Internet DRAFT - draft-grundemann-homenet-hipnet
draft-grundemann-homenet-hipnet
Network Working Group C. Grundemann
Internet-Draft C. Donley
Intended status: Informational CableLabs
Expires: August 29, 2013 J. Brzozowski
Comcast Cable Communications
L. Howard
Time Warner Cable
V. Kuarsingh
Rogers Communications
February 25, 2013
A Near Term Solution for Home IP Networking (HIPnet)
draft-grundemann-homenet-hipnet-01
Abstract
Home networks are becoming more complex. With the launch of new
services such as home security, IP video, Smart Grid, etc., many
Service Providers are placing additional IPv4/IPv6 routers on the
subscriber network. This document describes a self-configuring home
router that is capable of operating in such an environment, and that
requires no user interaction to configure it. Compliant with
draft-ietf-homenet-arch, it uses existing protocols in new ways
without the need for a routing protocol.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2013.
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Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Current End-User Network Architecture . . . . . . . . . . 5
3.2. HIPNet End-User Network Architecture . . . . . . . . . . . 6
4. Network Detection . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Edge Detection . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Directionless Home Routers . . . . . . . . . . . . . . . . 9
5. Routing and Addressing . . . . . . . . . . . . . . . . . . . . 10
5.1. Recursive Prefix Delegation . . . . . . . . . . . . . . . 11
5.2. Prefix Sub-Delegation Requirements . . . . . . . . . . . . 12
5.3. Multiple Address Family Support . . . . . . . . . . . . . 13
5.4. Hierarchical Routing . . . . . . . . . . . . . . . . . . . 13
6. Multiple ISPs . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. Backup Connection . . . . . . . . . . . . . . . . . . . . 14
6.2. Multi-homing . . . . . . . . . . . . . . . . . . . . . . . 14
6.2.1. Multihoming Requirements . . . . . . . . . . . . . . . 16
7. Mulicast Support . . . . . . . . . . . . . . . . . . . . . . . 17
7.1. Service Discovery . . . . . . . . . . . . . . . . . . . . 17
7.2. Multicast Proxy Support . . . . . . . . . . . . . . . . . 17
7.3. Multicast Requirements . . . . . . . . . . . . . . . . . . 17
8. Firewall Support . . . . . . . . . . . . . . . . . . . . . . . 18
8.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 19
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10. Security Considerations . . . . . . . . . . . . . . . . . . . 19
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
12.1. Normative References . . . . . . . . . . . . . . . . . . . 20
12.2. Informative References . . . . . . . . . . . . . . . . . . 20
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
This document expands upon [I-D.ietf-v6ops-6204bis] to describe IPv6/
IPv4 features for a residential or small-office router, referred to
as a HIPnet router. Consistent with [I-D.ietf-homenet-arch], it
focuses on network technology evolution to support increasingly large
residential/SoHo networks. While the primary focus is on IPv6
support, this document also describes how to leverage IPv6 to
configure IPv4 in a manner better than nested NATs in operation on
many networks today.
This document specifies how a HIPnet router automatically detects
both the edge of the customer network and its upstream interface, how
it subdivides an IPv6 prefix to distribute to downstream routers, and
how it leverages IPv6 address assignment to distribute IPv4
addresses. It also discusses how such a router can operate with a
backup ISP or limited multihoming across two ISPs.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology
End-User Network one or more links attached to the HIPnet
router that connect IPv6 and IPv4 hosts.
Home IP Network (HIPnet) Router a node intended for home or small-
office use that forwards packets not
explicitly addressed to itself.
Customer Edge Router (CER) a HIPnet router that connects the end-
user network to a service provider network.
Internal Router an additional HIPnet router deployed in the
home or small-office network that is not
attached to a service provider network.
Note that this is a functional role; it is
expected that there will not be a
difference in hardware or software between
a CER and IR, except in such cases when a
CER has a dedicated non-Ethernet WAN
interface (e.g. DSL/cable/ LTE modem) that
would preclude it from operating as an IR.
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Down Interface a HIPnet router's attachment to a link in
the end-user network on which it
distributes addresses and/or prefixes.
