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Microsoft SQL Server 2014 AlwaysOn Architecture 

This section provides an overview of the end-to-end design of the reference architecture for SQL Server 2014 with 

the AlwaysOn feature implemented in Cisco Intercloud Fabric.  

Figure 3 shows Microsoft Windows Server Failover Clustering (WSFC) with three SQL Server 2014 virtual 

machines and with the AlwaysOn availability group feature enabled. This feature combination provides 

infrastructure support for the high-availability and disaster-recovery features of the hosted database server. 

Figure 3.    Microsoft SQL Servers with Cisco Intercloud Fabric in a Hybrid Cloud  

 

 

An AlwaysOn availability group is composed of replicas of one or more databases. You can have one primary 

replica and one to eight secondary replicas. The sample configuration in this document shows multiple secondary 

replicas. A secondary replica is a copy of the database from the primary replica. When the database is modified, 

changes are replicated to all secondary replicas. 

This sample configuration also uses an availability group listener to direct the incoming connections to the primary 

replica or to a read-only secondary replica. The listener provides fast application failover after an availability group 

fails. An availability group listener is a virtual network name (VNN) to which the clients can connect to access a 

database in a primary or a secondary replica of an AlwaysOn availability group. 

The VNN is registered in the Domain Name System (DNS) and is always owned by the SQL Server instance on 

which the primary replica resides. All the IP addresses that are supplied while configuring the availability group 

listener are registered in DNS under the same VNN. In this document, the availability group listener is referred to 

as SQL AG. 

After SQL AG is created, verify that the clients can connect. The only change in the application connection is that 

instead of pointing to a specific server in the connection string, you point to SQL AG. SQL AG can connect only 

using TCP, and it can be resolved by your local DNS to the list of IP addresses and the TCP port (1433) mapped to 

the VNN. When failover occurs, client connections are reset, and the ownership of the availability group listener 

(SQL AG) moves to the SQL Server instance that takes over the primary replica role. The VNN endpoint is then 

bonded to the new IP addresses and TCP port of the new primary replica instance. Depending on the client,