Network Working Group E. Chen Internet Draft N. Shen Intended Status: Standards Track Cisco Systems Expiration Date: September 11, 2017 March 10, 2017 Extended Identifier Attribute for RADIUS draft-chen-radext-extended-header-01.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on September 11, 2017. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Chen & Shen [Page 1] Internet Draft draft-chen-radext-extended-header-01.txt March 2017 Abstract The limitation with the one-octet "Identifier" field in the RADIUS packet is well known. In this document we propose extensions to the RADIUS protocol to address this fundamental limitation, and thus allowing for more efficient and more scalable implementations. 1. Introduction The "Identifier" field in the RADIUS packet [RFC2865] is used to match outstanding requests and replies. As the field is one octet in size, only 256 requests can be in progress between two endpoints, which would present a significant bottleneck for performance. The workaround for this limitation is to use multiple source ports as documented and discussed in [RFC2865], [RFC3539], and [RFC6613]. Currently it is quite common to have hundreds of parallel connections between a RADIUS client and a server, especially in the deployment of controllers for wireless clients. As the scale requirement continues to increase, the number of "parallel connections" is expected to grow (perhaps reaching thousands), which will undoubtedly create a number of challenges with resource utilization, efficiency, and connection management (with RADIUS over TCP [RFC6613] in particular) on both the client and the server. In this document we propose extensions to the RADIUS protocol to address this fundamental limitation and thus allowing for more efficient and more scalable implementations. More specifically, a new attribute ("Extended Identifier Attribute") is defined that can be used to discover the support of this specification between a client and a server using the Status-Server packet [RFC5997]. Once the support is confirmed, the attribute can then be used to carry the extended "Identifier" field in subsequent RADIUS packets. The attribute also provides an option for carrying the RADIUS packet "code" in a larger field just in case that becomes necessary in the future. For brevity the extensions specified in this document are referred to as "the Extended Identifier feature" hereafter. Chen & Shen [Page 2] Internet Draft draft-chen-radext-extended-header-01.txt March 2017 1.1. Specification of Requirements 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]. 2. Protocol Extensions 2.1. Extended Identifier Attribute A new attribute, termed "Extended Identifier Attribute", is specified which can be used to discover the support for the Extended Identifier feature between a client and a server. It can also be used to carry the Identifier field (and optionally the Code field) in a RADIUS packet after the support is confirmed. The attribute number is TBD. The value of the attribute consists of the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Status | Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where the 4-bit Status field is to be used in a Status-Server packet to discover the support for the Extended Identifier feature. The following settings are defined: o It is set to 0 (for "request") when a client sends the Status-Server request to a server indicating its support for the Extended Identifier feature. o It is set to 1 (for "confirm") or 2 (for "reject") by the server in its response to indicate whether it supports the Extended Identifier feature. The 12-bit Code field, when needed, can be used in lieu of the Code field in the RADIUS packet header. The field is unused if its value is zero. The field is in use otherwise. The 4-octet Identifier field is to be used in lieu of the Identifier field in the RADIUS packet header. Chen & Shen [Page 3] Internet Draft draft-chen-radext-extended-header-01.txt March 2017 When the "Extended Identifier Attribute" is used in a Status-Server packet, only the Status field is used. All other fields SHOULD be set to zero by the sender and MUST be ignored by the receiver. When the "Extended Identifier Attribute" is used in a non Status- Server packet, the Status field is unused, and SHOULD be set to zero by the sender and MUST be ignored by the receiver. Other than the larger sizes for the Identifier field and optionally for the Code field, these two fields remain unchanged semantically as defined in RFC 2865 [RFC2865] (and subsequent documents using the same packet format). To simplify packet processing and for consistency, the "Extended Identifier Attribute" MUST be encoded as the very first attribute in the attribute list of a RADIUS packet. If the attribute does not appear as the first one in the attribute list of a RADIUS packet, the RADIUS packet MUST be treated as invalid and the packet be discarded according to [RFC2865]. Due to the hop-by-hop nature of RADIUS packet transmission between RADIUS devices, a PROXY server MUST strip the "Extended Identifier Attribute" (and reconstruct if appropriate) before sending the packet over a different session. 