Internet Engineering Task Force J. Palet Internet-Draft M. Diaz Expires: October 20, 2004 Consulintel April 21, 2004 Evaluation of IPv6 Auto-Transition Mechanism draft-palet-v6ops-auto-trans-00.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 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. This Internet-Draft will expire on October 20, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This draft evaluates a method called "auto-transition" to ensure that any device can obtain IPv6 connectivity at any time and whatever network is attached to. The method looks for the best transition mechanism according to performance criteria as well as the scenario where the device is located. By implementing such auto-transition method in either or both end nodes or middle boxes (CPEs), users can always obtain IPv6 Palet & Diaz Expires October 20, 2004 [Page 1] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 connectivity with no human intervention. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Auto-Transition Overview . . . . . . . . . . . . . . . . . . . 3 3. Auto-Transition Requirements . . . . . . . . . . . . . . . . . 4 3.1 Selection of the proper transition mechanism . . . . . . . 5 3.2 Change of transition mechanism . . . . . . . . . . . . . . 7 3.3 New transition mechanisms . . . . . . . . . . . . . . . . 8 3.3.1 Layer 2 tunnels . . . . . . . . . . . . . . . . . . . 8 3.3.2 Layer 3 tunnels . . . . . . . . . . . . . . . . . . . 9 3.3.3 Layer 4 tunnels . . . . . . . . . . . . . . . . . . . 10 3.4 Discovery of the IPv6 End Point . . . . . . . . . . . . . 10 4. Nomadicity Considerations . . . . . . . . . . . . . . . . . . 11 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.1 Normative References . . . . . . . . . . . . . . . . . . . . 14 8.2 Informative References . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . 17 Palet & Diaz Expires October 20, 2004 [Page 2] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 1. Introduction The main goal is to facilitate the IPv6 deployment in a seamless way for devices, users and applications. Lots of devices and applications around us will benefit obtaining IPv6 connectivity everywhere: home automation, wearable devices, cars, PDAs, mobile phones, peer-to-peer applications, remote control applications, etc. IPv6 is suitable to solve the network requirements that those devices/applications will need: addressing space, end-to-end secure peer-to-peer communication, autoconfiguration features and so on. IPv6 provides autoconfiguration features, enabling devices to work according to the plug-and-play philosophy, that is with no manual intervention. However they only can be applied once the device has obtained IPv6 connectivity. On the other hand, while native IPv6 connectivity is not available everywhere, there is not a good "auto-transition" to ensure this connectivity. While devices are located in a native IPv6 environment, no manual intervention is required, so non technical users can take advantage of IPv6. However until all or most of the networks are IPv6 native, we need to ensure that the same devices and users can use a transition mechanism that ensures the best possible IPv6 connectivity, without any technical knowledge. Is not acceptable require to the users to make manual configurations in order to get the IPv6 connectivity. The mechanism will deal with all the tasks required to configure automatically the best IPv6 connectivity at anytime, in any network scenario, which include native IPv6 connectivity detection and transition mechanism selection if required. It can be implemented either in stand-alone devices (hosts, PDA, etc.) or middle boxes like CPE routers. 2. Auto-Transition Overview When the device is attached to the network, the mechanism first must check if native IPv6 connectivity is possible. If so, either or both stateless [1] or stateful autoconfiguration [2] mechanism are performed. Otherwise, the auto-transition mechanism should try to obtain IPv6 connectivity by using the best transition mechanism according to the network where the devices is attached. Later, the conditions of the network can change, even the user/device can change the location while moving. Consequently the attachment point to the network can be different, and the previous transition mechanism no longer be so convenient. The auto-transition mechanism has to monitor periodically the network parameters (i.e. IPv4 Palet & Diaz Expires October 20, 2004 [Page 3] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 address, loss, delays, etc.) in order to detect those changes and decide if another transition mechanism different to the one currently