Internet Engineering Task Force I. Brown INTERNET-DRAFT University College London Expiration Date: 31 January 2003 July 2002 Terms of Reference for an Emergency Telecommunications Service Status of This Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Copyright (C) Internet Society 2002. All rights reserved. Reproduction or translation of the complete document, but not of extracts, including this notice, is freely permitted. Abstract An Emergency Telecommunications Service gives authorised emergency personnel a higher probability of successful communication under high network load conditions. This document explains the different terms and acronyms used in defining and implementing this service, and is intended to be used as a common basis for negotiations when emergency service providers are contracting with telecommunications operators to provide the service. It can also be used in procurement of and tendering for ETS provision. Brown Expires 31 January 2003 [Page 1] Internet-Draft ETS terms of reference July 2002 1. Definitions Assured Forwarding (AF) A set of DiffServ Per-Hop Behaviours that group packets into one of four independent classes, each of which has three levels of drop precedence [Heinanen99]. Diameter A protocol that provides authentication, authorisation and accounting services between home and remote networks and their users [Calhoun02]. Differentiated Services Code Point (DSCP) The value used in the DiffServ field of a packet header that selects a specific Per-Hop Behaviour [Grossman02]. Differentiated Services (DiffServ) A mechanism for classifying traffic flows into aggregates and providing specific forwarding treatment within a network. Flows are classified and policed at the edge of a network and forwarded according to the service provider's policies [Blake98]. Expedited Forwarding (EF) A DiffServ Per-Hop Behaviour that provides a flow with low loss, jitter and delay. This is achieved by ensuring that the output rate of an EF queue in a router is higher than the arrival rate of EF- marked packets over short and long time intervals [Davie02]. Government Emergency Telecommunications Service (GETS) A scheme operated under contract by US telecommunications providers that provides a High Probability of Completion for calls made by authorised emergency personnel in the Public Switched Telephone Network [Folts02]. Global System for Mobile communications (GSM) The family of European Telecommunications Standards Institute standards for first generation digital mobile telecommunications, used in many countries around the world for public land mobile networks. Contains an extended version of MLPP to allow precedence and preemption for calls from authorised users. High Probability of Completion (HPC) Brown Expires 31 January 2003 [Page 2] Internet-Draft ETS terms of reference July 2002 Emergency prioritised calls in the Public Switched Telephone Network are given a higher chance of successful setup by the network. These calls can be queued, exempted from restrictive management controls and routed via alternate carriers when they encounter congestion [ANSI93]. International Emergency Multimedia Service (IEMS) A counterpart to the International Emergency Preference Scheme that provides enhanced treatment for a wide range of multimedia services [ITU02]. International Emergency Preference Scheme (IEPS) An International Telecommunications Union standard that provides a High Probability of Completion for calls made by authorised emergency personnel in the international Public Switched Telephone Network [ITU00]. Integrated Services (IntServ) An extension to the Internet architecture to support real-time services for communications sessions [Braden94]. Bandwidth can be reserved using the Resource ReSerVation Protocol [Braden97]. IntServ is usually only supported within specific domains. Internet Protocol Security (IPSec) A set of extensions to the standard Internet Protocol that allows packets or the data they contain to be encrypted and signed, ensuring their confidentiality and integrity [Thayer98]. ISDN User Part (ISUP) A set of protocols used in SS7 networks to support ISDN services such as controlling telephone calls, and network maintenance such as blocking or resetting circuits [ITU99]. The ISUP Initial Address Message is used to carry the National Security/Emergency Preparedness codepoint which marks a GETS call as prioritised. Multimedia Internet Keying (MIKEY) A key agreement protocol designed to meet the low latency requirements of real-time media streams and to work with signalling protocols such as SIP [Arkko02]. Multi-Level Precedence and Preemption (MLPP) A system that allows higher-priority telephony calls to receive resources ahead of (and if necessary to tear down) lower priority calls [ITU90]. Brown Expires 31 January 2003 [Page 3] Internet-Draft ETS terms of reference July 2002 National Security/Emergency Preparedness (NS/EP) A codepoint set for GETS calls in the Calling Party Category of the SS7 ISUP Initial Address Message, indicating that the setup should have a High Probability of