Why was 17-gun salute given to CDS Bipin Rawat?

CDS General Bipin Rawat was martyred in a helicopter crash in Tamil Nadu. Along with him, 12 other passengers lost their lives as well. But why was 17-gun salute given to CDS General Bipin Rawat? Why not a 21-gun salute was given to the CDS? 

The reason was that CDS was a newer position as compared to other positions. Take a look at the detailed report.