Any CCNP or CCDP certification or any CCIE or CCDE certification can act as a prerequisite.
Cisco Specialist certifications are valid for two years. To recertify you must pass one of the following before your certification expiration date:
- The current required exam
- Any current CCIE written exam
- The current CCDE written exam or current CCDE Practical Exam
Visit Cisco's site for additional recertification information.