draft-ietf-6man-ra-pref64-09.txt   rfc8781.txt 
IPv6 Maintenance L. Colitti Internet Engineering Task Force (IETF) L. Colitti
Internet-Draft J. Linkova Request for Comments: 8781 J. Linkova
Intended status: Standards Track Google Category: Standards Track Google
Expires: June 21, 2020 December 19, 2019 ISSN: 2070-1721 April 2020
Discovering PREF64 in Router Advertisements Discovering PREF64 in Router Advertisements
draft-ietf-6man-ra-pref64-09
Abstract Abstract
This document specifies a Neighbor Discovery option to be used in This document specifies a Neighbor Discovery option to be used in
Router Advertisements to communicate NAT64 prefixes to hosts. Router Advertisements (RAs) to communicate prefixes of Network
Address and Protocol Translation from IPv6 clients to IPv4 servers
(NAT64) to hosts.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79.
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on June 21, 2020. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8781.
Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Terminology
2. Use cases for communicating the NAT64 prefix to hosts . . . . 3 2. Use Cases for Communicating the NAT64 Prefix to Hosts
3. Why include the NAT64 prefix in Router Advertisements . . . . 3 3. Why Include the NAT64 Prefix in Router Advertisements?
4. Option format . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Option Format
4.1. Scaled Lifetime Processing . . . . . . . . . . . . . . . 5 4.1. Scaled Lifetime Processing
5. Usage Guidelines . . . . . . . . . . . . . . . . . . . . . . 6 5. Usage Guidelines
5.1. Handling Multiple NAT64 Prefixes . . . . . . . . . . . . 6 5.1. Handling Multiple NAT64 Prefixes
5.2. PREF64 Consistency . . . . . . . . . . . . . . . . . . . 7 5.2. PREF64 Consistency
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 8. References
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.1. Normative References
9.1. Normative References . . . . . . . . . . . . . . . . . . 9 8.2. Informative References
9.2. Informative References . . . . . . . . . . . . . . . . . 9 Acknowledgements
9.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
NAT64 [RFC6146] with DNS64 [RFC6147] is a widely-deployed mechanism NAT64 [RFC6146] with DNS Extensions for Network Address Translation
to provide IPv4 access on IPv6-only networks. In various scenarios, from IPv6 clients to IPv4 servers (DNS64) [RFC6147] is a widely
the host must be aware of the NAT64 prefix in use by the network. deployed mechanism to provide IPv4 access on IPv6-only networks. In
This document specifies a Neighbor Discovery [RFC4861] option to be various scenarios, the host must be aware of the NAT64 prefix in use
used in Router Advertisements to communicate NAT64 prefixes to hosts. by the network. This document specifies a Neighbor Discovery
[RFC4861] option to be used in Router Advertisements (RAs) to
communicate NAT64 prefixes to hosts.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
1.2. Terminology 1.2. Terminology
PREF64 (or NAT64 prefix): an IPv6 prefix used for IPv6 address PREF64 (or NAT64 prefix): An IPv6 prefix used for IPv6 address
synthesis [RFC6146]; synthesis [RFC6146];
NAT64: Network Address and Protocol Translation from IPv6 Clients to NAT64: Network Address and Protocol Translation from IPv6 clients to
IPv4 Servers [RFC6146]; IPv4 servers [RFC6146];
Router Advertisement (RA): A message used by IPv6 routers to
advertise their presence together with various link and Internet
parameters [RFC4861];
RA: Router Advertisement, a message used by IPv6 routers to advertise
their presence together with various link and Internet parameters
[RFC4861];
DNS64: a mechanism for synthesizing AAAA records from A records DNS64: a mechanism for synthesizing AAAA records from A records
[RFC6147]; [RFC6147];
2. Use cases for communicating the NAT64 prefix to hosts 2. Use Cases for Communicating the NAT64 Prefix to Hosts
On networks employing NAT64, it is useful for hosts to know the NAT64 On networks employing NAT64, it is useful for hosts to know the NAT64
prefix for several reasons, including the following: prefix for several reasons, including the following:
o Enabling DNS64 functions on end hosts. In particular: * Enabling DNS64 functions on end hosts. In particular:
* Local DNSSEC validation (DNS64 in stub-resolver mode). As - Local DNSSEC validation (DNS64 in stub-resolver mode). As
discussed in [RFC6147] section 2, the stub resolver in the host discussed in [RFC6147], Section 2, the stub resolver in the
"will try to obtain (real) AAAA RRs, and in case they are not host "will try to obtain (real) AAAA RRs, and in case they are
available, the DNS64 function will synthesize AAAA RRs for not available, the DNS64 function will synthesize AAAA RRs for
internal usage." Therefore to perform the DNS64 function the internal usage." Therefore, to perform the DNS64 function, the
stub resolver needs to know the NAT64 prefix. This is required stub resolver needs to know the NAT64 prefix. This is required
in order to use DNSSEC on a NAT64 network. in order to use DNSSEC on a NAT64 network.