being used is convenient and provides better performance to activate it. All this process should be ideally automatic in order to avoid the user to make any manual configuration. At the most, users only should introduce some parameters by means of a wizard during the installation process of the application that implements the auto-transition mechanism, but once it is up and running, all the tasks should be made by the system and no manual intervention required. This approach should be available at least in two kind of platforms. o End devices: Devices that do not intend to provide IPv6 connectivity to others. They are typically devices that would get IPv6 connectivity by means of Router Advertisement if they were attached to a native IPv6 scenario. Examples are hosts, PDAs, mobile phones, cameras, home automation devices, white goods, consumer electronics, etc. o CPE devices: Devices that are located between two different networks or networks segments. Typically routers, IPv4 NAT boxes, etc. They should provide native IPv6 connectivity to the whole network(s) located behind them by announcing an IPv6 prefix. With this approach this kind of devices will be plug-and-play, so users only have to attach them to the network and they will deal with all the tasks to get IPv6 connectivity. A few applications include home networks, hotels, hot-spots and so on. 3. Auto-Transition Requirements The best IPv6 connectivity, in principle, is obviously the native one if available, since it should not add extra delays in the communication neither introduce more complexity to the networks. Consequently the auto-transition mechanism first must check if IPv6 native connectivity is available. However it strongly depends on the ISP support and can be expected that in the first IPv6 deployment stage, only a few ISPs will provide it. If native connectivity is not available the auto-transition mechanism must choose the right transition mechanism to be used to ensure the connectivity. A number of transition mechanism have been defined already: Teredo, TB/TS, TSP, STEP, ISATAP, 6to4, tunnels, etc. All of them work when Palet & Diaz Expires October 20, 2004 [Page 4] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 the host willing to get IPv6 connectivity has a public IPv4 address. Even some of them also work when the host is located behind a NAT box that allows proto-41 forwarding [3]. However there are other kind of NAT boxes that prevent the current transition mechanisms to work, so there is a gap that could be filled with new kind of solutions, possibly layer 2 or layer 4 tunnels. The adequate selection of the proper transition mechanism is one of the keys of the auto-transition concept. 3.1 Selection of the proper transition mechanism A few scenarios with particular network requirements had been defined already ([4], [5], [6], [7]). Not all the transition scenarios fit in such network scenarios, as being evaluated at [8], trying to make the best fit to each scenario. The auto-transition mechanism may take into account the results shown in [8], although it is also possible a wider focus to select the best transition mechanism to be used. What the end user always demands is the best performance on the IPv6 connectivity, so it should be the main criteria to choose the right transition mechanism. Distance, delays, loss, bandwidth, etc., are some of the related parameters that could be used as metrics to be measured for knowing the link performance. A device can present different values of such metrics according to the transition mechanism that is being used even when attached to the same network. A combination of all the metrics could provide a fine evaluation of the connection performance. However in order to make the mechanism as simple as possible only delay and loss should be considered. According to this philosophy the auto-transition mechanism could operate by means of the following simple algorithm: Palet & Diaz Expires October 20, 2004 [Page 5] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 loop detect_scenario if (native_IPv6_available and native_priority) use_native_IPv6_connectivity else if (first_check or performance_check_allowed) check_performance use_best_mechanism endif endif configure_connectivity wait (link_check_timeout) endloop Figure 1: Simple Auto-transition algorithm It is important to note what each task or parameter means: o detect_scenario: This task deals with detecting the scenario where the device willing to have IPv6 connectivity is located. It could check if native IPv6 is available, if a public IPv4 address is available, if a NAT is being used and what type, if there is a proxy