Examples are Ethernet (simple or bridged),
802.11 wireless, or other LAN technologies.
A HIPnet router may have one or more
network-layer down interfaces.
downstream router a router directly connected to a HIPnet
router's Down Interface.
Service Provider an entity that provides access to the
Internet. In this document, a service
provider specifically offers Internet
access using IPv6, and may also offer IPv4
Internet access. The service provider can
provide such access over a variety of
different transport methods such as DSL,
cable, wireless, and others.
Up Interface a HIPnet router's attachment to a link
where it receives one or more IP addresses
and/or prefixes. This is also the link to
which the HIPnet router points its default
route.
depth the number of layers of routers in a
network. A single router network would
have a depth of 1, while a router behind a
router behind a router would have a depth
of 3.
width The number of routers that can be directly
subtended to an upstream router. A network
with three directly attached routers behind
the CER would have a width of 3.
3. Architecture
3.1. Current End-User Network Architecture
An end-user network will likely support both IPv4 and IPv6. A
typical end-user network consists of a "plug and play" router with
IPv4 NAT functionality and a single link behind it, connected to the
service provider network.
A typical IPv4 NAT deployment by default blocks all incoming
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connections. Opening of ports is typically allowed using a Universal
Plug and Play Internet Gateway Device (UPnP IGD) [UPNnP-IGD] or some
other firewall control protocol.
Rewriting addresses on the edge of the network allows for some
rudimentary multihoming, even though using NATs for multihoming does
not preserve connections during a fail-over event [RFC4864].
Many existing routers support dynamic routing, and advanced end-users
can build arbitrary, complex networks using manual configuration of
address prefixes combined with a dynamic routing protocol.
3.2. HIPNet End-User Network Architecture
The end-user network architecture should provide equivalent or better
capabilities and functionality than the current architecture.
However, as end-user networks become more complex, the HIPnet
architecture needs to support more complicated networks. Figure 1
illustrates the model topology for the end-user network.
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+-------+-------+ \
| Service | \
| Provider | | Service
| Router | | Provider
+-------+-------+ | network
| /
| Customer /
| Internet connection /
|
+------+--------+ \
| IPv6 | \
| Customer Edge | \
| Router | /
+---+-------+-+-+ /
Network A | | Network B | End-User
---+-------------+----+- --+--+-------------+--- | network(s)
| | | | \
+----+-----+ +-----+----+ +----+-----+ +-----+----+ \
| Host | |Internal | | Host| |Internal | /
| | | Router | | | | Router | /
+----------+ +-----+----+ +----------+ +----------+ /
Network C | Network D | |
---+-------------+----+- --+--+-------------+--- |
| | | | \
+----+-----+ +-----+----+ +----+-----+ +-----+----+ \
| Host | | Host | | Host| | Host | /
| | | | | | | | /
+----------+ +-----+----+ +----------+ +----------+ /
Figure 1: Example End-User Network
This architecture describes the following:
o Prefix subdelegation supporting multiple subnets and routers
o Border Detection
o Router directionality supporting a hierarchical network
o Multicast forwarding rules to support common service discovery
protocols
While routers described in this document may be manually configured
in an arbitrary topology with or without a dynamic routing protocol,
this document only addresses automatic provisioning and
configuration.
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4. Network Detection
In multirouter home networks, routers have to determine where they
fit in the topology - whether they are at the edge or internal, and
which interface is up (that is, which interface points out of the
network).
4.1. Edge Detection
Customer Edge Routers (CER) will often be required to behave
differently from Internal Routers (IR) in several capacities. Some
examples include: Firewall settings, IPv4 NAT, ULA generation (if
supported), name services, multicast forwarding differences, and
others. This is a functional role, and will not typically be
differentiated by hardware/software (i.e. end users will not purchase
a specific CER model of router distinct from IR models).
