IETF INTERNET-DRAFT Thierry Ernst WIDE Project / INRIA Hong-Yon Lach Motorola Labs February 2002 Network Mobility Support Terminology draft-ernst-monet-terminology-00.txt 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. Abstract The purpose of traditional mobility support is to provide continuous Internet connectivity to mobile hosts (host mobility support). In contrast, network mobility support is concerned with situations where an entire network changes its point of attachment to the Internet and thus its reachability in the topology. We shall refer to such a network as a mobile network (MONET). There is presently no existing terminology to define the issues, goals, architecture elements, problems and requirements pertaining to network mobility support, but one is needed. It is therefore the object of this document to define a new terminology, to depict the characteristics of mobile networks and to make some observations. Ernst and Lach Expires August 2002 [Page 1] INTERNET-DRAFT Network Mobility Support Terminology February 2002 Contents Status of This Memo Abstract 1. Introduction 2. Terminology 2.1. Architecture Components 2.2. Other Terminology 3. Characteristics / Observations Acknowledgments References Author's Addresses 1. Introduction The purpose of traditional mobility support is to provide continuous Internet connectivity to mobile hosts (host mobility support). In contrast, network mobility support is concerned with situations where an entire network changes its point of attachment to the Internet and thus its reachability in the topology. We shall refer to such a network as a mobile network (MONET). Cases of mobile networks include networks attached to people (Personal Area Network or PAN, i.e. a network composed by all Internet appliances carried by people, like a PDA, a mobile phone, a digital camera, a laptop, etc.) and networks of sensors deployed in aircrafts, boats, busses, cars, trains, etc. An airline company that provides permanent on-board Internet access is an example of a mobile network. This allows passengers to use their laptops (this scenario is mentioned in [Tanenbaum96] under section 1.2.4 and section 5.5.8; [Perkins98] under section 5.12; [Solomon98] under section 11.2; and [RFC2002] section 4.5), PDA, or mobile phone to connect to remote hosts, download music or video, browse the web. Passengers could themselves carry a network with them (a PAN). At the same time, air control traffic could be exchanged between the aircraft and air traffic control stations (this scenario has already been investigated by Eurocontrol, the European Organization for the safety of air navigation, [Quinot98]). During a transatlantic flight, the aircraft changes its point of attachment to the Internet and may be reachable by distinct Internet Service Providers (ISPs). Over the oceans, the aircraft gets connected to the Internet through a geostationary Ernst and Lach Expires August 2002 [Page 2] INTERNET-DRAFT Network Mobility Support Terminology February 2002 satellite; over the ground, it's through a radio link. Handoffs do typically not occur very often (a radio link may cover 400-500 kilometers). Another similar scenario mentioning ships and aircrafts can be found in [RFC1726, section 5.15]. Similarly, a bus, the metropolitan public transport, or the taxi company could allow passengers to connect their PAN to the Internet via the embarked network, therefore ensuring, while on-board, an alternative to the metropolitan cellular network, in terms of price or available bandwidth, access control, etc. Meanwhile, a number of Internet appliances deployed in the mobile network are used to collect traffic and navigation data from the Internet while sensors within the mobile network collect and transmit to the Internet live information, like the current number of passengers, expected time to arrival, the amount of petrol left in the tank, etc. For a number of reasons (network management, security, performance,...), it is desirable to interconnect the Internet appliances deployed in cars, trains, busses by means of, for instance, an Ethernet cable, instead of connecting them individually and directly to the Internet, therefore exhibiting the need to displace an entire network. To describe such kind of scenarios, we need to agree on a terminology. However, there