The Standard Edition Server is designed for small organizations, and for pilot projects of large organizations. It enables many of the features of Microsoft Communications Server 2010, as well as the necessary databases, to run on a single server. This enables you to have Communications Server functionality for a lesser cost, but does not provide a true high-availability solution.

Standard Edition Server enables you to use IM, presence, conferencing, and Enterprise Voice, all running on one server.

For a high-availability solution, use Communications Server 2010 Enterprise Edition.

The Front End Server is the core server role, and runs many basic Communications Server functions. It, along with the Back End Servers that provide the database, are the only server roles required to be in any Communications Server Enterprise Edition deployment.

A Front End pool is a set of Front End Servers, configured identically, that work together to provide services for a common group of users. A pool provides scalability and failover capability your users.

Front End Server includes the following functionality:

• User authentication and registration.
  
  
• Presence information and contact card exchange.
  
  
• Address book services and distribution list expansion.
  
  
• IM functionality, including multi-party IM conferences.
  
  
• Web conferencing and application sharing (if deployed).
  
  
• Application hosting services, for both applications included with Communications Server (such as Conferencing Attendant and Response Group Service) and third-party applications.
  
  
• Application services Enables application hosting and hosts applications (for example, Response Group Application, and several others).
  
  

Additionally, one Front End pool in the deployment also runs the Central Management Server, which manages and deploys basic configuration data to all servers running Communications Server 2010. The Central Management Server also provides Communications Server Management Shell and file transfer capabilities.

The Back End Servers are database servers running Microsoft SQL Server, and provide the database services for the Front End pool. You can have a single Back End Server, but a cluster of two or more servers is recommended for failover. Back End Servers do not run any Communications Server software. If you already have a SQL Server cluster you are using for other applications, you can also use this cluster for Communications Server 2010, if performance allows.

Information stored in the Communications Server databases includes presence information, user’s contact lists, conferencing data including persistent data about the state of all current conferences, and conference scheduling data.

A/V Conferencing Server provides A/V conferencing functionality to your deployment. It can be collocated with Front End Server, or deployed separately as a single server or A/V Conferencing Server pool.

For details, see Web Conferencing and A/V Conferencing.

Edge Server enables your users to communicate and collaborate with users outside the organization’s firewalls. These external users can include the organization’s own users who are currently working offsite, users from federated partner organizations, and outside users who have been invited to join conferences hosted on your Communications Server deployment. Edge Server also enables connectivity to public instant messaging (IM) connectivity services, including Windows Live, AOL, and Yahoo!.

For details, see External User Access.

Mediation Server is a necessary component for implementing Enterprise Voice and dial-in conferencing. Mediation Server translates signaling and, in some configurations, media between your internal Communications Server infrastructure and an Internet Protocol/Public Switched Telephone Network (IP-PSTN) gateway or a Session Initiation Protocol (SIP) trunk.

For details, see Mediation Server Component.

Monitoring Server collects data about the quality of your network media, in both Enterprise Voice calls and A/V conferences. This information can help you provide the best possible media experience for your users. It also collects call error records (CERs), which you can use to troubleshoot failed calls. Additionally, it collects usage information (call detail records, or CDRs) about various Communications Server features so that you can calculate return on investment of your deployment, and plan the future growth of your deployment.

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.

Directors can authenticate Communications Server user requests, but do not home user accounts, or provide presence or conferencing services. Directors are 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. For details, see Director.