Internet DRAFT - draft-ietf-v6ops-host-addr-availability
draft-ietf-v6ops-host-addr-availability
IPv6 Operations L. Colitti
Internet-Draft V. Cerf
Intended status: Best Current Practice Google
Expires: November 26, 2016 S. Cheshire
D. Schinazi
Apple Inc.
May 25, 2016
Host address availability recommendations
draft-ietf-v6ops-host-addr-availability-07
Abstract
This document recommends that networks provide general-purpose end
hosts with multiple global IPv6 addresses when they attach, and
describes the benefits of and the options for doing so.
Status of This Memo
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This Internet-Draft will expire on November 26, 2016.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Common IPv6 deployment model . . . . . . . . . . . . . . . . 3
3. Benefits of providing multiple addresses . . . . . . . . . . 3
4. Problems with restricting the number of addresses per host . 4
5. Overcoming limits using Network Address Translation . . . . . 5
6. Options for providing more than one address . . . . . . . . . 6
7. Number of addresses required . . . . . . . . . . . . . . . . 7
8. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 8
9. Operational considerations . . . . . . . . . . . . . . . . . 8
9.1. Host tracking . . . . . . . . . . . . . . . . . . . . . . 8
9.2. Address space management . . . . . . . . . . . . . . . . 9
9.3. Addressing link layer scalability issues via IP routing . 10
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
12. Security Considerations . . . . . . . . . . . . . . . . . . . 11
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
13.1. Normative References . . . . . . . . . . . . . . . . . . 11
13.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
In most aspects, the IPv6 protocol is very similar to IPv4. This
similarity can create a tendency to think of IPv6 as 128-bit IPv4,
and thus lead network designers and operators to apply identical
configurations and operational practices to both. This is generally
a good thing because it eases the transition to IPv6 and the
operation of dual-stack networks. However, in some design and
operational areas it can lead to carrying over IPv4 practices that
are limiting or not appropriate in IPv6 due to differences between
the protocols.
One such area is IP addressing, particularly IP addressing of hosts.
This is substantially different because unlike IPv4 addresses, IPv6
addresses are not a scarce resource. In IPv6, a single link provides
over four billion times more address space than the whole IPv4
Internet [RFC7421]. Thus, unlike IPv4, IPv6 networks are not forced
by address availability considerations to provide only one address
per host. On the other hand, providing multiple addresses has many
benefits including application functionality and simplicity, privacy,
flexibility to accommodate future applications, and the ability to
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provide Internet access without the use of NAT. Providing only one
IPv6 address per host negates these benefits.
This document describes the benefits of providing multiple addresses
per host and the problems with not doing so. It recommends that
networks provide general-purpose end hosts with multiple global
addresses when they attach, and lists current options for doing so.
It does not specify any changes to protocols or host behavior.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
"Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].
2. Common IPv6 deployment model
IPv6 is designed to support multiple addresses, including multiple
global addresses, per interface ([RFC4291] section 2.1, [RFC6434]
section 5.9.4). Today, many general-purpose IPv6 hosts are
configured with three or more addresses per interface: a link-local
address, a stable address (e.g., using EUI-64 or Opaque Interface
Identifiers [RFC7217]), one or more privacy addresses [RFC4941], and
possibly one or more temporary or non-temporary addresses obtained
using DHCPv6 [RFC3315].
In most general-purpose IPv6 networks, including all 3GPP networks
([RFC6459] section 5.2) and Ethernet and Wi-Fi networks using SLAAC
[RFC4862], IPv6 hosts have the ability to configure additional IPv6
addresses from the link prefix(es) without explicit requests to the
network.
3. Benefits of providing multiple addresses
Today, there are many host functions that require more than one IP
address to be available to the host, including:
o Privacy addressing to prevent tracking by off-network hosts
[RFC4941].
o Multiple processors inside the same device. For example, in many
mobile devices both the application processor and baseband
processor need to communicate with the network, particularly for
technologies like I-WLAN [TS.24327] where the two processors share
the Wi-Fi network connection.
o Extending the network (e.g., "tethering").