or firewall, or if other protocols can be operated. o native_IPv6_available: Detects if native IPv6 is available. o native_priority: Detects if native IPv6 has priority, for instance, even in the case the performance is lower than alternative transition mechanism that may be used. This condition could be set by the OS, or even under user or applications control. o use_native_IPv6_connectivity: Configure the interface to use native IPv6 connectivity, using stateless or stateful autoconfiguration, upon their availability. o first_check: Defines if this is the first time this check is being done after an interface reset. o performance_check_allowed: Defines if the performance of the selected mechanism can be measured after selected, for instance, to avoid traffic being generated in non-flat rate links (3GPP, ISDN, ...). o check_performance: According to the detected scenario, a number of mechanisms could be used. This task checks the performance that each of such transition mechanism provides, including native IPv6 if available, by measuring delays and losses. The mechanism subset Palet & Diaz Expires October 20, 2004 [Page 6] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 will be defined by taking into account [8], but others could be considered. o use_best_mechanism: According to the measurement results, the best mechanism is selected. o configure_connectivity: Either native IPv6 connectivity or the best available transition mechanism is configured. o link_check_timeout: Once the IPv6 connectivity is obtained, the auto-transition mechanism periodically monitors the link status. The delay between consecutive checks is defined by this variable. A possible list of mechanism to be checked, ordered by preference could be: 1. Native IPv6 Connectivity 2. TS with proto-41 ([3]) 3. TS with UDP 4. ISATAP 5. STEP 6. 6to4 7. Teredo 3.2 Change of transition mechanism Change of transition mechanism refers to the task to abandon the transition mechanism that is actually being used and start to use another one that presents better performance. This is not an easy task at all, since it involves at least two important issues: 1. To maintain the current IPv6 address. This is a must since otherwise applications with communications opened will not work. Specially important is the case which the auto-transition mechanism is implemented in border devices that provide native IPv6 connectivity to the whole network. Either the prefix network (i.e. RA), or the IPv6 addresses (i.e. DHCPv6) that they provide, must be able to keep the IPv6 addressing parameters. If the auto-transition mechanism has to include the possibility of changing the transition mechanism used without discarding the current connection state, it is necessary to define a method that Palet & Diaz Expires October 20, 2004 [Page 7] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 solves this issue. MIPv6 concepts could be applied. 2. User authentication without human intervention. The philosophy of the auto-transition mechanism is that all the processes are done automatically, with no human intervention. So, for instance, if the device running the auto-transition mechanism needs to contact with a TB different to the actual one, and it requires user authentication, the process should be transparent to the user. It could be based on parameters (login and password) configured through the wizard during the installation process. AAA mechanisms should be used. 3.3 New transition mechanisms A number of devices do not allow tunnel-based transition mechanism to work properly. They are both NAT boxes, proxies or firewalls. Even building IPv6 tunnels over UDP is not always possible since some middle boxes do not forward those packets. When this happens it is required that the auto-transition mechanism uses a method that cannot be rejected by the middle box. The following solutions could be considered: 3.3.1 Layer 2 tunnels By using layer 2 encapsulating methods (L2TP [9], PPTP [10], PPPoE [11]), the middle boxes barriers can be easily overcome since this kind of protocols are very used when building layer 2 VPN. Consequently, one of the following protocol stacks might be used. +--------+ +--------+ | IPv6 | | IPv6 | +--------+ +--------+ | PPP | | PPP | +--------+ +--------+ +--------+ | L2TP | | PPTP | | IPv6 | +--------+ +--------+ +--------+ | UDP | | TCP | | PPP | +--------+ +--------+ +--------+ | IPv4 | | IPv4 | | IPv4 | +--------+ +--------+ +--------+ L2TP tunnel PPTP tunnel PPPoE tunnel Figure 2: Layer 2 tunnels Palet & Diaz Expires October 20, 2004 [Page 8] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 This kind of solution does not seem to be efficient due to the following drawbacks: o It requires that the TS is configured as VPN L2 server. o Overloaded stack. IPv6 connection will have low performance. o Complicated deployment and management due to the control plane for L2TP and PPTP. o Authentication is a must with PPP. It means added complexity. 