There are three methods that a router can use to determine if it is a
CER for its given network:
"/48 Check" Service providers will provide IPv6 WAN addresses
(DHCPv6 IA_NA) and IPv6 prefixes (DHCPv6 IA_PD) from different
pools of addresses. The largest IPv6 prefix that we can expect to
be delegated to a home router is a /48. Combining these two
observations, a home router can compare the WAN address assigned
to it with the prefix delegated to it to determine if it is
attached directly to a service provider network. If the router is
a CER, the WAN address will be from a different /48 than the
prefix. If the router is an IR, the WAN address will be from the
same /48 as the prefix. In this way, the router can determine if
it is recieving an "external" prefix from a service provider or an
"internal" prefix from another home router.
CER_ID A home router can use the CER_ID DHCPv6 option defined in
[I-D.donley-dhc-cer-id-option] to determine if it is a CER or an
IR. ISPs will not set the CER_ID option, but the first CPE router
sets its address in the option and other routers forward the
completed CER_ID to subdelegated routers.
Physical Some routers will have a physical differentiator built into
them by design that will indicate that they are a CER. Examples
include mobile routers, DSL routers, and cable eRouters. In the
case of a mobile router, the presence of an active cellular
connection indicates that the router is at the customer edge.
Likewise, for an eRouter, the presence of an active DOCSIS(R) link
tells the router that it is at the customer edge.
HIPnet routers can (and likely will) use more than one of the above
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techniques in combination to determine the edge. For example, an
internal router will check for the CER_ID option, but will also use
the 48 check in case its upstream router does not support CER_ID.
4.2. Directionless Home Routers
As home networks grow in complexity and scale, it will become more
common for end users to make mistakes with the physical connections
between multiple routers in their home or small office. This is
liklely to produce loops and improper uplink connections. While we
can safely assume that home networks will become more complex over
time, we cannot make the same assumption of the users of home
networks. Therefor, home routers will need to mitigate these
physical topology problems and create a working multi-router home
network dynamically, without any end user intervention.
Legacy home routers with a physically differentiated uplink port are
"directional;" they are pre-set to route from the 'LAN' or Internal
ports to a single, pre-defined uplink port labeled "WAN" or
"Internet". This means that an end-user can make a cabling mistake
which renders the router unusable (e.g. connecting two router's
uplink ports together). On the other hand, in enterprise and service
provider networks, routers are "directionless;" that is to say they
do not have a pre-defined 'uplink' port. While directional routers
have a pre-set routing path, directionless routers are required to
determine routing paths dynamically. Dynamic routing is often
achieved through the implementation of a dynamic routing protocol,
which all routers in a given network or network segment must support
equally. This section introduces an alternative to dynamic routing
protocols (such as OSPF) for creating routing paths on the fly in
directionless home routers.
Note that some routers (e.g. those with a dedicated wireless/DSL/
DOCSIS WAN interface) may continue to operate as directional routers.
The HIPnet mechanism described below is intended for general-purpose
routers.
The HIPnet mechanism uses address acquisition as described in
[I-D.ietf-v6ops-6204bis] and various tiebreakers to determine
directionality (up vs. down) and by so doing, creates a logical
hierarchy (cf. [I-D.chakrabarti-homenet-prefix-alloc]) from any
arbitrary physical topology:
1. After powering on, the HIPnet router sends Router Solicitations
(RS) ([RFC4861]on all interfaces (except Wi-Fi*)
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2. Other routers respond with Router Advertisements (RA)
3. Router adds any interface on which it receives an RA to the
candidate 'up' list
4. The router initiates DHCPv6 PD on all candidate 'up' interfaces.
If no RAs are received, the router generates a /48 ULA prefix.
5. The router evaluates the offers received (in order of preference):
a) Valid GUA preferred (preferred/valid lifetimes >0)
b) Internal prefix preferred over external (for failover - see
Section [6.1])
c) Largest prefix (e.g. /56 preferred to /60)
d) Link type/bandwidth (e.g. Ethernet vs. MoCA)
e) First response (wait 1 s after first response for additional
offers)
f) Lowest numerical prefix
6. The router chooses the winning offer as its Up Interface.
Once directionality is established, the router continues to listen
for RAs on all interfaces but doesn't acquire addresses on Down
Interfaces. If the router initially receives only a ULA address on
its Up Interface and GUA addressing becomes available on one of its
Down Interfaces, it restarts the process. If the router stops
receiving RAs on its Up Interface, it restarts the process.
