Individual Submission M. Jones Internet-Draft Bridgewater Systems Updates: 3588 (if approved) J. Korhonen Intended status: Standards Track Nokia Siemens Networks Expires: February 24, 2010 August 23, 2009 Diameter Extended NAPTR draft-jones-dime-extended-naptr-00 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. 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The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on February 24, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. Jones & Korhonen Expires February 24, 2010 [Page 1] Internet-Draft dime-extended-naptr August 2009 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document describes an extended format for the NAPTR service fields used in dynamic Diameter agent discovery. The extended format allows NAPTR queries contain Diameter Application-Id information. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Jones & Korhonen Expires February 24, 2010 [Page 2] Internet-Draft dime-extended-naptr August 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Extended NAPTR Service Field . . . . . . . . . . . . . . . . . 4 4. Extended NAPTR-based Diameter Peer Discovery . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 7. Normative References . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Jones & Korhonen Expires February 24, 2010 [Page 3] Internet-Draft dime-extended-naptr August 2009 1. Introduction The Diameter base protocol [RFC3588] specifies three mechanisms for the Diameter peer discovery. One of these involves the Diameter implementation performing a NAPTR query [RFC3403] for a server in a particular realm. These NAPTR records provide a mapping from a domain, to the SRV record [RFC2782] for contacting a server with the specific transport protocol in the NAPTR services field. Section 11.6 of RFC 3588 defines the following NAPTR service fields: Services Field Protocol AAA+D2T TCP AAA+D2S SCTP However, foreseen network topologies require border AAA nodes that will be specialized by Diameter application and the NAPTR service field does not allow a Diameter implementation to determine the application supported by the AAA node. Without this information, a Diameter implementation must connect and perform a capability negotiation with each candidate AAA node. This document addresses this problem by specifying an extended NAPTR service field format that permits discovery of Diameter peers that support a specific Diameter application. 2. Terminology The Diameter base protocol specification (Section 1.4 of RFC 3588) defines most of the terminology used in this document. 3. Extended NAPTR Service Field The Extended NAPTR service field ABNF specification for the discovery of Diameter agents supporting a specific Diameter application is show below. Jones & Korhonen Expires February 24, 2010 [Page 4] Internet-Draft dime-extended-naptr August 2009 naptr-svc-field = "AAA+D2" < protocol> [ *appln-list ] protocol = "T" / "S" ; "T" for TCP and "S" for SCTP. appln-list = "+AP:" appln-id [ *( "," appln-id ) ] ; Comma separated list of application ; identifiers prefixed by "+AP:". appln-id = *DIGIT ; Application identifier expressed as a ; decimal integer. For example, a NAPTR service field value of: 'AAA+D2S+AP:6' Means that the Diameter node in the SRV record supports the Diameter Session Initiation Protocol (SIP) Application ('6') and SCTP as the transport protocol. 'AAA+D2S+AP:6,1,5,4294967295' Means that the Diameter node in the SRV record supports the Diameter Session Initiation Protocol (SIP) Application ('6'), NASREQ Application ('1'), EAP Application ('5') and SCTP as the transport protocol. The Diameter node also provides Relay functionality ('4294967295'). The maximum length of the NAPTR service field is 256 octets including one octet length field (see Section 4.1 of RFC 3403 and Section 3.3 of [RFC1035]). The DNS administrator of some domain SHOULD also provision base RFC 3588 style NAPTR records in order to guarantee backwards compatibility with legacy RFC 3588 compliant Diameter peers. 4. Extended NAPTR-based Diameter Peer Discovery The basic Diameter Peer Discover principles are described in Section 5.2 of RFC 3588. This specification extends the step 3. Diameter peer discovery mechanism by allowing the querying node examine which applications are supported by resolved Diameter peers. The assumption for this mechanism to work is that the DNS administrator of the queried domain has provisioned the DNS with extended NAPTRs in the first place. The text below is slightly modified from RFC 3588. Jones & Korhonen Expires February 24, 2010 [Page 5] Internet-Draft dime-extended-naptr August 2009 1. ... 2. ... 3. The Diameter implementation performs a NAPTR query for a server in a particular realm. The Diameter implementation has to know in advance which realm to look for a Diameter agent in and which Application Identifier it is interested in. The realm could be deduced, for example, from the 'realm' in a NAI that a Diameter implementation needed to perform a Diameter operation on. 3.1 The services relevant for the task of transport protocol selection are those with NAPTR service fields with values "AAA+ D2x+AP:y", where 'x' is a letter that corresponds to a transport protocol supported by the domain and 'y' is one or more Application Identifiers. ... 3.2 A client MUST discard any service fields that identify a resolution service whose value is not "D2X", for values of X that indicate transport protocols supported by the client. The client SHOULD also discard any service fields that do not identify support for the application the client is looking for i.e. the desired Application Identifier is not listed in 'AP:y'. ... 5. IANA Considerations Editor's Note: Verify impacts to IANA registries. 6. Security Considerations This document specifies an enhancement to the NAPTR service field format defined in the Diameter base protocol and the same security considerations described in RFC 3588 are applicable to this document. No further extensions are required beyond the security mechanisms offered by RFC 3588. 7. Normative References [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. Jones & Korhonen Expires February 24, 2010 [Page 6] Internet-Draft dime-extended-naptr August 2009 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000. [RFC3403] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Three: The Domain Name System (DNS) Database", RFC 3403, October 2002. [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, "Diameter Base Protocol", RFC 3588, September 2003. Authors' Addresses Mark Jones Bridgewater Systems Email: mark.jones@bridgewatersystems.com Jouni Korhonen Nokia Siemens Networks Email: jouni.nospam@gmail.com Jones & Korhonen Expires February 24, 2010 [Page 7]