3.3.2 Layer 3 tunnels VPN's built by mean of layer 3 tunnels can be a solution to allow IPv6 connections cross NAT boxes with no proto-41 forwarding capabilities as well as proxies and firewalls. +--------+ +--------+ | IPv6 | | IPv6 | +--------+ +--------+ +--------+ | IPv4 | | IPv4 | | IPv6 | +--------+ +--------+ +--------+ | PPP | | IPsec | | IPv4 | +--------+ +--------+ +--------+ | IPv4 | | IPv4 | | IPv4 | +--------+ +--------+ +--------+ PPP-IPv4 IPsec IPv4-IPv4 Figure 3: Layer 3 tunnels Compared to the Layer 2 tunnels, the layer 3 tunnels have the following advantages: o Less overloaded stacks. o Tunnel management simpler. o There are some implementations (VTun, cIPE, TINC). However it also have important drawbacks: o It requires that the TS is configured as VPN L2 server. o Some NAT's could not support those. Palet & Diaz Expires October 20, 2004 [Page 9] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 3.3.3 Layer 4 tunnels The last resort is to try to overcome the middle barriers by means of the use of frequently used application protocols. There are two well known possibilities that frequently will not create difficulties with neither proxies nor firewalls: HTTP and SSH. Furthermore, they neither have problems with NAT boxes. The protocol stack for this solution is as follows: +--------+ +--------+ | IPv6 | | IPv6 | +--------+ +--------+ | HTTP | | SSH | +--------+ +--------+ | TCP | | TCP | +--------+ +--------+ | IPv4 | | IPv4 | +--------+ +--------+ HTTP tunnel SSH tunnel Figure 4: Layer 4 tunnels The main advantage of this approach is the simplicity for the configuration of the tunnel. Furthermore the tunnels can be secured by means of either SSL (using HTTPS instead of HTTP) or SSH. According to the different alternatives, it sounds reasonable that the better solution could be Layer 4-based tunnels since it is simpler than the others, and always will work, but the performance will not be optimal. Instead Layer 3 and Layer 2-based tunnels should be taken into account in implementations of the auto-transition mechanism in order to guarantee the IPv6 connectivity by covering all the possible alternatives. The usage of those new mechanism is discouraged, unless there is no other choice. In any case, the standardization of those different tunnel options is out of the scope of this document. 3.4 Discovery of the IPv6 End Point Devices running the auto-transition mechanism need to know where to find the IPv6 (tunnel) end point or tunnel server (TS) that provides them the IPv6 connectivity. If native IPv6 connectivity is provided by the ISP and used, this TS will be obviously the link end point and no further work is required. This is slightly more complex when a transition mechanism is required to obtain the IPv6 connectivity. Palet & Diaz Expires October 20, 2004 [Page 10] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 Having in mind that users want plug-and-play devices/services, and that most of them do not have any knowledge about how the transition mechanism works or where the nearest Tunnel Broker/Tunnel Sever, 6to4 relay, etc. are located, it is required considering the auto-discovery of the IPv6 TS, so the device can find it automatically. Different transition mechanisms have different IPv6 type of end points. For example, the Tunnel Broker/Tunnel Server uses mainly 6in4 tunnels; TSP can used either 6in4 or IPv6 over UDP tunnels; Teredo uses IPv6 over UDP tunnel, etc. Furthermore, each transition mechanism has its own tunnel setup handshake, so it is not only important to know where the nearest IPv6 TS is located but also what type of transition mechanism/s is able to manage. On the other hand, there are situations where people are crowded, i.e. either conferences, airports, urban areas with high population density, etc. In this scenario is very likely that most of the users choose a particular IPv6 TS, usually because it is nearer or more well known. It is possible that while there exist a few IPv6 TS attending many connections, there can exist a lot of them that are not being used. In this way, most of the users have poor performance in their connections while users using TS without congestion will have good performance. It would be desirable that there were some kind of load balancing in order to uniformly distribute the IPv6 tunnel requests among all available IPv6 TS. The different approaches to cope with this issue are analysed in [12]. 