Script

[This is pre-release documentation and subject to change in future releases. This topic's current status is: Milestone-Ready]

Topic Last Modified: 2010-07-18

This topology is for a small to medium organization with one central site. The exact topology in this diagram is for an organization of 15,000 users. Typically, the type of topology shown in this diagram would be recommended for organizations with 5,000 to 30,000 users, but it can support many more users than that.

• Active Directory Deployment—All Communications Server deployments reside in a single Active Directory forest. For this topology, the customer has Communications Server deployed in the child domain, retail.contoso.com.
  
  
• To Accommodate More Users, Add More Front End Servers—The exact topology in this diagram has two Front End Servers, so it supports up to 16,000 users. If you have a single central site and more users, you can simply add Front End Servers to the pool. One Front End pool can have as many as 10 servers, so a single Front End pool at a single site can support up to 80,000 users.
  
  However, the single site topology can support even more users by adding another Front End pool to the site. To support these extra users only another Front End pool needs to be added; just one pool each of A/V Conferencing Servers, Edge Servers, and Directors are still sufficient, although more servers may need to be added to these pools.
  
  
• A/V Conferencing Can Be Collocated in Smaller Organizations—If this organization has 10,000 or fewer users, you could decide to collocate A/V Conferencing Services with the Front End Pool, instead of deploying a separate A/V Conferencing Pool. Collocating these services is not recommended for organizations with 10,000 or more users, for performance reasons.
  
  
• Monitoring Server Database Server Options—In this topology, the Monitoring Server pool is using the same pair of database servers that the Front End pool uses. A topology in which the Monitoring Server pool has its own database servers is also supported. In each case, we recommend more than one database server in each pool, for high availability.
  
  
• High Availability for All Server Pools—In this example organization with 15,000 users, just one Director server, Edge Server and A/V Conferencing server would be sufficient for performance. However, there are pools of two servers of each type deployed to provide high availability for each feature.
  
  
• Branch Office Deployment Options—The organization in this topology has Enterprise Voice deployed as their voice solution. Branch Site 1 does not have a resilient WAN link to the central site, so it has a Survivable Branch Appliance deployed to provide telephone service in case the WAN link to the central site goes down. Branch Site 2 however has a resilient WAN link, so only a PSTN gateway is needed. The PSTN gateway deployed there supports media bypass, so no Mediation Server is needed at Branch Site B. For details about deciding what to install at a branch site, see Branch-Site Voice Resiliency.
  
  
• DNS Load Balancing—The Front End pool, Edge Server pool, and the Director pool have DNS load balancing for SIP traffic deployed. This eliminates the need for hardware load balancers for the internal interface of the Edge Servers, and significantly lessens the setup and maintenance of the hardware load balancers for the other pools, as the hardware load balancers are needed only for HTTP traffic. For details about DNS load balancing, see DNS Load Balancing.
  
  
• Exchange UM Deployment—Each of the reference topologies includes an Exchange UM Server, which runs Exchange, not Communications Server. The Exchange UM routing functionality for Communications Server runs on the Front End pool. For details about Exchange UM, see Exchange Unified Messaging Integration.
  
  
• Edge Servers Recommended—Although deploying an Edge Server is not required, it is recommended for any size of deployment. You can maximize your Communications Server investment by deploying an Edge Server to provide service to users currently outside your organization’s firewalls. The benefits include the following:
  
  
  • Your organization’s own users can use Communications Server functionality, if they are working from home or are out on the road.
    
    
  • Your users can invite outside users to participate in meetings.
    
    
  • If you have a partner, vendor or customer organization that also uses Communications Server, you can form a federated relationship with that organization. Your Communications Server deployment would then recognize users from that federated organization, leading to better collaboration.
    
    
  • Your users can exchange instant messages with users of public instant messaging (IM) services, including any or all of the following: Windows Live, AOL, and Yahoo!, as well as XMPP-based providers and servers, such as Google Talk and Jabber. A separate license might be required for public IM connectivity with Windows Live, AOL, and Yahoo!