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diff --git a/doc/rfc/rfc4214.txt b/doc/rfc/rfc4214.txt new file mode 100644 index 0000000..7311750 --- /dev/null +++ b/doc/rfc/rfc4214.txt @@ -0,0 +1,787 @@ + + + + + + +Network Working Group F. Templin +Request for Comments: 4214 Nokia +Category: Experimental T. Gleeson + Cisco Systems K.K. + M. Talwar + D. Thaler + Microsoft Corporation + October 2005 + + + Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) + +Status of This Memo + + This memo defines an Experimental Protocol for the Internet + community. It does not specify an Internet standard of any kind. + Discussion and suggestions for improvement are requested. + Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2005). + +IESG Note + + The content of this RFC was at one time considered by the IETF, and + therefore it may resemble a current IETF work in progress or a + published IETF work. This RFC is not a candidate for any level of + Internet Standard. The IETF disclaims any knowledge of the fitness + of this RFC for any purpose, and in particular notes that the + decision to publish is not based on IETF review for such things as + security, congestion control or inappropriate interaction with + deployed protocols. The RFC Editor has chosen to publish this + document at its discretion. Readers of this RFC should exercise + caution in evaluating its value for implementation and deployment. + See RFC 3932 for more information. + +Abstract + + The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) connects + IPv6 hosts/routers over IPv4 networks. ISATAP views the IPv4 network + as a link layer for IPv6 and views other nodes on the network as + potential IPv6 hosts/routers. ISATAP supports an automatic tunneling + abstraction similar to the Non-Broadcast Multiple Access (NBMA) + model. + + + + + + +Templin, et al. Experimental [Page 1] + +RFC 4214 ISATAP October 2005 + + +1. Introduction + + This document specifies a simple mechanism called the Intra-Site + Automatic Tunnel Addressing Protocol (ISATAP) that connects IPv6 + hosts/routers over IPv4 networks. Dual-stack (IPv6/IPv4) nodes use + ISATAP to automatically tunnel IPv6 packets in IPv4, i.e., ISATAP + views the IPv4 network as a link layer for IPv6 and views other nodes + on the network as potential IPv6 hosts/routers. + + ISATAP enables automatic tunneling whether global or private IPv4 + addresses are used, and presents a Non-Broadcast Multiple Access + (NBMA) abstraction similar to [RFC2491][RFC2492][RFC2529][RFC3056]. + + The main objectives of this document are to: 1) describe the domain + of applicability, 2) specify addressing requirements, 3) specify + automatic tunneling using ISATAP, 4) specify the operation of IPv6 + Neighbor Discovery over ISATAP interfaces, and 5) discuss Site + Administration, Security, and IANA considerations. + +2. Requirements + + The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, + SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this + document, are to be interpreted as described in [BCP14]. + + This document also uses internal conceptual variables to describe + protocol behavior and external variables that an implementation must + allow system administrators to change. The specific variable names, + how their values change, and how their settings influence protocol + behavior are provided in order to demonstrate protocol behavior. An + implementation is not required to have them in the exact form + described here, as long as its external behavior is consistent with + that described in this document. + +3. Terminology + + The terminology of [RFC2460][RFC2461] applies to this document. The + following additional terms are defined: + + ISATAP node: + A node that implements the specifications in this document. + + ISATAP interface: + An ISATAP node's Non-Broadcast Multi-Access (NBMA) IPv6 interface, + used for automatic tunneling of IPv6 packets in IPv4. + + + + + + +Templin, et al. Experimental [Page 2] + +RFC 4214 ISATAP October 2005 + + + ISATAP interface identifier: + An IPv6 interface identifier with an embedded IPv4 address + constructed as specified in Section 6.1. + + ISATAP address: + An IPv6 unicast address that matches an on-link prefix on an + ISATAP interface of the node, and that includes an ISATAP + interface identifier. + + locator: + An IPv4 address-to-interface mapping; i.e., a node's IPv4 address + and its associated interface. + + locator set: + A set of locators associated with an ISATAP interface. Each + locator in the set belongs to the same site. + +4. Domain of Applicability + + The domain of applicability for this technical specification is + automatic tunneling of IPv6 packets in IPv4 for ISATAP nodes within + sites that observe the security considerations found in this + document, including host-to-router, router-to-host, and host-to-host + automatic tunneling in certain enterprise networks and 3GPP/3GPP2 + wireless operator networks. (Other scenarios with a sufficient trust + basis ensured by the mechanisms specified in this document also fall + within this domain of applicability.) + + Extensions to the above domain of applicability (e.g., by combining + the mechanisms in this document with those in other technical + specifications) are out of the scope of this document. + +5. Node Requirements + + ISATAP nodes observe the common functionality requirements for IPv6 + nodes found in [NODEREQ] and the requirements for dual IP layer + operation found in ([MECH], Section 2). They also implement the + additional features specified in this document. + +6. Addressing Requirements + +6.1. ISATAP Interface Identifiers + + ISATAP interface identifiers are constructed in Modified EUI-64 + format ([RFC3513], Section 2.5.1 and Appendix A) by concatenating the + 24-bit IANA OUI (00-00-5E), the 8-bit hexadecimal value 0xFE, and a + 32-bit IPv4 address in network byte order as follows: + + + + +Templin, et al. Experimental [Page 3] + +RFC 4214 ISATAP October 2005 + + + |0 1|1 3|3 6| + |0 5|6 1|2 3| + +----------------+----------------+--------------------------------+ + |000000ug00000000|0101111011111110|mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm| + +----------------+----------------+--------------------------------+ + + When the IPv4 address is known to be globally unique, the "u" bit + (universal/local) is set to 1; otherwise, the "u" bit is set to 0. + "g" is the individual/group bit, and "m" are the bits of the IPv4 + address. + +6.2. ISATAP Interface Address Configuration + + Each ISATAP interface configures a set of locators consisting of IPv4 + address-to-interface mappings from a single site; i.e., an ISATAP + interface's locator set MUST NOT span multiple sites. + + When an IPv4 address is removed from an interface, the corresponding + locator SHOULD be removed from its associated locator set(s). When a + new IPv4 address is assigned to an interface, the corresponding + locator MAY be added to the appropriate locator set(s). + + ISATAP interfaces form ISATAP interface identifiers from IPv4 + addresses in their locator set and use them to create link-local + ISATAP addresses ([RFC2462], Section 5.3). + +6.3. Multicast/Anycast + + It is not possible to assume the general availability of wide-area + IPv4 multicast, so (unlike 6over4 [RFC2529]) ISATAP must assume that + its underlying IPv4 carrier network only has unicast capability. + Support for IPv6 multicast over ISATAP interfaces is not described in + this document. + + Similarly, support for Reserved IPv6 Subnet Anycast Addresses is not + described in this document. + +7. Automatic Tunneling + + ISATAP interfaces use the basic tunneling mechanisms specified in + ([MECH], Section 3). The following sub-sections describe additional + specifications. + +7.1. Encapsulation + + ISATAP addresses are mapped to a link-layer address by a static + computation; i.e., the last four octets are treated as an IPv4 + address. + + + +Templin, et al. Experimental [Page 4] + +RFC 4214 ISATAP October 2005 + + +7.2. Handling ICMPv4 Errors + + ISATAP interfaces SHOULD process ARP failures and persistent ICMPv4 + errors as link-specific information indicating that a path to a + neighbor may have failed ([RFC2461], Section 7.3.3). + +7.3. Decapsulation + + The specification in ([MECH], Section 3.6) is used. Additionally, + when an ISATAP node receives an IPv4 protocol 41 datagram that does + not belong to a configured tunnel interface, it determines whether + the packet's IPv4 destination address and arrival interface match a + locator configured in an ISATAP interface's locator set. + + If an ISATAP interface that configures a matching locator is found, + the decapsulator MUST verify that the packet's IPv4 source address is + correct for the encapsulated IPv6 source address. The IPv4 source + address is correct if: + + - the IPv6 source address is an ISATAP address that embeds the + IPv4 source address in its interface identifier, or + + - the IPv4 source address is a member of the Potential Router + List (see Section 8.1). + + Packets for which the IPv4 source address is incorrect for this + ISATAP interface are checked to determine whether they belong to + another tunnel interface. + +7.4. Link-Local Addresses + + ISATAP interfaces use link-local addresses constructed as specified + in Section 6 of this document. + +7.5. Neighbor Discovery over Tunnels + + ISATAP interfaces use the specifications for neighbor discovery found + in the following section of this document. + +8. Neighbor Discovery for ISATAP Interfaces + + ISATAP interfaces