We can work with SQL Server 2008 R2 in network mode also. For that we have to enable named pipes, TCP IP and VIA in SQL configuration.


Steps: 
Start-->Programs-->Microsoft SQL Server 2008 R2-->Configuration Services-->SQL Server Configuration Manager-->SQL Server Network Configuration-->Protocols for SQL Server

Enable following Options

1.Named Pipes
2.TCP/IP
3.VIA
After enabling above options restart the system.


Thanks to Rajesh H System Administrator