* Trusted DNS server. AAAA synthesis is required for the host to - 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., be able to use a DNS server not provided by the network (e.g.,
a DNS-over-TLS [RFC7858] or DNS-over-HTTPS [RFC8484] server a DNS-over-TLS [RFC7858] or DNS-over-HTTPS [RFC8484] server
with which the host has an existing trust relationship). with which the host has an existing trust relationship).
* Networks with no DNS64 server. Hosts that support AAAA - Networks with no DNS64 server. Hosts that support AAAA
synthesis and that are aware of the NAT64 prefix in use do not synthesis and are aware of the NAT64 prefix in use do not need
need the network to perform the DNS64 function at all. the network to perform the DNS64 function at all.
o Enabling NAT64 address translation functions on end hosts. For * Enabling NAT64 address-translation functions on end hosts. For
example: example:
* IPv4 address literals on an IPv6-only host. As described in - IPv4 address literals on an IPv6-only host. As described in
[RFC8305] section 7.1, IPv6-only hosts connecting to IPv4 [RFC8305], Section 7.1, IPv6-only hosts connecting to IPv4
address literals can translate the IPv4 literal to an IPv6 address literals can translate the IPv4 literal to an IPv6
literal. literal.
* 464XLAT [RFC6877]. 464XLAT requires the host be aware of the - 464XLAT [RFC6877]. 464XLAT requires the host be aware of the
NAT64 prefix. NAT64 prefix.
3. Why include the NAT64 prefix in Router Advertisements 3. Why Include the NAT64 Prefix in Router Advertisements?
Fate sharing: NAT64 requires routing to be configured. IPv6 routing Fate sharing: NAT64 requires routing to be configured. IPv6 routing
configuration requires receiving an IPv6 Router Advertisement configuration requires receiving an IPv6 RA [RFC4861]. Therefore,
[RFC4861]. Therefore using Router Advertisements to provide hosts using RAs to provide hosts with the NAT64 prefix ensures that
with NAT64 prefix ensures that NAT64 reachability information shares NAT64 reachability information shares the fate of the rest of the
fate with the rest of network configuration on the host. network configuration on the host.
Atomic configuration: including the NAT64 prefix in the Router Atomic configuration: Including the NAT64 prefix in the RA minimizes
Advertisement minimizes the number of packets required to configure a the number of packets required to configure a host. Only one
host. Only one packet (a Router Advertisement) is required to packet (an RA) is required to complete the network configuration.
complete the network configuration. This speeds up the process of This speeds up the process of connecting to a network that
connecting to a network that supports NAT64/DNS64, and simplifies supports NAT64/DNS64. It also simplifies host implementation by
host implementation by removing the possibility that the host can removing the possibility that the host can have an incomplete
have an incomplete layer 3 configuration (e.g., IPv6 addresses and Layer 3 configuration (e.g., IPv6 addresses and prefixes, but no
prefixes, but no NAT64 prefix). NAT64 prefix).
