Certificate based IPsec between Cisco router and fortinet firewall

Reason behind failing the IPSEC is fortinet does not specify CA trustpoint to be used in its certificate. In order to force cisco router to use a specific CA trustpoint containing a specific comman name or subject name do the following,

• use GUI to configure IPsec in fortigate firewall
  
• import certificate in both cisco and fortigate
  
• use the following configuration in global configuration mode at cisco router
• crypto pki certificate map name1 10
• subject name co cn=name2 //various options are there
• crypto isakmp profile name3
• ca trustpoint CAname
• match certificate name1

here you are done.
goodluck.