is presently no existing terminology to define the issues, goals, architecture elements, problems and requirements pertaining to the scenarios outlined here above, but one is needed. It is therefore the object of this document to define such a new terminology and to make some observations. The material presented in this document is based on [Ernst01] and on our former internet-draft that was submitted in July 2001 [OLD-draft] for the consideration of the Mobile IP Working Group. In addition to the present terminology, this former draft was also presenting a set of requirements and issues as an attempt to clarify the problem caused by networks in motion. We decided to split this former document in two because requirements are more subject to discussion and disagreements that the terminology on which we must agree on to base our discussion. Our proposed requirements can therefore now be found in [REQUIREMENTS]. Additional requirements may be found in [REQUIREMENTS-NOKIA] and [REQUIREMENTS-MOTOROLA]. A comprehensive description of the problem and issues posed by networks in motion is discussed in [SCOPE]. More information may be found on the MONET web page [WEB-MONET]. 2. Terminology Our proposed terminology defines a number of new terms in conformance with the terminology already defined in the IPv6 [RFC2460] and Mobile IPv6 [MIPv6] specifications. Note that our terminology is primarily targeted to IPv6, but is not limited to it. The first section defines Ernst and Lach Expires August 2002 [Page 3] INTERNET-DRAFT Network Mobility Support Terminology February 2002 the architecture components, and the second section defines a number of other terms useful to discuss requirements. 2.1. Architecture Components Mobile Network (MONET) A set of nodes composed by one or more IP-subnets attached to a mobile router (MR) and mobile as a unit, with respect to the rest of the Internet, i.e. a MR and all its attached nodes. The MR changes dynamically its point of attachment to the Internet and thus its reachability in the Internet. Mobile IP-subnet A MONET composed of a single IP-subnet. ____ | | | CN | |____| ___|____________________ | | | | | Internet | | | |________________________| __|_ __|_ | | Access | | | AR | Router | AR | |____| |____| ______|__ foreign __|_____________ home link __|_ link | | | MR | Mobile Router |____| _________|_______ internal __|__ __|__ link | | | | | MNN | | MNN | Mobile Network Nodes |_____| |_____| Figure 1: Terminology Mobile Network Node (MNN) Any host or router located within the MONET, either permanently or temporarily. A MNN could be any of a MR, LFN, VMN, or LMN. The distinction between LFN, LMN and VMN is necessary to discuss Ernst and Lach Expires August 2002 [Page 4] INTERNET-DRAFT Network Mobility Support Terminology February 2002 issues related to mobility management and access control, but does not preclude that mobility should be handled differently. Mobile Router (MR) A router which attaches the MONET to the rest of the Internet. The MR maintains the Internet connectivity for the MONET. It is used as a gateway to route packets between the MONET and the Internet. The MR has at least two interfaces, an egress interface, and an ingress interface. When transmitting a packet to the Internet (i.e. outside), it sends it through the egress interface; when transmitting it withing the MONET (i.e. inside), it sends it through the ingress interface. ____ | | | CN | |____| ___|____________________ | | | | | Internet | | | |________________________| __|_ __|_ | | Access | | | AR | Router | AR | |____| |____| __|_ _____|_____________ home | | _|__ link | MN ] | | | |____| |__| MR | Mobile Router | |____| | __|_____________ internal | __|__ __|__ link 1 _____ | | | | | | |__| | LFN | | LMN | | LFN | | |_____| |_____| |_____| | | internal link 2 Figure 2: Larger Mobile Network with 2 subnets Local Fixed Node (LFN) A node permanently located within the MONET and that does not change its point of attachment. A LFN can either be a LFH (Local Fixed Host) or a LFR (Local Fixed Router). Ernst and Lach Expires August 2002 [Page 5] INTERNET-DRAFT Network Mobility Support Terminology February 2002 Local Mobile Node (LMN) A mobile node that belongs to the MONET and that changes its point of attachment from a link within the mobile network