Updatability: it is possible to change the NAT64 prefix at any time, Updatability: It is possible to change the NAT64 prefix at any time,
because when it changes, it is possible to notify hosts by sending a because when it changes, it is possible to notify hosts by sending
new Router Advertisement. a new RA.
Deployability: all IPv6 hosts and networks are required to support Deployability: All IPv6 hosts and networks are required to support
Neighbor Discovery [RFC4861] so just a minor extension to the Neighbor Discovery [RFC4861] so just a minor extension to the
existing implementation is required. Other options such as [RFC7225] existing implementation is required. Other options, such as
require implementing other protocols (e.g. PCP [RFC7225]) which [RFC7225], require implementing other protocols (e.g., Port
could be considered an obstacle for deployment. Control Protocol (PCP) [RFC7225]), which could be considered an
obstacle for deployment.
4. Option format 4. Option Format
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Scaled Lifetime | PLC | | Type | Length | Scaled Lifetime | PLC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| Highest 96 bits of the Prefix | | Highest 96 bits of the Prefix |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: NAT64 Prefix Option Format Figure 1: NAT64 Prefix Option Format
Fields: Fields:
Type 8-bit identifier of the PREF64 option type as assigned by Type: 8-bit identifier of the PREF64 option type (38)
IANA: TBD
Length 8-bit unsigned integer. The length of the option
(including the Type and Length fields) is in units of 8
octets. The sender MUST set the length to 2. The receiver
MUST ignore the PREF64 option if the length field value is
not 2.
Scaled 13-bit unsigned integer. The maximum time in units of 8 Length: 8-bit unsigned integer. The length of the option (including
Lifetime seconds over which this NAT64 prefix MAY be used. See the Type and Length fields) is in units of 8 octets. The sender
Section 4.1 for the Scaled Lifetime field processing rules. MUST set the length to 2. The receiver MUST ignore the PREF64
option if the Length field value is not 2.
PLC 3-bit unsigned integer. This field encodes the NAT64 Prefix Scaled Lifetime: 13-bit unsigned integer. The maximum time in units
(Prefix Length defined in [RFC6052]. The PLC field values 0, 1, 2, of 8 seconds over which this NAT64 prefix MAY be used. See
Length 3, 4 and 5 indicate the NAT64 prefix length of 96, 64, 56, Section 4.1 for the Scaled Lifetime field processing rules.
Code) 48, 40 and 32 bits respectively. The receiver MUST ignore
the PREF64 option if the prefix length code field is not set
to one of those values.
Highest 96-bit unsigned integer. Contains bits 0 - 95 of the NAT64 PLC (Prefix Length Code): 3-bit unsigned integer. This field
96 bits prefix. encodes the NAT64 Prefix Length defined in [RFC6052]. The PLC
of the field values 0, 1, 2, 3, 4, and 5 indicate the NAT64 prefix length
prefix of 96, 64, 56, 48, 40, and 32 bits, respectively. The receiver
MUST ignore the PREF64 option if the Prefix Length Code field is
not set to one of those values.
Highest 96 bits of the Prefix: 96-bit unsigned integer. Contains
bits 0 - 95 of the NAT64 prefix.
4.1. Scaled Lifetime Processing 4.1. Scaled Lifetime Processing
It would be highly undesirable for the NAT64 prefix to have a It would be highly undesirable for the NAT64 prefix to have a
lifetime shorter than the Router Lifetime, which is defined in the lifetime shorter than the Router Lifetime, which is defined in
Section 4.2 of [RFC4861] as 16-bit unsigned integer. If the NAT64 Section 4.2 of [RFC4861] as a 16-bit unsigned integer. If the NAT64
prefix lifetime is not at least equal to the default router lifetime prefix lifetime is not at least equal to the default Router Lifetime,
it might lead to scenarios when the NAT64 prefix lifetime expires it might lead to scenarios in which the NAT64 prefix lifetime expires
before the arrival of the next unsolicited RA. Therefore the Scaled before the arrival of the next unsolicited RA. Therefore, the Scaled
Lifetime encodes the NAT64 prefix lifetime in units of 8 seconds. Lifetime encodes the NAT64 prefix lifetime in units of 8 seconds.
