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Diameter NASreq (RFC 4005) and RADIUS Compatibility. draft-mitton-diameter-radius-vsas-01.txt. David Mitton RSA Security Inc. Overview. Diameter designed to be upwards compatible with RADIUS There will be encodings in Diameter that are not expressible in RADIUS
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Diameter NASreq (RFC 4005) and RADIUS Compatibility draft-mitton-diameter-radius-vsas-01.txt David MittonRSA Security Inc. IETF 65, Dallas
Overview • Diameter designed to be upwards compatible with RADIUS • There will be encodings in Diameter that are not expressible in RADIUS • Most RADIUS attributes are supported in RFC 4005, exceptions are noted in Section 9. • Difficulty arises with Vendor Specific Attributes (VSAs) IETF 65, Dallas
Problems • RADIUS VSA typical practice involves unknown formats for sub-types and lengths. Gateway must know format to translate • RFC 4005 Section 9.6 only works for some RADIUS VSAs • Imposes limitations on Vendor type space • Diameter VS AVPs must be restrained to fit into RADIUS • Diameter AVP type space larger than RADIUS suggested format • Diameter AVP data can be longer • Diameter AVPs have flags IETF 65, Dallas
RADIUS VSAs vs Diameter Vendor Specific AVPs RADIUS VSA format Suggested format Length:8 != 24 Type: 8 != 32 Diameter Vendor AVP format IETF 65, Dallas
Goals • Provide a mapping that allows bidirectional communication through a translating gateway system or bilingual server • Minimize special cases and vendor specific knowledge in gateways • Allow mix of Diameter and RADIUS speaking equipment and servers that don’t use different AVPs for same information IETF 65, Dallas
Proposal draft-mitton-diameter-radius-vsas-01.txt • Translate RADIUS VSAs as Diameter AVP #26. This is NOT as described in RFC 4005 Sect 9.6 • Translate Diameter VS AVPs to a new RADIUS attribute. IETF 65, Dallas
RADIUS VSAs as Diameter AVP 26 • No transformation of attribute data – Avoids vendor specific knowledge which allows transparent pass-through • Only end clients & servers need to know inner format • No additional encoding overhead • Length must be constrained to RADIUS limits. IETF 65, Dallas
Proposed RADIUS VSA to Diameter AVP 26 mapping RADIUS VSA Diameter AVP 26 IETF 65, Dallas
Diameter Vendor Specific AVPsin a RADIUS attribute • Add a new RADIUS attribute • Provide fields of the proper length • Define fragmentation and aggregation • Similar to EAP message attribute • Add segment number for concatenation • Suppress redundant VID and VType on non-first segment IETF 65, Dallas
Proposed RADIUS Diameter VS Attribute Diameter Vendor Attribute RADIUSDiameter VSA IETF 65, Dallas
Affects Documents: • Changing Diameter Vendor EncapsulationAffects Diameter Base RFC 3588, and Diameter NAS Application RFC 4005 • Specify RADIUS format of Diameter TLVsAffects RADIUS document ???Need to make one ! IETF 65, Dallas
Generic Diameter AVP to RADIUS Attribute • While we’re at it, why not define a way to map Diameter AVPs (Type > 255) to RADIUS and vice versa. • Use same format as VS mapping without Vendor stuff IETF 65, Dallas
Proposed RADIUS Diameter AVP Attribute Diameter Vendor Attribute RADIUSDiameter VSA IETF 65, Dallas
Conclusion • If we get rid of the RADIUS VSAs transformation in RFC 4005 Section 9 and add AVP #26 can transit Diameter with no transformational knowledge or loss of data • Add a RADIUS attribute to hold Diameter VS and regular AVPs • The two vendor spaces end up independent, but can be used by either. IETF 65, Dallas