4. Nomadicity Considerations When users move across networks, several situations are possible. From the network point of view, users can or cannot maintain the IPv6 address assigned from their home TS. From the transition mechanisms point of view, the new one can or cannot require an authentication process. So clearly some considerations are required regarding the auto-transition mechanism behavior while user is moving. 1. Nodes that do not need to maintain the IPv6 address assigned from their home TS. They are typically nomadic users who get connectivity to "passive" Internet users (browsing, emailing, etc.), but do not need to be "identified" from Internet (nevertheless this situation is changing with next generation p2p applications, VoIP, etc.). Looking for the best IPv6 connectivity can lead the auto-transition mechanism to define as the best TS one of the following: Palet & Diaz Expires October 20, 2004 [Page 11] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 * TSs that do not require authentication process. They are TSs that provide IPv6 connectivity and they do not make any authentication process (TEREDO, 6to4, etc.). This approach does not represent any innovation, so the auto-transition mechanism just contact to the TS and the IPv6 connectivity is obtained. * TSs that require authentication process. They are TSs that only provide IPv6 connectivity to authenticated users (users that previously were somehow registered in the entity providing the IPv6 TS service or some related entity). Automatic AAA mechanism must be defined, in order to ensure the no-human intervention requirement. The TS can or cannot belong to the entity which the user was registered. If so, authentication process is simpler. However, a global authentication only will be possible if there are roaming agreements between the entity that is selected to obtain IPv6 connectivity and the "home" entity which the user is registered. These roaming agreements could be used for billing purposes among others. If there are not such agreements, automatic connectivity is not possible and the auto-transition mechanism has to options: + To choose an alternative transition mechanism, even although it does not offer the best performance. + To inform to the user that the best IPv6 connection is only possible if a new manual registration/authentication process is done. * The behavior should be defined during the wizard installation process of the auto-transition implementation. 2. Nodes that need to maintain the IPv6 address assigned from their home TS. Users belonging to this group are typically users with either server or peer-to-peer applications, devices that need to be tracked (cars, suitcases, etc.), etc. MIPv6 should be applied to this kind of nodes, but the following considerations must to taken into account by the auto-transition mechanism: * Mobility capability should be an option that should be configured by means of the installation wizard. If chosen, the first time that the auto-transition mechanism is run, it must check if a Home Agent (HA) exists either in the current IPv6 network or in the TS. In fact, this option should condition the order of searching for the best transition mechanism to get IPv6 connectivity. In this way, only mechanisms compatible with the presence of HA should be taken into account Palet & Diaz Expires October 20, 2004 [Page 12] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 (mechanisms providing static IPv6 network prefix like TB, TSP, ISATAP, etc.). The auto-transition mechanism should record the mechanism used to get IPv6 connectivity. Some transition mechanisms like ISATAP, allow the HA deployment into the home network which the nomadic device is initially attached. Others, like TB, could be deployed in different networks from the one where the device is physically attached, but the HA could be implemented into the TS that provides the IPv6 connectivity. On the other hand, the auto-transition mechanism should discard transition mechanisms that build the IPv6 network prefix from the IPv4 address (6to4, TEREDO, etc.). This is required because it is no possible the deployment of the HA into the same IPv6 network, so no mobility features would be possible. If no HA is discovered the first time that the auto-transition mechanism is run, then no MIPv6 support is possible, so the user should be informed and the usual auto-transition algorithm must be applied to get IPv6 connectivity. * Once the node is away from home network, it needs to get IPv6 connectivity. The auto-transition mechanism should first check