Internet Engineering Task Force Ken Carlberg INTERNET DRAFT UCL January 20, 2003 Ran Atkinson Extreme Networks General Requirements for Emergency Telecommunication Service Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. 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. For potential updates to the above required-text see: http://www.ietf.org/ietf/1id-guidelines.txt Abstract This document presents a list of general requirements in support of Emergency Telecommunications Service (ETS). Solutions to these requirements are not presented in this document. Additional requirements pertaining to specific applications, or types of applications, are to be specified in separate document(s). 1. Introduction Effective telecommunications capabilities can be imperative to facilitate immediate recovery operations for serious disaster events, such as, hurricanes, floods, earthquakes, and terrorist attacks. Disasters can happen any time, any place, unexpectedly. Quick response for recovery operations requires immediate access to any public telecommunications capabilities at hand. These capabilities Carlberg & Atkinson Expires June 20, 2003 [Page 1] ^L Internet Draft ETS General Requirements January 20, 2003 include: conventional telephone, cellular phones, and Internet access via online terminals, IP telephones, and wireless PDAs. The commercial telecommunications infrastructure is rapidly evolving to Internet-based technology. Therefore, the Internet community needs to consider how it can best support emergency management and recovery operations. 1.1 Existing Emergency Related Standards The following are standards from other organizations that are specifically aimed at supporting emergency communications. Most of these standards specify telephony mechanisms or define telephony related labels. Standard / Organization -------------------------- 1) T1.631 / ANSI 2) E.106 / ITU 3) F.706 / ITU 4) H.460.4 / ITU 5) I.255.3 / ITU The first specifies an indicator for SS7 networks that signals the need for a High Probability of Completion (HPC) service. This indicator is termed National Security / Emergency Preparedness (NS/EP) The T1.631 standard [2] is the basis for the U.S. Government Emergency Telecomunications Service (GETS) [7]. The second standard describes functional capabilities for the PSTN to support International Emergency Preparedness System (IEPS) [3]. From the PSTN perspective, one can view NS/EP as a standard with national boundaries, while IEPS is extention to international boundaries for telephony. The third standard extends IEPS beyond the scope of telephony into other forms that encompass multimedia [4]. The fourth and fifth standard focuses on a multi-level labeling mechanism distinguishing emergency type traffic from that which is not. The former case focuses on call signaling for H.323 networks [5], while the latter has been applied for both SS7 [6] and data networks. 1.2 Problem One problem faced by the IEPREP working group entails how, and to what degree, support for these standards are to be realized within Carlberg & Atkinson Expires June 20, 2003 [Page 2] ^L Internet Draft ETS General Requirements January 20, 2003 the Internet architecture and the existing suite of IETF standards and associated working groups. A subsequent problem is to ensure that this support is not focused just on IP telephony applications. The I-Am-Alive (IAA) database system is an example of an emergency related application used in Japan that supports both signaled and non-signaled access by users[10]. Hence, requirements and subsequent solutions that address these problems must not assume the existance of signaling and must be able to support applications that only have labels in data packets. These label(s) may be in various places, such as the application or IP header. Further comments on labels are discussed below in section 3. 2. Scope This document defines a set of general system requirements to achieve support for ETS and addressing the problem space presented in Section 1.2. In defining these requirements, we consider known systems such as GETS and IAA that represent existing manifestations of emergency related systems. These two examples also represent a broad spectrum of characteristics that range from signaling/interactive non-elastic applications to non-signaled/elastic applications. We stress that ETS, and its associated requirements, is not the only means of supporting authorized emergency communications. It is simply an approach influenced by by existing systems and standards. Solutions to requirements are not defined. This document does not specify protocol enhancements or specifications. Requirements for specific types of applications that go beyond the general set stated in section 3 are to be specified in other document(s). At the current writing of this document, [9] has been written for the case of IP telephony. Below we present a structural relationship of documents for the IEPREP working group. Specific solutions that are proposed in response to the requirements are to be developed in other working groups. We note that other specific requrements (like that of IP telephony) may be defined as an extension of the general requirements presented in section 3 below. 