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o Running virtual machines on hosts.
o Translation-based transition technologies such as 464XLAT
[RFC6877] that provide IPv4 over IPv6. Some of these technologies
require the availability of a dedicated IPv6 address in order to
determine whether inbound packets are translated or native
([RFC6877] section 6.3).
o ILA ("Identifier-locator addressing") [I-D.herbert-nvo3-ila].
o Future applications (e.g., per-application IPv6 addresses [TARP]).
Examples of how the availability of multiple addresses per host has
already allowed substantial deployment of new applications without
explicit requests to the network are:
o 464XLAT. 464XLAT is usually deployed within a particular network,
and in this model the operator can ensure that the network is
appropriately configured to provide the CLAT with the additional
IPv6 address it needs to implement 464XLAT. However, there are
deployments where the PLAT (i.e., NAT64) is provided as a service
by a different network, without the knowledge or cooperation of
the residential ISP (e.g., the IPv6v4 Exchange Service
<http://www.jpix.ad.jp/en/service/ipv6v4.html>). This type of
deployment is only possible because those residential ISPs provide
multiple IP addresses to their users, and thus those users can
freely obtain the extra IPv6 address required to run 464XLAT.
o /64 sharing [RFC7278]. When the topology supports it, this is a
way to provide IPv6 tethering without needing to wait for network
operators to deploy DHCPv6 PD, which is only available in 3GPP
release 10 or above ([RFC6459] section 5.3).
4. Problems with restricting the number of addresses per host
Providing a restricted number of addresses per host implies that
functions that require multiple addresses will either be unavailable
(e.g., if the network provides only one IPv6 address per host, or if
the host has reached the limit of the number of addresses available),
or that the functions will only be available after an explicit
request to the network is granted. The necessity of explicit
requests has the following drawbacks:
o Increased latency, because a provisioning operation, and possibly
human intervention with an update to the service level agreement,
must complete before the functionality is available.
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o Uncertainty, because it is not known if a particular operation
function will be available until the provisioning operation
succeeds or fails.
o Complexity, because implementations need to deal with failures and
somehow present them to the user. Failures may manifest as
timeouts, which may be slow and frustrating to users.
o Increased load on the network's provisioning servers.
Some operators may desire to configure their networks to limit the
number of IPv6 addresses per host. Reasons might include hardware
limitations (e.g., TCAM or neighbor cache table size constraints),
business models (e.g., a desire to charge the network's users on a
per-device basis), or operational consistency with IPv4 (e.g., an IP
address management system that only supports one address per host).
However, hardware limitations are expected to ease over time, and an
attempt to generate additional revenue by charging per device may
prove counterproductive if customers respond (as they did with IPv4)
by using NAT, which results in no additional revenue, but leads to
more operational problems and higher support costs.
5. Overcoming limits using Network Address Translation
These limits can mostly be overcome by end hosts by using NAT, and
indeed in IPv4 most of these functions are provided by using NAT on
the host. Thus, the limits could be overcome in IPv6 as well by
implementing NAT66 on the host.
Unfortunately NAT has well-known drawbacks. For example, it causes
application complexity due to the need to implement NAT traversal.
It hinders development of new applications. On mobile devices, it
reduces battery life due to the necessity of frequent keepalives,
particularly for UDP. Applications using UDP that need to work on
most of the Internet are forced to send keepalives at least every 30
seconds <http://www.ietf.org/proceedings/88/slides/slides-88-tsvarea-
10.pdf>. For example, the QUIC protocol uses a 15-second keepalive
[I-D.tsvwg-quic-protocol]. Other drawbacks of NAT are well known and
documented [RFC2993]. While IPv4 NAT is inevitable due to the
limited amount of IPv4 space available, that argument does not apply
to IPv6. Guidance from the IAB is that deployment of IPv6 NAT is not
desirable [RFC5902].