to another link within or outside the MONET (the home link of the LMN is a link within MONET). A LMN can either be a LMH (Local Mobile Host) or a LMR (Local Mobile Router). ____ | | | CN | |____| ___|____________________ | | | | | Internet | | | |________________________| __|_ __|_ | | Access | | | AR | Router | AR | |____| |____| __|_ _____|_____________ home | | _|__ link | MN | | | | |____| _____ |__| MR | Mobile Router | |__| |____| |--> | LMN | | __|_____________ internal | |_____| | __|__ | link 1 | _____ | | | | | |__| | LFN | | | LFN | | |_____| | | |_____| | | | | internal | | link 2 | |------------------------------| Figure 3: LMN changing subnet Visiting Mobile Node (VMN) A mobile node that does not belong to the MONET and that changes its point of attachment from a link outside the MONET to a link within the MONET (the home link of the VMN is not a link within the MONET). A VMN that attaches to a link within the MONET obtains an address on that link. A VMN can either be a VMH (Visiting Mobile Host) or a VMR (Visiting Mobile Router). Ernst and Lach Expires August 2002 [Page 6] INTERNET-DRAFT Network Mobility Support Terminology February 2002 Top-Level Mobile Router (TLMR) In case there are more MONETs aggregated into the MONET, the TLMR is the MR(s) used to direcly connect the aggregated MONET to the fixed Internet. Node behind the MR Any MNN in a MONET that is not a MR for this MONET. Correspondent Node (CN) of a MONET Any node located outside the MONET that is communicating with one or more MNNs. CNs corresponding with MNNs located in the same MONET are said to be CNs of this MONET. Access Router (AR) Any subsequent point of attachment of the MONET at the network layer. Basically, a router on the home link or the foreign link. When considering nested mobility, an AR seen by the MONET may be a MR or a LFR for the entire network. Home subnet prefix A bit string that consists of some number of initial bits of an IP address which identifies the home link within the Internet topology (i.e. the IP subnet prefix corresponding to the mobile node's home address, as defined in [MIPv6]). Foreign subnet prefix A bit string that consists of some number of initial bits of an IP address which identifies a foreign link within the Internet topology. Mobile Network Prefix A bit string that consists of some number of initial bits of an IP address which identifies a MONET within the Internet topology. Nodes belonging to the MONET (i.e. at least MR, LFNs and LMNs) share the same IPv6 "network identifier". For a single mobile IP- subnet, the Mobile Network Prefix is the "network identifier" of this subnet. Egress Interface of a MR The interface attached to the home link if the MONET is at home, Ernst and Lach Expires August 2002 [Page 7] INTERNET-DRAFT Network Mobility Support Terminology February 2002 or attached to a foreign link if the MONET is in a foreign network. Ingress Interface of a MR The interface attached to a link inside the MONET. This interface is configured with the Mobile Network Prefix. ____ | | | CN | |____| ___|____________________ | | | | | Internet | | | |________________________| __|_ __|_ | | Access | | | AR | Router | AR | |____| |____| _____|_____________ home | _|__ link | | | | | _____ |__| MR | Mobile Router | | |__| |____| ----------> | VMN | | __|_____________ internal |_____| | __|__ __|__ link 1 _____ | | | | | | |__| | LFN | | LMN | | LFN | | |_____| |_____| |_____| | | internal link 2 Figure 4: Nested Mobility: Visiting Mobile Node (VMN) The terminology is summarized in fig.1 and to 5. Fig.1 shows a single mobile IP-subnet. Fig.2. shows a large mobile network. Fig.3 illustrates a LMN changing subnet within the mobile network whereas fig.4 illustrates the case of a VMN that enters the mobile network. Fig 5. illustrates the case of a mobile IP-subnet that attaches to a MONET. 