In all cases, the router's Up Interface becomes its uplink interface;
the router acts as a DHCP client on this interface. The router's
remaining interfaces are Down Interfaces; it acts as a DHCP server on
these interfaces. Also, per [I-D.ietf-v6ops-6204bis], the router
only sends RAs on Down Interfaces.
*Note: By default, Wi-Fi interfaces are considered to point "down."
This requires manual configuration to enable a wireless uplink, which
is preferred to avoid accidental or unwanted linking with nearby
wireless networks.
5. Routing and Addressing
HIPnet routers use DHCPv6 prefix sub-delegation ([RFC3633]) to
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recursively build a hierarchical network
([I-D.chakrabarti-homenet-prefix-alloc]). This approach requires no
new protocols to be supported on any home routers.
Default router settings: Only CER instantiates guest network. Wifi
defaults to 'down' direction, default route uses wired interface.
Firewall considers Wifi an inside port. Wi-Fi bridged with first
wired Down Interface.
5.1. Recursive Prefix Delegation
Once directionality is established, the home router will acquire a
WAN IPv6 address and an IPv6 prefix per [I-D.ietf-v6ops-6204bis]. As
HIPnet routers (other than the CER) do not know their specific
location in the hierarchical network, all HIPnet routers use the same
generic rules for recursive prefix delegation to facilitate route
aggregation, multihoming, and IPv4 support (described below). This
methodology expounds upon that previously described in
[I-D.chakrabarti-homenet-prefix-alloc].
The process can be illustrated in the following way:
1. Per [I-D.ietf-v6ops-6204bis], the HIPnet router assigns a
separate /64 from its delegated prefix(es) for each of its Down
Interfaces in numerical order, starting from the numerically
lowest.
2. If the received prefix is too small to number all Down
Interfaces, the router collapses them into a single interface,
assigns a single /64 to that interface, and logs an error
message.
3. The HIPnet router subdivides the IPv6 prefix received via DHCPv6
([RFC3315]) into sub-prefixes. To support a suggested depth of
three routers, with as large a width as possible, it is
recommended to divide the prefix on 2-, 3-, or 4-bit boundaries.
If the received prefix is not large enough, it is broken into as
many /64 sub-prefixes as possible and logs an error message. By
default, this document suggests that the router divide the
delegated prefix based on the aggregate prefix size and the
HIPnet router's number of physical Down Interfaces. This is to
allow for enough prefixes to support a downstream router on each
down port.
* If the received prefix is smaller than a /56 (e.g. a /60),
+ 8 or more port routers divide on 3-bit boundaries (e.g.
/63).
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+ 7 or fewer port routers divide on 2-bit boundaries (e.g.
/62).
* If the received prefix is a /56 or larger,
+ 8 or more port routers divide on 4-bit boundaries (e.g.
/60).
+ 7 or fewer port routers divide on 3-bit boundaries (e.g.
/59).
4. The HIPnet router delegates remaining prefixes to downstream
routers per [RFC3633]in reverse numerical order, starting with
the numerically highest. This is to minimize the renumbering
impact of enabling an inactive interface.
For example, a four port router with two LANs (two Down Interfaces)
that receives 2001:db8:0:b0::/60 would start by numbering its two
Down Interfaces with 2001:db8:0:b0::/64 and 2001:db8:0:b1::/64
respectively, and then begin prefix delegation by giving 2001:db8:0:
bc::/62 to the first directly attached downstream router.
5.2. Prefix Sub-Delegation Requirements
PSD-1: The HIPnet router MUST support [I-D.ietf-v6ops-6204bis]
address acquisition and LAN addressing.
PSD-2: The HIPnet router MUST support Delegating Router behavior
for the IA-PD Option [RFC3633] on all Down Interfaces.
PSD-3: HIPnet routers MUST NOT act as both a DHCP client and server
on the same link.
PSD-4: The HIPnet router MAY support other methods of dividing the
received prefix.
PSD-5: The HIPnet router MUST delegate prefixes of the same size to
downstream routers.