The desire to overcome the problems listed in Section 4 without
disabling any features has resulted in developers implementing IPv6
NAT. There are fully-stateful address+port NAT66 implementations in
client operating systems today: for example, Linux has supported
NAT66 since late 2012 <http://kernelnewbies.org/Linux_3.7#head-
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103e14959eeb974bbd4e862df8afe7c118ba2beb>. A popular software
hypervisor also recently implemented NAT66 to work around these
issues <https://communities.vmware.com/docs/DOC-29954>. Wide
deployment of networks that provide a restricted number of addresses
will cause proliferation of NAT66 implementations.
This is not a desirable outcome. It is not desirable for users
because they may experience application brittleness. It is likely
not desirable for network operators either, as they may suffer higher
support costs, and even when the decision to provide only one IPv6
address per device is dictated by the network's business model, there
may be little in the way of incremental revenue, because devices can
share their IPv6 address with other devices. Finally, it is not
desirable for operating system manufacturers and application
developers, who will have to build more complexity, lengthening
development time and/or reducing the time spent on other features.
Indeed, it could be argued that the main reason for deploying IPv6,
instead of continuing to scale the Internet using only IPv4 and
large-scale NAT44, is because doing so can provide all the hosts on
the planet with end-to-end connectivity that is constrained not by
accidental technical limitations, but only by intentional security
policies.
6. Options for providing more than one address
Multiple IPv6 addresses can be provided in the following ways:
o Using Stateless Address Autoconfiguration [RFC4862]. SLAAC allows
hosts to create global IPv6 addresses on demand by simply forming
new addresses from the global prefix(es) assigned to the link.
Typically, SLAAC is used on shared links, but it is also possible
to use SLAAC while providing a dedicated /64 prefix to each host.
This is the case, for example, if the host is connected via a
point-to-point link such as in 3GPP networks, on a network where
each host has its own dedicated VLAN, or on a wireless network
where every MAC address is placed in its own broadcast domain.
o Using stateful DHCPv6 address assignment [RFC3315]. Most DHCPv6
clients only ask for one non-temporary address, but the protocol
allows requesting multiple temporary and even multiple non-
temporary addresses, and the server could choose to provide
multiple addresses. It is also technically possible for a client
to request additional addresses using a different DUID, though the
DHCPv6 specification implies that this is not expected behavior
([RFC3315] section 9). The DHCPv6 server will decide whether to
grant or reject the request based on information about the client,
including its DUID, MAC address, and so on. The maximum number of
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IPv6 addresses that can be provided in a single DHCPv6 packet,
given a typical MTU of 1500 bytes or smaller, is approximately 30.
o DHCPv6 prefix delegation [RFC3633]. DHCPv6 PD allows the client
to request and be delegated a prefix, from which it can
autonomously form other addresses. If the prefix is shorter than
/64, it can be divided into multiple subnets which can be further
delegated to downstream clients. If the prefix is a /64, it can
be extended via L2 bridging, ND proxying [RFC4389] or /64 sharing
[RFC7278], but it cannot be further subdivided, as a prefix longer
than /64 is outside the current IPv6 specifications [RFC7421].
While [RFC3633] assumes that the DHCPv6 client is a router, DHCPv6
PD itself does not require that the client forward IPv6 packets
not addressed to itself, and thus does not require that the client
be an IPv6 router as defined in [RFC2460]. Also, in many cases
(such as tethering, or hosting virtual machines), hosts are
already forwarding IPv6 packets and thus operating as IPv6 routers
as defined in [RFC2460].
+--------------------------+-------+-------------+--------+---------+
| | SLAAC | DHCPv6 | DHCPv6 | DHCPv4 |
| | | IA_NA / | PD | |
| | | IA_TA | | |
+--------------------------+-------+-------------+--------+---------+
| Can extend network | No+ | No | Yes | Yes |
| | | | | (NAT44) |
| Can number "unlimited" | Yes* | Yes* | No | No |
| endpoints | | | | |
| Uses stateful, request- | No | Yes | Yes | Yes |
| based assignment | | | | |
| Is immune to layer 3 on- | No | Yes | Yes | Yes |
| link resource exhaustion | | | | |
| attacks | | | | |
+--------------------------+-------+-------------+--------+---------+
[*] Subject to network limitations, e.g., ND cache entry size limits.