The receiver MUST multiply the Scaled Lifetime value by 8 (for The receiver MUST multiply the Scaled Lifetime value by 8 (for
example, by logical left shift) to calculate the maximum time in example, by a logical left shift) to calculate the maximum time in
seconds the prefix MAY be used. The maximum lifetime of the NAT64 seconds the prefix MAY be used. The maximum lifetime of the NAT64
prefix is thus 65528 seconds. To ensure that the NAT64 prefix does prefix is thus 65528 seconds. To ensure that the NAT64 prefix does
not expire before the default router, when using this option it is not expire before the default router, it is NOT RECOMMENDED to
NOT RECOMMENDED to configure default router lifetimes greater than configure default Router Lifetimes greater than 65528 seconds when
65528 seconds. Lifetime of 0 indicates that the prefix SHOULD NOT be using this option. A lifetime of 0 indicates that the prefix SHOULD
used anymore. NOT be used anymore.
The value of the Scaled Lifetime field SHOULD by default be set to By default, the value of the Scaled Lifetime field SHOULD be set to
the lesser of 3 x MaxRtrAdvInterval ([RFC4861]) divided by 8, or the lesser of 3 x MaxRtrAdvInterval [RFC4861] divided by 8, or 8191.
8191.
Router vendors SHOULD allow administrators to specify non-zero Router vendors SHOULD allow administrators to specify nonzero
lifetime values which are not divisible by 8. In such cases the lifetime values that are not divisible by 8. In such cases, the
router SHOULD round the provided value up to the nearest integer that router SHOULD round the provided value up to the nearest integer that
is divisible by 8 and smaller than 65536, then divide the result by 8 is divisible by 8 and smaller than 65536, then divide the result by 8
(or perform a logical right-shift by 3), and set the Scaled Lifetime (or perform a logical right shift by 3) and set the Scaled Lifetime
field to the resulting value. If such a non-zero lifetime value to field to the resulting value. If a nonzero lifetime value that is to
be divided by 8 (to be subjected to a logical right-shift by 3) is be divided by 8 (or subjected to a logical right shift by 3) is less
less than 8 then the Scaled Lifetime field SHOULD be set to 1. This than 8, then the Scaled Lifetime field SHOULD be set to 1. This last
last step ensures that lifetimes under 8 seconds are encoded as a step ensures that lifetimes under 8 seconds are encoded as a nonzero
non-zero Scaled Lifetime. Scaled Lifetime.
5. Usage Guidelines 5. Usage Guidelines
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 wants to route different parts
parts of the IPv4 address space to different NAT64 devices, this can of the IPv4 address space to different NAT64 devices, this can be
be accomplished by routing more specific sub-prefixes of the NAT64 accomplished by routing more specific subprefixes of the NAT64 prefix
prefix to those devices. For example, suppose an operator is using to those devices. For example, suppose an operator is using the
the [RFC1918] address space 10.0.0.0/8 internally. That operator [RFC1918] address space 10.0.0.0/8 internally. That operator might
might want to route 10.0.0.0/8 through NAT64 device A, and the rest want to route 10.0.0.0/8 through NAT64 device A, and the rest of the
of the IPv4 space through NAT64 device B. If the operator's NAT64 IPv4 space through NAT64 device B. If the operator's NAT64 prefix is
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::/96 to NAT64 B. 2001:db8:a:b::a00:0/104 to NAT64 A and 2001:db8:a:b::/96 to NAT64 B.
