This document is obsolete. Please
refer to RFC 6434.
Network Working Group J. Loughney, Ed. Request for Comments: 4294 Nokia Category: Informational April 2006
IPv6 Node Requirements
Status of This Memo
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines requirements for IPv6 nodes. It is expected that IPv6 will be deployed in a wide range of devices and situations. Specifying the requirements for IPv6 nodes allows IPv6 to function well and interoperate in a large number of situations and deployments.
Table of Contents
1. Introduction ....................................................2 1.1. Requirement Language .......................................3 1.2. Scope of This Document .....................................3 1.3. Description of IPv6 Nodes ..................................3 2. Abbreviations Used in This Document .............................3 3. Sub-IP Layer ....................................................4 3.1. Transmission of IPv6 Packets over Ethernet Networks - RFC 2464 .................................................4 3.2. IP version 6 over PPP - RFC 2472 ...........................4 3.3. IPv6 over ATM Networks - RFC 2492 ..........................4 4. IP Layer ........................................................5 4.1. Internet Protocol Version 6 - RFC 2460 .....................5 4.2. Neighbor Discovery for IPv6 - RFC 2461 .....................5 4.3. Path MTU Discovery and Packet Size .........................6 4.4. ICMP for the Internet Protocol Version 6 (IPv6) - RFC 2463 ...................................................7 4.5. Addressing .................................................7 4.6. Multicast Listener Discovery (MLD) for IPv6 - RFC 2710 .....8 5. DNS and DHCP ....................................................8 5.1. DNS ........................................................8
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5.2. Dynamic Host Configuration Protocol for IPv6 (DHCPv6) - RFC 3315 ........................................9 6. IPv4 Support and Transition ....................................10 6.1. Transition Mechanisms .....................................10 7. Mobile IP ......................................................10 8. Security .......................................................10 8.1. Basic Architecture ........................................10 8.2. Security Protocols ........................................11 8.3. Transforms and Algorithms .................................11 8.4. Key Management Methods ....................................12 9. Router-Specific Functionality ..................................12 9.1. General ...................................................12 10. Network Management ............................................12 10.1. Management Information Base Modules (MIBs) ...............12 11. Security Considerations .......................................13 12. References ....................................................13 12.1. Normative References .....................................13 12.2. Informative References ...................................16 13. Authors and Acknowledgements ..................................18
The goal of this document is to define the common functionality required from both IPv6 hosts and routers. Many IPv6 nodes will implement optional or additional features, but this document summarizes requirements from other published Standards Track documents in one place.
This document tries to avoid discussion of protocol details, and references RFCs for this purpose. This document is informational in nature and does not update Standards Track RFCs.
Although the document points to different specifications, it should be noted that in most cases, the granularity of requirements are smaller than a single specification, as many specifications define multiple, independent pieces, some of which may not be mandatory.
As it is not always possible for an implementer to know the exact usage of IPv6 in a node, an overriding requirement for IPv6 nodes is that they should adhere to Jon Postel's Robustness Principle:
Be conservative in what you do, be liberal in what you accept from others [RFC-793].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC-2119].
IPv6 covers many specifications. It is intended that IPv6 will be deployed in many different situations and environments. Therefore, it is important to develop the requirements for IPv6 nodes to ensure interoperability.
This document assumes that all IPv6 nodes meet the minimum requirements specified here.
An IPv6 node must include support for one or more IPv6 link-layer specifications. Which link-layer specifications are included will depend upon what link-layers are supported by the hardware available on the system. It is possible for a conformant IPv6 node to support IPv6 on some of its interfaces and not on others.
As IPv6 is run over new layer 2 technologies, it is expected that new specifications will be issued. This section highlights some major layer 2 technologies and is not intended to be complete.
3.1. Transmission of IPv6 Packets over Ethernet Networks - RFC 2464
Nodes supporting IPv6 over Ethernet interfaces MUST implement Transmission of IPv6 Packets over Ethernet Networks [RFC-2464].
Nodes supporting IPv6 over ATM Networks MUST implement IPv6 over ATM Networks [RFC-2492]. Additionally, RFC 2492 states:
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A minimally conforming IPv6/ATM driver SHALL support the PVC mode of operation. An IPv6/ATM driver that supports the full SVC mode SHALL also support PVC mode of operation.
