PSTN gateway
    • Designed for branch sites with between 1000 and 5000 users

Server Roles

• Standard Edition Server
  • Uses local SQL Express database to host users
  • One Standard Edition server supports as many as 5,000 users
  • In virtual deployments this is reduced to about 2,500 users
  • Can be part of a backup pool topology
• Front End Server and Back End Server
  • Front End pool is a set of Front End Servers, configured identically, that work together to provide services for a common group of users
    • One Front End pool in the deployment also runs the Central Management Server
    • The Central Management Server also provides Lync Server Management Shell and file transfer capabilities
  • Back End Servers do not run any Lync Server software
    • Can be a single SQL server, but its recommended to run a cluster of two or more
    • Information stored in the Back End Server databases includes
      • presence information
      • users’ Contacts lists
      • conferencing data including persistent data about the state of all current conferences
      • conference scheduling data
  • Front End Server scalability
    • One Front End Server for every 10,000 users homed in the pool
    • In virtual deployments this is reduced to about 5,000 users
    • The maximum number of users in one Front End pool is 80,000, if more than this, deploy an additional pool
• A/V Conferencing Server
  • It can be collocated with Front End Server, or deployed separately as a single server or A/V Conferencing Server pool
  • One A/V Conferencing Server deployed as a single server for each 20,000 users at a site
• EDGE Server
  • Server enables your users to communicate and collaborate with users outside the organization’s firewalls
  • Can be deployed with
    • One external IP
    • Three external IP’s
    • Can be behind NAT
    • But when in HA scenario, AV EDGE need to be directly routable
  • Deploy one Edge Server for every 15,000 users you expect to access a site remotely
  • In virtual deployments this is reduced to about 7,500 users
• Mediation Server
  • Mediation Server translates signaling and, in some configurations, media between your internal Lync Server infrastructure and
    • Public switched telephone network (PSTN) gateway
    • IP-PBX
    • Session Initiation Protocol (SIP) trunk
  • Estimating Voice Usage and Traffic
    • For Light traffic (one PSTN call per user per hour) figure 15 users per port
    • For Medium traffic (2 PSTN calls per user per hour) figure 10 users per port
    • For Heavy traffic (3 or more PSTN per user calls per hour) figure 5 users per port
• Monitoring Server
  • Monitoring Server collects data about the quality of your network media and collects call error records (CERs), which you can use to troubleshoot failed calls
  • can support up to 250,000 users if not collocated with Archiving Server
  • If collocated, it can support up to 100,000 users
• Archiving Server
  • Enables you to archive IM communications and meeting content for compliance reasons
  • If you do not have legal compliance concerns, you do not need to deploy Archiving Server
  • Archiving Server can support up to 500,000 users if not collocated with Monitoring Server
  • If collocated, it can support up to 100,000 users
• Director
  • Can authenticate Lync Server user requests, but do not home user accounts, or provide presence or conferencing services
  • Most useful in deployments that enable external user access, where the Director can authenticate requests before sending them on to internal servers
  • Directors can also improve performance in organizations with multiple Front End pools
  • Deploy one Director for every 15,000 users who will access a site remote
  • In virtual deployments this is reduced to about 7,500 users