Hi Abbas,
the common name from the certificate needs to be the same as the hostname the users will have to enter as part of the URL. This is independant whether you forward the traffic or terminate the certificate at the webdispatcher. The difference is only where to install the certificate, as you need to install it on the system, where the SSL session started by the browser is terminated.
In your case, this should be abcportal.abc.com.
Did you configure webdispatcher to listen on port 443? Pleas check the docs for more details on this.
regards,
Patrick