ASA Modular Policy Framework - Global vs. Interface

Question

I understand from the Cisco documentation that a service-policy applied to an interface on an ASA 5500 series firewall, will override the default global service-policy.  However, I am not clear on whether it will override the entire global service-policy, or only the parts where they overlap.  In other words, would the resulting service-policy on the interface in question be just what was applied in the service-policy on the interface, completely replacing the global service-policy?  Or, would it be a combination of the global and interface service-policies, with the interface one taking precedence where they overlap?
if I wanted an interface to have the same service-policy as the global service-policy plus on other item, can I just add the one item in a service-policy that I apply to the interface, or do I have to replicate all the items from the global policy, plus the one additional item, and apply that to the interface.
Thank you.

Answer 1

Hi,
Interface  service policies take precedence over the global service policy for a  given feature. For example, if you have a global policy with FTP  inspection, and an interface policy with TCP normalization, then both  FTP inspection and TCP normalization are applied to the interface.  However, if you have a global policy with FTP inspection, and an  interface policy with FTP inspection, then only the interface policy FTP  inspection is applied to that interface.
Here is a doc for detailed study:
http://www.cisco.com/en/US/partner/docs/security/asa/asa82/configuration/guide/mpf.html
Hope this clears out your doubt.
Thanks,
Varun