[+] Except on certain networks, e.g., [RFC7278].
Table 1: Comparison of multiple address assignment options
7. Number of addresses required
If we itemize the use cases from section Section 3, we can estimate
the number of addresses currently used in normal operations. In
typical implementations, privacy addresses use up to 8 addresses -
one per day ([RFC4941] section 3.5). Current mobile devices may
typically support 8 clients, with each one requiring one or more
addresses. A client might choose to run several virtual machines.
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Current implementations of 464XLAT require use of a separate address.
Some devices require another address for their baseband chip. Even a
host performing just a few of these functions simultaneously might
need on the order of 20 addresses at the same time. Future
applications designed to use an address per application or even per
resource will require many more. These will not function on networks
that enforce a hard limit on the number of addresses provided to
hosts. Thus, in general is is not possible to estimate in advance
how many addresses are required.
8. Recommendations
In order to avoid the problems described above, and preserve the
Internet's ability to support new applications that use more than one
IPv6 address, it is RECOMMENDED that IPv6 network deployments provide
multiple IPv6 addresses from each prefix to general-purpose hosts.
To support future use cases, it is NOT RECOMMENDED to impose a hard
limit on the size of the address pool assigned to a host.
Particularly, it is NOT RECOMMENDED to limit a host to only one IPv6
address per prefix.
Due to the drawbacks imposed by requiring explicit requests for
address space (see section Section 4), it is RECOMMENDED that the
network give the host the ability to use new addresses without
requiring explicit requests. This can be achieved either by allowing
the host to form new addresses autonomously (e.g., via SLAAC), or by
providing the host with a dedicated /64 prefix. The prefix MAY be
provided using DHCPv6 PD, SLAAC with per-device VLANs, or any other
means.
Using stateful address assignment (DHCPv6 IA_NA or IA_TA) to provide
multiple addresses when the host connects (e.g. the approximately 30
addresses that can fit into a single packet) would accommodate
current clients, but sets a limit on the number of addresses
available to hosts when they attach and would limit the development
of future applications.
9. Operational considerations
9.1. Host tracking
Some network operators - often operators of networks that provide
services to third parties such as university campus networks - are
required to track which IP addresses are assigned to which hosts on
their network. Maintaining persistent logs that map user IP
addresses and timestamps to hardware identifiers such as MAC
addresses may be used to attribute liability for copyright
infringement or other illegal activity.
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It is worth noting that this requirement can be met without using
DHCPv6 address assignment. For example, it is possible to maintain
these mappings by monitoring IPv6 neighbor table: routers typically
allow periodic dumps of the neighbor cache via SNMP or other means,
and many can be configured to log every change to the neighbor cache.
Using SLAAC with a dedicated /64 prefix simplifies tracking, as it
does not require logging each address formed by the host, but only
the prefix assigned to the host when it attaches to the network.
Similarly, providing address space using DHCPv6 PD has the same
tracking properties as DHCPv6 address assignment, but allows the
network to provide unrestricted address space.
Many large enterprise networks are fully dual-stack and implement
address monitoring without using or supporting DHCPv6. The authors
are directly aware of several networks that operate in this way,
including the Universities of Loughborough, Minnesota, Reading,
Southampton, Wisconsin and Imperial College London, in addition to
the enterprise networks of the authors' employers.
It should also be noted that using DHCPv6 address assignment does not
ensure that the network can reliably track the IPv6 addresses used by
hosts. On any shared network without L2 edge port security, hosts
are able to choose their own addresses regardless of what address
provisioning methodology is in use. The only way to restrict the
addresses used by hosts is to use layer 2 security mechanisms that
enforce that particular IPv6 addresses are used by particular link-
layer addresses (for example, SAVI [RFC7039]). If those mechanisms
are available, it is possible to use them to provide tracking; this
form of tracking is more secure and reliable than server logs because
it operates independently of how addresses are allocated. Finally,
tracking address information via DHCPv6 server logs is likely to
become decreasingly viable due to ongoing efforts to improve the
privacy of DHCPv6 and MAC address randomization [RFC7844].
