rfc-6218
Cisco Vendor-Specific RADIUS Attributes for the Delivery of Keying Material
This document defines a set of vendor-specific RADIUS Attributes designed to allow both the secure transmission of cryptographic keying material and strong authentication of any RADIUS message. These attributes have been allocated from the Cisco vendor-specific space and have been implemented by multiple vendors. This document is not an Internet Standards Track specification; it is published for informational purposes.