Internet Engineering Task Force Ken Carlberg INTERNET DRAFT G11 May 14, 2004 Charlie Perkins Nokia Requirements for MIPv4 Mobility Agents Support of 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. 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 requirements for the IPv4 Mobile IP (MIP) protocol to support Emergency Telecommunications Service (ETS). 1. Introduction Effective telecommunications capabilities can be imperative to facilitate immediate recovery operations for serious disaster events, such as, hurricanes, floods, earthquakes, and attacks by hostile individuals. 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 include: conventional telephone, cellular phones, and Internet access (possibly at 802.11 hotspots) via online terminals, Carlberg & Perkins Expires November 14, 2004 [Page 1] Internet Drafts ETS Requirements for MIP May 14, 2004 IP telephones, and wireless PDAs. The commercial telecommunications infrastructure is rapidly evolving to Internet-based technology. Therefore, the Internet community should accept the responsibility to consider how it can best support emergency management and recovery operations. Emergency Telecommunications Service (ETS) involves authorized access and use of services (i.e., resources) set aside for users involved in disaster response or recovery. The manner in which these resources are identified and allocated for ETS users is outside the scope of this document. A general set of requirements for ETS has been defined in [2], and is meant to act as a baseline for future and more specific requirements. The requirements presented in section 3 below represent an extension to [2] and are aimed at the mobility agents specified in the Mobile IP (MIP) protocol [3]. Note, all references to MIP in this document refer to the IPv4 version of the protocol. However, similar considerations can be expected to be applied for IPv6 MIP whenever the appropriate access control points are able to be identified. For IPv4, it is easy to specify the foreign agent as the requisite control point. 2. Mobile IP MIP is used to support a mobile host that operates in either its home or in foreign networks. These networks have mobility agents, designated as either foreign agents or home agents, that forward traffic between the mobile device and correspondent hosts. Agent Discovery involves an exchange of messages (Agent Advertisements) that allow the mobile host to determine whether it is connected within its home domain or in a foreign network. This discovery process also indicates if the host has moved to a different IP network. Beyond the discovery of other MIP nodes and movement, Agent Advertisements are used by mobility agents to advertise services on a link. These messages are sent as an extension of the ICMP Router Advertisement. The Mobility Agent Advertisement Extension message is an example of the extentions defined in MIP and is used to convey one of several services that are offered by the node -- such as "this node is a Home Agent and/or Foreign Agent". Of particular importance to this document is that this extension may indicate that the Foreign Agent is BUSY and will not accept registrations from additional mobile nodes. Carlberg & Perkins Expires November 14, 2004 [Page 2] Internet Drafts ETS Requirements for MIP May 14, 2004 The existance of a busy condition implies that a threshold exists that prevents any additional registrations to be accepted by that mobility agent. During times of disasters, a need may arise to allow mobile users involved in disaster recovery or response to bypass this "busy" condition. This function, and the requirements of how it is accomplished, is the concern of this document. The precise manner in which this bypass is accomplished with respect to conveying existing and requested service is outside the scope of this document. However, contraints and references to previous related RFCs with respect to security are listed. 3. Requirements We divide the set of requirements into two subgroups. The first involves the list of requirements concerning the advertisement of ETS support and the request/registration of that service. The second set of requirements pertain to security and the authorization & authentication features needed by the system to ensure that the correct set of users are enabled to obtain their desired service. 3.1 Conveying ETS Information The requirements below pertain to those entities that choose to support ETS type users. For those that choose not to provide this support users, either because of legacy implementations of [3] or because of lack of configuration, the following do not apply. 3.1.1 Mobility Agent Indicates ETS Support In order for mobile hosts to determine if ETS type users are supported, mobility agents are required to be able to advertise this service and therefore distinguish themselves from other mobility agents. 3.1.2 Form of ETS Advertisement by Mobility Agent The advertisement of ETS support by mobility agents can either be a binary indicator, or a more descriptive format that identifies the sets of ETS users supported by that agent. Tradeoffs regarding scarcity of unreserved fields in existing MIP messages versus significant changes to MIP deserve close consideration. 3.1.3 Role of Mobility Agents Mobility Agents may support non-ETS users at the same time as providing support for ETS users. Carlberg & Perkins Expires November 14, 2004 [Page 3] Internet Drafts ETS Requirements for MIP May 14, 2004 3.1.4 Mobile Host Requesting ETS Support If a mobile host needs to use an ETS capable mobility agent, the means by which a mobile host obtains that service has to be specified -- this is particularly important when mobile agents support for ETS and non-ETS users. This is likely to involve defining a new message format that explicitly signals the requested service, but it may also involve others means of identification. 3.1.5 Preemption Mobility agents that provide ETS support may preempt (or even terminate) existing registrations of non-ETS users in favor of ETS users. This action is subject to local policies of that agent. Refer to [2] for additional insight in the role of policies with respect to ETS. 3.2 Security Requirements The operation of ETS is expected to introduce certain security requirements, which are mentioned in this section. 3.2.1 MIP AAA compatibility Solutions are expected to remain compatible with the MIP AAA requirements document of RFC 2977[4]. 3.2.2 Foreign agent operation Foreign agents are required to be able to check that a mobile device is authorized to use ETS. Otherwise, arbitrary mobile devices could routinely obtain services for applications that have no requirement for emergency services. 4. Security Considerations If a foreign agent does not protect against unauthorized invocation of ETS features, the danger exists that the additional resources required would be unavailable in the case of real need. Moreover, a malicious node would typically target ETS to disable the delivery of needed support in conflict situations. Vulnerability to such attacks should be minimized. Carlberg & Perkins Expires November 14, 2004 [Page 4] Internet Drafts ETS Requirements for MIP May 14, 2004 5. References 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 Carlberg, K., Atkinson, R., "General Requirements for Emergency Telecommunication Service (ETS)", RFC 3689, February 2004 3 Perkins, C., ed., "IP Mobility Support for IPv4", RFC 3344, August 2002. 4 Glass, S., et. al, "Mobile IP Authentication, Authorization, and Accounting Requirements", RFC 2977, October 2000 6. Author's Addresses Ken Carlberg Charlie Perkins G11 Communications Systems Laboratory 123a Versailles Circle Nokia Research Center Baltimore, MD 313 Fairchild Drive USA Mountain View, CA 94303 USA carlberg@g11.org.uk Charles.Perkins@nokia.com Full Copyright Statement "Copyright (C) The Internet Society (2004). All Rights Reserved. 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Carlberg & Perkins Expires November 14, 2004 [Page 5] Internet Drafts ETS Requirements for MIP May 14, 2004 This document and the information contained herein is provided as 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 OR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Carlberg & Perkins Expires November 14, 2004 [Page 6]