The Internet Protocol Version 6 is specified in [RFC-2460]. This specification MUST be supported.
Unrecognized options in Hop-by-Hop Options or Destination Options extensions MUST be processed as described in RFC 2460.
The node MUST follow the packet transmission rules in RFC 2460.
Nodes MUST always be able to send, receive, and process fragment headers. All conformant IPv6 implementations MUST be capable of sending and receiving IPv6 packets; the forwarding functionality MAY be supported.
RFC 2460 specifies extension headers and the processing for these headers.
A full implementation of IPv6 includes implementation of the following extension headers: Hop-by-Hop Options, Routing (Type 0), Fragment, Destination Options, Authentication and Encapsulating Security Payload [RFC-2460].
An IPv6 node MUST be able to process these headers. It should be noted that there is some discussion about the use of Routing Headers and possible security threats [IPv6-RH] that they cause.
Neighbor Discovery SHOULD be supported. [RFC-2461] states:
"Unless specified otherwise (in a document that covers operating IP over a particular link type) this document applies to all link types. However, because ND uses link-layer multicast for some of its services, it is possible that on some link types (e.g., NBMA links) alternative protocols or mechanisms to implement those services will be specified (in the appropriate document covering the operation of IP over a particular link type). The services described in this document that are not directly dependent on multicast, such as Redirects, Next-hop determination, Neighbor Unreachability Detection, etc., are expected to be provided as
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specified in this document. The details of how one uses ND on NBMA links is an area for further study."
Some detailed analysis of Neighbor Discovery follows:
Router Discovery is how hosts locate routers that reside on an attached link. Router Discovery MUST be supported for implementations.
Prefix Discovery is how hosts discover the set of address prefixes that define which destinations are on-link for an attached link. Prefix discovery MUST be supported for implementations. Neighbor Unreachability Detection (NUD) MUST be supported for all paths between hosts and neighboring nodes. It is not required for paths between routers. However, when a node receives a unicast Neighbor Solicitation (NS) message (that may be a NUD's NS), the node MUST respond to it (i.e., send a unicast Neighbor Advertisement).
Duplicate Address Detection MUST be supported on all links supporting link-layer multicast (RFC 2462, Section 5.4, specifies DAD MUST take place on all unicast addresses).
A host implementation MUST support sending Router Solicitations.
Receiving and processing Router Advertisements MUST be supported for host implementations. The ability to understand specific Router Advertisement options is dependent on supporting the specification where the RA is specified.
Sending and Receiving Neighbor Solicitation (NS) and Neighbor Advertisement (NA) MUST be supported. NS and NA messages are required for Duplicate Address Detection (DAD).
Redirect functionality SHOULD be supported. If the node is a router, Redirect functionality MUST be supported.
Path MTU Discovery [RFC-1981] SHOULD be supported, though minimal implementations MAY choose to not support it and avoid large packets. The rules in RFC 2460MUST be followed for packet fragmentation and reassembly.
IPv6 Stateless Address Autoconfiguration is defined in [RFC-2462]. This specification MUST be supported for nodes that are hosts. Static address can be supported as well.
Nodes that are routers MUST be able to generate link local addresses as described in RFC 2462 [RFC-2462].
From 2462:
The autoconfiguration process specified in this document applies only to hosts and not routers. Since host autoconfiguration uses information advertised by routers, routers will need to be configured by some other means. However, it is expected that routers will generate link-local addresses using the mechanism described in this document. In addition, routers are expected to successfully pass the Duplicate Address Detection procedure described in this document on all addresses prior to assigning them to an interface.
Duplicate Address Detection (DAD) MUST be supported.
4.5.3. Privacy Extensions for Address Configuration in IPv6 - RFC 3041
Privacy Extensions for Stateless Address Autoconfiguration [RFC-3041] SHOULD be supported. It is recommended that this behavior be configurable on a connection basis within each application when available. It is noted that a number of applications do not work with addresses generated with this method, while other applications work quite well with them.
