draft-ietf-homenet-arch-00.txt   draft-ietf-homenet-arch-01.txt 
Network Working Group J. Arkko Network Working Group J. Arkko
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Informational T. Chown Intended status: Informational A. Brandt
Expires: June 12, 2012 University of Southampton Expires: August 2, 2012 Sigma Designs
T. Chown
University of Southampton
J. Weil J. Weil
Time Warner Cable Time Warner Cable
O. Troan O. Troan
Cisco Systems, Inc. Cisco Systems, Inc.
December 10, 2011 January 30, 2012
Home Networking Architecture for IPv6 Home Networking Architecture for IPv6
draft-ietf-homenet-arch-00 draft-ietf-homenet-arch-01
Abstract Abstract
This text describes evolving networking technology within small This text describes evolving networking technology within small
"residential home" networks. The goal of this memo is to define the "residential home" networks. The goal of this memo is to define the
architecture for IPv6-based home networking and the associated architecture for IPv6-based home networking and the associated
principles and considerations. The text highlights the impact of principles, considerations and requirements. The text highlights the
IPv6 on home networking, illustrates topology scenarios, and shows impact of IPv6 on home networking, illustrates topology scenarios,
how standard IPv6 mechanisms and addressing can be employed in home and shows how standard IPv6 mechanisms and addressing can be employed
networking. The architecture describes the need for specific in home networking. The architecture describes the need for specific
protocol extensions for certain additional functionality. It is protocol extensions for certain additional functionality. It is
assumed that the IPv6 home network runs as an IPv6-only or dual-stack assumed that the IPv6 home network is not actively managed, and runs
network, but there are no recommendations in this memo for the IPv4 as an IPv6-only or dual-stack network. There are no recommendations
part of the network. in this text for the IPv4 part of the network.
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.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on June 12, 2012. This Internet-Draft will expire on August 2, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Effects of IPv6 on Home Networking . . . . . . . . . . . . . . 3 1.1. Terminology and Abbreviations . . . . . . . . . . . . . . 5
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Effects of IPv6 on Home Networking . . . . . . . . . . . . . . 5
3.1. Network Models . . . . . . . . . . . . . . . . . . . . . . 8 2.1. Multiple subnets and routers . . . . . . . . . . . . . . . 5
3.2. Requirements . . . . . . . . . . . . . . . . . . . . . . . 12 2.2. Multi-Addressing of devices . . . . . . . . . . . . . . . 6
3.3. Considerations . . . . . . . . . . . . . . . . . . . . . . 13 2.3. Unique Local Addresses (ULAs) . . . . . . . . . . . . . . 6
3.4. Principles . . . . . . . . . . . . . . . . . . . . . . . . 15 2.4. Security, Borders, and the elimination of NAT . . . . . . 7
3.5. Summary of Homenet Architecture Recommendations . . . . . 21 2.5. Naming, and manual configuration of IP addresses . . . . . 9
3.6. Implementing the Architecture on IPv6 . . . . . . . . . . 22 3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 9
4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.1. Network Models . . . . . . . . . . . . . . . . . . . . . . 9
4.1. Normative References . . . . . . . . . . . . . . . . . . . 22 3.1.1. A: Single ISP, Single CER, Single subnet . . . . . . . 10
4.2. Informative References . . . . . . . . . . . . . . . . . . 23 3.1.2. B: Single ISP, Single CER, Multiple subnets . . . . . 11
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 25 3.1.3. C: Single ISP, Single CER, Multiple internal
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26 subnets . . . . . . . . . . . . . . . . . . . . . . . 12
3.1.4. D: Two ISPs, Two CERs, Shared subnets with
multiple internal routers . . . . . . . . . . . . . . 14
3.1.5. E: Two ISPs, One CER, Isolated subnets with
multiple internal routers . . . . . . . . . . . . . . 15
3.1.6. F: Two ISPs, One CER, Shared subnets with multiple
internal routers . . . . . . . . . . . . . . . . . . . 16
3.2. Determining the Requirements . . . . . . . . . . . . . . . 16
3.3. Considerations . . . . . . . . . . . . . . . . . . . . . . 17
3.3.1. Multihoming . . . . . . . . . . . . . . . . . . . . . 17
3.3.2. Quality of Service in multi-service home networks . . 19
3.3.3. Privacy considerations . . . . . . . . . . . . . . . . 19
3.4. Principles . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.1. Reuse existing protocols . . . . . . . . . . . . . . . 19
3.4.2. Dual-stack Operation . . . . . . . . . . . . . . . . . 20
3.4.3. Largest Possible Subnets . . . . . . . . . . . . . . . 21
3.4.4. Transparent End-to-End Communications . . . . . . . . 21
3.4.5. IP Connectivity between All Nodes . . . . . . . . . . 22
3.4.6. Routing functionality . . . . . . . . . . . . . . . . 23
3.4.7. Self-Organising . . . . . . . . . . . . . . . . . . . 25
3.4.8. Fewest Topology Assumptions . . . . . . . . . . . . . 27
3.4.9. Naming and Service Discovery . . . . . . . . . . . . . 27
3.4.10. Proxy or Extend? . . . . . . . . . . . . . . . . . . . 28
3.4.11. Adapt to ISP constraints . . . . . . . . . . . . . . . 28
3.5. Summary of Homenet Architecture Recommendations . . . . . 29
3.6. Implementing the Architecture on IPv6 . . . . . . . . . . 29
4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.1. Normative References . . . . . . . . . . . . . . . . . . . 29
4.2. Informative References . . . . . . . . . . . . . . . . . . 30
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction 1. Introduction
This memo focuses on evolving networking technology within small This document focuses on evolving networking technology within small
"residential home" networks and the associated challenges. For "residential home" networks and the associated challenges. For
example, a trend in home networking is the proliferation of example, a trend in home networking is the proliferation of
networking technology in an increasingly broad range of devices and networking technology in an increasingly broad range of devices and
media. This evolution in scale and diversity sets requirements on media. This evolution in scale and diversity sets requirements on
IETF protocols. Some of these requirements relate to the need for IETF protocols. Some of these requirements relate to the need for
multiple subnets, for example for private and guest networks, the multiple subnets, for example for private and guest networks, the
introduction of IPv6, and the introduction of specialized networks introduction of IPv6, and the introduction of specialized networks
for home automation and sensors. for home automation and sensors.
While advanced home networks have been built, most operate based on While some advanced home networks exist, most operate based on IPv4,
IPv4, employ solutions that we would like to avoid such as (cascaded) employ solutions that we would like to avoid such as (cascaded)
network address translation (NAT), or require expert assistance to network address translation (NAT), or require expert assistance to
set up. The architectural constructs in this document are focused on set up. The assumption of this document is that the homenet is "not
the problems to be solved when introducing IPv6 with a eye towards a actively managed". The architectural constructs in this document are
better result than what we have today with IPv4, as well as a better focused on the problems to be solved when introducing IPv6 with an
result than if the IETF had not given this specific guidance. eye towards a better result than what we have today with IPv4, as
well as a better result than if the IETF had not given this specific
guidance.
This architecture document aims to provide the basis and guiding This architecture document aims to provide the basis and guiding
principles for how standard IPv6 mechanisms and addressing [RFC2460] principles for how standard IPv6 mechanisms and addressing [RFC2460]
[RFC4291] can be employed in home networking, while coexisting with [RFC4291] can be employed in home networking, while coexisting with
existing IPv4 mechanisms. In emerging dual-stack home networks it is existing IPv4 mechanisms. In emerging dual-stack home networks it is
vital that introducing IPv6 does not adversely affect IPv4 operation. vital that introducing IPv6 does not adversely affect IPv4 operation.
Future deployments, or specific subnets within an otherwise dual- Future deployments, or specific subnets within an otherwise dual-
stack home network, may be IPv6-only. stack home network, may be IPv6-only.
[RFC6204] defines basic requirements for customer edge routers [RFC6204] defines basic requirements for customer edge routers
(CPEs). The scope of this text is the homenet, and thus the internal (CERs). The scope of this text is the homenet, and thus the internal
facing interface described that RFC as well as other components facing interface described in RFC 6204 as well as other components
within the home network. While the network may be dual-stack or within the home network. While the network may be dual-stack or
IPv6-only, specific transition tools on the CPE are out of scope of IPv6-only, the definition of specific transition tools on the CER are
this text, as is any advice regarding architecture of the IPv4 part out of scope of this text, as is any advice regarding architecture of
of the network. We assume that IPv4 network architecture in home the IPv4 part of the network. We assume that IPv4 network
networks is what it is, and can not be affected by new architecture in home networks is what it is, and can not be affected
recommendations. by new recommendations.
Discussion in the homenet WG has led to a suggestion that there
should be a baseline homenet "version 1" architecture, based on
protocols and implementations that are as far as possible proven and
robust. A future architecture may incorporate more advanced
elements. Feedback is sought on what if anything do we want to say
about potential homenet versions here.
1.1. Terminology and Abbreviations
In this section we define terminology and abbreviations used
throughout the text.
o CER: Customer Edge Router. The border router at the edge of the
homenet.
o LLN: Low-power and lossy network.
o NAT: Network Address Translation. Typically referring to Network
Address and Port Translation (NAPT).
o NPTv6: Network Prefix Translation for IPv6 [RFC6296].
o PCP: Port Control Protocol [I-D.ietf-pcp-base].
o ULA: Unique Local Addresses [RFC4193].
o uPnP: Universal Plug and Play.
o VM: Virtual machine.
2. Effects of IPv6 on Home Networking 2. Effects of IPv6 on Home Networking
Service providers are deploying IPv6, content is becoming available Service providers are deploying IPv6, content is becoming available
on IPv6, and support for IPv6 is increasingly available in devices on IPv6, and support for IPv6 is increasingly available in devices
and software used in the home. While IPv6 resembles IPv4 in many and software used in the home. While IPv6 resembles IPv4 in many
ways, it changes address allocation principles, makes multi- ways, it changes address allocation principles, makes multi-
addressing the norm, and allows direct IP addressability and routing addressing the norm, and allows direct IP addressability and routing
to devices in the home from the Internet. This section presents an to devices in the home from the Internet. This section presents an
overview of some of the key areas impacted by the implementation of overview of some of the key areas impacted by the introduction of
IPv6 into the home network that are both promising and problematic: IPv6 into the home network that are both promising and problematic.
Multiple segments and routers 2.1. Multiple subnets and routers
Simple layer 3 topologies involving as few subnets as possible are Simple layer 3 topologies involving as few subnets as possible are
preferred in home networks for a variety of reasons including preferred in home networks for a variety of reasons including simpler
simpler management and service discovery. However, the management and service discovery. However, the incorporation of
incorporation of dedicated (routed) segments remains necessary for dedicated (routed) subnets remains necessary for a variety of
a variety of reasons. reasons.