This option may appear more than once in a Router Advertisement (e.g. This option may appear more than once in an RA (e.g., when gracefully
in case of graceful renumbering the network from one NAT64 prefix to renumbering the network from one NAT64 prefix to another). Host
another). Host behaviour with regards to synthesizing IPv6 addresses behavior with regard to synthesizing IPv6 addresses from IPv4
from IPv4 addresses SHOULD follow the recommendations given in addresses SHOULD follow the recommendations given in Section 3 of
Section 3 of [RFC7050], limited to the NAT64 prefixes that have non- [RFC7050], limited to the NAT64 prefixes that have a nonzero
zero lifetime. lifetime.
In a network (or a provisioning domain) that provides both IPv4 and In a network (or a provisioning domain) that provides both IPv4 and
NAT64, it may be desirable for certain IPv4 addresses not to be NAT64, it may be desirable for certain IPv4 addresses not to be
translated. An example might be private address ranges that are translated. An example might be private address ranges that are
local to the network/provisioning domain and should not be reached local to the network/provisioning domain and that should not be
through the NAT64. This type of configuration cannot be conveyed to reached through the NAT64. This type of configuration cannot be
hosts using this option, or through other NAT64 prefix provisioning conveyed to hosts using this option, or through other NAT64 prefix
mechanisms such as [RFC7050] or [RFC7225]. This problem does not provisioning mechanisms such as [RFC7050] or [RFC7225]. This problem
apply in IPv6-only networks, because in such networks, the host does does not apply in IPv6-only networks: the host in an IPv6-only
not have an IPv4 address and cannot reach any IPv4 destinations network does not have an IPv4 address and cannot reach any IPv4
without the NAT64. destinations without the NAT64.
5.1. Handling Multiple NAT64 Prefixes 5.1. Handling Multiple NAT64 Prefixes
In some cases a host may receive multiple NAT64 prefixes from In some cases, a host may receive multiple NAT64 prefixes from
different sources. Possible scenarios include (but are not limited different sources. Possible scenarios include (but are not limited
to): to):
o the host is using multiple mechanisms to discover PREF64 prefixes * the host is using multiple mechanisms to discover PREF64 prefixes
(e.g. by using PCP [RFC7225]) and/or by resolving IPv4-only fully (e.g., by using PCP [RFC7225]) and/or resolving an 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; * the PREF64 option presents in a single RA more than once;
o the host receives multiple RAs with different PREF64 prefixes on a * the host receives multiple RAs with different PREF64 prefixes on a
given interface. given interface.
When multiple PREF64 were discovered via RA PREF64 Option (the Option When multiple PREF64s are discovered via the RA PREF64 Option (either
presents more than once in a single RA or multiple RAs were the Option presents more than once in a single RA or multiple RAs are
received), host behaviour with regards to synthesizing IPv6 addresses received), host behavior with regard to synthesizing IPv6 addresses
from IPv4 addresses SHOULD follow the recommendations given in from IPv4 addresses SHOULD follow the recommendations given in
Section 3 of [RFC7050], limited to the NAT64 prefixes that have non- Section 3 of [RFC7050], limited to the NAT64 prefixes that have a
zero lifetime. nonzero lifetime.
When different PREF64 are discovered by using multiple mechanisms, When different PREF64s are discovered using multiple mechanisms,
hosts SHOULD select one source of information only. The RECOMMENDED hosts SHOULD select one source of information only. The RECOMMENDED
order is: order is:
o PCP-discovered prefixes [RFC7225], if supported; * PCP-discovered prefixes [RFC7225], if supported;
o PREF64 discovered via RA Option; * PREF64s discovered via the RA Option;
o PREF64 resolving IPv4-only fully qualified domain name [RFC7050] * PREF64s resolving an IPv4-only fully qualified domain name
[RFC7050]
Note that if the network provides PREF64 both via this RA option and Note: If the network provides PREF64s via both this RA Option and
[RFC7225], hosts that receive the PREF64 via RA option may choose to [RFC7225], hosts that receive the PREF64 via the RA Option may choose
use it immediately before waiting for PCP to complete, and therefore to use it immediately (before waiting for the PCP to complete);
some traffic may not reflect any more detailed configuration provided therefore, some traffic may not reflect any more detailed
by PCP. configuration provided by the PCP.
