Network Working Group E. Lear Internet-Draft Cisco Systems Expires: May 31, 2004 December 2003 Things MULTI6 Developers should think about draft-lear-multi6-things-to-think-about-01 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. This Internet-Draft will expire on May 31, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document specifies a set of questions that authors should be prepared to answer as part of a solution to multihoming with IPv6. The questions do not assume that multihoming is the only problem of interest, nor do they demand a more general solution either. Lear Expires May 31, 2004 [Page 1] Internet-Draft MULTI6 Solution Questionaire December 2003 1. Introduction At the time of this writing there are some six separate solutions looking at the problem of multihoming within IPv6 and related problems, such as the locator/identifier split. In order to sort through how proposed solutions compare against one another, and potentially, how they can borrow mechanisms and design decisions from one another, this document contains a list of pointed questions. This document contains only some useful questions. There are others that should be added. If you know of one, please email the author, as he has assuredly missed many. Unless it is blatantly obvious, each question contains some reasoning as to why it is being asked. It is envisioned that no solution will answer every question with completeness, but that there will be tradeoffs to be made. The answers by the various designers of solutions will hopefully shed some light on which tradeoffs we as a community wish to make. It would seem silly for people who have written out detailed answers to these questions to have to repeat the exercise. Therefore, a simple reference to existing documents will suffice, so long as the answer is complete. If it is not complete, then feel free to reference it and add what text is necessary to make the answer complete. This document presumes a familiarity with RFC 3582 [2], and does not attempt to repeat the requirements work gathered there. 1.1 Differences between -00 and -01 In section 2.1.2.1, address whether rendezvous SHOULD be handled in a solution. In section 2.2.3, clarified wording. New subsection 2.4.3 on what if you do not use DNS new subsections 2.3,4, 2.4.7, 2.4.8, 2.4.9, 2.4.14 Clarifications on 2.4.15, and perhaps elsewhere. Lear Expires May 31, 2004 [Page 2] Internet-Draft MULTI6 Solution Questionaire December 2003 2. The Questions 2.1 Routing 2.1.1 How will your solution solve the multihoming problem? That's why we're here. Remember, a reference is fine. 2.1.2 Uniqueness 2.1.2.1 Does your solution address mobility? If so, how are rendezvous handled? Can your solution handle both locators changing at the same time? If so, please explain. Should it? If not, how will your solution interact with MOBILEIP-V6 [3] (MIPv6) 2.2 Identifiers and locators 2.2.1 Does your solution provide for a split between identifiers and locators? 2.2.2 What is the lifetime of a binding from an identifier to a locator? 2.2.3 How is the binding updated? Will transport connections remain up when new paths become available or when old ones become unavailable? How does the end node discover these events? 2.3 On The Wire 2.3.1 At what layer is your solution applied, and how? Is it applied in every packet? If so, what fields are used? 2.3.2 Why is the layer you chose the correct one? Each layer has its benefits and tradeoffs. For instance, transport layer solutions would require that EVERY transport be modified, while IP layer solutions may entail expansion of the packet or a change to the pseudo-header (thus requiring changes to the transport layer). 2.3.3 Does your solution expand the size of an IP packet? Expanding the size of an IP packet may cause excessive fragmentation in some circumstances. Lear Expires May 31, 2004 [Page 3] Internet-Draft MULTI6 Solution Questionaire December 2003 2.3.4 Will your solution add additional latency? Latency is an important factor in many applications, including voice. Any substantial amount of additional latency, including session initiation would be highly undesirable. 2.3.5 Do you change the way fragmenting is handled? If you use a shim approach, do you fragment above or below the shim? How are fragments identified, so that they can be reassembled? If you use any additional names, do they need to be associated with fragments? If not, why not? If so, how will that happen? 2.3.6 Are there any changes to ICMP error semantics? Do you create new codes? If so, why and what do they mean? Will a host that is not aware of your scheme see them? 2.4 Names, Hosts, Endpoints, or none of the above? 2.4.1 Please explain the relationship of your solution to DNS If your solution uses new names for identifiers, please explain what mappings are defined, and how they are performed? If there are any additional administrative requirements, such as new zones or RR types to manage, please explain them as well. 2.4.2 If you have separate locators and identifiers, how will they be mapped? Does the mapping work in both directions? How would someone debugging a network determine which end stations are involved? 2.4.3 If you are not using DNS... Please describe the mechanism you are using. 2.4.3.1 Please describe authentication/authorization How are bindings authenticated and authorized. What technology do you build on for this mechanism? 2.4.3.2 Is your mechanism hierarchical? Please describe the hierarchical breakdown. Lear Expires May 31, 2004 [Page 4] Internet-Draft MULTI6 Solution Questionaire December 2003 2.4.4 Please explain interactions with "2-faced" DNS 2-faced DNS is used so that hosts behind a NAT get one address for internal hosts, while hosts outside the NAT get another. Similar mechanisms are used for application layer gateways, such as SOCKS [5]. 