For instance, a common feature in modern home routers is the For instance, a common feature in modern home routers is the ability
ability to support both guest and private network segments. Also, to support both guest and private network subnets. Also, link layer
link layer networking technology is poised to become more networking technology is poised to become more heterogeneous, as
heterogeneous, as networks begin to employ both traditional networks begin to employ both traditional Ethernet technology and
Ethernet technology and link layers designed for low-powered and link layers designed for low-power and lossy networks (LLNs) such as
lossy networks (LLNs) such as those used for certain types of those used for certain types of sensor devices. Similar needs for
sensor devices. Similar needs for segmentation may occur in other subnetting may occur in other cases, such as separating building
cases, such as separating building control or corporate extensions control or corporate extensions from the Internet access network.
from the Internet access network. Also, different segments may be Also, different subnets may be associated with parts of the homenet
associated with subnets that have different routing and security that have different routing and security policies.
policies.
Documents that provide some more specific background and depth on Documents that provide some more specific background and depth on
this topic include: [I-D.herbst-v6ops-cpeenhancements], this topic include: [I-D.herbst-v6ops-cpeenhancements],
[I-D.baker-fun-multi-router], and [I-D.baker-fun-routing-class]. [I-D.baker-fun-multi-router], and [I-D.baker-fun-routing-class].
In addition to routing, rather than NATing, between subnets, there In addition to routing, rather than NATing, between subnets, there
are issues of when and how to extend mechanisms such as service are issues of when and how to extend mechanisms such as service
discovery which currently rely on link-local addressing to limit discovery which currently rely on link-local addressing to limit
scope. scope.
The presence of a multiple segment, multi-router network implies The presence of a multiple subnet, multi-router network implies that
that there is some kind of automatic routing mechanism in place. there is some kind of automatic routing mechanism in place. In
In advanced configurations similar to those used in multihomed advanced configurations similar to those used in multihomed corporate
corporate networks, there may also be a need to discover border networks, there may also be a need to discover border router(s) by an
router(s) by an appropriate mechanism. appropriate mechanism.
Multi-Addressing of devices 2.2. Multi-Addressing of devices
In an IPv6 network, devices may acquire multiple addresses, In an IPv6 network, devices may acquire multiple addresses, typically
typically at least a link-local address and a globally unique at least a link-local address and a globally unique address. Thus it
address. Thus it should be considered the norm for devices on should be considered the norm for devices on IPv6 home networks to be
IPv6 home networks to be multi-addressed, and to also have an IPv4 multi-addressed, and to also have an IPv4 address where the network
address where the network is dual-stack. Default address is dual-stack. Default address selection mechanisms
selection mechanisms [I-D.ietf-6man-rfc3484-revise] allow a node [I-D.ietf-6man-rfc3484-revise] allow a node to select appropriate
to select appropriate src/dst address pairs for communications, src/dst address pairs for communications, though such selection may
though such selection may face problems in the event of face problems in the event of multihoming, where nodes will be
multihoming, where nodes will be configured with one address from configured with one address from each upstream ISP prefix, and the
each upstream ISP prefix, and the presence of upstream ingress presence of upstream ingress filtering thus requires multi-addressed
filtering thus requires multi-addressed nodes to select the right nodes to select the right source address to be used for the
source address to be used for the corresponding uplink. corresponding uplink.
Unique Local Addresses (ULAs) 2.3. Unique Local Addresses (ULAs)
[RFC4193] defines Unique Local Addresses (ULAs) for IPv6 that may [RFC4193] defines Unique Local Addresses (ULAs) for IPv6 that may be
be used to address devices within the scope of a single site. used to address devices within the scope of a single site. Support
Support for ULAs for IPv6 CPEs is described in [RFC6204]. A home for ULAs for IPv6 CERs is described in [RFC6204]. A home network
network running IPv6 may deploy ULAs for communication between running IPv6 may deploy ULAs for communication between devices within
devices within the network. ULAs have the potential to be used the network. ULAs have the potential to be used for stable
for stable addressing in a home network where the externally addressing in a home network where the externally allocated global
allocated global prefix changes over time or where external prefix changes over time (either due to renumbering within the
connectivity is temporarily unavailable. However, it is subscriber's ISP or a change of ISP) or where external connectivity
undesirable to aggressively deprecate global prefixes for is temporarily unavailable. However, it is undesirable to
temporary loss of connectivity, so for this to matter there would aggressively deprecate global prefixes for temporary loss of
have to be a connection breakage longer than the lease period, and connectivity, so for this to matter there would have to be a
even then, deprecating prefixes when there is no connectivity may connection breakage longer than the lease period, and even then,
not be advisable. However, while setting a network up there may deprecating prefixes when there is no connectivity may not be
be a period with no connectivity. advisable. However, while setting a network up there may be a period
with no connectivity.
Another possible reason for using ULAs would be to provide an Another possible reason for using ULAs would be to provide an
indication to applications that the traffic is local. This could indication to applications that the traffic is local. This could
then be used with security settings to designate where a then be used with security settings to designate where a particular
particular application is allowed to connect to. application is allowed to connect to.
Address selection mechanisms should ensure a ULA source address is ULA addresses will allow constrained LLN devices to create permanent
used to communicate with ULA destination addresses. The use of relations between IPv6 addresses, e.g. from a wall controller to a
ULAs does not imply IPv6 NAT, rather that external communications lamp. Symbolic host names would require additional non-volatile
should use a node's global IPv6 source address. memory. Updating global prefixes in sleeping LLN devices might also
be problematic.
Security, Borders, and the elimination of NAT Address selection mechanisms should ensure a ULA source address is
used to communicate with ULA destination addresses. The use of ULAs
does not imply use of host-based IPv6 NAT, or NPTv6 prefix-based NAT
[RFC6296], rather that external communications should use a node's
global IPv6 source address.
Current IPv4 home networks typically receive a single global IPv4 2.4. Security, Borders, and the elimination of NAT
address from their ISP and use NAT with private [RFC1918].
addressing for devices within the network. An IPv6 home network
removes the need to use NAT given the ISP offers a sufficiently
large IPv6 prefix to the homenet, allowing every device on every
link to be assigned a globally unique IPv6 address.
The end-to-end communication that is potentially enabled with IPv6 Current IPv4 home networks typically receive a single global IPv4
is both an incredible opportunity for innovation and simpler address from their ISP and use NAT with private [RFC1918] addresses
network operation, but it is also a concern as it exposes nodes in for devices within the network. An IPv6 home network removes the
the internal networks to receipt of otherwise unwanted traffic need to use NAT given the ISP offers a sufficiently large IPv6 prefix
from the Internet. to the homenet, allowing every device on every link to be assigned a
globally unique IPv6 address.
In IPv4 NAT networks, the NAT provides an implicit firewall The end-to-end communication that is potentially enabled with IPv6 is
function. [RFC4864] suggests that IPv6 networks with global both an incredible opportunity for innovation and simpler network
addresses utilise "Simple Security" in border firewalls to operation, but it is also a concern as it exposes nodes in the
restrict incoming connections through a default deny policy. internal networks to receipt of otherwise unwanted traffic from the
Applications or hosts wanting to accept inbound connections then Internet.
need to signal that desire through a protocol such as uPNP or PCP
[I-D.ietf-pcp-base].
Such an approach would reduces the efficacy of end-to-end In IPv4 NAT networks, the NAT provides an implicit firewall function.
connectivity that IPv6 has the potential to restore, since the [RFC4864] suggests that IPv6 networks with global addresses utilise
need for IPv4 NAT traversal is replaced by a need to use a "Simple Security" in border firewalls to restrict incoming
signalling protocol to request a firewall hole be opened. connections through a default deny policy. Applications or hosts
[RFC6092] provides recommendations for an IPv6 firewall that wanting to accept inbound connections then need to signal that desire
applies "limitations on end-to-end transparency where security through a protocol such as uPNP or PCP [I-D.ietf-pcp-base]. In
considerations are deemed important to promote local and Internet networks with multiple CERs, PCP will need to handle the cases of
security." The firewall operation is "simple" in that there is an flows that may use one or both exit routers.
assumption that traffic which is to be blocked by default is
defined in the RFC and not expected to be updated by the user or
otherwise. The RFC does however state that CPEs should have an
option to be put into a "transparent mode" of operation.
It is important to distinguish between addressability and Such an approach would reduce the efficacy of end-to-end connectivity
reachability; i.e. IPv6 through use of globally unique addressing that IPv6 has the potential to restore, since the need for IPv4 NAT
in the home makes all devices potentially reachable from anywhere. traversal is replaced by a need to use a signalling protocol to
Whether they are or not should depend on firewall or filtering request a firewall hole be opened. [RFC6092] provides
configuration, and not the presence or use of NAT. recommendations for an IPv6 firewall that applies "limitations on
end-to-end transparency where security considerations are deemed
important to promote local and Internet security." The firewall
operation is "simple" in that there is an assumption that traffic
which is to be blocked by default is defined in the RFC and not
expected to be updated by the user or otherwise. The RFC does
however state that CERs should have an option to be put into a
"transparent mode" of operation.
Advanced Security for IPv6 CPE [I-D.vyncke-advanced-ipv6-security] It is important to distinguish between addressability and
takes the approach that in order to provide the greatest end-to- reachability; i.e. while IPv6 offers global addressability through
end transparency as well as security, security polices must be use of globally unique addresses in the home, whether they are
updated by a trusted party which can provide intrusion signatures globally reachable or not would depend on firewall or filtering
and other "active" information on security threats. This is much configuration, and not the presence or use of NAT.
like a virus-scanning tool which must receive updates in order to
detect and/or neutralize the latest attacks as they arrive. As
the name implies "advanced" security requires significantly more
resources and infrastructure (including a source for attack
signatures) in comparision to "simple" security.
In addition to establishing the security mechanisms themselves, it Advanced Security for IPv6 CPEs [I-D.vyncke-advanced-ipv6-security]
is important to know where to enable them. If there is some takes the approach that in order to provide the greatest end-to-end
indication as to which router is connected to the "outside" of the transparency as well as security, security policies must be updated
home network, this is feasible. Otherwise, it can be difficult to by a trusted party which can provide intrusion signatures and other
know which security policies to apply where. Further, security "active" information on security threats. This is much like a virus-
policies may be different for various address ranges if ULA scanning tool which must receive updates in order to detect and/or
addressing is setup to only operate within the homenet itself and neutralize the latest attacks as they arrive. As the name implies
not be routed to the Internet at large. Finally, such policies "advanced" security requires significantly more resources and
must be able to be applied by typical home users, e.g. to give a infrastructure (including a source for attack signatures) in
visitor in a "guest" network access to media services in the home. comparison to "simple" security.