2.2. Other Terminology Nested mobility Ernst and Lach Expires August 2002 [Page 8] INTERNET-DRAFT Network Mobility Support Terminology February 2002 We speak about nested mobility when a MONET comprises mobile nodes (LMNs or VMNs) and even MONETs. In the bus instance, the bus is a MONET whereas a passenger is either a VMN in a MONET if it carries a mobile phone or a MONET in the MONET if it carries a PAN. ____ | | | CN | |____| ___|____________________ | | | | | Internet | | | |________________________| __|_ __|_ | | Access | | | AR | Router | AR | |____| |____| _____|_____________ home _|__ link | | | | _____ |__| MR | Mobile Router (TLMR) |_| |__| |____| | | VMR | | __|_____________ internal | |_____| | __|__ __|__ link 1 _____ | | | | | | | | | | | LFN | | LMN | | LFN |__| | |_____| |_____| |_____| | | | | internal link 2 Figure 5: Nested Mobility: mobile IP-subnet in a MONET Multi-Homing A MONET is multi-homed when it has two or more active egress interfaces connected to distinct parts of the Internet. This could either be a single MR with two egress interfaces simultaneously connected to the Internet, or the MONET may be connected to the Internet via two or more MRs. In the first case, we could think of a unique router used to connect a car both to the cellular phone network and to a satellite. In the second case, we may think of a PAN where a phone is used to connect the PAN to the cellular phone network whereas a Bluetooth PDA is used to collect bus timetables from the city bus network. In this situation both the phone and the PDA are MRs. Ernst and Lach Expires August 2002 [Page 9] INTERNET-DRAFT Network Mobility Support Terminology February 2002 Local-Area Mobility Mobility within a single administrative domain, i.e. between subnetworks topologically close in the IP hierarchy. In the literature, and depending on the definition of ``closeness'', this is also termed intra-site mobility, intra-domain mobility, local mobility or micro-mobility. As an instance of Local-Area Mobility, the displacement of a node within a limited vicinity of adjacent subnetworks, like in a campus, that belong to the same organization or between ARs that belong to the same ISP. Wide-Area Mobility Mobility across domain boundaries, i.e. between subnetworks topologically distant in the IP hierarchy. In the literature, and depending on the definition of ``remoteness'', this is also termed inter-site mobility, inter-domain mobility, or global mobility, or macro-mobility. As an instance of Wide-Area Mobility, displacement of a node between distinct ISPs or organizations, or between widely separated sites of a single organization. Idle MNN A MNN that does not engage in any communication. Idle Mobile Network A MONET that does not engage in any communication outside the network may be considered as idle from the point of view of the Internet. This doesn't preclude that MNNs are themselves idle. Internal traffic between any two MNNs located in the same MONET is not concerned by this statement. Ernst and Lach Expires August 2002 [Page 10] INTERNET-DRAFT Network Mobility Support Terminology February 2002 3. Observations Structure of the mobile network A MR changing its point of attachment does not cause the MNNs behind the MR to change their own physical point of attachment. Thus, the internal structure of a MONET is not modified as a result of the MONET changing its point of attachment and a MNN may not notice such a displacement. However, MNNs MAY appear to move from the point of view of an other node in the Internet. Mobile Router is a transit point All packets sent from a CN to a MNN necessarily transit through a MR. Size of the MONET A MONET may comprise one or more subnets. Its size could scale from a sole subnet with a few IP devices, such as in the case of a PAN, to a collection of subnets with hundreds of IP devices, such as in a train. Large number of CNs A MONET may have a very large number of CNs. For instance, each passenger in a train may be considered a MNN. Each of them may be communicating with a few CNs. As a result, the total number of CNs could be several times as large as the number of MNNs and scale up to a few thousands. Sparseness of the CNs CNs are typically sparsely distributed in the Internet and belong to distinct administrative domains. Handoff frequency MONETs may not move with the same speed and frequency. For instance, a PAN connected to the Internet via a 802.11b WLAN (e.g. user in a shopping mall) is likely to change its point of attachment very frequently, while an aircraft or a boat may be connected to the Internet via the same satellite link for a couple of hours. Obviously, MONETs may not move at all for a large amount of time. Ad-Hoc Network Ernst and Lach Expires August 2002 [Page 11] INTERNET-DRAFT