4.5.4. Default Address Selection for IPv6 - RFC 3484
The rules specified in the Default Address Selection for IPv6 [RFC-3484] document MUST be implemented. It is expected that IPv6 nodes will need to deal with multiple addresses.
Stateful Address Autoconfiguration MAY be supported. DHCPv6 [RFC-3315] is the standard stateful address configuration protocol; see Section 5.3 for DHCPv6 support.
Nodes which do not support Stateful Address Autoconfiguration may be unable to obtain any IPv6 addresses, aside from link-local addresses, when it receives a router advertisement with the 'M' flag (Managed address configuration) set and that contains no prefixes advertised for Stateless Address Autoconfiguration (see Section 4.5.2). Additionally, such nodes will be unable to obtain other configuration information, such as the addresses of DNS servers when it is connected to a link over which the node receives a router advertisement in which the 'O' flag ("Other stateful configuration") is set.
4.6. Multicast Listener Discovery (MLD) for IPv6 - RFC 2710
Nodes that need to join multicast groups SHOULD implement MLDv2 [RFC-3810]. However, if the node has applications that only need support for Any-Source Multicast [RFC-3569], the node MAY implement MLDv1 [RFC-2710] instead. If the node has applications that need support for Source-Specific Multicast [RFC-3569, SSM-ARCH], the node MUST support MLDv2 [RFC-3810].
When MLD is used, the rules in the "Source Address Selection for the Multicast Listener Discovery (MLD) Protocol" [RFC-3590] MUST be followed.
DNS is described in [RFC-1034], [RFC-1035], [RFC-3152], [RFC-3363], and [RFC-3596]. Not all nodes will need to resolve names; those that will never need to resolve DNS names do not need to implement resolver functionality. However, the ability to resolve names is a basic infrastructure capability that applications rely on and generally needs to be supported. All nodes that need to resolve names SHOULD implement stub-resolver [RFC-1034] functionality, as in RFC 1034, Section 5.3.1, with support for:
The method by which IPv6 nodes that use DHCP for address assignment can obtain IPv6 addresses and other configuration information upon receipt of a Router Advertisement with the 'M' flag set is described in Section 5.5.3 of RFC 2462.
In addition, in the absence of a router, those IPv6 nodes that use DHCP for address assignment MUST initiate DHCP to obtain IPv6 addresses and other configuration information, as described in Section 5.5.2 of RFC 2462. Those IPv6 nodes that do not use DHCP for address assignment can ignore the 'M' flag in Router Advertisements.
The method by which IPv6 nodes that use DHCP to obtain other configuration information can obtain other configuration information upon receipt of a Router Advertisement with the 'O' flag set is described in Section 5.5.3 of RFC 2462.
Those IPv6 nodes that use DHCP to obtain other configuration information initiate DHCP for other configuration information upon receipt of a Router Advertisement with the 'O' flag set, as described in Section 5.5.3 of RFC 2462. Those IPv6 nodes that do not use DHCP for other configuration information can ignore the 'O' flag in Router Advertisements.
An IPv6 node can use the subset of DHCP (described in [RFC-3736]) to obtain other configuration information.
5.3.3. Use of Router Advertisements in Managed Environments
Nodes using the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) are expected to determine their default router information and on- link prefix information from received Router Advertisements.
The Mobile IPv6 [RFC-3775] specification defines requirements for the following types of nodes:
- mobile nodes
- correspondent nodes with support for route optimization
- home agents
- all IPv6 routers
Hosts MAY support mobile node functionality described in Section 8.5 of [RFC-3775], including support of generic packet tunneling [RFC- 2473] and secure home agent communications [RFC-3776].
Hosts SHOULD support route optimization requirements for correspondent nodes described in Section 8.2 of [RFC-3775].
Routers SHOULD support the generic mobility-related requirements for all IPv6 routers described in Section 8.3 of [RFC-3775]. Routers MAY support the home agent functionality described in Section 8.4 of [RFC-3775], including support of [RFC-2473] and [RFC-3776].