It may be useful to classify the border of the home network as a In addition to establishing the security mechanisms themselves, it is
unique logical interface separating the home network from service important to know where to enable them. If there is some indication
provider network/s. This border interface may be a single as to which router is connected to the "outside" of the home network,
physical interface to a single service provider, multiple layer 2 this is feasible. Otherwise, it can be difficult to know which
sub-interfaces to a single service provider, or multiple security policies to apply where. Further, security policies may be
connections to a single or multiple providers. This border is different for various address ranges if ULA addressing is setup to
useful for describing edge operations and interface requirements only operate within the homenet itself and not be routed to the
across multiple functional areas including security, routing, Internet at large. Finally, such policies must be able to be applied
service discovery, and router discovery. by typical home users, e.g. to give a visitor in a "guest" network
access to media services in the home.
Naming, and manual configuration of IP addresses It may be useful to classify the border of the home network as a
unique logical interface separating the home network from service
provider network/s. This border interface may be a single physical
interface to a single service provider, multiple layer 2 sub-
interfaces to a single service provider, or multiple connections to a
single or multiple providers. This border is useful for describing
edge operations and interface requirements across multiple functional
areas including security, routing, service discovery, and router
discovery.
In IPv4, a single subnet NATed home network environment is 2.5. Naming, and manual configuration of IP addresses
currently the norm. As a result, it is for example common
practice for users to be able to connect to a router for
configuration via a literal address such as 192.168.1.1 or some
other commonly used RFC 1918 address. In IPv6, while ULAs exist
and could potentially be used to address internally-reachable
services, little deployment experience exists to date. Given a
true ULA prefix is effectively a random 48-bit prefix, it is not
reasonable to expect users to manually enter such address literals
for configuration or other purposes. As such, even for the
simplest of functions, naming and the associated discovery of
services is imperative for an easy to administer homenet.
In a multi-subnet homenet, naming and service discovery should be In IPv4, a single subnet NATed home network environment is currently
expected to operate across the scope of the entire home network, the norm. As a result, it is for example common practice for users
and thus be able to cross subnet boundaries. It should be noted to be able to connect to a router for configuration via a literal
that in IPv4, such services do not generally function across home address such as 192.168.1.1 or some other commonly used RFC 1918
router NAT boundaries, so this is one area where there is scope address. In IPv6, while ULAs exist and could potentially be used to
for an improvement in IPv6. address internally-reachable services, little deployment experience
exists to date. Given a true ULA prefix is effectively a random 48-
bit prefix, it is not reasonable to expect users to manually enter
such address literals for configuration or other purposes. As such,
even for the simplest of functions, naming and the associated
discovery of services is imperative for easy administration of the
homenet.
In a multi-subnet homenet, naming and service discovery should be
expected to operate across the scope of the entire home network, and
thus be able to cross subnet boundaries. It should be noted that in
IPv4, such services do not generally function across home router NAT
boundaries, so this is one area where there is scope for an
improvement in IPv6.
3. Architecture 3. Architecture
An architecture outlines how to construct home networks involving An architecture outlines how to construct home networks involving
multiple routers and subnets. In this section, we present a set of multiple routers and subnets. In this section, we present a set of
typical home network topology models/scenarios, followed by a list of typical home network topology models/scenarios, followed by a list of
topics that may influence the architecture discussions, and a set of topics that may influence the architecture discussions, and a set of
architectural principles that govern how the various nodes should architectural principles that govern how the various nodes should
work together. Finally, some guidelines are given for realizing the work together. Finally, some guidelines are given for realizing the
architecture with the IPv6 addressing, prefix delegation, global and architecture with the IPv6 addressing, prefix delegation, global and
ULA addresses, source address selection rules and other existing ULA addresses, source address selection rules and other existing
components of the IPv6 architecture. The architecture also drives components of the IPv6 architecture. The architecture also drives
what protocol extensions are necessary, as will be discussed in what protocol extensions are necessary, as will be discussed in
Section 3.6. Section 3.6.
3.1. Network Models 3.1. Network Models
In this section we list six network models.
A) Single ISP, Single CER, Single subnet
B) Single ISP, Single CER, Multiple subnets
C) Single ISP, Single CER, Multiple internal routers
D) Two ISPs, Two CERs, Shared subnets with multiple internal routers
E) Two ISPs, One CER, Isolated subnets with multiple internal
routers
F) Two ISPs, One CER, Shared subnets with multiple internal routers
The models are presented to frame the discussion as to which models
are in scope for the homenet architecture, and which multi-homing
requirements should be met in the architecture.
3.1.1. A: Single ISP, Single CER, Single subnet
Figure 1 shows the simplest possible home network topology, involving Figure 1 shows the simplest possible home network topology, involving
just one router, a local area network, and a set of hosts. Setting just one router, a local area network, and a set of hosts. Setting
up such networks is in principle well understood today [RFC6204]. up such networks is in principle well understood today [RFC6204].
+-------+-------+ \ +-------+-------+ \
| Service | \ | Service | \
| Provider | | Service | Provider | | Service
| Router | | Provider | Router | | Provider
+-------+-------+ | network +-------+-------+ | network
| / | /
skipping to change at page 8, line 42 skipping to change at page 11, line 36
| | | | / | | | | /
+----------+ +-----+----+ / +----------+ +-----+----+ /
Figure 1 Figure 1
Two possible demarcation points are illustrated in Figure 1, which Two possible demarcation points are illustrated in Figure 1, which
indicate which party is responsible for configuration or indicate which party is responsible for configuration or
autoconfiguration. Demarcation #1 makes the Customer Edge Router the autoconfiguration. Demarcation #1 makes the Customer Edge Router the
responsibility of the customer. This is only practical if the responsibility of the customer. This is only practical if the
Customer Edge Router can function with factory defaults installed. Customer Edge Router can function with factory defaults installed.
The Customer Edge Router may be pre-configured by the ISP, or by some The Customer Edge Router may be pre-configured by the ISP, or by the
suitably simple method by the home customer. Demarcation #2 makes home user by some suitably simple method. Demarcation #2 makes the
the Customer Edge Router the responsibility of the provider. Both Customer Edge Router the responsibility of the provider. Both models
models of operation must be supported in the homenet architecture, of operation must be supported in the homenet architecture, including
including the scenarios below with multiple ISPs and demarcation the scenarios below with multiple ISPs and demarcation points.
points.
3.1.2. B: Single ISP, Single CER, Multiple subnets
Figure 2 shows another network that now introduces multiple local Figure 2 shows another network that now introduces multiple local
area networks. These may be needed for reasons relating to different area networks. These may be needed for reasons relating to different
link layer technologies in use or for policy reasons. Note that a link layer technologies in use or for policy reasons. A common
common arrangement is to have different link types supported on the arrangement is to have different link types supported on the same
same router, bridged together. router, bridged together. This example however presents two subnets.
This could be classic Ethernet in the one subnet and a LLN link layer
technology in the other subnet.
This topology is also relatively well understood today [RFC6204], This topology is also relatively well understood today [RFC6204],
though it certainly presents additional demands with regards suitable though it certainly presents additional demands with regards to
firewall policies and limits the operation of certain applications suitable firewall policies and limits the operation of certain
and discovery mechanisms (which may typically today only succeed applications and discovery mechanisms (which may typically today only
within a single subnet). succeed within a single subnet).
+-------+-------+ \ +-------+-------+ \
| Service | \ | Service | \
| Provider | | Service | Provider | | Service
| Router | | Provider | Router | | Provider
+------+--------+ | network +------+--------+ | network
| / | /
| Customer / | Customer /
| Internet connection / | Internet connection /
| |
skipping to change at page 9, line 33 skipping to change at page 12, line 29
| IPv6 | \ | IPv6 | \
| Customer Edge | \ | Customer Edge | \
| Router | / | Router | /
+----+-------+--+ / +----+-------+--+ /
Network A | | Network B | End-User Network A | | Network B | End-User
---+-------------+----+- --+--+-------------+--- | network(s) ---+-------------+----+- --+--+-------------+--- | network(s)
| | | | \ | | | | \
+----+-----+ +-----+----+ +----+-----+ +-----+----+ \ +----+-----+ +-----+----+ +----+-----+ +-----+----+ \
|IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | / |IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | /
| | | | | | | | / | | | | | | | | /
+----------+ +-----+----+ +----------+ +----------+ / +----------+ +----------+ +----------+ +----------+ /
Figure 2 Figure 2
3.1.3. C: Single ISP, Single CER, Multiple internal subnets
Figure 3 shows a little bit more complex network with two routers and Figure 3 shows a little bit more complex network with two routers and
eight devices connected to one ISP. This network is similar to the eight devices connected to one ISP. This network is similar to the
one discussed in [I-D.ietf-v6ops-ipv6-cpe-router-bis]. The main one discussed in [I-D.ietf-v6ops-ipv6-cpe-router-bis]. The main
complication in this topology compared to the ones described earlier complication in this topology compared to the ones described earlier
is that there is no longer a single router that a priori understands is that there is no longer a single router that a priori understands
the entire topology. The topology itself may also be complex. It the entire topology. The topology itself may also be complex. It
may not be possible to assume a pure tree form, for instance. This may not be possible to assume a pure tree form, for instance. This
would be a consideration if there was an assumption that home users is a valid consideration as home users may plug routers together to
may plug routers together to form arbitrary topologies. form arbitrary topologies including loops. In the following sections
we discuss support for arbitrary topologies.