Completion. Per-Hop Behaviour (PHB) The forwarding behaviour applied by a DiffServ node to flows marked with a specific DSCP. Real-time Transport Protocol A network-independent end-to-end transport protocol for real-time data such as audio,video and simulation results [Schulzrinne96]. Secure Real-time Transport Protocol A Real-time Transport Protocol profile that provides confidentiality, authentication and replay protection for RTP and associated control traffic [Baugher02]. Session Initiation Protocol (SIP) A signalling protocol used to set up, manage and tear down communications sessions between one or more participants. Telephone calls, video conferences and multimedia distribution are all supported [Rosenberg02]. Signalling System No. 7 (SS7) The procedures and protocols by which network elements in the Public Switched Telephone Network exchange information over a digital signalling network for call setup, routing and control [ITU93]. Telephony Routing over IP (TRIP) A protocol that allows IP telephony gateways to advertise and exchange routes to specific numbers in the Public Switched Telephone Network [Rosenberg00]. Traffic Class DiffServ packets are marked as part of a specific traffic aggregate using a DiffServ Code Point. This DSCP goes in the traffic class field of the packet header [Grossman02]. Transport Layer Security (TLS) A set of cryptographic protocols that allow processes running on two separate hosts to communicate across an insecure network such as the Internet with protection against eavesdropping and modification of Brown Expires 31 January 2003 [Page 4] Internet-Draft ETS terms of reference July 2002 data [Dierks99]. 2. Security Considerations The security aspects of an Emergency Telecommunications Service are described in [Brown02]. 3. Acknowledgements Thanks to Alistair Munro for comments on this document. 4. Author's Address Ian Brown Department of Computer Science University College London Gower Street London WC1E 6BT United Kingdom Phone: +44 20 7679 3704 Fax: +44 20 7387 1397 E-mail: I.Brown@cs.ucl.ac.uk 5. Informative References [ANSI93] ANSI Recommendation T1.631, "Signaling System No. 7 (SS7) - High Probability of Completion (HPC) Network Capability", 1993. [Arkko02] Arkko, J., Carrara, E., Lindholm, F., Naslund, M. and K. Norrman, "MIKEY: Multimedia Internet KEYing", Internet draft, July 2002. [Blake98] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., and W. Weiss, "An Architecture for Differentiated Services", RFC 2475, December 1998. [Baugher02] Baugher, M., Blom, R., Carrara, E., McGrew, D., Naslund, M., Norrman, K., and D. Oran, "The Secure Real-time Transport Protocol", IETF work-in-progress, June 2002. [Braden94] Braden, B., Clark, D. and S. Shenker, "Integrated Services in the Internet Architecture: an Overview", RFC 1633, June 1994. [Braden97] Braden, B. (Ed.), "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [Brown02] Brown, I., "A Security Framework for Emergency Communications", IETF work-in-progress, June 2002. [Calhoun02] Calhoun, P., Arkko, J., Guttman, E., Zorn, G. and J. Brown Expires 31 January 2003 [Page 5] Internet-Draft ETS terms of reference July 2002 Loughney, "Diameter Base Protocol", IETF work-in-progress, April 2002. [Davie02] Davie, B. et al., "An Expedited Forwarding PHB (Per-Hop Behavior)", RFC 3246, March 2002. [Dierks99] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [Folts02] Folts, H. and C. Beard, "Requirements for Emergency Telecommunication Capabilities in the Internet", Internet draft, June 2002. [Grossman02] D. Grossman, "New Terminology and Clarifications for Diffserv", RFC 3260, April 2002. [Heinanen99] Heinanen, J., Baker, F., Weiss, W. and J. Wroclawski, "Assured Forwarding PHB Group", RFC 2597, June 1999. [ITU90] ITU-T Recommendation I.255.3, "Multilevel precedence and preemption service (MLPP)", July 1990. [ITU93] ITU-T Recommendation Q.700, "Introduction to CCITT Signalling System No. 7", March 1993. [ITU99] ITU-T Recommendation ITU-T Q.764, "Signaling System No. 7; ISDN User Part Signaling procedures", December 1999. [ITU00] ITU-T Recommendation E.106, "Description of an International Emergency Preference Scheme (IEPS)", March 2000. [ITU02] ITU-T Draft Recommendation F.706, "International Emergency Multimedia Service", 2002. [Rosenberg00] Rosenberg, J. and H. Schulzrinne, "A Framework for Telephony Routing over IP", RFC 2871, June 2000. [Rosenberg02] Rosenberg, J. et al, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [Schulzrinne96] Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson, "RTP: A Transport Protocol for Real-time Applications", RFC 1889, January 1996. [Thayer98] Thayer, R., Doraswamy, N. and R. Glenn, "IP Security Document Roadmap", RFC 2411, November 1998. 6. Full Copyright Statement Copyright (C) The Internet Society (2002). All Rights Reserved. This document and translations of it may be copied and furnished to Brown Expires 31 January 2003 [Page 6] Internet-Draft ETS terms of reference July 2002 others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Brown Expires 31 January 2003 [Page 7]