PSD-6: Per [I-D.ietf-v6ops-6204bis] L-2, the HIPnet router
allocates a /64 to each Down Interface. The HIPnet router
SHOULD allocate these /64 interface-prefixes in numerical
order, starting with the lowest.
PSD-7: If there are insufficient /64s for each Down Interface, the
HIPnet router SHOULD assign the lowest numbered /64 for all
Down Interfaces and log an error message.
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PSD-8: The HIPnet router MAY reserve additional /64 interface-
prefixes for interfaces that will be enabled in the future.
PSD-9: The HIPnet router SHOULD delegate sub-prefixes to downstream
routers starting from the numerically highest sub-prefix and
working down in reverse numerical order.
PSD-10: If there are not enough sub-prefixes remaining to delegate
to all downstream routers, the HIPnet router SHOULD log an
error message.
5.3. Multiple Address Family Support
The recursive prefix delegation method described above can be
extended to support additional address types such as IPv4, additional
GUAs, or ULAs. When the HIPnet router receives its prefix via DHCPv6
([RFC3633]), it computes its 8-bit router ID (bits 56-64) from the
received IA_PD. It then prepends additional prefixes received in one
or more IPv6 Router Advertisements ([RFC4861]) or from the DHCPv4-
assigned ([RFC2131]) IPv4 network address received on the Up
Interface.
As the network is hierarchical, upstream routers know the router ID
for each downstream router, and know the prefix(es) on each LAN
segment. Accordingly, HIPnet routers automatically calculate
downstream routes to all downstream routers.
In networks using this mechanism for IPv4 provisioning, it is
suggested that the CER use addresses in the 10.0.0.0/8 ([RFC1918])
range for downstream interface provisioning.
5.4. Hierarchical Routing
The recursive prefix delegation method described above, coupled with
"up detection", enables very simple hierarchical routing. By this we
mean that each router installs a single default 'up' route and a more
specific 'down' route for each prefix delegated to a downstream IR.
Each of these 'down' routes simply points all packets destined to a
given prefix to the WAN IP address of the router to which that prefix
was delegated. This combination of a default 'up' route and more
specific 'down' routes provides complete reachability within the home
network with no need for any additional message exchange or routing
protocol support.
6. Multiple ISPs
HIPnet routers can support either active/standby multihoming with
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multiple ISPs or limited active/active multihoming without a routing
protocol.
6.1. Backup Connection
Using the procedure described above, multi-router home networks with
multiple ISP connections can easily operate in an active/standby
manner, switching from one Internet connection to the other when the
active connection fails. Lacking a default priority, HIPnet routers
will have to default to a "first online" method of primary CER
selection. In other words, by default, the first CER to come online
becomes the primary CER and the second CER to turn on becomes the
backup. In this text, the primary ISP is the ISP connected to the
primary CER and the backup ISP is simply the ISP atached to the
backup CER.
In an active/standby multi-ISP scenario, a backup CER sets its Up
Interface to point to the primary CER, not the backup ISP. Hence, it
does not acquire or advertise the backup ISP prefix. Instead, it
discovers the internally advertised GUA prefix being distributed by
the currently active primary CER.
In the case of a primary ISP failure, per [I-D.ietf-v6ops-6204bis],
the CER sends an RA advertising the preferred lifetime as 0 for the
ISP-provided prefix, and its router lifetime as 0. The backup CER
becomes active when it sees the primary ISP GUA prefix advertised
with a preferred lifetime of 0. In the case of CER failure, if the
backup CER sees the Primary CER stop sending RAs altogether, the
Backup CER becomes active.
When the backup CER becomes active, it obtains and advertises its own
external GUA. When advertising the GUA delegated by its ISP, the
backup CER sets the valid, prefered, and router lifetimes to a value
greater than 0. Other routers see this and re-determine the network
topology via "up" detection, placing the new CER at the root of the
new hiearchical tree.
Using this approach, manual intervention may be required to
transition back to the primary ISP. This prevents flapping in the
event of intermittent network failures. Another alternative is to
have a user-defined priority, which would facilitate pre-emption.