+-------+-------+ \ +-------+-------+ \
| Service | \ | Service | \
| Provider | | Service | Provider | | Service
| Router | | Provider | Router | | Provider
+-------+-------+ | network +-------+-------+ | network
| / | /
| Customer / | Customer /
| Internet connection | Internet connection
| |
skipping to change at page 10, line 25 skipping to change at page 13, line 25
| IPv6 | \ | IPv6 | \
| Customer Edge | \ | Customer Edge | \
| Router | | | Router | |
+----+-+---+----+ | +----+-+---+----+ |
Network A | | | Network B/E | Network A | | | Network B/E |
----+-------------+----+ | +---+-------------+------+ | ----+-------------+----+ | +---+-------------+------+ |
| | | | | | | | | | | | | | | |
+----+-----+ +-----+----+ | +----+-----+ +-----+----+ | | +----+-----+ +-----+----+ | +----+-----+ +-----+----+ | |
|IPv6 Host | |IPv6 Host | | | IPv6 Host| |IPv6 Host | | | |IPv6 Host | |IPv6 Host | | | IPv6 Host| |IPv6 Host | | |
| | | | | | | | | | | | | | | | | | | | | |
+----------+ +-----+----+ | +----------+ +----------+ | | +----------+ +----------+ | +----------+ +----------+ | |
| | | | | | | | | |
| ---+------+------+-----+ | | ---+------+------+-----+ |
| | Network B/E | | | Network B/E |
+------+--------+ | | End-User +------+--------+ | | End-User
| IPv6 | | | networks | IPv6 | | | networks
| Interior +------+ | | Interior +------+ |
| Router | | | Router | |
+---+-------+-+-+ | +---+-------+-+-+ |
Network C | | Network D | Network C | | Network D |
----+-------------+---+- --+---+-------------+--- | ----+-------------+---+- --+---+-------------+--- |
| | | | | | | | | |
+----+-----+ +-----+----+ +----+-----+ +-----+----+ | +----+-----+ +-----+----+ +----+-----+ +-----+----+ |
|IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | | |IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | |
| | | | | | | | / | | | | | | | | /
+----------+ +-----+----+ +----------+ +----------+ / +----------+ +----------+ +----------+ +----------+ /
Figure 3 Figure 3
3.1.4. D: Two ISPs, Two CERs, Shared subnets with multiple internal
routers
+-------+-------+ +-------+-------+ \ +-------+-------+ +-------+-------+ \
| Service | | Service | \ | Service | | Service | \
| Provider A | | Provider B | | Service | Provider A | | Provider B | | Service
| Router | | Router | | Provider | Router | | Router | | Provider
+------+--------+ +-------+-------+ | network +------+--------+ +-------+-------+ | network
| | / | | /
| Customer | / | Customer | /
| Internet connections | / | Internet connections | /
| | | |
+------+--------+ +-------+-------+ \ +------+--------+ +-------+-------+ \
skipping to change at page 11, line 26 skipping to change at page 14, line 29
| Customer Edge | | Customer Edge | \ | Customer Edge | | Customer Edge | \
| Router 1 | | Router 2 | / | Router 1 | | Router 2 | /
+------+--------+ +-------+-------+ / +------+--------+ +-------+-------+ /
| | / | | /
| | | End-User | | | End-User
---+---------+---+---------------+--+----------+--- | network(s) ---+---------+---+---------------+--+----------+--- | network(s)
| | | | \ | | | | \
+----+-----+ +-----+----+ +----+-----+ +-----+----+ \ +----+-----+ +-----+----+ +----+-----+ +-----+----+ \
|IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | / |IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | /
| | | | | | | | / | | | | | | | | /
+----------+ +-----+----+ +----------+ +----------+ +----------+ +----------+ +----------+ +----------+
Figure 4 Figure 4
Figure 4 illustrates a multihomed home network model, where the Figure 4 illustrates a multihomed home network model, where the
customer has connectivity via CPE1 to ISP A and via CPE2 to ISP B. customer has connectivity via CER1 to ISP A and via CER2 to ISP B.
This example shows one shared subnet where IPv6 nodes would This example shows one shared subnet where IPv6 nodes would
potentially be multihomed and receive multiple IPv6 global addresses, potentially be multihomed and receive multiple IPv6 global addresses,
one per ISP. This model may also be combined with that shown in one per ISP. This model may also be combined with that shown in
Figure 3 for example to create a more complex scenario. Figure 3 to create a more complex scenario with subnets that my be
behind multiple internal routers.
3.1.5. E: Two ISPs, One CER, Isolated subnets with multiple internal
routers
+-------+-------+ +-------+-------+ \ +-------+-------+ +-------+-------+ \
| Service | | Service | \ | Service | | Service | \
| Provider A | | Provider B | | Service | Provider A | | Provider B | | Service
| Router | | Router | | Provider | Router | | Router | | Provider
+-------+-------+ +-------+-------+ | network +-------+-------+ +-------+-------+ | network
| | / | | /
| Customer | / | Customer | /
| Internet | / | Internet | /
| connections | | | connections | |
skipping to change at page 12, line 26 skipping to change at page 15, line 29
| Customer Edge | \ | Customer Edge | \
| Router 1 | / | Router 1 | /
+---------+---------+ / +---------+---------+ /
| | / | | /
| | | End-User | | | End-User
---+---------+---+-- --+--+----------+--- | network(s) ---+---------+---+-- --+--+----------+--- | network(s)
| | | | \ | | | | \
+----+-----+ +-----+----+ +----+-----+ +-----+----+ \ +----+-----+ +-----+----+ +----+-----+ +-----+----+ \
|IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | / |IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | /
| | | | | | | | / | | | | | | | | /
+----------+ +-----+----+ +----------+ +----------+ +----------+ +----------+ +----------+ +----------+
Figure 5 Figure 5
Figure 5 illustrates a model where a home network may have multiple Figure 5 illustrates a model where a home network may have multiple
connections to multiple providers or multiple logical connections to connections to multiple providers or multiple logical connections to
the same provider, but the associated subnet(s) are isolated. Some the same provider, but the associated subnet(s) are isolated. Some
deployment scenarios may require this model. deployment scenarios may require this model.
3.2. Requirements 3.1.6. F: Two ISPs, One CER, Shared subnets with multiple internal
routers
+-------+-------+ +-------+-------+ \
| Service | | Service | \
| Provider A | | Provider B | | Service
| Router | | Router | | Provider
+-------+-------+ +-------+-------+ | network
| | /
| Customer | /
| Internet | /
| connections | |
+---------+---------+ \
| IPv6 | \
| Customer Edge | \
| Router 1 | /
+---------+---------+ /
| | /
| | | End-User
---+------------+-+------------+-+-------------+--- | network(s)
| | | | \
+----+-----+ +----+-----+ +----+-----+ +-----+----+ \
|IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | /
| | | | | | | | /
+----------+ +----------+ +----------+ +----------+
Figure 6
Figure 6 illustrates a model where a home network may have multiple
connections to multiple providers or multiple logical connections to
the same provider, with shared internal subnets, that may be multiple
layers deep.
3.2. Determining the Requirements
[RFC6204] defines "basic" requirements for IPv6 Customer Edge [RFC6204] defines "basic" requirements for IPv6 Customer Edge
Routers, while [I-D.ietf-v6ops-ipv6-cpe-router-bis] describes Routers, while [I-D.ietf-v6ops-ipv6-cpe-router-bis] describes
"advanced" features. In general, home network equipment needs to "advanced" features. In general, home network equipment needs to
cope with the different types of network topologies discussed above. cope with the different types of network topologies discussed above.
Manual configuration is rarely, if at all, possible, given the Manual configuration is rarely, if at all, possible, given the
knowledge lying with typical home users. The equipment needs to be knowledge level of typical home users. The equipment needs to be
prepared to handle at least prepared to handle at least
o Prefix configuration for routers o Prefix configuration for routers
o Managing routing o Managing routing
o Name resolution o Name resolution
o Service discovery o Service discovery
o Network security o Network security
The remainder of the architecture document is presented as
considerations and principles that lead to more specific requirements
for the five general areas listed above.
3.3. Considerations 3.3. Considerations
This section lists some considerations for home networking that may This section lists some considerations for home networking that may
affect the architecture and associated requirements. affect the architecture and associated requirements.
Multihoming 3.3.1. Multihoming
A homenet may be multihomed to multiple providers. This may A homenet may be multihomed to multiple providers. This may either
either take a form where there are multiple isolated networks take a form where there are multiple isolated networks within the
within the home or a more integrated network where the home (see Network Model E above) or a more integrated network where
connectivity selection is dynamic. Current practice is typically the connectivity selection is dynamic (see Network Model D or F
of the former kind, but the latter is expected to become more above). Current practice is typically of the former kind, but the
commonplace. latter is expected to become more commonplace.
In an integrated network, specific appliances or applications may There are some specific multihoming considerations for homenet
use their own external connectivity, or the entire network may scenarios. First, it may be the case that multihoming applies due to
change its connectivity based on the status of the different an ISP migration from a transition method to a native deployment,
upstream connections. Many general solutions for IPv6 multihoming e.g. a 6rd [RFC5969] sunset scenario. Second, one upstream may be a
have been worked on for years in the IETF, though to date there is "walled garden", and thus only appropriate to be used for
little deployment of these mechanisms. While an argument can be connectivity to the services of that provider.
made that home networking standards should not make another
attempt at this, the obvious counter-argument is that multihoming
support will be necessary for many deployment situations.
One such approach is the use of NPTv6 [RFC6296], which is a prefix In an integrated network, specific appliances or applications may use
translation-based mechanism. An alternative is presented in their own external connectivity, or the entire network may change its
[I-D.v6ops-multihoming-without-ipv6nat]. Host-based methods such connectivity based on the status of the different upstream
as Shim6 [RFC5533] have also been defined. connections. The complexity of the multihoming solution required
will depend on the Network Model deployed. For example, Network
Models E and F have a single CER and thus could perform source
routing at the single network exit point.
In any case, if multihoming is supported additional requirements The general approach for IPv6 multihoming is for a hosts to receive
are necessary. The general multihoming problem is broad, and multiple addresses from multiple providers, and to select the
solutions may include complex architectures for monitoring appropriate source address to communicate via a given provider. An
connectivity, traffic engineering, identifier-locator separation, alternative is to deploy ULAs with a site and then use NPTv6
connection survivability across multihoming events, and so on. [RFC6296], a prefix translation-based mechanism, at the edge. This
However, there is a general agreement that for the home case, if obviously comes at some architectural cost, which is why approaches
there is any support for multihoming it should be limited to a such as [I-D.v6ops-multihoming-without-ipv6nat] have been suggested.
very small subset of the overall problem. Specifically, multi- There has been much work on multihoming in the IETF, without (yet)
addressed hosts selecting the right source address to avoid widespread deployment of proposed solutions. Host-based methods such
falling foul of ingress filtering on upstream ISP connections as Shim6 [RFC5533] have also been defined, but of course require
[I-D.baker-fun-multi-router]. A solution to this particular support in the hosts.
problem is desirable.
Some similar multihoming issues have already been teased out in If multihoming is supported additional requirements apply. The
the work described in [I-D.ietf-mif-dns-server-selection], which general multihoming problem is broad, and solutions may include
has led to the definition of a DHCPv6 route option complex architectures for monitoring connectivity, traffic
[I-D.ietf-mif-dhcpv6-route-option]. engineering, identifier-locator separation, connection survivability
across multihoming events, and so on. This implies that if there is
any support for multihoming defined in the homenet architecture it
should be limited to a very small subset of the overall problem.
One could also argue that a "happy eyeballs" approach, not too The current set of assumptions and requirements proposed by the
dissimilar to that proposed for multiple interface (mif) homenet architecture team is:
scenarios, is also acceptable if such support becomes commonplace
in hosts and applications.