Network Mobility Support Terminology February 2002 An Ad-hoc network as defined in the IETF MANET Working Group is not to be confused with a MONET. An ad-hoc network is an autonomous system of mobile nodes (i.e. routers) connected by wireless links. The routers are free to move randomly and to organize themselves arbitrary. In a mobile network, some routers may effectively move arbitrary, but this not a common case. However, an Ad-hoc network connected to the Internet and that changes its point of attachment may be considered as a special instance of a MONET. Routers in the Mobile Network All routers in the Internet are considered to run a number of protocols such as a routing protocol, Neighbor Discovery, ICMP, and others. This also applies to routers in the MONET, including the MR. Ernst and Lach Expires August 2002 [Page 12] INTERNET-DRAFT Network Mobility Support Terminology February 2002 Acknowledgments The first author would like to thank both Motorola Labs Paris and INRIA Rhône-Alpes, for the opportunity to bring this topic to the IETF, and particularly Claude Castelluccia (INRIA) for its advices, suggestions, and direction. We also acknowledge Alexandru Petrescu (Motorola), Christophe Janneteau (Motorola), Hesham Soliman (Ericsson) and Mattias Petterson (Ericsson) for their comments on this draft. References [Ernst01] Thierry Ernst "Network Mobility Support in IPv6", PhD Thesis, University Joseph Fourier Grenoble, France. October 2001. [MIPv6] David B. Johnson and C. Perkins. "Mobility Support in IPv6". Internet Draft draft-ietf-mobileip-ipv6-14.txt, Internet Engineering Task Force (IETF), July 2001. Work in progress. [OLD-draft] Thierry Ernst, Hong-Yon Lach, Claude Castelluccia "Network Mobility Support in IPv6: Problem Statement and Requirements", IETF Internet-Draft draft-ernst-mobileip- monetv6-00.txt, July 2001. Expiration pending. [Perkins98] C. E. Perkins. Mobile IP, Design Principles and Practices. Wireless Communications Series. Addison-Wesley, 1998. ISBN 0-201-63469-4. [Quinot98] Thomas Quinot. An IPv6 architecture for Aeronautical Telecommunication Network. Master's thesis, Ecole Nationale Superieure des Telecommunications Paris, EUROCONTROL - European Organization for the Safety of Air Navigation - ISA project (IPv6, Satellite communication and ATMode for ATN), 1998. http://www.eurocontrol.fr/. [RFC1726] C. Partridge "Technical Criteria for Choosing IP the Next Generation (IPng)", IETF RFC 1726 section 5.15, December 1994. [RFC2460] S. Deering and R. Hinden. "Internet Protocol Version 6 (IPv6) Specification". IETF RFC 2460, Internet Engineering Task Force (IETF), December 1998. [RFC2002] C. Perkins (Editor). IP Mobility Support. IETF RFC 2002, October 1996. [REQUIREMENTS] Thierry Ernst "Requirements for Network Mobility Support", IETF Internet-Draft draft-ernst-monet-requirements-00.txt, February 2001. Work in progress. Ernst and Lach Expires August 2002 [Page 13] INTERNET-DRAFT Network Mobility Support Terminology February 2002 [REQUIREMENTS-MOTOROLA] Hong-Yon Lach "Mobile Network Scenarios, Scope and Requirements", IETF Internet-Draft draft-lach-monet- requirements-00.txt, February 2002. Work in progress. [REQUIREMENTS-NOKIA] draft-kniveton-monet-requirements.txt, February 2002. Work in progress. [SCOPE] Hesham Soliman "Problem Scope", IETF Internet-Draft draft- soliman-monet-scope-00.txt, February 2002. Work in progress. [Solomon98] J. D. Solomon. Mobile IP, The Internet Unplugged. Prentice Hall Series in Computer Networking and Distributed Systems. Prentice Hall PTR, 1998. ISBN 0-13-856246-6. [Tanenbaum96] Andrew Tanenbaum "Computer Networks", Prentice-Hall, Third Edition. 1996 [WEB-MONET] MONET web page http://www.nal.motlabs.com/monet Author's Addresses Questions about this document can be directed to the authors: Thierry Ernst, WIDE Project Jun Murai lab. Faculty of Environmental Information, Keio University. 5322 Endo, Fujisawa-shi, Kanagawa 252-8520, Japan. Phone : +81-466-49-1100 Fax : +81-466-49-1395 E-mail: ernst@sfc.wide.ad.jp Web: http://www.sfc.wide.ad.jp/~ernst/ Hong-Yon Lach Motorola Labs Paris, Lab Manager, Networking and Applications Lab (NAL) Espace Technologique - Saint Aubin 91193 Gif-sur-Yvette Cedex, France Phone: +33-169-35-25-36 Email: Hong-Yon.Lach@crm.mot.com Ernst and Lach Expires August 2002 [Page 14]