6.2. Multi-homing
The HIPnet algorithm also allows for limited active/active
multihoming in two cases:
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1. When one ISP router is used as the primary connection and the
second ISP router is used for limited connectivity e.g. for a
home office
2. When both ISP routers are connected to the same LAN segment at
the top of the tree.
In case 1, the subscriber has a primary ISP connection and a
secondary connection used for a limited special purpose. (e.g. for
work VPN, video network, etc.). Devices connected under the
secondary network router access the Internet through the secondary
ISP. All devices still have access to all network resources in the
home. Devices under the secondary connection can use the primary ISP
if the secondary fails, but other devices do not use the secondary
ISP.
+-------+-------+ \
| Service | \
| Provider | | Service
| Router | | Provider
+-------+-------+ | network
+------------+ | /
| ISP 2 | | Customer /
+------------+ | Internet connection /
| |
| +------+--------+ \
| | IPv6 | \
| | Customer Edge | \
| | Router | /
| +---+-------+---+ /
| Network A | | Network B | End-User
| -------+----+- --+--+-------------+--- | network(s)
| | | | \
| +-----+----+ +----+-----+ +-----+----+ \
+-----|Secondary | | Host 1| |Internal | /
| CER | | | | Router | /
+-----+----+ +----------+ +----------+ /
Network C | Network D | |
---+-------------+----+- --+--+-------------+--- |
| | | | \
+----+-----+ +-----+----+ +----+-----+ +-----+----+ \
| Host 2| | Host 3 | | Host 4| | Host 5 | /
| | | | | | | | /
+----------+ +-----+----+ +----------+ +----------+ /
Figure 2: An Example of a multihomed End-User Network
As described above, the primary CER performs prefix sub-delegation to
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create the hierarchical tree network. The secondary edge router then
obtains a second prefix from ISP2 and advertises the ISP2 prefix as
part of its RA. The Secondary CER thus includes sub-prefixes from
both ISPs in all IA_PD messages to downstream routers with the same
"router id.". In a change from the single-homing (or backup router)
case, the secondary CER points its default route to ISP2, and adds an
internal /48 route to its upstream internal router (e.g. R1).
Devices below the the secondary CER (e.g. Host 2, Host 3) use ISP2,
but have full access to all internal devices using the ISP1 prefix
(and/or ULAs). If the ISP2 link fails, the secondary CER points its
default route 'up' and traffic flows to ISP1. Devices not below the
secondary CER (e.g. Hosts 1, 4, 5) use ISP1, but have full access to
all internal devices using the ISP1 prefix (or ULAs).
In case 2, the secondary CER is installed on the same LAN segment as
the primary CER. As above, it acquires a prefix from both the CER
and secondary ISP. Since it is on the same LAN segment as the CER,
the secondary CER does not delegate prefixes to that interface via
DHCP. However, it does generate an RA for the ISP2 prefix on the
LAN.
As described above, downstream routers receiving the secondary CER RA
acquire an address using SLAAC and generate a prefix for sub-
delegation by prepending the secondary CER prefix with the router ID
generated during the receipt of the prefix from the CER. Such
routers then generate their own RAs on downstream interfaces and
include the secondary prefix as an IA_PD option in future prefix
delegations.
6.2.1. Multihoming Requirements
MH-1: HIPnet routers configured for active multi-ISP support MUST
support DHCP address/prefix acquisition (per
[I-D.ietf-v6ops-6204bis] on two interfaces (their WAN and
upstream LAN interfaces).
MH-2: HIPnet routers configured for active multi-ISP support MAY
route packets based on the source IP address of incoming
packets using [RFC6724] logic. This allows traffic sourced
from the first ISP prefix to be directed to the first ISP, and
traffic sourced from the second ISP prefix to be directed to
the second ISP.
MH-3: HIPnet routers configured for active multi-ISP support MUST
advertise RAs for prefixes on all interfaces except the one
from which the prefix was acquired or one directly attached to
a Service Provider network.
