Chapter 15 Unified Threat Management for FortiOS 5.0 : Application control : Application traffic shaping : Shaper re-use
  
Shaper re-use
Shapers are created independently of firewall policies and application sensors so you are free to reuse the same shapers in multiple list entries and policies. Shared shapers can be configured to apply separately to each security policy or across all policies. This means that if a shaper is configured to guaranteed 1000 KB/s bandwidth, each security policy using the shaper will have its own 1000 KB/s reserved, or all of the policies using the shaper will share a pool if 1000 KB/s, depending on how it is configured.
The same thing happens when a shaper is used in application sensors. If an application sensor using a shaper is applied to two separate policies, how the bandwidth is limited or guaranteed depends on whether the shaper is set to apply separately to each policy or across all policies. In fact, if a shaper is applied directly to one security policy, and it is also included in an application sensor that is applied to another security policy, the same issue occurs. How the bandwidth is limited or guaranteed depends on the shaper configuration.
If a shaper is used more than once within a single application sensor, all of the applications using the shaper are restricted to the maximum bandwidth or share the same guaranteed bandwidth.
For example, you want to limit the bandwidth used by Skype and Facebook chat to no more than 100 KB/s. Create a shaper, enable Maximum Bandwidth, and enter 100. Then create an application sensor with an entry for Skype and another entry for Facebook chat. Apply the shaper to each entry and select the application sensor in the security policy that allows your users to access both services.
This configuration uses the same shaper for each entry, so Skype and Facebook chat traffic are limited to no more than 100 KB/s in total. That is, traffic from both applications is added and the total is limited to 100 KB/s. If you want to limit Skype traffic to 100 KB/s and Facebook chat traffic to 100 KB/s, you must use separate shapers for each application control entry.