draft-ietf-6man-ra-pref64-03.txt   draft-ietf-6man-ra-pref64-04.txt 
IPv6 Maintenance L. Colitti IPv6 Maintenance L. Colitti
Internet-Draft J. Linkova Internet-Draft J. Linkova
Intended status: Standards Track Google Intended status: Standards Track Google
Expires: January 25, 2020 July 24, 2019 Expires: February 12, 2020 August 11, 2019
Discovering PREF64 in Router Advertisements Discovering PREF64 in Router Advertisements
draft-ietf-6man-ra-pref64-03 draft-ietf-6man-ra-pref64-04
Abstract Abstract
This document specifies a Router Advertisement option to communicate This document specifies a Router Advertisement option to communicate
NAT64 prefixes to clients. NAT64 prefixes to clients.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 25, 2020. This Internet-Draft will expire on February 12, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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o IPv4 address literals on an IPv6-only host. As described in o IPv4 address literals on an IPv6-only host. As described in
[RFC8305] section 7.1, IPv6-only hosts connecting to IPv4 address [RFC8305] section 7.1, IPv6-only hosts connecting to IPv4 address
literals can resolve the IPv4 literal to an IPv6 address. literals can resolve the IPv4 literal to an IPv6 address.
o 464XLAT [RFC6877]. 464XLAT is widely deployed and requires that o 464XLAT [RFC6877]. 464XLAT is widely deployed and requires that
the host be aware of the NAT64 prefix. the host be aware of the NAT64 prefix.
o Trusted DNS server. AAAA synthesis is required for the host to be o Trusted DNS server. AAAA synthesis is required for the host to be
able to use a DNS server not provided by the network (e.g., a DNS- able to use a DNS server not provided by the network (e.g., a DNS-
over-TLS server with which the host has an existing trust over-TLS server ([RFC7858]) with which the host has an existing
relationship). trust relationship).
o Networks with no DNS64 server. Hosts that support AAAA synthesis o Networks with no DNS64 server. Hosts that support AAAA synthesis
and that are aware of the NAT64 prefix in use do not need the and that are aware of the NAT64 prefix in use do not need the
network to perform the DNS64 function at all. network to perform the DNS64 function at all.
3. Why include the NAT64 prefix in Router Advertisements 3. Why include the NAT64 prefix in Router Advertisements
Fate sharing: NAT64 requires a routing to be configured. IPv6 Fate sharing: NAT64 requires a routing to be configured. IPv6
routing configuration requires receiving an IPv6 Router Advertisement routing configuration requires receiving an IPv6 Router Advertisement
[RFC4861]. Compared to currently-deployed NAT64 prefix discovery [RFC4861]. Compared to currently-deployed NAT64 prefix discovery
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new Router Advertisement. new Router Advertisement.
Deployability: all IPv6 hosts and networks are required to support Deployability: all IPv6 hosts and networks are required to support
[RFC4861]. Other options such as [RFC7225] require implementing [RFC4861]. Other options such as [RFC7225] require implementing
other protocols. other protocols.
4. Semantics 4. Semantics
To support prefix lengths defined in ([RFC6052]) this option contains To support prefix lengths defined in ([RFC6052]) this option contains
the prefix length field. However as /96 prefix is considered to be the prefix length field. However as /96 prefix is considered to be
the most common usecase, the prefix length field is optional and only the most common use case, the prefix length field is optional and
presents for non-/96 prefixes. It allows to keep the option length only presents for non-/96 prefixes. It allows to keep the option
to a minimum (16 bytes) for the most common case and increase it to length to a minimum (16 bytes) for the most common case and increase
20 bytes for non-/96 prefixes only (see Section 5 below for more it to 20 bytes for non-/96 prefixes only (see Section 5 below for
details). more details).
