Xavier Milà (pictured) and Victor Pascual, Acme Packet, provide more information on the "a new version of Diameter, RFC 6733 (this was previously known as RFC 3588bis)".
"The main improvements in this new version include:
- Improved transport efficiency and clarifications of security mechanisms, adopting TLS/TCP and DTLS/SCTP as primary security mechanisms and IPsec as a secondary alternative
- Correlation of application-Id fields, which are necessary due to the proliferation of applications based on Diameter
- Clarifications and enhancements regarding routing and agent discovery
- Advanced redirect capabilities to reflect modern requirements for flexibility to route based on multiple parameters including user, realm, application, etc.