The host SHOULD treat the PREF64 as being specific to the network The host SHOULD treat the PREF64 as being specific to the network
interface it was received on. Provisioning Domain (PvD, [RFC7556]) interface it was received on. Hosts that are aware of Provisioning
aware hosts MUST treat the PREF64 as being scoped to the implicit or Domain (PvD, [RFC7556]) MUST treat the PREF64 as being scoped to the
explicit PvD. implicit or explicit PvD.
5.2. PREF64 Consistency 5.2. PREF64 Consistency
Section 6.2.7 of [RFC4861] recommends that routers inspect RAs sent Section 6.2.7 of [RFC4861] recommends that routers inspect RAs sent
by other routers to ensure that all routers onlink advertise by other routers to ensure that all routers onlink advertise
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; * set of PREF64s with a nonzero lifetime;
o set of PREF64 with zero lifetime.
Provisioning Domain (PvD, [RFC7556]) aware routers MUST only compare * set of PREF64s with a zero lifetime.
Routers that are aware of PvD ([RFC7556]) MUST only compare
information scoped to the same implicit or explicit PvD. information scoped to the same implicit or explicit PvD.
6. IANA Considerations 6. IANA Considerations
The IANA is requested to assign a new IPv6 Neighbor Discovery Option IANA has assigned a new IPv6 Neighbor Discovery Option type for the
type for the PREF64 option defined in this document. PREF64 option defined in this document in the "IPv6 Neighbor
Discovery Option Formats" registry [IANA].
+---------------+-------+
| Option Name | Type |
+---------------+-------+
| PREF64 option | (TBD) |
+---------------+-------+
Table 1
The IANA registry for these options is: +---------------+------+
| Description | Type |
+===============+======+
| PREF64 option | 38 |
+---------------+------+
https://www.iana.org/assignments/icmpv6-parameters [1] Table 1: New IANA
Registry Assignment
7. Security Considerations 7. Security Considerations
Because Router Advertisements are required in all IPv6 configuration Because RAs are required in all IPv6 configuration scenarios, on
scenarios, on IPv6-only networks, Router Advertisements must already IPv6-only networks, RAs must already be secured -- e.g., by deploying
be secured, e.g., by deploying RA guard [RFC6105]. Providing all an RA-Guard [RFC6105]. Providing all configuration in RAs reduces
configuration in Router Advertisements reduces the attack surface to the attack surface to be targeted by malicious attackers trying to
be targeted by malicious attackers to provide hosts with invalid provide hosts with invalid configuration, as compared to distributing
configuration as compared to distributing the configuration through the configuration through multiple different mechanisms that need to
multiple different mechanisms that need to be secured independently. be secured independently.
If a host is provided with an incorrect NAT64 prefix the IPv6-only If a host is provided with an incorrect NAT64 prefix, the IPv6-only
host might not be able to communicate with IPv4-only destinations. host might not be able to communicate with IPv4-only destinations.
Connectivity to destinations reachable over IPv6 would not be Connectivity to destinations reachable over IPv6 would not be
impacted just by providing a host with an incorrect prefix (however impacted just by providing a host with an incorrect prefix; however,
if attackers are capable of sending rogue RAs they can perform if attackers are capable of sending rogue RAs, they can perform
denial-of-service or man-in-the-middle attacks, as described in denial-of-service or man-in-the-middle attacks, as described in
[RFC6104]). [RFC6104].
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 RAs are only received from legitimate sources eliminate the problem
eliminate the problem of NAT64 prefix validation described in section of NAT64 prefix validation described in Section 3.1 of [RFC7050].
3.1 of [RFC7050].