This option specifies exactly one NAT64 prefix for all IPv4 This option specifies exactly one NAT64 prefix for all IPv4
destinations. If the network operator desires to route different destinations. If the network operator desires to route different
parts of the IPv4 address space to different NAT64 devices, this can parts of the IPv4 address space to different NAT64 devices, this can
be accomplished by routing more specifics of the NAT64 prefix to be accomplished by routing more specifics of the NAT64 prefix to
those devices. For example, if the operator would like to route those devices. For example, if the operator would like to route
10.0.0.0/8 through NAT64 device A and the rest of the IPv4 space 10.0.0.0/8 through NAT64 device A and the rest of the IPv4 space
through NAT64 device B, and the operator's NAT64 prefix is through NAT64 device B, and the operator's NAT64 prefix is
2001:db8:a:b::/96, then the operator can route 2001:db8:a:b::/96, then the operator can route
2001:db8:a:b::a00:0/104 to NAT64 A and 2001:db8:a:b::/64 to NAT64 B. 2001:db8:a:b::a00:0/104 to NAT64 A and 2001:db8:a:b::/64 to NAT64 B.
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(e.g. by using PCP ([RFC7225]) and/or by resolving IPv4-only fully (e.g. by using PCP ([RFC7225]) and/or by resolving IPv4-only fully
qualified domain name ([RFC7050]) in addition to receiving the qualified domain name ([RFC7050]) in addition to receiving the
Pref64 RA option); Pref64 RA option);
o The pref64 option presents in a single RA more than once; o The pref64 option presents in a single RA more than once;
o the host receives multiple RAs with different Pref64 prefixes on o the host receives multiple RAs with different Pref64 prefixes on
one or multiple interfaces. one or multiple interfaces.
When multiple Pref64 were discovered via RA Pref64 Option (the Option When multiple Pref64 were discovered via RA Pref64 Option (the Option
presents more than once in a singe RA or multiple RAs were received), presents more than once in a single RA or multiple RAs were
host behaviour with regards to synthesizing IPv6 addresses from IPv4 received), host behaviour with regards to synthesizing IPv6 addresses
addresses SHOULD follow the recommendations given in Section 3 of from IPv4 addresses SHOULD follow the recommendations given in
[RFC7050], limited to the NAT64 prefixes that have non-zero Section 3 of [RFC7050], limited to the NAT64 prefixes that have non-
lifetime.. zero lifetime..
When different Pref64 are discovered by using multiple mechanisms, When different Pref64 are discovered by using multiple mechanisms,
hosts SHOULD select one source of infromation only. The RECOMMENDED hosts SHOULD select one source of information only. The RECOMMENDED
order is: order is:
o PCP-discovered prefixes ([RFC7225]), if supported; o PCP-discovered prefixes ([RFC7225]), if supported;
o Pref64 discovered via RA Option; o Pref64 discovered via RA Option;
o Pref64 resolving IPv4-only fully qualified domain name ([RFC7050]) o Pref64 resolving IPv4-only fully qualified domain name ([RFC7050])
Note that if the network provides Pref64 both via this RA option and Note that if the network provides Pref64 both via this RA option and
[RFC7225], hosts that receive the Pref64 via RA option may choose to [RFC7225], hosts that receive the Pref64 via RA option may choose to
use it imediately before waiting for PCP to complete, and therefore use it immediately before waiting for PCP to complete, and therefore
some traffic may not reflect any more detailed configuration provided some traffic may not reflect any more detailed configuration provided
by PCP. by PCP.
7. Multihoming 7. Multihoming
Like most IPv6 configuration information, the Pref64 option is Like most IPv6 configuration information, the Pref64 option is
specific to the network on which it is received. For example, a specific to the network on which it is received. For example, a
Pref64 option received on a particular wireless network may not be Pref64 option received on a particular wireless network may not be
usable unless the traffic is also sourced on that network. usable unless the traffic is also sourced on that network.
Similarly, a host connected to a cellular network that povides NAT64 Similarly, a host connected to a cellular network that provides NAT64
generally cannot use that NAT64 for destinations reached through a generally cannot use that NAT64 for destinations reached through a
VPN tunnel that terminates outside that network. VPN tunnel that terminates outside that network.