9.2. Address space management
In IPv4, all but the world's largest networks can be addressed using
private space [RFC1918], with each host receiving one IPv4 address.
Many networks can be numbered in 192.168.0.0/16 which has roughly 64k
addresses. In IPv6, that is equivalent to a /48, with each of 64k
hosts receiving a /64 prefix. Under current RIR policies, a /48 is
easy to obtain for an enterprise network. Networks that need a
bigger block of private space use 10.0.0.0/8, which has roughly 16
million addresses. In IPv6, that is equivalent to a /40, with each
host receiving /64 prefix. Enterprises of such size can easily
obtain a /40 under current RIR policies.
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In the above cases, aggregation and routing can be equivalent to
IPv4: if a network aggregates per-host IPv4 addresses into prefixes
of length /32 - n, it can aggregate per-host /64 prefixes into the
same number of prefixes of length /64 - n.
Currently, residential users typically receive one IPv4 address and a
/48, /56 or /60 IPv6 prefix. While such networks do not provide
enough space to assign a /64 per host, such networks almost
universally use SLAAC, and thus do not pose any particular limit to
the number of addresses hosts can use.
Unlike IPv4 where addresses came at a premium, in all these networks,
there is enough IPv6 address space to supply clients with multiple
IPv6 addresses.
9.3. Addressing link layer scalability issues via IP routing
The number of IPv6 addresses on a link has direct impact for
networking infrastructure nodes (routers, switches) and other nodes
on the link. Setting aside exhaustion attacks via Layer 2 address
spoofing, every (Layer 2, IP) address pair impacts networking
hardware requirements in terms of memory, MLD snooping, solicited
node multicast groups, etc. Many of these costs are incurred by
neighboring hosts.
Hosts on such networks that create unreasonable numbers of addresses
risk impairing network connectivity for themselves and other hosts on
the network, and in extreme cases (e.g., hundreds or thousands of
addresses) may even find their network access restricted by denial-
of-service protection mechanisms.
We expect these scaling limitations to change over time as hardware
and applications evolve. However, switching to a dedicated /64
prefix per host can resolve these scaling limitations. If the prefix
is provided via DHCPv6 PD, or if the prefix can be used by only one
link-layer address (e.g., if the link layer uniquely identifies or
authenticates hosts based on MAC addresses), then there will be only
one routing entry and one ND cache entry per host on the network.
Furthermore, if the host is aware that the prefix is dedicated (e.g.,
if it was provided via DHCPv6 PD and not SLAAC), it is possible for
the host to assign IPv6 addresses from this prefix to an internal
interface such as a loopback interface. This obviates the need to
perform Neighbor Discovery and Duplicate Address Detection on the
network interface for these addresses, reducing network traffic.
Thus, assigning a dedicated /64 prefix per host is operationally
prudent. Clearly, however, it requires more IPv6 address space than
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using shared links, so the benefits provided must be weighed with the
operational overhead of address space management.
10. Acknowledgements
The authors thank Tore Anderson, Brian Carpenter, David Farmer,
Wesley George, Geoff Huston, Erik Kline, Victor Kuarsingh, Shucheng
(Will) Liu, Dieter Siegmund, Mark Smith, Sander Steffann, Fred
Templin and James Woodyatt for their input and contributions.
11. IANA Considerations
This memo includes no request to IANA.
12. Security Considerations
As mentioned in section 9.3, on shared networks using SLAAC it is
possible for hosts to attempt to exhaust network resources and
possibly deny service to other hosts by creating unreasonable numbers
(e.g., hundreds or thousands) of addresses. Networks that provide
access to untrusted hosts can mitigate this threat by providing a
dedicated /64 prefix per host. It is also possible to mitigate the
threat by limiting the number of ND cache entries that can be created
for a particular host, but care must be taken to ensure that the
network does not restrict the IP addresses available to non-malicious
hosts.