A further consideration and complexity here is that at least one MH1) The homenet WG should not try to make another attempt at
upstream may be a "walled garden", and thus only appropriate to be solving complex multihoming; we should prefer to support
used for connectivity to the services of that provider. scenarios for which solutions exist today.
Quality of Service in multi-service home networks MH2) Single CER Network Models E and F are in scope, and may be
solved by source routing at the CER.
Support for QoS in a multi-service homenet may be a requirement, MH3) It is desirable to avoid deployment of NPTv6 at the CER. Hosts
e.g. for a critical system (perhaps healthcare related), or for should be multi-addressed from each ISP they may communicate
differentiation between different types of traffic (file sharing, with or through.
cloud storage, live streaming, VoIP, etc). Different media types
may have different QoS properties or capabilities.
However, homenet scenarios should require no new QoS protocols. A MH4) Solutions that involve host changes should be avoided.
DiffServ [RFC2475] approach with a small number of predefined
traffic classes should generally be sufficient, though at present
there is little experience of QoS deployment in home networks.
There may also be complementary mechanisms that could be
beneficial in the homenet domain, such as ensuring proper
buffering algorithms are used as described in [Gettys11].
DNS services MH5) Walled garden multihoming is in scope.
A desirable target may be a fully functional self-configuring MH6) Transition method sunsetting is in scope. The topic of
secure local DNS service so that all devices are referred to by multihoming with specific (6rd) transition coexistence is
name, and these FQDNs are resolved locally. This will make clean discussed in [I-D.townsley-troan-ipv6-ce-transitioning].
use of ULAs and multiple ISP-provided prefixes much easier. The
local DNS service should be (by default) authoritative for the
local name space in both IPv4 and IPv6. A dual-stack residential
gateway should include a dual-stack DNS server.
Consideration will also need to be given for existing protocols MH7) "Just" picking the right source address to use to fall foul of
that may be used within a network, e.g. mDNS, and how these ingress filtering on upstream ISP connections (as per Network
interact with unicast-based DNS services. Model D) is not a trivial task. A solution is highly
desirable, but out of scope of homenet.
With the introduction of new top level domains, there is potential MH8) Source routing throughout the homenet, a la
for ambiguity between for example a local host called apple and [I-D.baker-fun-multi-router], requires relatively significant
(if it is registered) an apple gTLD, so some local name space is routing changes. The network should "guarantee" routing the
probably required, which should also be configurable to something packet to the correct exit given the source address, but hosts
else by a home user if desired. are responsible for anything extra, e.g. detecting failure, or
choosing a new src/dst address combination.
Privacy considerations Feedback is sought on the above points.
There are no specific privacy concerns for this text. It should 3.3.2. Quality of Service in multi-service home networks
be noted that most ISPs are expected to offer static IPv6 prefixes
to customers, and thus the addresses they use would not generally Support for QoS in a multi-service homenet may be a requirement, e.g.
change over time. for a critical system (perhaps healthcare related), or for
differentiation between different types of traffic (file sharing,
cloud storage, live streaming, VoIP, etc). Different media types may
have different QoS properties or capabilities.
However, homenet scenarios should require no new QoS protocols. A
DiffServ [RFC2475] approach with a small number of predefined traffic
classes should generally be sufficient, though at present there is
little experience of QoS deployment in home networks.
There may also be complementary mechanisms that could be beneficial
in the homenet domain, such as ensuring proper buffering algorithms
are used as described in [Gettys11].
3.3.3. Privacy considerations
There are no specific privacy concerns for this text. It should be
noted that many ISPs are expected to offer relatively stable IPv6
prefixes to customers, and thus the network prefix associated with
the host addresses they use would not generally change over a
reasonable period of time, e.g. between restructuring of an ISPs
residential network provision.
3.4. Principles 3.4. Principles
There is little that the Internet standards community can do about There is little that the Internet standards community can do about
the physical topologies or the need for some networks to be separated the physical topologies or the need for some networks to be separated
at the network layer for policy or link layer compatibility reasons. at the network layer for policy or link layer compatibility reasons.
However, there is a lot of flexibility in using IP addressing and However, there is a lot of flexibility in using IP addressing and
inter-networking mechanisms. In this section we provide some inter-networking mechanisms. In this section we discuss how this
guidance on how this flexibility should be used to provide the best flexibility should be used to provide the best user experience and
user experience and ensure that the network can evolve with new ensure that the network can evolve with new applications in the
applications in the future. future.
The following principles should be used as a guide in designing these The following principles should be followed when designing homenet
networks in the correct manner. There is no implied priority by the solutions. Where requirements are associated with those principles,
order in which the principles are listed. they are listed here. There is no implied priority by the order in
which the principles themselves are listed.
Reuse existing protocols 3.4.1. Reuse existing protocols
It is desirable to reuse existing protocols where possible, but at It is desirable to reuse existing protocols where possible, but at
the same time to avoid consciously precluding the introduction of the same time to avoid consciously precluding the introduction of new
new or emerging protocols. For example, or emerging protocols.
[I-D.baker-fun-routing-class] suggests introducing a routing
protocol that may may route on both source and destination
addresses.
A generally conservative approach, giving weight to running code, A generally conservative approach, giving weight to running code, is
is preferable. Where new protocols are required, evidence of preferable. Where new protocols are required, evidence of commitment
commitment to implementation by appropriate vendors or development to implementation by appropriate vendors or development communities
communities is highly desirable. Protocols used should be is highly desirable. Protocols used should be backwardly compatible.
backwardly compatible.
Where possible, changes to hosts should be minimised. Some Where possible, changes to hosts should be minimised. Some changes
changes may be unavoidable however, e.g. signalling protocols to may be unavoidable however, e.g. signalling protocols to punch holes
punch holes in firewalls where "Simple Security" is deployed in a in firewalls where "Simple Security" is deployed in a CER.
CPE.
Liaisons with other appropriate standards groups and related Changes to routers should also be minimised, e.g.
organisations is desirable, e.g. the IEEE and Wi-Fi Alliance. [I-D.baker-fun-routing-class] suggests introducing a routing protocol
that may route on both source and destination addresses, which would
be a significant change compared to current practices.
Dual-stack Operation Liaisons with other appropriate standards groups and related
organisations is desirable, e.g. the IEEE and Wi-Fi Alliance.
The homenet architecture targets both IPv6-only and dual-stack 3.4.2. Dual-stack Operation
networks. While the CPE requirements in RFC 6204 are targeted at
IPv6-only networks, it is likely that dual-stack homenets will be
the norm for some period of time. IPv6-only networking may first
be deployed in home networks in "greenfield" scenarios, or perhaps
as one element of an otherwise dual-stack network. The homenet
architecture must operate in the absence of IPv4, and IPv6 must
work in the same scenarios as IPv4 today. Running IPv6-only may
require documentation of additional considerations such as:
Ensuring there is a way to access content in the IPv4 Internet. The homenet architecture targets both IPv6-only and dual-stack
This can be arranged through incorporating NAT64 [RFC6144] networks. While the CER requirements in RFC 6204 are aimed at IPv6-
functionality in the home gateway router, for instance. only networks, it is likely that dual-stack homenets will be the norm
for some period of time. IPv6-only networking may first be deployed
in home networks in "greenfield" scenarios, or perhaps as one element
of an otherwise dual-stack network. The homenet architecture must
operate in the absence of IPv4, and IPv6 must work in the same
scenarios as IPv4 today.
DNS discovery mechanisms are enabled even for IPv6. Both Running IPv6-only may require documentation of additional
stateless DHCPv6 [RFC3736] [RFC3646] and Router Advertisement considerations such as:
options [RFC6106] may have to be supported and turned on by
default to ensure maximum compatibility with all types of hosts
in the network. This requires, however, that a working DNS
server is known and addressable via IPv6.
All nodes in the home network support operations in IPv6-only Ensuring there is a way to access content in the IPv4 Internet.
mode. Some current devices work well with dual-stack but fail This can be arranged through incorporating NAT64 [RFC6144]
to recognize connectivity when IPv4 DHCP fails, for instance. functionality in the home gateway router, for instance.
In dual-stack networks, solutions for IPv6 must not adversely DNS discovery mechanisms are enabled for IPv6. Both stateless
affect IPv4 operation. It is likely that topologies of IPv4 and DHCPv6 [RFC3736] [RFC3646] and Router Advertisement options
IPv6 networks would be as congruent as possible. [RFC6106] may have to be supported and turned on by default to
ensure maximum compatibility with all types of hosts in the
network. This requires, however, that a working DNS server is
known and addressable via IPv6.
Note that specific transition tools, particularly those running on All nodes in the home network support operations in IPv6-only
the border CPE, are out of scope. The homenet architecture mode. Some current devices work well with dual-stack but fail to
focuses on the internal home network. recognize connectivity when IPv4 DHCP fails, for instance.
Largest Possible Subnets In dual-stack networks, solutions for IPv6 must not adversely affect
IPv4 operation. It is likely that topologies of IPv4 and IPv6
networks would be as congruent as possible.
Today's IPv4 home networks generally have a single subnet, and Note that specific transition tools, particularly those running on
early dual-stack deployments have a single congruent IPv6 subnet, the border CER to support transition tools being used inside the
possibly with some bridging functionality. homenet, are out of scope. Use of tools, such as 6rd, on the border
CER to support ISP access network transition are to be expected, but
not within scope of homenet, which focuses on the internal
networking.
Future home networks are highly likely to need multiple subnets, 3.4.3. Largest Possible Subnets
for the reasons described earlier. As part of the self-
organisation of the network, the network should subdivide itself
to the largest possible subnets that can be constructed within the
constraints of link layer mechanisms, bridging, physical
connectivity, and policy. For instance, separate subnetworks are
necessary where two different links cannot be bridged, or when a
policy requires the separation of a private and visitor parts of
the network.
While it may be desirable to maximise the chance of link-local Today's IPv4 home networks generally have a single subnet, and early
protocols succeeding, multiple subnet home networks are dual-stack deployments have a single congruent IPv6 subnet, possibly
inevitable, so their support must be included. A general with some bridging functionality.
recommendation is to follow the same topology for IPv6 as is used
for IPv4, but not to use NAT. Thus there should be routed IPv6
where an IPv4 NAT is used, and where there is no NAT there should
be bridging.
In some cases IPv4 NAT home networks may feature cascaded NATs, Future home networks are highly likely to need multiple subnets, for
e.g. where NAT routers are included within VMs or Internet the reasons described earlier. As part of the self-organisation of
connection services are used. IPv6 routed versions of such tools the network, the network should subdivide itself to the largest
will be required. possible subnets that can be constructed within the constraints of
link layer mechanisms, bridging, physical connectivity, and policy.
For instance, separate subnetworks are necessary where two different
link layers cannot be bridged, or when a policy requires the
separation of a private and visitor parts of the network.