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7. Mulicast Support
7.1. Service Discovery
There are several common service discovery protocols such as mDNS
[I-D.cheshire-dnsext-multicastdns]/DNS-SD
[I-D.cheshire-dnsext-dns-sd] and SSDP [SSDP]. In a multirouter
network, service discovery needs to work across the entire home
network (e.g. site-scoped rather than link-scoped). This requires
that HIPnet routers forward relevant multicast traffic appropriately,
to enable service discovery across the home network.
7.2. Multicast Proxy Support
In addition to multicast support for service discovery, it is
recommended that HIPnet routers support external multicast traffic.
7.3. Multicast Requirements
MULTI-1: A HIPnet router MUST discard IP multicast packets that fail
a Reverse Path Forwarding Check (RPFC).
MULTI-2: A HIPnet router that determines itself to be at the edge of
a home network (e.g. via CER_ID option, /48 verification,
or other mechanism) MUST NOT forward IPv4 administratively
scoped (239.0.0.0/8) packets onto the WAN interface.
MULTI-3: HIPnet Routers MUST forward IPv4 Local Scope multicast
packets (239.255.0.0/16) to all LAN interfaces except the
one from which they were received.
MULTI-4: A HIPnet router that determines itself to be at the edge of
a home network (e.g. via CER_ID option, /48 verification,
or other mechanism) MUST NOT forward site-scope (FF05::)
IPv6 multicast packets onto the WAN interface.
MULTI-5: HIPnet routers MUST forward site-scoped (FF05::/16) IPv6
multicast packets to all LAN interfaces except the one from
which they were received.
MULTI-6: A home router MAY discard IP multicast packets sent between
Down Interfaces (different VLANs).
MULTI-7: HIPnet routers SHOULD support an IGMP/MLD proxy, as
described in [RFC4605].
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8. Firewall Support
In a home network, routers need to be equipped with stateful firewall
capabilities. Home routers will need to provide "on by default"
security where incoming traffic is limited to return traffic
resulting from outgoing packets. They also need to allow users to
create inbound 'pinholes' for specific purposes, such as online
gaming, manually similar to those described in Simple Security
([RFC6092]). "Advanced Security" [I-D.vyncke-advanced-ipv6-security]
features optionally could be added to provide intrusion detection
(IDS/IPS) support.
Local Network Protection for IPv6 [RFC4864] recommends firewall
functions that replace NAT security and calls for simple security.
Simple Security [RFC6092] defines firewall filtering rules for IPv6
traffic. Advanced Security [I-D.vyncke-advanced-ipv6-security]
supports the concept of end-to-end IPv6 reachability and uses
adaptive filtering based on Intrusion Prevention System (IPS)
functions.
It is recommended that the CER enable a stateful [RFC6092] firewall
by default. IRs have three options described below:
IR Firewall Option 1 - Filtering Disabled: Once a home router
determines that it is not the CER, it disables its firewall and
allows all traffic to pass. The advantages of this approach are that
is is simple and easy to troubleshoot and it facilitates whole-home
service discovery and media sharing. The disadvantages are that it
does not protect home devices from each other (e.g. infected machines
could affect entire home network).
IR Firewall Option 2 - Simple Security + PCP: Home routers have a
[RFC6092] firewall on by default, regardless of CER/IR status but IRs
allow "pin-holing" using PCP [I-D.ietf-pcp-base]. CERs can restrict
opening PCP pinholes on the up interface. The advantages of this
approach are that it protects the home network from internal threats
in other LAN segments and it mirrors legacy IPv4 router behavior.
The disadvantages to this approach are that it is less predictable;
it relies on application "pin-holing", a "default deny" rule that may
interfere with service discovery and/or content sharing, and requires
PCP clients (e.g. on PCs and CPE devices).
IR Firewall Option 3 - Advanced Security: Once a home router
determines that it is not the CER, it disables its [RFC6092] firewall
but activates an [I-D.vyncke-advanced-ipv6-security] firewall (IPS).
The advantages to this approach are that it protects the home network
from internal threats in other segments and is more predictable than
Option 2, since internal traffic is allowed by default. The
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disadvantages are that adaptive filtering is more complex than static
filtering and typically requires a "fingerprint" subscription to work
well.