8. Acknowledgements
Thanks to the following people (in alphabetical order) for their 8. References
review and feedback: Mikael Abrahamsson, Mark Andrews, Brian E
Carpenter, David Farmer, Nick Heatley, Robert Hinden, Martin Hunek,
Tatuya Jinmei, Benjamin Kaduk, Erik Kline, Suresh Krishnan, Warren
Kumari, David Lamparter, Barry Leiba, Jordi Palet Martinez, Tommy
Pauly, Alexandre Petrescu, Michael Richardson, David Schinazi, Ole
Troan, Eric Vynke, Bernie Volz.
9. References 8.1. Normative References
9.1. Normative References [IANA] IANA, "Internet Control Message Protocol version 6
(ICMPv6) Parameters",
<https://www.iana.org/assignments/icmpv6-parameters>.
[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, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
skipping to change at page 9, line 43 skipping to change at line 395
[RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of [RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
the IPv6 Prefix Used for IPv6 Address Synthesis", the IPv6 Prefix Used for IPv6 Address Synthesis",
RFC 7050, DOI 10.17487/RFC7050, November 2013, RFC 7050, DOI 10.17487/RFC7050, November 2013,
<https://www.rfc-editor.org/info/rfc7050>. <https://www.rfc-editor.org/info/rfc7050>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 8.2. Informative References
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.
and E. Lear, "Address Allocation for Private Internets", J., and E. Lear, "Address Allocation for Private
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918,
<https://www.rfc-editor.org/info/rfc1918>. February 1996, <https://www.rfc-editor.org/info/rfc1918>.
[RFC6104] Chown, T. and S. Venaas, "Rogue IPv6 Router Advertisement [RFC6104] Chown, T. and S. Venaas, "Rogue IPv6 Router Advertisement
Problem Statement", RFC 6104, DOI 10.17487/RFC6104, Problem Statement", RFC 6104, DOI 10.17487/RFC6104,
February 2011, <https://www.rfc-editor.org/info/rfc6104>. February 2011, <https://www.rfc-editor.org/info/rfc6104>.
[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>.
skipping to change at page 11, line 5 skipping to change at line 450
[RFC8305] Schinazi, D. and T. Pauly, "Happy Eyeballs Version 2: [RFC8305] Schinazi, D. and T. Pauly, "Happy Eyeballs Version 2:
Better Connectivity Using Concurrency", RFC 8305, Better Connectivity Using Concurrency", RFC 8305,
DOI 10.17487/RFC8305, December 2017, DOI 10.17487/RFC8305, December 2017,
<https://www.rfc-editor.org/info/rfc8305>. <https://www.rfc-editor.org/info/rfc8305>.
[RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
<https://www.rfc-editor.org/info/rfc8484>. <https://www.rfc-editor.org/info/rfc8484>.
9.3. URIs Acknowledgements
[1] https://www.iana.org/assignments/icmpv6-parameters Thanks to the following people (in alphabetical order) for their
review and feedback: Mikael Abrahamsson, Mark Andrews, Brian E
Carpenter, David Farmer, Nick Heatley, Robert Hinden, Martin Hunek,
Tatuya Jinmei, Benjamin Kaduk, Erik Kline, Suresh Krishnan, Warren
Kumari, David Lamparter, Barry Leiba, Jordi Palet Martinez, Tommy
Pauly, Alexandre Petrescu, Michael Richardson, David Schinazi, Ole
Troan, Eric Vynke, Bernie Volz.
Authors' Addresses Authors' Addresses
Lorenzo Colitti Lorenzo Colitti
Google Google
Shibuya 3-21-3 Shibuya 3-21-3, Tokyo
Shibuya, Tokyo 150-0002 150-0002
JP Japan
Email: lorenzo@google.com Email: lorenzo@google.com
Jen Linkova Jen Linkova
Google Google
1 Darling Island Rd 1 Darling Island Rd
Pyrmont, NSW 2009 Pyrmont NSW 2009
AU Australia
Email: furry@google.com Email: furry@google.com
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