Transparent End-to-End Communications While it may be desirable to maximise the chance of link-local
protocols operating across a homenet by maximising the size of a
subnet across the homenet, multiple subnet home networks are
inevitable, so their support must be included. A general
recommendation is to follow the same topology for IPv6 as is used for
IPv4, but not to use NAT. Thus there should be routed IPv6 where an
IPv4 NAT is used, and where there is no NAT there should be bridging
if the link layer allows this.
An IPv6-based home network architecture should naturally offer a In some cases IPv4 NAT home networks may feature cascaded NATs, e.g.
transparent end-to-end communications model. Each device should where NAT routers are included within VMs or Internet connection
be addressable by a unique address. Security perimeters can of services are used. IPv6 routed versions of such tools will be
course restrict the end-to-end communications, but it is simpler required.
given the availability of globally unique addresses to block
certain nodes from communicating by use of an appropriate
filtering device than to configure the address translation device
to enable appropriate address/port forwarding in the presence of a
NAT.
As discussed previously, it is important to note the difference 3.4.4. Transparent End-to-End Communications
between hosts being addressable and reachable. Thus filtering is
to be expected, while IPv6 NAT is not. End-to-end communications
are important for their robustness to failure of intermediate
systems, where in contrast NAT is dependent on state machines
which are not self-healing.
When configuring filters, protocols for securely associating An IPv6-based home network architecture should naturally offer a
devices are desirable. In the presence of "Simple Security" the transparent end-to-end communications model. Each device should be
use of signalling protocols such as uPnP or PCP may be expected to addressable by a unique address. Security perimeters can of course
punch holes in the firewall. Alternatively, RFC 6092 supports the restrict the end-to-end communications, but it is simpler given the
option for a border CPE to run in "transparent mode", in which availability of globally unique addresses to block certain nodes from
case a protocol like PCP is not required, but the security model communicating by use of an appropriate filtering device than to
is more open. configure the address translation device to enable appropriate
address/port forwarding in the presence of a NAT.
IP Connectivity between All Nodes As discussed previously, it is important to note the difference
between hosts being addressable and reachable. Thus filtering is to
be expected, while host-based IPv6 NAT is not. End-to-end
communications are important for their robustness against failure of
intermediate systems, where in contrast NAT is dependent on state
machines which are not self-healing.
A logical consequence of the end-to-end communications model is When configuring filters, protocols for securely associating devices
that the network should by default attempt to provide IP-layer are desirable. In the presence of "Simple Security" the use of
connectivity between all internal parts as well as between the signalling protocols such as uPnP or PCP may be expected to punch
internal parts and the Internet. This connectivity should be holes in the firewall (and be able to handle cases where there are
established at the link layer, if possible, and using routing at multiple CERs/firewall(s). Alternatively, RFC 6092 supports the
the IP layer otherwise. option for a border CER to run in "transparent mode", in which case a
protocol like PCP is not required, but the security model is more
open.
Local addressing (ULAs) may be used within the scope of a home 3.4.5. IP Connectivity between All Nodes
network. It would be expected that ULAs may be used alongside one
or more globally unique ISP-provided addresses/prefixes in a
homenet. ULAs may be used for all devices, not just those
intended to have internal connectivity only. ULAs may then be
used for stable internal communications should the ISP-provided
prefix change, or external connectivity be temporarily lost. The
use of ULAs should be restricted to the homenet scope through
filtering at the border(s) of the homenet; thus "end-to-end" for
ULAs is limited to the homenet.
In some cases full internal connectivity may not be desirable, A logical consequence of the end-to-end communications model is that
e.g. in certain utility networking scenarios, or where filtering the network should by default attempt to provide IP-layer
is required for policy reasons against guest network subnet(s). connectivity between all internal parts as well as between the
Note that certain scenarios may require co-existence of ISP internal parts and the Internet. This connectivity should be
connectivity providing a general Internet service with provider established at the link layer, if possible, and using routing at the
connectivity to a private "walled garden" network. IP layer otherwise.
Some home networking scenarios/models may involve isolated Local addressing (ULAs) may be used within the scope of a home
subnet(s) with their own CPEs. In such cases connectivity would network. It would be expected that ULAs may be used alongside one or
only be expected within each isolated network (though traffic may more globally unique ISP-provided addresses/prefixes in a homenet.
potentially pass between them via external providers). ULAs may be used for all devices, not just those intended to have
internal connectivity only. ULAs may then be used for stable
internal communications should the ISP-provided prefix (suddenly)
change, or external connectivity be temporarily lost. The use of
ULAs should be restricted to the homenet scope through filtering at
the border(s) of the homenet; thus "end-to-end" for ULAs is limited
to the homenet.
Routing functionality In some cases full internal connectivity may not be desirable, e.g.
in certain utility networking scenarios, or where filtering is
required for policy reasons against guest network subnet(s). Note
that certain scenarios may require co-existence of ISP connectivity
providing a general Internet service with provider connectivity to a
private "walled garden" network.
Routing functionality is required when multiple subnets are in Some home networking scenarios/models may involve isolated subnet(s)
use. This functionality could be as simple as the current with their own CERs. In such cases connectivity would only be
"default route is up" model of IPv4 NAT, or it could involve expected within each isolated network (though traffic may potentially
running an appropriate routing protocol. pass between them via external providers).
The homenet routing environment may include traditional IP LLNs provide an example of where there may be secure perimeters
networking where existing link-state or distance-vector protocols inside the homenet. Constrained LLN nodes may implement WPA-style
may be used, but also new LLN or other "constrained" networks network key security but may depend on access policies enforced by
where other protocols may be more appropriate. IPv6 VM solutions the LLN border router.
may also add additional routing requirements. Current home
deployments use largely different mechanisms in sensor and basic
Internet connectivity networks. In general, LLN or other networks
should be able to attach and participate the same way or map/be
gatewayed to the main homenet.
It is desirable that the routing protocol has knowledge of the 3.4.6. Routing functionality
homenet topology, which implies a link-state protocol may be
preferable. If so, it is also desirable that the announcements
and use of LSAs and RAs are appropriately coordinated.
The routing environment should be self-configuring, as discussed Routing functionality is required when there are multiple routers in
in the next subsection. An example of how OSPFv3 can be self- use. This functionality could be as simple as the current "default
configuring in a homenet is described in route is up" model of IPv4 NAT, or it could involve running an
[I-D.acee-ospf-ospfv3-autoconfig]. It is important that self- appropriate routing protocol.
configuration with "unintended" devices is avoided.
To support multihoming within a homenet, a routing protocol that The homenet routing environment may include traditional IP networking
can make routing decisions based on source and destination where existing link-state or distance-vector protocols may be used,
addresses is desirable, to avoid upstream ISP ingress filtering but also new LLN or other "constrained" networks where other
problems. In general the routing protocol should support multiple protocols may be more appropriate. IPv6 VM solutions may also add
ISP uplinks and prefixes in concurrent use. additional routing requirements. Current home deployments use
largely different mechanisms in sensor and basic Internet
connectivity networks.
Self-Organisation In this section we list the requirements and assumptions for routing
functionality within the homenet environment.
A home network architecture should be naturally self-organising RT1) The protocol should preferably be an existing deployed
and self-configuring under different circumstances relating to the protocol that has been proven to be reliable and robust.
connectivity status to the Internet, number of devices, and
physical topology.
The most important function in this respect is prefix delegation RT2) It is preferable that the protocol is "lightweight".
and management. Delegation should be autonomous, and not assume a
flat or hierarchical model. From the homenet perspective, a
single prefix should be received on the border CPE from the
upstream ISP, via [RFC3363]. The ISP should only see that
aggregate, and not single /64 prefixes allocated within the
homenet.
Each link in the homenet should receive a prefix from within the RT3) The protocol should provide reachability between all nodes in
ISP-provided prefix. Delegation within the homenet should give the homement.
each link a prefix that is persistent across reboots, power
outages and similar short-term outages. Addition of a new routing
device should not affect existing persistent prefixes, but
persistence may not be expected in the face of significant
"replumbing" of the homenet. Persistence should not depend on
router boot order. Persistent prefixes may imply the need for
stable storage on routing devices, and also a method for a home
user to "reset" the stored prefix should a significant
reconfiguration be required.
The assignment mechanism should provide reasonable efficiency, so RT4) In general, LLN or other networks should be able to attach and
that typical home network prefix allocation sizes can accommodate participate the same way or map/be gatewayed to the main
all the necessary /64 allocations in most cases. For instance, homenet.
duplicate assignment of multiple /64s to the same network should
be avoided.
Several proposals have been made for prefix delegation within a RT5) Multiple interface PHYs must be accounted for in the homenet
homenet. One group of proposals is based on DHCPv6 PD, as routed topology. Technologies such as Ethernet, WiFi, MoCA,
described in [I-D.baker-homenet-prefix-assignment], etc must be capable of coexisting in the same environment and
[I-D.chakrabarti-homenet-prefix-alloc], [RFC3315] and [RFC3363]. should be tested as part of any routed deployment. The
The other uses OSPFv3, as described in inclusion of the PHY layer characteristics including
[I-D.arkko-homenet-prefix-assignment]. bandwidth, loss, and latency in path computation should be
considered for optimizing communication in the homenet.
While the homenet should be self-organising, it should be possible RT6) Minimizing convergence time should be a goal in any routed
to manually adjust (override) the current configuration. The environment, but as a guideline a maximum convergence time of
network should also cope gracefully in the event of prefix a couple of minutes should be the target.
exhaustion.
The network elements will need to be integrated in a way that RT7) It is desirable that the routing protocol has knowledge of the
takes account of the various lifetimes on timers that are used, homenet topology, which implies a link-state protocol may be
e.g. DHCPv6 PD, router, valid prefix and preferred prefix timers. preferable. If so, it is also desirable that the
announcements and use of LSAs and RAs are appropriately
coordinated.
The homenet will have one or more borders, with external RT8) Any routed solution will require a means for determining the
connectivity providers and potentially parts of the internal boundaries of the homenet. Borders may include but are not
network (e.g. for policy-based reasons). It should be possible to limited to the interface to the upstream ISP, a gateway device
automatically perform border discovery at least for the ISP to a separate home network such as a SmartGrid or similar LLN
borders. Such borders determine for example the scope of ULAs, network, and in some cases there may be no border such as
site scope multicast boundaries and where firewall policies may be before an upstream connection has been established. Devices
applied. in the homenet must be able to find the path to the Internet
as well as other devices on the home intranet. The border
discovery functionality may be integrated into the routing
protocol itself, but may also be imported via a separate
discovery mechanism.