2.1 Out of Scope While the problem space stated in section 1.2 includes standards related to telephony, this document is meant to be broader in scope. Hence, emulation of specific architectures, like the PSTN, or focus on a specific application is out of scope. Further, the Carlberg & Atkinson Expires June 20, 2003 [Page 3] ^L Internet Draft ETS General Requirements January 20, 2003 specifications of requirements that are aimed at adhering to regulations or laws of governments is also out of scope of this document. The focus of the IETF and its working groups is technical positions that follow the architecture of the Internet. Another item that is not in scope of this document is mandating acceptance and support of the requirements presented in this document. There is an expectation that business contracts, (e.g., Service Level Agreements) , will be used to satisfy those requirements that apply to service providers. Absence of an SLA implies best effort service is provided. 3. General Requirements These are general requirements that apply to authorized emergency telecommunications service. The first requirement is presented as a conditional one since not all applications use or are reliant on signaling. 1) Signaling IF signaling is to be used to convey the state or existance of emergency, then signaling mechanism(s) MUST exist to carry applicable labels. 2) Labels Labels may exist in various forms at different layers. They might be carried as part of signaling, and/or as part of the header of a data packet. Labels from different layers are NOT required to be the same, but MAY be related to each other. 3) Policy Policy MUST be kept separate from label(s). This topic has generated a fair amount of debate, and so we provide additional guidance from the following: A set of labels may be defined as being related to each other. Characteristics (e.g., drop precedence) may also be attributed to these labels. [11] is an example of a related set of labels based on a specific characteristic. However, the mechanisms used to achieve a stated characteristic MUST NOT be stated in the definition of a label. Local policy determines mechanism(s) used to achieve or support a specific characteristic. This allows for the possibility of different mechanisms to achieve the same stated characteristic. Carlberg & Atkinson Expires June 20, 2003 [Page 4] ^L Internet Draft ETS General Requirements January 20, 2003 The interaction between unrelated labels MUST NOT be embedded within the definition of a label. Local policy states the actions (if any) to be taken if unrelated labeled traffic merges at a node. Finally, labels may have additional characteristics added to them as a result of local policy. 4) Network Functionality Functionality to support better than best effort SHOULD focus on probability versus guarantees. Probability can be realized in terms of reduced probability of packet loss, and/or minimal jitter, and/or minimal end-to-end delay. There is NO requirement that better than best effort functionality MUST exist. There is NO requirement that if better-than-best effort functionality exists then it must be ubuiquitous between end users. 5) Authorisation Authorisation is a method of validating that a user or some traffic is authorized by policy to use a particular service offering. Mechanisms must be implemented so that only authorised users have access to emergency telecommunications services. Any mechanism for providing such authorisation beyond closed private networks should meet IETF Security Area criterion (e.g. clear-text passwords would not generally be acceptable). Authorization protects network resources from excessive use, from abuse, and might also support billing and accounting for the offered service. Such authorization mechanisms should be flexible enough to provide various levels of restriction and authorization depending on the expectations of a particular service or customer. 