2.4.5 Does your solution require centralized registration? For instance, if you are using the DNS, what will be the top level domain, and how will the name space distribute through it? Also, how will the centralized registration be managed? 2.4.6 Have you checked for DNS circular dependencies? If you are using the DNS in your solution, is it required for connectivity? What happens if the DNS fails? Can communication between the DNS resolver and the server make use of your solution? What about between the application and the resolver? 2.4.7 How does a host know its identity? If you are establishing a new identity, how does the host learn it? 2.4.8 What if a DNS server itself is multihomed? If a link fails or a service is dropped, how will it impact DNS? Again are there any dependency loops? Perhaps diagram out your dependencies to make sure. 2.4.9 What additional load will be placed on DNS servers? Can the load be distributed? Remember that DNS is optomized for READ operations. 2.4.10 Any upstream provider support required? If so, please describe. 2.4.11 What application/API changes are needed? Will old code just work with the new mechanism? For instance, what about code that uses gethostbyname()? Will getaddrinfo() need to change? What about other API calls? Lear Expires May 31, 2004 [Page 5] Internet-Draft MULTI6 Solution Questionaire December 2003 2.4.12 Is this solution backward compatable with "old" IP version 6? Can it be deployed incrementally? Please describe how. Does your solution impose requirements on non-multihomed/non-mobile hosts? What happens if someone plugs in a normal IPv6 node? 2.4.13 Is your solution backward compatable with IPv4? How will your mechanism interact with 6to4 gateways and IPv4 hosts? 2.4.14 Can IPv4 devices take advantage of this solution? Can the same mechanism somehow be used on the existing network? N.B. this is NOT a requirement, but more a consideration. 2.4.15 What is the impact of your solution on different types of sites? How are single homed sites impacted? How are small multihomed sites impacted? How does it scale for large multihomed sites? What about ad-hoc sites such as an IETF event? 2.4.16 How will your solution interact with other middleboxes? What are the implications for firewalls? What are the interactions with NAT? What are the interactions with web caches? What complications are introduced with your solution? 2.4.17 Are there any implications for scoped addressing? Please see RFC 3513 [1]. How does your mechanism interact with multicast? How does your solution interact with link-local addressing How does your solution interact with Son-Of-Sitelocal (whatever that will be)? 2.4.18 Are there any layer 2 implications to your proposal? While Ipv6 has a simplified approach to layer 2, perhaps you unsimplifiied it. If so, please provide details. Lear Expires May 31, 2004 [Page 6] Internet-Draft MULTI6 Solution Questionaire December 2003 2.4.19 Referrals How will your solution handle referrals, such as those within FTP? It must be possible for existing applications to continue to work. Referrals exist within various other protocols, such as so-called "peer to peer" applications. 2.4.20 What new information should applications be aware of? If there are new bindings, what does the application need to take advantage of them? How does the application present a &dquot;connection&dquot;? 2.5 Legal Stuff Are you introducing a namespace that might involve mnemonics? Doing so might introduce trademark concerns. If so, how do you plan to address such concerns? Are there any organizations required to manage a new name space? If so, please describe what they are and how the method will scale. Lear Expires May 31, 2004 [Page 7] Internet-Draft MULTI6 Solution Questionaire December 2003 3. Security Considerations How secure should a multi6 solution be? This is a reasonable question for each solution to answer. The author opines that the worst case should be no worse than what we have today. However, any additional risks should be clearly stated by the authors. Considerable time should be spent on threat analysis. Please see [4] for more details. Lear Expires May 31, 2004 [Page 8] Internet-Draft MULTI6 Solution Questionaire December 2003 4. Acknowledgments The author wishes to acknoledge everyone in the multi6 group and elsewhere that is putting forward proposals. It is easy to ask questions like the ones found in this draft. It is quite a bit harder to develop running code to answer them. Marcelo Bagnulo, Kurt Erik Lindqvist, Patrik Faltstrom, Brian Carpenter, and Iljitsch van Beijnim provided input to this document. Lear Expires May 31, 2004 [Page 9] Internet-Draft MULTI6 Solution Questionaire December 2003 Normative References [1] Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6) Addressing Architecture", RFC 3513, April 2003. [2] Abley, J., Black, B. and V. Gill, "Goals for IPv6 Site-Multihoming Architectures", RFC 3582, August 2003. [3] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in IPv6", draft-ietf-mobileip-ipv6-24 (work in progress), July 2003. [4] Nordmark, E. and T. Li, "Threats relating to IPv6 multihoming solutions", draft-nordmark-multi6-threats-00 (work in progress), October 2003. Lear Expires May 31, 2004 [Page 10] Internet-Draft MULTI6 Solution Questionaire December 2003 Informative References [5] Kitamura, H., "A SOCKS-based IPv6/IPv4 Gateway Mechanism", RFC 3089, April 2001. Author's Address Eliot Lear Cisco Systems 170 W. Tasman Dr. San Jose, CA 95134-1706 US EMail: lear@cisco.com Lear Expires May 31, 2004 [Page 11] Internet-Draft MULTI6 Solution Questionaire December 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property 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; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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