use the neighbor discovery mechanisms specified in + [RFC2461]. The following sub-sections describe specifications that + are also implemented. + + + + + + + +Templin, et al. Experimental [Page 5] + +RFC 4214 ISATAP October 2005 + + +8.1. Conceptual Model of a Host + + To the list of Conceptual Data Structures ([RFC2461], Section 5.1), + ISATAP interfaces add the following: + + Potential Router List (PRL) + A set of entries about potential routers; used to support router + and prefix discovery. Each entry ("PRL(i)") has an associated + timer ("TIMER(i)"), and an IPv4 address ("V4ADDR(i)") that + represents a router's advertising ISATAP interface. + +8.2. Router and Prefix Discovery - Router Specification + + Advertising ISATAP interfaces send Solicited Router Advertisement + messages as specified in ([RFC2461], Section 6.2.6) except that the + messages are sent directly to the soliciting node; i.e., they might + not be received by other nodes on the link. + +8.3. Router and Prefix Discovery - Host Specification + + The Host Specification in ([RFC2461], Section 6.3) is used. The + following sub-sections describe specifications added by ISATAP + interfaces. + +8.3.1. Host Variables + + To the list of host variables ([RFC2461], Section 6.3.2), ISATAP + interfaces add the following: + + PrlRefreshInterval + Time in seconds between successive refreshments of the PRL after + initialization. The designated value of all ones (0xffffffff) + represents infinity. + Default: 3600 seconds + + MinRouterSolicitInterval + Minimum time in seconds between successive solicitations of the + same advertising ISATAP interface. The designated value of all + ones (0xffffffff) represents infinity. + +8.3.2. Potential Router List Initialization + + ISATAP nodes initialize an ISATAP interface's PRL with IPv4 addresses + discovered via manual configuration, a DNS Fully Qualified Domain + Name (FQDN) [STD13], a DHCPv4 option, a DHCPv4 vendor-specific + option, or an unspecified alternate method. FQDNs are established + via manual configuration or an unspecified alternate method. FQDNs + are resolved into IPv4 addresses through a static host file lookup, + + + +Templin, et al. Experimental [Page 6] + +RFC 4214 ISATAP October 2005 + + + querying the DNS service, querying a site-specific name service, or + with an unspecified alternate method. + + After initializing an ISATAP interface's PRL, the node sets a timer + for the interface to PrlRefreshInterval seconds and re-initializes + the interface's PRL as specified above when the timer expires. When + an FQDN is used, and when it is resolved via a service that includes + TTLs with the IPv4 addresses returned (e.g., DNS 'A' resource records + [STD13]), the timer SHOULD be set to the minimum of + PrlRefreshInterval and the minimum TTL returned. (Zero-valued TTLs + are interpreted to mean that the PRL is re-initialized before each + Router Solicitation event; see Section 8.3.4.) + +8.3.3. Processing Received Router Advertisements + + To the list of checks for validating Router Advertisement messages + ([RFC2461], Section 6.1.1), ISATAP interfaces add the following: + + - IP Source Address is a link-local ISATAP address that embeds + V4ADDR(i) for some PRL(i). + + Valid Router Advertisements received on an ISATAP interface are + processed as specified in ([RFC2461], Section 6.3.4). + +8.3.4. Sending Router Solicitations + + To the list of events after which Router Solicitation messages may be + sent ([RFC2461], Section 6.3.7), ISATAP interfaces add the following: + + - TIMER(i) for some PRL(i) expires. + + Since unsolicited Router Advertisements may be incomplete and/or + absent, ISATAP nodes MAY schedule periodic Router Solicitation events + for certain PRL(i)s by setting the corresponding TIMER(i). + + When periodic Router Solicitation events are scheduled, the node + SHOULD set TIMER(i) so that the next event will refresh remaining + lifetimes stored for PRL(i) before they expire, including the Router + Lifetime, Valid Lifetimes received in Prefix Information Options, and + Route Lifetimes received in Route Information Options [DEFLT]. + TIMER(i) MUST be set to no less than MinRouterSolicitInterval seconds + where MinRouterSolicitInterval is configurable for the node, or for a + specific PRL(i), with a conservative default value (e.g., 2 minutes). + + When TIMER(i) expires, the node sends Router Solicitation messages as + specified in ([RFC2461], Section 6.3.7) except that the messages are + sent directly to PRL(i); i.e., they might not be received by other + routers. While the node continues to require periodic Router + + + +Templin, et al. Experimental [Page 7] + +RFC 4214 ISATAP October 2005 + + + Solicitation events for PRL(i), and while PRL(i) continues to act as + a router, the node