The network cannot be expected to be completely self-organising, RT9) The routing environment should be self-configuring, as
e.g. some security parameters are likely to need manual discussed in the next subsection. An example of how OSPFv3
configuration, e.g. WPA2 configuration for wireless access can be self-configuring in a homenet is described in
control. [I-D.acee-ospf-ospfv3-autoconfig]. The exception is
configuration of a "secret" for authentication methods. It is
important that self-configuration with "unintended" devices is
avoided.
Fewest Topology Assumptions RT10) The protocol should not require upstream ISP connectivity to
be established to continue routing within the homenet.
There should be ideally no built-in assumptions about the topology RT11) Multiple upstreams should be supported, as described in the
in home networks, as users are capable of connecting their devices Network Models earlier.
in ingenious ways. Thus arbitrary topologies will need to be
supported.
It is important not to introduce new IPv6 scenarios that would RT12) To support multihoming within a homenet, a routing protocol
break with IPv4+NAT, given dual-stack homenets will be commonplace that can make routing decisions based on source and
for some time. There may be IPv6-only topologies that work where destination addresses is desirable, to avoid upstream ISP
IPv4 is not used or required. ingress filtering problems. In general the routing protocol
should support multiple ISP uplinks and delegated prefixes in
concurrent use.
Naming and Service Discovery RT13) The routing system should support walled garden environments.
The most natural way to think about naming and service discovery RT14) Load-balancing to multiple providers is not a requirement, but
within a home is to enable it to work across the entire residence, failover from a primary to a backup link when available must
disregarding technical borders such as subnets but respecting be a requirement.
policy borders such as those between visitor and internal
networks.
This may imply support is required for IPv6 multicast across the RT15) It is assumed that the typical router designed for residential
scope of the home network, and thus at least all routing devices use does not contain the memory or cpu required to process a
in the network. full Internet routing table this should not be a requirement
for any homenet device.
Homenet naming systems will be required that work internally or A new I-D has been published on homenet routing requirements, see
externally, though the domains used may be different in each case. [I-D.howard-homenet-routing-comparison] and evaluations of common
routing protocols made against those requirements, see
[I-D.howard-homenet-routing-requirements]. The requirements from the
former document have been worked into this architecture text.
Feedback is sought on how these documents move forward.
Proxy or Extend? 3.4.7. Self-Organising
Related to the above, we believe that general existing discovery A home network architecture should be naturally self-organising and
protocols that are designed to only work within a subnet are self-configuring under different circumstances relating to the
modified/extended to work across subnets, rather than defining connectivity status to the Internet, number of devices, and physical
proxy capabilities for those functions. topology. While the homenet should be self-organising, it should be
possible to manually adjust (override) the current configuration.
We may need to do more analysis (a survey?) on which functions/ The most important function in this respect is prefix delegation and
protocols assume subnet-only operation, in the context of existing management. The requirements and assumptions for the prefix
home networks. Some experience from enterprises may be relevant delegation function are summarised as follows:
here.
Adapt to ISP constraints PD1) From the homenet perspective, a single prefix should be
received on the border CER [RFC3633]. The ISP should only see
that aggregate, and not single /64 prefixes allocated within
the homenet.
The home network may receive an arbitrary length IPv6 prefix from PD2) Each link in the homenet should receive a prefix from within
its provider, e.g. /60 or /56. The offered prefix may be static the ISP-provided prefix.
or dynamic. The home network needs to be adaptable to such ISP
policies, e.g. on constraints placed by the size of prefix offered
by the ISP. The ISP may use [I-D.ietf-dhc-pd-exclude] for
example.
The internal operation of the home network should not also depend PD3) Delegation should be autonomous, and not assume a flat or
on the availability of the ISP network at any given time, other hierarchical model.
than for connectivity to services or systems off the home network.
This implies the use of ULAs as supported in RFC6204. If used,
ULA addresses should be stable so that they can always be used
internally, independent of the link to the ISP.
It is expected that ISPs will deliver a static home prefix to PD4) The assignment mechanism should provide reasonable efficiency,
customers. However, it is possible, however unlikely, that an ISP so that typical home network prefix allocation sizes can
may need to restructure and in doing so renumber its customer accommodate all the necessary /64 allocations in most cases.
homenets. In such cases "flash" renumbering may be imposed. Thus A currently typical /60 allocation gives 16 /64 subnets.
it's desirable that homenet protocols or operational processes
don't add unnecessary complexity for renumbering.
3.5. Summary of Homenet Architecture Recommendations PD5) Duplicate assignment of multiple /64s to the same network
should be avoided.
In this section we present a summary of the homenet architecture PD6) The network should behave as gracefully as possible in the
recommendations that were discussed in more detail in the previous event of prefix exhaustion.
sections.
(Bullet points to be added in next version) PD7) Where multiple CERs exist with multiple ISP prefix pools, it
is expected that routers within the homenet would assign
themselves prefixes from each ISP they communicate with/
through.
PD8) Where ULAs are used, most likely but not necessarily in
parallel with global prefixes, one router will need to be
elected as the generator of ULA prefixes for the homenet.
PD9) Delegation within the homenet should give each link a prefix
that is persistent across reboots, power outages and similar
short-term outages.
PD10) Addition of a new routing device should not affect existing
persistent prefixes, but persistence may not be expected in
the face of significant "replumbing" of the homenet.
PD11) Persistence should not depend on router boot order.
PD12) Persistent prefixes may imply the need for stable storage on
routing devices, and also a method for a home user to "reset"
the stored prefix should a significant reconfiguration be
required (though ideally the home user should not be involved
at all).
PD13) The delegation method should support "flash" renumbering.
Several proposals have been made for prefix delegation within a
homenet. One group of proposals is based on DHCPv6 PD, as described
in [I-D.baker-homenet-prefix-assignment],
[I-D.chakrabarti-homenet-prefix-alloc], [RFC3315] and [RFC3633]. The
other uses OSPFv3, as described in
[I-D.arkko-homenet-prefix-assignment]. More detailed analysis of
these approaches needs to be made against the requirements/
assumptions listed above.
Other parameters of the network will need to be self-organising. The
network elements will need to be integrated in a way that takes
account of the various lifetimes on timers that are used on those
different elements, e.g. DHCPv6 PD, router, valid prefix and
preferred prefix timers.
The homenet will have one or more borders, with external connectivity
providers and potentially parts of the internal network (e.g. for
policy-based reasons). It should be possible to automatically
perform border discovery at least for the ISP borders. Such borders
determine for example the scope of ULAs, site scope multicast
boundaries and where firewall policies may be applied.
The network cannot be expected to be completely self-organising, e.g.
some security parameters are likely to need manual configuration,
e.g. WPA2 configuration for wireless access control. Some existing
mechanisms exist to assist home users to associate devices as simply
as possible, e.g. "connect" button support.
3.4.8. Fewest Topology Assumptions
There should ideally be no built-in assumptions about the topology in
home networks, as users are capable of connecting their devices in
ingenious ways. Thus arbitrary topologies will need to be supported.
It is important not to introduce new IPv6 scenarios that would break
with IPv4+NAT, given that dual-stack homenets will be commonplace for
some time. There may be IPv6-only topologies that work where IPv4 is
not used or required.
3.4.9. Naming and Service Discovery
The most natural way to think about naming and service discovery
within a homenet is to enable it to work across the entire residence,
disregarding technical borders such as subnets but respecting policy
borders such as those between visitor and internal networks.
Homenet naming systems will be required that work internally or
externally, though the domains used may be different from those
different perspectives.
A desirable target may be a fully functional self-configuring secure
local DNS service so that all devices are referred to by name, and
these FQDNs are resolved locally. This would make clean use of ULAs
and multiple ISP-provided prefixes much easier. The local DNS
service should be (by default) authoritative for the local name space
in both IPv4 and IPv6. A dual-stack residential gateway should
include a dual-stack DNS server.
Consideration will also need to be given for existing protocols that
may be used within a network, e.g. mDNS, and how these interact with
unicast-based DNS services.
With the introduction of new top level domains, there is potential
for ambiguity between for example a local host called apple and (if
it is registered) an apple gTLD, so some local name space is probably
required, which should also be configurable to something else by a
home user, e.g. ".home", if desired.
It is also important to note here that there is also potential
ambiguity if a mobile device should move between two local name
spaces called ".home", for example.
For service discovery, support may be required for IPv6 multicast
across the scope of the home network, and thus at least all routing
devices in the network.
3.4.10. Proxy or Extend?
Related to the above, we believe that general existing discovery
protocols that are designed to only work within a subnet should be
modified/extended to work across subnets, rather than defining proxy
capabilities for each of those functions.
Feedback is desirable on which other functions/protocols assume
subnet-only operation, in the context of existing home networks.
Some experience from enterprises may be relevant here.
3.4.11. Adapt to ISP constraints
The home network may receive an arbitrary length IPv6 prefix from its
provider, e.g. /60 or /56. The offered prefix may be stable over
time or change frequently. The home network needs to be adaptable to
such ISP policies, e.g. on constraints placed by the size of prefix
offered by the ISP. The ISP may use [I-D.ietf-dhc-pd-exclude] for
example.
The internal operation of the home network should also not depend on
the availability of the ISP network at any given time, other than for
connectivity to services or systems off the home network. This
implies the use of ULAs as supported in RFC6204. If used, ULA
addresses should be stable so that they can always be used
internally, independent of the link to the ISP.
It is expected that ISPs will deliver a relatively stable home prefix
to customers. The norm for residential customers of large ISPs may
similar to their single IPv4 address provision; by default it is
likely to remain persistent for some time, but changes in the ISP's
own provisioning systems may lead to the customer's IP (and in the
IPv6 case their prefix pool) changing.
When an ISP needs to restructure and in doing so renumber its
customer homenets, "flash" renumbering is likely to be imposed. This
implies a need for the homenet to be able to handle a sudden
renumbering event which, unlike the process described in [RFC4192],
would be without a "flag day". The customer may of course also
choose to move to a new ISP, and thus begin using a new prefix. Thus
it's desirable that homenet protocols or operational processes don't
add unnecessary complexity for renumbering.
The 6renum WG is studying IPv6 renumbering for enterprise networks.
It is not currently targetting homenets, but may produce outputs that
are relevant.
3.5. Summary of Homenet Architecture Recommendations
Feedback sought on whether a summary section would be useful.