It is recommended that dual-stack routers configure IPv4 support to
mirror IPv6, as described above.
While this section describes default router behavior, device
manufacturers are encouraged to make router security options user-
configurable.
8.1. Requirements
SEC-1: The CER MUST enable a stateful [RFC6092] firewall by default.
SEC-2: HIPnet routers MUST only perform IPv4 NAT when serving as the
CER.
SEC-3: By default, HIPnet routers SHOULD configure IPv4 firewalling
rules to mirror IPv6.
SEC-4: HIPnet routers serving as CER SHOULD NOT enable UPnP IGD
([UPnP-IGD]) control by default.
9. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
10. Security Considerations
Security considerations are discussed in the Firewall Support section
above.
11. Acknowledgements
TBD
12. References
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12.1. Normative References
[I-D.ietf-v6ops-6204bis]
Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
Requirements for IPv6 Customer Edge Routers",
draft-ietf-v6ops-6204bis-12 (work in progress),
October 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
[RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick,
"Internet Group Management Protocol (IGMP) / Multicast
Listener Discovery (MLD)-Based Multicast Forwarding
("IGMP/MLD Proxying")", RFC 4605, August 2006.
[RFC4864] Van de Velde, G., Hain, T., Droms, R., Carpenter, B., and
E. Klein, "Local Network Protection for IPv6", RFC 4864,
May 2007.
[RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in
Customer Premises Equipment (CPE) for Providing
Residential IPv6 Internet Service", RFC 6092,
January 2011.
12.2. Informative References
[I-D.chakrabarti-homenet-prefix-alloc]
Nordmark, E., Chakrabarti, S., Krishnan, S., and W.
Haddad, "Simple Approach to Prefix Distribution in Basic
Home Networks", draft-chakrabarti-homenet-prefix-alloc-01
(work in progress), October 2011.
[I-D.cheshire-dnsext-dns-sd]
Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", draft-cheshire-dnsext-dns-sd-11 (work in
progress), December 2011.
[I-D.cheshire-dnsext-multicastdns]
Cheshire, S. and M. Krochmal, "Multicast DNS",
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draft-cheshire-dnsext-multicastdns-15 (work in progress),
December 2011.
[I-D.donley-dhc-cer-id-option]
Donley, C. and C. Grundemann, "Customer Edge Router
Identification Option", draft-donley-dhc-cer-id-option-01
(work in progress), September 2012.
[I-D.ietf-homenet-arch]
Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
"Home Networking Architecture for IPv6",
draft-ietf-homenet-arch-07 (work in progress),
February 2013.
[I-D.ietf-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)",
draft-ietf-pcp-base-29 (work in progress), November 2012.
[I-D.vyncke-advanced-ipv6-security]
Vyncke, E., Yourtchenko, A., and M. Townsley, "Advanced
Security for IPv6 CPE",
draft-vyncke-advanced-ipv6-security-03 (work in progress),
October 2011.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012.
[SSDP] UPnP Forum, "Universal Plug and Play (UPnP) Device
Architecture 1.1", October 2008, <http://www.upnp.org/>.
[UPnP-IGD]
UPnP Forum, "Universal Plug and Play (UPnP) Internet
Gateway Device (IGD)", November 2001,
<http://www.upnp.org/>.
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Authors' Addresses
Chris Grundemann
CableLabs
858 Coal Creek Circle
Louisville, CO 80027
USA
Phone: +1-303-351-1539
Email: c.grundemann@cablelabs.com
Chris Donley
CableLabs
858 Coal Creek Circle
Louisville, CO 80027
USA
Email: c.donley@cablelabs.com
John Jason Brzozowski
Comcast Cable Communications
1306 Goshen Parkway
Chester, PA 19380
USA
Email: john_brzozowski@cable.comcast.com
Lee Howard
Time Warner Cable
13241 Woodland Park Rd
Herndon, VA 20171
USA
Email: william.howard@twcable.com
Victor Kuarsingh
Rogers Communications
8200 Dixie Road
Brampton, ON L6T 0C1
Canada
Email: victor.kuarsingh@rci.rogers.com
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