Current IPsec RFCs specify the support of transforms and algorithms for use with AH and ESP: NULL encryption, DES-CBC, HMAC-SHA-1-96, and HMAC-MD5-96. However, "Cryptographic Algorithm Implementation Requirements For ESP And AH" [RFC-4305] contains the current set of mandatory to implement algorithms for ESP and AH. It also specifies algorithms that should be implemented because they are likely to be promoted to mandatory at some future time. IPv6 nodes SHOULD conform to the requirements in [RFC-4305], as well as the requirements specified below.
Since ESP encryption and authentication are both optional, support for the NULL encryption algorithm [RFC-2410] and the NULL authentication algorithm [RFC-4303] MUST be provided to maintain consistency with the way these services are negotiated. However, while authentication and encryption can each be NULL, they MUST NOT both be NULL. The NULL encryption algorithm is also useful for debugging.
The DES-CBC encryption algorithm [RFC-2405] SHOULD NOT be supported within ESP. Security issues related to the use of DES are discussed in [DESDIFF], [DESINT], and [DESCRACK]. DES-CBC is still listed as required by the existing IPsec RFCs, but updates to these RFCs will be published in the near future. DES provides 56 bits of protection, which is no longer considered sufficient.
The use of the HMAC-SHA-1-96 algorithm [RFC-2404] within AH and ESP MUST be supported. The use of the HMAC-MD5-96 algorithm [RFC-2403] within AH and ESP MAY also be supported.
The 3DES-CBC encryption algorithm [RFC-2451] does not suffer from the same security issues as DES-CBC, and the 3DES-CBC algorithm within ESP MUST be supported to ensure interoperability.
The AES-128-CBC algorithm [RFC-3602] MUST also be supported within ESP. AES-128 is expected to be a widely available, secure, and efficient algorithm. While AES-128-CBC is not required by the current IPsec RFCs, it is expected to become required in the future.
An implementation MUST support the manual configuration of the security key and SPI. The SPI configuration is needed in order to delineate between multiple keys.
Key management SHOULD be supported. Examples of key management systems include IKEv2 [RFC-4306] and Kerberos; S/MIME and TLS include key management functions.
Where key refresh, anti-replay features of AH and ESP, or on-demand creation of Security Associations (SAs) is required, automated keying MUST be supported.
Key management methods for multicast traffic are also being worked on by the MSEC WG.
This section defines general host considerations for IPv6 nodes that act as routers. Currently, this section does not discuss routing- specific requirements.
The IPv6 Router Alert Option [RFC-2711] is an optional IPv6 Hop-by- Hop Header that is used in conjunction with some protocols (e.g., RSVP [RFC-2205] or MLD [RFC-2710]). The Router Alert option will need to be implemented whenever protocols that mandate its usage are implemented. See Section 4.6.
Network Management MAY be supported by IPv6 nodes. However, for IPv6 nodes that are embedded devices, network management may be the only possible way of controlling these nodes.
This document does not affect the security of the Internet, but implementations of IPv6 are expected to support a minimum set of security features to ensure security on the Internet. "IP Security Document Roadmap" [RFC-2411] is important for everyone to read.
The security considerations in RFC 2460 state the following:
The security features of IPv6 are described in the Security Architecture for the Internet Protocol [RFC-2401].
RFC 2401 has been obsoleted by RFC 4301, therefore refer RFC 4301 for the security features of IPv6.
[RFC-1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987.
[RFC-1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery for IP version 6", RFC 1981, August 1996.
[RFC-2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-Hashing for Message Authentication", RFC 2104, February 1997.
[RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC-2403] Madson, C. and R. Glenn, "The Use of HMAC-MD5-96 within ESP and AH", RFC 2403, November 1998.
[RFC-2404] Madson, C. and R. Glenn, "The Use of HMAC-SHA-1-96 within ESP and AH", RFC 2404, November 1998.
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[RFC-2405] Madson, C. and N. Doraswamy, "The ESP DES-CBC Cipher Algorithm With Explicit IV", RFC 2405, November 1998.
[RFC-2410] Glenn, R. and S. Kent, "The NULL Encryption Algorithm and Its Use With IPsec", RFC 2410, November 1998.