resets TIMER(i) after each expiration event as + described above. + +8.4. Neighbor Unreachability Detection + + Hosts SHOULD perform Neighbor Unreachability Detection ([RFC2461], + Section 7.3). Routers MAY perform neighbor unreachability detection, + but this might not scale in all environments. + + After address resolution, hosts SHOULD perform an initial + reachability confirmation by sending Neighbor Solicitation messages + and receiving a Neighbor Advertisement message. Routers MAY perform + this initial reachability confirmation, but this might not scale in + all environments. + +9. Site Administration Considerations + + Site administrators maintain a Potential Router List (PRL) of IPv4 + addresses representing advertising ISATAP interfaces of routers. + + The PRL is commonly maintained as an FQDN for the ISATAP service in + the site's name service (see Section 8.3.2). There are no mandatory + rules for the selection of the FQDN, but site administrators are + encouraged to use the convention "isatap.domainname" (e.g., + isatap.example.com). + + When the site's name service includes TTLs with the IPv4 addresses + returned, site administrators SHOULD configure the TTLs with + conservative values to minimize control traffic. + +10. Security Considerations + + Implementors should be aware that, in addition to possible attacks + against IPv6, security attacks against IPv4 must also be considered. + Use of IP security at both IPv4 and IPv6 levels should nevertheless + be avoided, for efficiency reasons. For example, if IPv6 is running + encrypted, encryption of IPv4 would be redundant unless traffic + analysis is felt to be a threat. If IPv6 is running authenticated, + then authentication of IPv4 will add little. Conversely, IPv4 + security will not protect IPv6 traffic once it leaves the ISATAP + domain. Therefore, implementing IPv6 security is required even if + IPv4 security is available. + + The threats associated with IPv6 Neighbor Discovery are described in + [RFC3756]. + + + + + +Templin, et al. Experimental [Page 8] + +RFC 4214 ISATAP October 2005 + + + There is a possible spoofing attack in which spurious ip-protocol-41 + packets are injected into an ISATAP link from outside. Since an + ISATAP link spans an entire IPv4 site, restricting access to the link + can be achieved by restricting access to the site; i.e., by having + site border routers implement IPv4 ingress filtering and ip- + protocol-41 filtering. + + Another possible spoofing attack involves spurious ip-protocol-41 + packets injected from within an ISATAP link by a node pretending to + be a router. The Potential Router List (PRL) provides a list of IPv4 + addresses representing advertising ISATAP interfaces of routers that + hosts use in filtering decisions. Site administrators should ensure + that the PRL is kept up to date, and that the resolution mechanism + (see Section 9) cannot be subverted. + + The use of temporary addresses [RFC3041] and Cryptographically + Generated Addresses [CGA] on ISATAP interfaces is outside the scope + of this specification. + +11. IANA Considerations + + The IANA has specified the format for Modified EUI-64 address + construction ([RFC3513], Appendix A) in the IANA Ethernet Address + Block. The text in Appendix A of this document has been offered as + an example specification. The current version of the IANA registry + for Ether Types can be accessed at: + + http://www.iana.org/assignments/ethernet-numbers + +12. Acknowledgements + + The ideas in this document are not original, and the authors + acknowledge the original architects. Portions of this work were + sponsored through SRI International internal projects and government + contracts. Government sponsors include Monica Farah-Stapleton and + Russell Langan (U.S. Army CECOM ASEO), and Dr. Allen Moshfegh (U.S. + Office of Naval Research). SRI International sponsors include Dr. + Mike Frankel, J. Peter Marcotullio, Lou Rodriguez, and Dr. Ambatipudi + Sastry. + + The following are acknowledged for providing peer review input: Jim + Bound, Rich Draves, Cyndi Jung, Ambatipudi Sastry, Aaron Schrader, + Ole Troan, and Vlad Yasevich. + + The following are acknowledged for their significant contributions: + Alain Durand, Hannu Flinck, Jason Goldschmidt, Nathan Lutchansky, + Karen Nielsen, Mohan Parthasarathy, Chirayu Patel, Art Shelest, + Markku Savela, Pekka Savola, Margaret Wasserman, and Brian Zill. + + + +Templin, et al. Experimental [Page 9] + +RFC 4214 ISATAP October 2005 + + + The authors acknowledge the work of Quang Nguyen on "Virtual + Ethernet", under the guidance of Dr. Lixia Zhang, that proposed very + similar ideas to those that appear in this document. This work was + first brought to the authors' attention on September 20, 2002. