# Hierarchical Policy Configuration Considerations

When you configure hierarchical policies for interface groups, be aware of the following considerations:

- Loops—The system performs basic checks to prevent formation of loops when external parent groups refer to other external parent groups. Also, you cannot chain together more than four rate-limits in a hierarchy.
- Asynchronous Policy Parameter Configuration—You can individually configure the policy parameter configuration in an interface and the policy attachments. If a policy parameter is not configured in the interface before a policy is attached, the value configured in Global Configuration mode for this parameter is used. You can later change the parameter value for the interface.
- Asynchronous Parent Group Rate Limit Configuration—You can configure an external parent group without a rate-limit-profile reference. In this case, the system doe not invoke a rate-limit for the external parent group (even if other nodes point to it) and calls the next node in the hierarchy.
- Parent Group Reference—The configuration fails if you do not first create an external parent group before it is referenced elsewhere.