if it possible to maintain the same IPv6 home address, according to the mechanism used, before moving for getting the home address. There are some kinds of transition mechanism that allow this operation like a TB with several TS associated. In this scenario, the node first gets the IPv6 home address from a TS. After the node move to other location, it could get IPv6 connectivity from a different TS that is associated to the same TB. It is possible that either the new TS has the same /64 network prefix that the old TS or it can be configured by the TB to forward/send tunneled packets coming/going from/to the nomadic node. In this way the nomadic device could maintain the IPv6 home address. Even if the new TS does not belong to the same TB but there are roaming agreements between the involved entities, the maintenance of the IPv6 address/prefix could be possible. How to do this configuration is out of scope of this document. * If the IPv6 home address can not be maintained, then once the nomadic device has a new IPv6 address by means of any transition mechanism, it must contact to the HA to communicate the care of address following MIPv6. Other considerations pointed out in [12] should be taken into account. Palet & Diaz Expires October 20, 2004 [Page 13] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 5. Conclusions TBD. 6. Security Considerations The auto-transition mechanism should secure at least the following points: 1. Communication with TS for administrative purposes. 2. Communication with TS for authentication purposes. 3. Tunnel building is according to the chosen TS. 4. General tunnel security consideration pointed at [13]. 7. Acknowledgements This memo was written as a consequence of real experience using IPv6 when traveling, number of talks during IETF meetings and specially the work with the unmanaged, ISP and enterprise v6ops design teams. The authors would also like to acknowledge the European Commission support in the co-funding of the Euro6IX project, where this work is being developed. 8. References 8.1 Normative References 8.2 Informative References [1] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998. [2] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [3] Palet, J., "Forwarding Protocol 41 in NAT Boxes", draft-palet-v6ops-proto41-nat-03 (work in progress), October 2003. [4] Huitema, C., "Evaluation of Transition Mechanisms for Unmanaged Networks", draft-ietf-v6ops-unmaneval-01 (work in progress), February 2004. Palet & Diaz Expires October 20, 2004 [Page 14] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 [5] Lind, M., "Scenarios and Analysis for Introducing IPv6 into ISP Networks", draft-ietf-v6ops-isp-scenarios-analysis-01 (work in progress), February 2004. [6] Wiljakka, J., "Analysis on IPv6 Transition in 3GPP Networks", draft-ietf-v6ops-3gpp-analysis-09 (work in progress), March 2004. [7] Bound, J., "IPv6 Enterprise Network Scenarios", draft-ietf-v6ops-ent-scenarios-01 (work in progress), February 2004. [8] Savola, P. and J. Soininen, "Evaluation of v6ops Tunneling Scenarios and Mechanisms", draft-savola-v6ops-tunneling-01 (work in progress), April 2004. [9] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn, G. and B. Palter, "Layer Two Tunneling Protocol "L2TP"", RFC 2661, August 1999. [10] Hamzeh, K., Pall, G., Verthein, W., Taarud, J., Little, W. and G. Zorn, "Point-to-Point Tunneling Protocol", RFC 2637, July 1999. [11] Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D. and R. Wheeler, "A Method for Transmitting PPP Over Ethernet (PPPoE)", RFC 2516, February 1999. [12] Palet, J. and M. Diaz, "Evaluation of v6ops Auto-discovery for Tunneling Mechanisms", draft-palet-v6ops-tun-auto-disc-00 (work in progress), April 2004. [13] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms for IPv6 Hosts and Routers", draft-ietf-v6ops-mech-v2-02 (work in progress), February 2004. Authors' Addresses Jordi Palet Martinez Consulintel San Jose Artesano, 1 Alcobendas - Madrid E-28108 - Spain Phone: +34 91 151 81 99 Fax: +34 91 151 81 98 EMail: jordi.palet@consulintel.es Palet & Diaz Expires October 20, 2004 [Page 15] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 Miguel Angel Diaz Fernandez Consulintel San Jose Artesano, 1 Alcobendas - Madrid E-28108 - Spain Phone: +34 91 151 81 99 Fax: +34 91 151 81 98 EMail: miguelangel.diaz@consulintel.es Palet & Diaz Expires October 20, 2004 [Page 16] Internet-Draft Evaluation of IPv6 Auto-Transition April 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the IETF's procedures with respect to rights in IETF Documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Palet & Diaz Expires October 20, 2004 [Page 17]