2.2. Status-Server Considerations This section extends processing of Status-Server packets as described in Sections 4.1 and 4.2 of [RFC5997]. Prior to sending a RADIUS packet (other than the Status-Server request) with the "Extended Identifier Attribute", a client implementing this specification SHOULD first send a Status-Server request with the "Extended Identifier Attribute" to indicate its support for the Extended Identifier feature. When a server implementing this specification receives a Status- Server request with the "Extended Identifier Attribute", it MUST include the "Extended Identifier Attribute" in its response to indicate whether it supports the Extended Identifier feature. If the Status-server reply from a server does not contain the "Extended Identifier Attribute", the client MUST treat this case as "reject" by the server for the Extended Identifier feature. Unless specified by configuration, a client MUST not send a RADIUS packet (other than the Status-Server request) with the "Extended Identifier Attribute" to a server until it has received a response Chen & Shen [Page 4] Internet Draft draft-chen-radext-extended-header-01.txt March 2017 from the server confirming its support for the Extended Identifier feature using the "Extended Identifier Attribute". When TCP is used as the transport protocol for RADIUS [RFC6613] between a client and a server, the Extended Identifier feature SHOULD be discovered each time the TCP session is established. 2.3. Co-existence of Identifier Fields After the functionality defined in this specification is discovered between the client and the server, RADIUS packets can be exchanged using either the Identifier field in the RADIUS packet header (without the "Extended Identifier Attribute" in the packet), or the Identifier field in the "Extended Identifier Attribute" as the very first attribute in the attribute list. When the "Extended Identifier Attribute" is present in a RADIUS packet other than the Status-Server packet, the Identifier field in the attribute MUST be used in lieu of the Identifier field in the RADIUS packet header. Similarly the Code field in the attribute, if it is non-zero, MUST be used in lieu of the Code field in the RADIUS packet header. When the "Extended Identifier Attribute" is used to carry the Identifier field, for better debugability it is RECOMMENDED that 255 be used in the Identifier field of the RADIUS packet header. Similarly it is RECOMMENDED that 255 be used in the code field of the RADIUS packet header when the attribute is used to carry the Code field as well. To simplify implementation, it is RECOMMENDED that the numbers 256 and larger be used as the "Identifier" in the "Extended Identifier Attribute". In response to a request from a client, the server SHOULD format the Identifier field in the same way as in the request, i.e., using either the Identifier field in the RADIUS packet header or the one in the Extended Identifier Attribute. Chen & Shen [Page 5] Internet Draft draft-chen-radext-extended-header-01.txt March 2017 3. IANA Considerations A new attribute ("Extended Identifier Attribute") is defined for the RADIUS protocol. The type value [RFC3575] needs to be assigned using the assignment rules in section 10.3 of [RFC6929]. 4. Security Considerations TBD 5. Acknowledgments TBD 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000. [RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote Authentication Dial In User Service)", RFC 3575, July 2003. [RFC5997] DeKok, A., "Use of Status-Server Packets in the Remote Authentication Dial In User Service (RADIUS) Protocol", RFC 5997, August 2010. 6.2. Informative References [RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000. [RFC3539] Aboba, B. and J. Wood, "Authentication, Authorization and Accounting (AAA) Transport Profile", RFC 3539, June 2003. Chen & Shen [Page 6] Internet Draft draft-chen-radext-extended-header-01.txt March 2017 [RFC3579] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication Dial In User Service) Support For Extensible Authentication Protocol (EAP)", RFC 3579, September 2003. [RFC5080] Nelson, D. and A. DeKok, "Common Remote Authentication Dial In User Service (RADIUS) Implementation Issues and Suggested Fixes", RFC 5080, December 2007. [RFC6613] DeKok, A., "RADIUS over TCP", RFC 6613, May 2012. [RFC6614] Winter, S., McCauley, M., Venaas, S., and K. Wierenga, "Transport Layer Security (TLS) Encryption for RADIUS", RFC 6614, May 2012. [RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User Service (RADIUS) Protocol Extensions", RFC 6929, April 2013. 7. Authors' Addresses Enke Chen Cisco Systems 560 McCarthy Blvd. Milpitas, CA 95035 USA Email: enkechen@cisco.com Naiming Shen Cisco Systems 560 McCarthy Blvd. Milpitas, CA 95035 USA Email: naiming@cisco.com Chen & Shen [Page 7]