v6ops J. Palet Martinez
Internet-Draft Consulintel, S.L.
Intended status: Informational August 3, 2017
Expires: February 4, 2018
IPv6-only Terminology Definition
draft-palet-v6ops-ipv6-only-00
Abstract
This document clarify the terminology regarding the usage of
expressions such as "IPv6-only", ir order to avoid confusions when
using them in IETF and other documents, in reference to what is the
actual functionalities being used (not the actual protocol support).
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Context . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. IPv6-only . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. IPv6-only host/router . . . . . . . . . . . . . . . . . . . . 4
5. IPv6-only WAN/access . . . . . . . . . . . . . . . . . . . . 4
6. IPv6-only LAN . . . . . . . . . . . . . . . . . . . . . . . . 4
7. IPv6-only core . . . . . . . . . . . . . . . . . . . . . . . 4
8. Other cases . . . . . . . . . . . . . . . . . . . . . . . . . 4
9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Due to the nature of the Internet and the different types of users,
part of a network, providers, flows, etc., there is no a single and
easy way to categorically say something such as "IPv6-only".
The goal of this document is to depict this situation and agree in a
common language to be used for IETF and other documents, in order to
facilitate ourselves and future readers, the correct understanting of
what we are talking about.
Note that al the references in this document are regarding the actual
usage of IPv4/IPv6, not the support of those. For example, a device
or access network may support both IPv4 and IPv6, however actually is
only using (forwarding at layer-2), IPv6.
2. Context
The transition from IPv4 to IPv6 is not something that can be done,
in the large majority of the cases, overnight and in a single step.
Consequently, in general, we MUST NOT talk about a whole network
having a "single and uniform" status regarding IPv6, at least not in
the early deployment stages.
Even if it is possible, it is not frequent to deploy new IPv6
networks which have no IPv4 connectivity at all, because at the
current phase of the universal goal of the IPv6 deployment, almost
every network still need to provide some kind of access to IPv4
sites. It is not feasible for most of the operators de tell their
customers "I can provide you IPv6 service, but you will not be able
to access all Internet because some of the contents or applications
still don't support it, so you will miss every content that it is
IPv4-only".
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So what often happens is that some networks may have IPv6-only
support for specific purposes. For example, a DOCSIS provider may
have decided that is worth the effort to get rid of IPv4 for the
management network of the cable-modems. Or a network that provides
connectivity only to IoT devices, may be IPv6-only.
However, despite the IETF and vendor efforts to get rid-off IPv4 as
soon as possible in every network or part of it, there are many
devices, in both corporate and end-user networks (smartTV, IP
cameras, security devices, etc.), which are IPv4-only and it is not
feasible (vendors may even be out of the market, or devices have no
easy way to be updated with new firmware, or de vendor have more
interest in selling a new model, etc.), the "end-networks" in
general, need to keep supporting IPv4.
It is true that this IPv4 support maybe done by using tools, or sets
of them, developed by IETF as part of the transition mechanisms
efforts. So, we could talk today about a situation where we can have
"most parts" of operator (or even enterprises/organizations) networks
being IPv6-only, however have some kind of "IPv4" support, which in
general we are calling "IPv4-as-a-service", which means typically
that IPv4 is transported using the IPv6 layer-3 infrastructure as an
IPv4 layer-2 one (for example by means of encapsulation or
translation).
Let's describe the situation in the cellular networks. Because the
nature of the applications in those networks, it is easier to have
more control on how the developers work, and for example, mandate
IPv6 support in order to allow the apps to be installed in the
smartphones, as actually has been done by Apple. What that means is
that it is theoretically possible to have an IPv6-only access network
for a complete cellular operator network. It may be even possible
that the core and other parts of the operator network are IPv6-only
if all the management of those is done by means of IPv6. However, as
soon as any application in the smartphone requires access to
IPv4-only end sites (example web servers), there must be some kind of
IPv4 support in that network, for example PLAT (NAT64/DNS64) and
consequently, some IPv4 addresses, which allow the IPv4-only traffic
flow to end-sites by means of the upstream providers/peers.
Now, if those smartphones in an IPv6-only cellular network provide
tethering (sharing of a smartphone Internet connection with other
devices), they may also need to "transport" IPv4 (those devices may
be IPv4-only), in a seamless way, over the IPv6-only network.
We can extrapolate the example above to, instead of smartphones to
LTE routers, or CEs with any wired technology (FTTH, xDSL, Cable,
etc.). At the end, no matter which is the access technology, we
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can't talk, in general, in the customer LANs, about IPv6-only,
because today is very common that we must provide still some sort of
IPv4 support ("IPv4-as-a-service").
Consequently, if we want to be precise and avoid confusing others, we
MUST NOT use the terminology "IPv6-only" in a generic way, and we
need to define what part of the network we are referring to.
From that perspective, we define the "IPv6-only" status depending on
if there is actual layer-2 forwarding of IPv4.
3. IPv6-only
IPv6-only MUST be used only if, a complete network, end-to-end, is
actually not forwarding IPv4 at layer-2, which will mean that no-IPv4
addresses are configured, neither used for management, neither the
network is providing transition/translation support, neither there is
IPv4 transit/peering.
4. IPv6-only host/router
IPv6-only host/router MUST be used only if the host or router that we
are referring to, isn't actually forwarding IPv4 at layer-2.
5. IPv6-only WAN/access
IPv6-only WAN or access MUST be used only if the WAN or access
network that we are referring to, isn't actually forwarding IPv4 at
layer-2.
6. IPv6-only LAN
IPv6-only LAN (or LANs) MUST be used only if the LAN(s) that we are
referring to, isn't actually forwarding IPv4 at layer-2.
7. IPv6-only core
IPv6-only core MUST be used only if the core network that we are
referring to, isn't actually forwarding IPv4 at layer-2.
8. Other cases
Similar other cases or parts of the network MUST be considered as
IPv6-only if there is no actual forwarding of IPv4 at layer-2 over
them and in that case, after "IPv6-only" MUST be some word/short text
pointing to the specific case or part of the network.
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9. Security Considerations
This document does not have any specific security considerations.
10. IANA Considerations
This document does not have any IANA considerations.
11. Acknowledgements
The author would like to acknowledge the inputs of TBD ...
Author's Address
Jordi Palet Martinez
Consulintel, S.L.
Molino de la Navata, 75
La Navata - Galapagar, Madrid 28420
Spain
Email: jordi.palet@consulintel.es
URI: http://www.consulintel.es/
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