3.6. Implementing the Architecture on IPv6 3.6. Implementing the Architecture on IPv6
The necessary mechanisms are largely already part of the IPv6 The necessary mechanisms are largely already part of the IPv6
protocol set and common implementations, though there are some protocol set and common implementations, though there are some
exceptions. For automatic routing, it is expected that existing exceptions. For automatic routing, it is expected that existing
routing protocols can be used as is. However, a new mechanism may be routing protocols can be used as is. However, a new mechanism may be
needed in order to turn a selected protocol on by default. Support needed in order to turn a selected protocol on by default. Support
for multiple exit routers and multi-homing would also require for multiple exit routers and multi-homing would also require
extensions, even if focused on the problem of multi-addressed hosts extensions, even if focused on the problem of multi-addressed hosts
skipping to change at page 22, line 50 skipping to change at page 30, line 9
(IPv6) Specification", RFC 2460, December 1998. (IPv6) Specification", RFC 2460, December 1998.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998. Services", RFC 2475, December 1998.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3363] Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T. [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Hain, "Representing Internet Protocol version 6 (IPv6) Host Configuration Protocol (DHCP) version 6", RFC 3633,
Addresses in the Domain Name System (DNS)", RFC 3363, December 2003.
August 2002.
[RFC4192] Baker, F., Lear, E., and R. Droms, "Procedures for
Renumbering an IPv6 Network without a Flag Day", RFC 4192,
September 2005.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005. Addresses", RFC 4193, October 2005.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006. Architecture", RFC 4291, February 2006.
[RFC4864] Van de Velde, G., Hain, T., Droms, R., Carpenter, B., and [RFC4864] Van de Velde, G., Hain, T., Droms, R., Carpenter, B., and
E. Klein, "Local Network Protection for IPv6", RFC 4864, E. Klein, "Local Network Protection for IPv6", RFC 4864,
May 2007. May 2007.
[RFC5533] Nordmark, E. and M. Bagnulo, "Shim6: Level 3 Multihoming [RFC5533] Nordmark, E. and M. Bagnulo, "Shim6: Level 3 Multihoming
Shim Protocol for IPv6", RFC 5533, June 2009. Shim Protocol for IPv6", RFC 5533, June 2009.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification",
RFC 5969, August 2010.
[RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in [RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in
Customer Premises Equipment (CPE) for Providing Customer Premises Equipment (CPE) for Providing
Residential IPv6 Internet Service", RFC 6092, Residential IPv6 Internet Service", RFC 6092,
January 2011. January 2011.
[RFC6204] Singh, H., Beebee, W., Donley, C., Stark, B., and O. [RFC6204] Singh, H., Beebee, W., Donley, C., Stark, B., and O.
Troan, "Basic Requirements for IPv6 Customer Edge Troan, "Basic Requirements for IPv6 Customer Edge
Routers", RFC 6204, April 2011. Routers", RFC 6204, April 2011.
[RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix [RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix
skipping to change at page 24, line 5 skipping to change at page 31, line 18
RFC 6106, November 2010. RFC 6106, November 2010.
[RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for [RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
IPv4/IPv6 Translation", RFC 6144, April 2011. IPv4/IPv6 Translation", RFC 6144, April 2011.
[I-D.baker-fun-multi-router] [I-D.baker-fun-multi-router]
Baker, F., "Exploring the multi-router SOHO network", Baker, F., "Exploring the multi-router SOHO network",
draft-baker-fun-multi-router-00 (work in progress), draft-baker-fun-multi-router-00 (work in progress),
July 2011. July 2011.
[I-D.townsley-troan-ipv6-ce-transitioning]
Townsley, M. and O. Troan, "Basic Requirements for
Customer Edge Routers - multihoming and transition",
draft-townsley-troan-ipv6-ce-transitioning-02 (work in
progress), December 2011.
[I-D.baker-fun-routing-class] [I-D.baker-fun-routing-class]
Baker, F., "Routing a Traffic Class", Baker, F., "Routing a Traffic Class",
draft-baker-fun-routing-class-00 (work in progress), draft-baker-fun-routing-class-00 (work in progress),
July 2011. July 2011.
[I-D.howard-homenet-routing-comparison]
Howard, L., "Evaluation of Proposed Homenet Routing
Solutions", draft-howard-homenet-routing-comparison-00
(work in progress), December 2011.
[I-D.howard-homenet-routing-requirements]
Howard, L., "Homenet Routing Requirements",
draft-howard-homenet-routing-requirements-00 (work in
progress), December 2011.
[I-D.herbst-v6ops-cpeenhancements] [I-D.herbst-v6ops-cpeenhancements]
Herbst, T. and D. Sturek, "CPE Considerations in IPv6 Herbst, T. and D. Sturek, "CPE Considerations in IPv6
Deployments", draft-herbst-v6ops-cpeenhancements-00 (work Deployments", draft-herbst-v6ops-cpeenhancements-00 (work
in progress), October 2010. in progress), October 2010.
[I-D.vyncke-advanced-ipv6-security] [I-D.vyncke-advanced-ipv6-security]
Vyncke, E., Yourtchenko, A., and M. Townsley, "Advanced Vyncke, E., Yourtchenko, A., and M. Townsley, "Advanced
Security for IPv6 CPE", Security for IPv6 CPE",
draft-vyncke-advanced-ipv6-security-03 (work in progress), draft-vyncke-advanced-ipv6-security-03 (work in progress),
October 2011. October 2011.
skipping to change at page 24, line 36 skipping to change at page 32, line 18
[I-D.ietf-6man-rfc3484-revise] [I-D.ietf-6man-rfc3484-revise]
Matsumoto, A., Kato, J., Fujisaki, T., and T. Chown, Matsumoto, A., Kato, J., Fujisaki, T., and T. Chown,
"Update to RFC 3484 Default Address Selection for IPv6", "Update to RFC 3484 Default Address Selection for IPv6",
draft-ietf-6man-rfc3484-revise-05 (work in progress), draft-ietf-6man-rfc3484-revise-05 (work in progress),
October 2011. October 2011.
[I-D.ietf-dhc-pd-exclude] [I-D.ietf-dhc-pd-exclude]
Korhonen, J., Savolainen, T., Krishnan, S., and O. Troan, Korhonen, J., Savolainen, T., Krishnan, S., and O. Troan,
"Prefix Exclude Option for DHCPv6-based Prefix "Prefix Exclude Option for DHCPv6-based Prefix
Delegation", draft-ietf-dhc-pd-exclude-03 (work in Delegation", draft-ietf-dhc-pd-exclude-04 (work in
progress), August 2011. progress), December 2011.
[I-D.v6ops-multihoming-without-ipv6nat] [I-D.v6ops-multihoming-without-ipv6nat]
Troan, O., Miles, D., Matsushima, S., Okimoto, T., and D. Troan, O., Miles, D., Matsushima, S., Okimoto, T., and D.
Wing, "IPv6 Multihoming without Network Address Wing, "IPv6 Multihoming without Network Address
Translation", draft-v6ops-multihoming-without-ipv6nat-00 Translation", draft-v6ops-multihoming-without-ipv6nat-00
(work in progress), March 2011. (work in progress), March 2011.
[I-D.ietf-mif-dns-server-selection]
Savolainen, T., Kato, J., and T. Lemon, "Improved DNS
Server Selection for Multi-Interfaced Nodes",
draft-ietf-mif-dns-server-selection-07 (work in progress),
October 2011.
[I-D.ietf-mif-dhcpv6-route-option]
Dec, W., Mrugalski, T., Sun, T., and B. Sarikaya, "DHCPv6
Route Options", draft-ietf-mif-dhcpv6-route-option-03
(work in progress), September 2011.
[I-D.baker-homenet-prefix-assignment] [I-D.baker-homenet-prefix-assignment]
Baker, F. and R. Droms, "IPv6 Prefix Assignment in Small Baker, F. and R. Droms, "IPv6 Prefix Assignment in Small
Networks", draft-baker-homenet-prefix-assignment-00 (work Networks", draft-baker-homenet-prefix-assignment-00 (work
in progress), October 2011. in progress), October 2011.
[I-D.arkko-homenet-prefix-assignment] [I-D.arkko-homenet-prefix-assignment]
Arkko, J. and A. Lindem, "Prefix Assignment in a Home Arkko, J. and A. Lindem, "Prefix Assignment in a Home
Network", draft-arkko-homenet-prefix-assignment-01 (work Network", draft-arkko-homenet-prefix-assignment-01 (work
in progress), October 2011. in progress), October 2011.
[I-D.acee-ospf-ospfv3-autoconfig] [I-D.acee-ospf-ospfv3-autoconfig]
Lindem, A. and J. Arkko, "OSPFv3 Auto-Configuration", Lindem, A. and J. Arkko, "OSPFv3 Auto-Configuration",
draft-acee-ospf-ospfv3-autoconfig-00 (work in progress), draft-acee-ospf-ospfv3-autoconfig-00 (work in progress),
October 2011. October 2011.
[I-D.ietf-pcp-base] [I-D.ietf-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)", Selkirk, "Port Control Protocol (PCP)",
draft-ietf-pcp-base-18 (work in progress), December 2011. draft-ietf-pcp-base-22 (work in progress), January 2012.
[I-D.chakrabarti-homenet-prefix-alloc] [I-D.chakrabarti-homenet-prefix-alloc]
Nordmark, E., Chakrabarti, S., Krishnan, S., and W. Nordmark, E., Chakrabarti, S., Krishnan, S., and W.
Haddad, "Simple Approach to Prefix Distribution in Basic Haddad, "Simple Approach to Prefix Distribution in Basic
Home Networks", draft-chakrabarti-homenet-prefix-alloc-01 Home Networks", draft-chakrabarti-homenet-prefix-alloc-01
(work in progress), October 2011. (work in progress), October 2011.
[Gettys11] [Gettys11]
Gettys, J., "Bufferbloat: Dark Buffers in the Internet", Gettys, J., "Bufferbloat: Dark Buffers in the Internet",
March 2011, March 2011,
skipping to change at page 26, line 14 skipping to change at page 33, line 32
Authors' Addresses Authors' Addresses
Jari Arkko Jari Arkko
Ericsson Ericsson
Jorvas 02420 Jorvas 02420
Finland Finland
Email: jari.arkko@piuha.net Email: jari.arkko@piuha.net
Anders Brandt
Sigma Designs
Emdrupvej 26A, 1
Copenhagen DK-2100
Denmark
Email: abr@sdesigns.dk
Tim Chown Tim Chown
University of Southampton University of Southampton
Highfield Highfield
Southampton, Hampshire SO17 1BJ Southampton, Hampshire SO17 1BJ
United Kingdom United Kingdom
Email: tjc@ecs.soton.ac.uk Email: tjc@ecs.soton.ac.uk
Jason Weil Jason Weil
Time Warner Cable Time Warner Cable
13820 Sunrise Valley Drive 13820 Sunrise Valley Drive
Herndon, VA 20171 Herndon, VA 20171
USA USA
Email: jason.weil@twcable.com Email: jason.weil@twcable.com
Ole Troan Ole Troan
Cisco Systems, Inc. Cisco Systems, Inc.
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