Security issues related to host tracking are discussed in section
9.1.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
13.2. Informative References
[I-D.herbert-nvo3-ila]
Herbert, T., "Identifier-locator addressing for network
virtualization", draft-herbert-nvo3-ila-02 (work in
progress), March 2016.
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[I-D.tsvwg-quic-protocol]
Hamilton, R., Iyengar, J., Swett, I., and A. Wilk, "QUIC:
A UDP-Based Secure and Reliable Transport for HTTP/2",
draft-tsvwg-quic-protocol-02 (work in progress), January
2016.
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
and E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
<http://www.rfc-editor.org/info/rfc1918>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC2993] Hain, T., "Architectural Implications of NAT", RFC 2993,
DOI 10.17487/RFC2993, November 2000,
<http://www.rfc-editor.org/info/rfc2993>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <http://www.rfc-editor.org/info/rfc3315>.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
DOI 10.17487/RFC3633, December 2003,
<http://www.rfc-editor.org/info/rfc3633>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.
[RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery
Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April
2006, <http://www.rfc-editor.org/info/rfc4389>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<http://www.rfc-editor.org/info/rfc4941>.
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[RFC5902] Thaler, D., Zhang, L., and G. Lebovitz, "IAB Thoughts on
IPv6 Network Address Translation", RFC 5902,
DOI 10.17487/RFC5902, July 2010,
<http://www.rfc-editor.org/info/rfc5902>.
[RFC6434] Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node
Requirements", RFC 6434, DOI 10.17487/RFC6434, December
2011, <http://www.rfc-editor.org/info/rfc6434>.
[RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen,
T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
Partnership Project (3GPP) Evolved Packet System (EPS)",
RFC 6459, DOI 10.17487/RFC6459, January 2012,
<http://www.rfc-editor.org/info/rfc6459>.
[RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
Combination of Stateful and Stateless Translation",
RFC 6877, DOI 10.17487/RFC6877, April 2013,
<http://www.rfc-editor.org/info/rfc6877>.
[RFC7039] Wu, J., Bi, J., Bagnulo, M., Baker, F., and C. Vogt, Ed.,
"Source Address Validation Improvement (SAVI) Framework",
RFC 7039, DOI 10.17487/RFC7039, October 2013,
<http://www.rfc-editor.org/info/rfc7039>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>.
[RFC7278] Byrne, C., Drown, D., and A. Vizdal, "Extending an IPv6
/64 Prefix from a Third Generation Partnership Project
(3GPP) Mobile Interface to a LAN Link", RFC 7278,
DOI 10.17487/RFC7278, June 2014,
<http://www.rfc-editor.org/info/rfc7278>.
[RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S.,
Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit
Boundary in IPv6 Addressing", RFC 7421,
DOI 10.17487/RFC7421, January 2015,
<http://www.rfc-editor.org/info/rfc7421>.
[RFC7844] Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity
Profiles for DHCP Clients", RFC 7844,
DOI 10.17487/RFC7844, May 2016,
<http://www.rfc-editor.org/info/rfc7844>.
Colitti, et al. Expires November 26, 2016 [Page 13]
Internet-Draft Host address availability recommendations May 2016
[TARP] Gleitz, PM. and SM. Bellovin, "Transient Addressing for
Related Processes: Improved Firewalling by Using IPv6 and
Multiple Addresses per Host", August 2001.
[TS.24327]
3GPP, "Mobility between 3GPP Wireless Local Area Network
(WLAN) interworking (I-WLAN) and 3GPP systems; General
Packet Radio System (GPRS) and 3GPP I-WLAN aspects; Stage
3", June 2011.
Authors' Addresses
Lorenzo Colitti
Google
Roppongi 6-10-1
Minato, Tokyo 106-6126
JP
Email: lorenzo@google.com
Vint Cerf
Google
1875 Explorer St
10th Floor
Reston, VA 20190
US
Email: vint@google.com
Stuart Cheshire
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
US
Email: cheshire@apple.com
David Schinazi
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
US
Email: dschinazi@apple.com
Colitti, et al. Expires November 26, 2016 [Page 14]