Thus, correct use of this option on a multihomed host generally Thus, correct use of this option on a multihomed host generally
requires the host to support the concept of multiple Provisioning requires the host to support the concept of multiple Provisioning
Domains (PvD, a set of configuration information associated with a Domains (PvD, a set of configuration information associated with a
network, [RFC7556]) and to be able to use these PvDs. network, [RFC7556]) and to be able to use these PvDs.
This issue is not specific to the Pref64 RA option and, for example, This issue is not specific to the Pref64 RA option and, for example,
is quite typical for DNS resolving on multihomed hosts (e.g. a host is quite typical for DNS resolving on multihomed hosts (e.g. a host
might resolve a destination name by using the corporate DNS server might resolve a destination name by using the corporate DNS server
via the VPN tunnel but then send the traffic via its Internet-facing via the VPN tunnel but then send the traffic via its Internet-facing
interface). interface).
8. Pref64 Consistency 8. Pref64 Consistency
Section 6.2.7 of [RFC4861] recommends that routers inspects RAs sent Section 6.2.7 of [RFC4861] recommends that routers inspect RAs sent
by other routers to ensure that all routers onlink advertise the by other routers to ensure that all routers onlink advertise the
consistent information. Routers SHOULD inspect valid Pref64 options consistent information. Routers SHOULD inspect valid Pref64 options
received on a given link and verify the consistency. Detected received on a given link and verify the consistency. Detected
inconsistencies indicate that one or more routers might be inconsistencies indicate that one or more routers might be
misconfigured. Routers SHOULD log such cases to system or network misconfigured. Routers SHOULD log such cases to system or network
management. Routers SHOULD check and compare the following management. Routers SHOULD check and compare the following
information: information:
o set of Pref64 with non-zero lifetime; o set of Pref64 with non-zero lifetime;
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The security measures that must already be in place to ensure that The security measures that must already be in place to ensure that
Router Advertisements are only received from legitimate sources Router Advertisements are only received from legitimate sources
eliminate the problem of NAT64 prefix validation described in section eliminate the problem of NAT64 prefix validation described in section
3.1 of [RFC7050]. 3.1 of [RFC7050].
11. Acknowledgements 11. Acknowledgements
Thanks to the following people (in alphabetical order) for their Thanks to the following people (in alphabetical order) for their
review and feedback: Mikael Abrahamsson, Mark Andrews, Brian E review and feedback: Mikael Abrahamsson, Mark Andrews, Brian E
Carpenter, Nick Heatley, Martin Hunek, Tatuya Jinmei, Erik Kline, Carpenter, David Farmer, Nick Heatley, Martin Hunek, Tatuya Jinmei,
Erik Kline, David Lamparter, Jordi Palet Martinez, Tommy Pauly,
Michael Richardson, David Schinazi. Michael Richardson, David Schinazi.
12. References 12. References
12.1. Normative References 12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010, DOI 10.17487/RFC6052, October 2010,
<https://www.rfc-editor.org/info/rfc6052>. <https://www.rfc-editor.org/info/rfc6052>.
12.2. Informative References 12.2. Informative References
[I-D.ietf-intarea-provisioning-domains] [I-D.ietf-intarea-provisioning-domains]
Pfister, P., Vyncke, E., Pauly, T., Schinazi, D., and W. Pfister, P., Vyncke, E., Pauly, T., Schinazi, D., and W.
Shao, "Discovering Provisioning Domain Names and Data", Shao, "Discovering Provisioning Domain Names and Data",
draft-ietf-intarea-provisioning-domains-05 (work in draft-ietf-intarea-provisioning-domains-05 (work in
progress), June 2019. progress), June 2019.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements", Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC4033, March 2005, RFC 4033, DOI 10.17487/RFC4033, March 2005,
<https://www.rfc-editor.org/info/rfc4033>. <https://www.rfc-editor.org/info/rfc4033>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
DOI 10.17487/RFC6105, February 2011, DOI 10.17487/RFC6105, February 2011,
<https://www.rfc-editor.org/info/rfc6105>. <https://www.rfc-editor.org/info/rfc6105>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6 NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <https://www.rfc-editor.org/info/rfc6146>. April 2011, <https://www.rfc-editor.org/info/rfc6146>.
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