6) Integrity & Authentication In practice, authentication and integrity for IP based communications are generally bound within a single mechanism, even though conceptually they are different. Authentication ensures that the user or traffic is who it claims to be. Integrity offers assurance that unauthorised modifications to objects can be detected. Carlberg & Atkinson Expires June 20, 2003 [Page 5] ^L Internet Draft ETS General Requirements January 20, 2003 Authorised emergency traffic needs to have reduced risk of adverse impact from denial of service. This implies a need to ensure integrity of the authorised emergency network traffic. Users of emergency network services SHOULD consider deploying end-to-end integrity and authentication, rather than relying on services that might be offered by any single provider of emergency network services. Users should also carefully consider which application-layer security services might be appropriate to use. 7) Confidentiality Some emergency communications might have a requirement that they not be susceptible to interception or viewing by others, due to the sensitive and urgent nature of emergency response activities. An emergency telecommunications service MAY offer options to provide confidentiality for certain authorised user traffic. Consistent with other IETF standards and the Internet Architecture, this document recommends that IEprep users deploy end-to-end security mechanisms, rather than rely on security services that might be offered by a single network operator. IEPREP users should carefully consider security alternatives (e.g. PGP, TLS, IPsec transport-mode) at different layers (e.g. Application Layer, Session Layer, Transport Layer) of the Internet Architecture before deployment. 4. Issues This section presents issues that arise in considering solutions for the requirements that have been defined for ETS. This section does not specify solutions nor is it to be confused with requirements. Subsequent documents that articulate a more specific set of requirements for a particular service may make a statement about the following issues. 1) Accounting Accounting represents a method of tracking actual usage of a service. We assume that the usage of any service better than best effort will be tracked and subsequently billed to the user. Accounting is not addressed as a general requirement for ETS. However, solutions used to realize ETS should not preclude an accounting mechanism. 2) Admission Control Carlberg & Atkinson Expires June 20, 2003 [Page 6] ^L Internet Draft ETS General Requirements January 20, 2003 The requirements of section 3 discuss labels and security. In going beyond this, the ability to distinguish emergency flows implies the need for admission control if resources become scarce. Solutions must recognize this when trying to satisfy the above requirements such that the simple presence of a label does not imply admission control always exists along the end-to-end path. 3) Digital Signatures Verification of digital signatures is computationally expensive. If an operator acts upon a label and hence needs to verify the authenticity of the label, then there is a potential denial-of- service attack on the entity performing the authentication. The DoS attack works by flooding the entity performing the authentication with invalid (i.e. not authentic) labelled information, causing the victim to spend excessive amounts of computing resources on signature validation. Even though the invalid information might get discarded after the signature validation fails, the adversary has already forced the victim to expend significant amounts of computing resource. Accordingly, any system requiring such validation SHOULD define operational and protocol measures to reduce the vulnerability to such a DoS attack. 5. Security Security in terms of requirements is discussed section 3 and 4. 6. References 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 ANSI, "Signaling System No. 7(SS7) "High Probability of Completion (HPC) Network Capability" , ANSI T1.631-1993 (R1999). 3 "Description of an International Emergency Preference Scheme (IEPS)", ITU-T Recommendation E.106 March, 2000. 4 "Description for an International Emergency Multimedia Service", ITU Draft Recommendation F.706, February, 2002. 5 "Call Priority Designation for H.323 Calls", ITU Recommendation H.460.4, November, 2002. Carlberg & Atkinson Expires June 20, 2003 [Page 7] ^L Internet Draft ETS General Requirements January 20, 2003 6 ITU, "Multi-Level Precedence and Preemption Service, ITU, Recomendation, I.255.3, July, 1990. 7 U.S. National Communications System: http://www.ncs.gov 8 U.K Office of Telecommunications (Oftel): http://www.oftel.gov.uk/ 9 Carlberg, K., Atkinson, R., "General Requirements for Emergency Telecommunications Service", Internet Draft, Work In Progress, September, 2002 10 Tada, N., et. al., "IAA System (I Am Alive): The Experiences of the Internet Disaster Drills", Proceedings of INET-2000, June. 11 Heinanen, J., et. al., "Assured Forwarding PHB Group", RFC 2597, June 1999 7. Author's Addresses Ken Carlberg Ran Atkinson University College London Extreme Networks Department of Computer Science 3585 Monroe Street Gower Street Santa Clara, CA London, WC1E 6BT 95051 USA United Kingdom k.carlberg@cs.ucl.ac.uk rja@extremenetworks.com Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to 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. 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