[RFC-2411] Thayer, R., Doraswamy, N., and R. Glenn, "IP Security Document Roadmap", RFC 2411, November 1998.
[RFC-2451] Pereira, R. and R. Adams, "The ESP CBC-Mode Cipher Algorithms", RFC 2451, November 1998.
[RFC-2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998.
[RFC-2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998.
[RFC-2462] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998.
[RFC-2463] Conta, A. and S. Deering, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC 2463, December 1998.
[RFC-2472] Haskin, D. and E. Allen, "IP Version 6 over PPP", RFC 2472, December 1998.
[RFC-2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, December 1998.
[RFC-2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC 2671, August 1999.
[RFC-2710] Deering, S., Fenner, W., and B. Haberman, "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, October 1999.
[RFC-2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option", RFC 2711, October 1999.
[RFC-3041] Narten, T. and R. Draves, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 3041, January 2001.
[RFC-3152] Bush, R., "Delegation of IP6.ARPA", BCP 49, RFC 3152, August 2001.
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[RFC-3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC-3363] Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T. Hain, "Representing Internet Protocol version 6 (IPv6) Addresses in the Domain Name System (DNS)", RFC 3363, August 2002.
[RFC-3484] Frye, R., Levi, D., Routhier, S., and B. Wijnen, "Coexistence between Version 1, Version 2, and Version 3 of the Internet-standard Network Management Framework", BCP 74, RFC 3584, August 2003.
[RFC-3513] Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6) Addressing Architecture", RFC 3513, April 2003.
[RFC-3590] Haberman, B., "Source Address Selection for the Multicast Listener Discovery (MLD) Protocol", RFC 3590, September 2003.
[RFC-3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, "DNS Extensions to Support IP Version 6", RFC 3596, October 2003.
[RFC-3602] Frankel, S., Glenn, R., and S. Kelly, "The AES-CBC Cipher Algorithm and Its Use with IPsec", RFC 3602, September 2003.
[RFC-3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004.
[RFC-3776] Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to Protect Mobile IPv6 Signaling Between Mobile Nodes and Home Agents", RFC 3776, June 2004.
[RFC-3810] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
[RFC-3879] Huitema, C. and B. Carpenter, "Deprecating Site Local Addresses", RFC 3879, September 2004.
[DESDIFF] Biham, E., Shamir, A., "Differential Cryptanalysis of DES-like cryptosystems", Journal of Cryptology Vol 4, Jan 1991.
[DESCRACK] Cracking DES, O'Reilly & Associates, Sebastapol, CA 2000.
[DESINT] Bellovin, S., "An Issue With DES-CBC When Used Without Strong Integrity", Proceedings of the 32nd IETF, Danvers, MA, April 1995.
[IPv6-RH] P. Savola, "Security of IPv6 Routing Header and Home Address Options", Work in Progress.
[RFC-793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981.
[RFC-1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987.
[RFC-2205] Braden, R., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997.
[RFC-2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998.
[RFC-2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM Networks", RFC 2492, January 1999.
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[RFC-2675] Borman, D., Deering, S., and R. Hinden, "IPv6 Jumbograms", RFC 2675, August 1999.
[RFC-4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms for IPv6 Hosts and Routers", RFC 4213, October 2005.
[RFC-3569] Bhattacharyya, S., "An Overview of Source-Specific Multicast (SSM)", RFC 3569, July 2003.
[RFC-3736] Droms, R., "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6", RFC 3736, April 2004.
[RFC-4001] Daniele, M., Haberman, B., Routhier, S., and J. Schoenwaelder, "Textual Conventions for Internet Network Addresses", RFC 4001, February 2005.
[RFC-4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, March 2005.
[RFC-4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, March 2005.
[RFC-4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, March 2005.
The authors would like to thank Ran Atkinson, Jim Bound, Brian Carpenter, Ralph Droms, Christian Huitema, Adam Machalek, Thomas Narten, Juha Ollila, and Pekka Savola for their comments.
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Editor's Contact Information
Comments or questions regarding this document should be sent to the IPv6 Working Group mailing list (ipv6@ietf.org) or to:
John Loughney Nokia Research Center Itamerenkatu 11-13 00180 Helsinki Finland
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