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Templin, et al. Experimental [Page 10] + +RFC 4214 ISATAP October 2005 + + +Appendix A. Modified EUI-64 Addresses in the IANA Ethernet Address + Block + + Modified EUI-64 addresses ([RFC3513], Section 2.5.1 and Appendix A) + in the IANA Ethernet Address Block are formed by concatenating the + 24-bit IANA OUI (00-00-5E) with a 40-bit extension identifier and + inverting the "u" bit; i.e., the "u" bit is set to one (1) to + indicate universal scope and set to zero (0) to indicate local scope. + + Modified EUI-64 addresses have the following appearance in memory + (bits transmitted right-to-left within octets, octets transmitted + left-to-right): + + 0 23 63 + | OUI | extension identifier | + 000000ug00000000 01011110xxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx + + When the first two octets of the extension identifier encode the + hexadecimal value 0xFFFE, the remainder of the extension identifier + encodes a 24-bit vendor-supplied id as follows: + + 0 23 39 63 + | OUI | 0xFFFE | vendor-supplied id | + 000000ug00000000 0101111011111111 11111110xxxxxxxx xxxxxxxxxxxxxxxx + + When the first octet of the extension identifier encodes the + hexadecimal value 0xFE, the remainder of the extension identifier + encodes a 32-bit IPv4 address as follows: + + 0 23 31 63 + | OUI | 0xFE | IPv4 address | + 000000ug00000000 0101111011111110 xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx + +Normative References + + [BCP14] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, March 1997. + + [STD13] Mockapetris, P., "Domain names - implementation and + specification", STD 13, RFC 1035, November 1987. + + [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 + (IPv6) Specification", RFC 2460, December 1998. + + [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor + Discovery for IP Version 6 (IPv6)", RFC 2461, December + 1998. + + + + +Templin, et al. Experimental [Page 11] + +RFC 4214 ISATAP October 2005 + + + [RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address + Autoconfiguration", RFC 2462, December 1998. + + [RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6 + (IPv6) Addressing Architecture", RFC 3513, April 2003. + + [MECH] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms + for IPv6 Hosts and Routers", RFC 4213, October 2005. + +Informative References + + [RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 + over Non-Broadcast Multiple Access (NBMA) networks", RFC + 2491, January 1999. + + [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM + Networks", RFC 2492, January 1999. + + [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 + Domains without Explicit Tunnels", RFC 2529, March 1999. + + [RFC3041] Narten, T. and R. Draves, "Privacy Extensions for + Stateless Address Autoconfiguration in IPv6", RFC 3041, + January 2001. + + [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains + via IPv4 Clouds", RFC 3056, February 2001. + + [RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor + Discovery (ND) Trust Models and Threats", RFC 3756, May + 2004. + + [CGA] Aura, T., "Cryptographically Generated Addresses (CGA)", + RFC 3972, March 2005. + + [DEFLT] Draves, R. and D. Thaler, "Default Router Preferences and + More-Specific Routes", Work in Progress, December 2003. + + [NODEREQ] Loughney, J., Ed., "IPv6 Node Requirements", Work in + Progress, May 2004. + + + + + + + + + + + +Templin, et al. Experimental [Page 12] + +RFC 4214 ISATAP October 2005 + + +Authors' Addresses + + Fred L. Templin + Nokia + 313 Fairchild Drive + Mountain View, CA 94110 + US + + EMail: fltemplin@acm.org + + + Tim Gleeson + Cisco Systems K.K. + Shinjuku Mitsui Building + 2-1-1 Nishishinjuku, Shinjuku-ku + Tokyo 163-0409 + Japan + + EMail: tgleeson@cisco.com + + + Mohit Talwar + Microsoft Corporation + One Microsoft Way + Redmond, WA 98052-6399 + US + + Phone: +1 425 705 3131 + EMail: mohitt@microsoft.com + + + Dave Thaler + Microsoft Corporation + One Microsoft Way + Redmond, WA 98052-6399 + US + + Phone: +1 425 703 8835 + EMail: dthaler@microsoft.com + + + + + + + + + + + + +Templin, et al. Experimental [Page 13] + +RFC 4214 ISATAP October 2005 + + +Full Copyright Statement + + Copyright (C) The Internet Society (2005). + + This document is subject to the rights, licenses and restrictions + contained in BCP 78 and at www.rfc-editor.org/copyright.html, and + except as set forth therein, the authors retain all their rights. + + 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. + +Intellectual Property + + 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 procedures with respect to rights in RFC 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. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + +Templin, et al. Experimental [Page 14] + |