Basic Requirements for IPv6
Customer Edge RoutersConsulintel, S.L.Molino de la Navata, 75La Navata - GalapagarMadrid28420Spainjordi.palet@consulintel.eshttp://www.consulintel.es/IPv6 Operations (v6ops)IPv6 CE requirementsThis document specifies requirements for an IPv6 Customer Edge (CE)
router. Specifically, the current version of this document focuses on
the basic provisioning of an IPv6 CE router and the provisioning of IPv6
hosts attached to it. The document also covers several transition technologies,
as required in a world where IPv4 addresses are no longer available, so hosts
in the customer LANs with IPv4-only or IPv6-only applications or devices, requiring
to communicate with IPv4-only services at the Internet, are able to do so.
The document obsoletes RFC 7084.This document defines basic IPv6 features for a residential or small-
office router, referred to as an "IPv6 CE router", in order to
establish an industry baseline for features to be implemented on such
a router.
These routers typically also support IPv4, at least in the LAN side.
This document specifies how an IPv6 CE router automatically
provisions its WAN interface, acquires address space for provisioning of
its LAN interfaces, and fetches other configuration information from the
service provider network. Automatic provisioning of more complex
topology than a single router with multiple LAN interfaces is out of
scope for this document. In some cases, manual provisioning may be acceptable,
when intended for a small number of customers.See for a discussion of options
available for deploying IPv6 in service provider access networks.This document also covers the IP transition technologies required in a world
where IPv4 addresses are no longer available, so the service providers need to
provision IPv6-only WAN access, while at the same time ensuring that IPv4-only or
IPv6-only devices or applications in the customer LANs can still reach IPv4-only
devices or applications in Internet, which still don't have IPv6 support.
Take careful note: Unlike other IETF documents, the key words "MUST",
"MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document are not used as
described in RFC 2119. This document uses
these keywords not
strictly for the purpose of interoperability, but rather for the
purpose of establishing industry-common baseline functionality. As
such, the document points to several other specifications (preferable
in RFC or stable form) to provide additional guidance to implementers
regarding any protocol implementation required to produce a
successful CE router that interoperates successfully with a
particular subset of currently deploying and planned common IPv6
access networks.
one or more links attached to the
IPv6 CE router that connect IPv6 hosts.a node intended for home or
small-office use that forwards IPv6 packets not explicitly addressed
to itself. The IPv6 CE router connects the end-user network to a
service provider network. In other documents, the CE is named as CPE
(Customer Premises Equipment or Customer Provided Equipment). In the
context of this document, both terminologies are synonymous.any device implementing an IPv6 stack
receiving IPv6 connectivity through the IPv6 CE router.an IPv6 CE router's attachment to a link
in the end-user network. Examples are Ethernet (simple or bridged),
802.11 wireless, or other LAN technologies. An IPv6 CE router may
have one or more network-layer LAN interfaces.an entity that provides access to the
Internet. In this document, a service provider specifically offers
Internet access using IPv6, and it may also offer IPv4 Internet access.
The service provider can provide such access over a variety of
different transport methods such as FTTH, DSL, cable, wireless, LTE, and
others.an IPv6 CE router's attachment to a link
used to provide connectivity to the service provider network;
example link technologies include Ethernet (simple or bridged), PPP
links, Frame Relay, or ATM networks, as well as Internet-layer (or
higher-layer) "tunnels", such as tunnels over IPv4 or IPv6
itself.The IPv6 CE router described in this document is expected to be used typically,
in any of the following scenarios:Residential/household users. Common usage is any kind of Internet access
(web, email, streaming, online gaming, etc.).Residential with Small Office/Home Office (SOHO). Same usage as for the
first scenario.Small Office/Home Office (SOHO). Same usage as for the first scenario.Small and Medium Enterprise (SME). Same usage as for the first scenario.Residential/household with advanced requirements. Same basic usage
as for the first scenario, however there may be requirements for exporting
services to the WAN (IP cameras, web, DNS, email, VPN, etc.).Small and Medium Enterprise (SME) with advanced requirements. Same
basic usage as for the first scenario, however there may be requirements for
exporting services to the WAN (IP cameras, web, DNS, email, VPN, etc.).The above list is not intended to be comprehensive of all the possible usage
scenarios, just the main ones. In fact, combinations of the above usages are also
possible, for example a residential with SOHO and advanced requirements.The mechanisms for exporting IPv6 services are commonly "naturally" available
in any IPv6 router, as when using GUA, unless they are blocked by firewall rules,
which may require some manual configuration by means of a GUI and/or CLI.However, in the case of IPv4, because the usage of private addresses and NAT, it
typically requires some degree of manual configuration such as setting up a DMZ,
virtual servers, or port/protocol forwarding. In general, CE routers already
provide GUI and/or CLI to manually configure them, or the possibility to setup the
CE in bridge mode, so another CE behind it, takes care of that. It is out of the
scope of this document the definition of any requirements for that.The main difference for an IPv6 CE router to support one or several of the above
indicated scenarios, is related to the packet processing capabilities, performance,
even other details such as the number of WAN/LAN interfaces, their maximum speed,
memory for keeping tables or tracking connections, etc. So, it is out of the scope
of this document to classify them.For example, an SME may have just 10 employees (micro-SME), which commonly will
be considered same as a SOHO, but a small SME can have up to 50 employees, or 250
for a medium one. Depending on the IPv6 CE router capabilities or even how it is
being configured (for instance, using SLAAC or DHCPv6), it may support even a
higher number of employees if the traffic in the LANs is low, or switched by
another device(s), or the WAN bandwidth requirements are low, etc. The actual
bandwidth capabilities of access with technologies such as FTTH, cable and even
LTE, allows the support of such usages, and indeed, is a very common situation that
access networks and the CE provided by the service provider are the same for SMEs
and residential users.There is also no difference in terms of who actually provides the IPv6 CE
router. In most of the cases is the service provider, and in fact is responsible,
typically, of provisioning/managing at least the WAN side. However, commonly the
user has access to configure the LAN interfaces, firewall, DMZ, and many other
aspects. In fact, in many cases, the user must supply, or at least can replace the
IPv6 CE router, which makes even more relevant that all the IPv6 CE routers,
support the same requirements defined in this document.The IPv6 CE router described in this document is not intended for usage in other
scenarios such as bigger Enterprises, Data Centers, Content Providers, etc. So,
even if the documented requirements meet their needs, may have additional
requirements, which are out of the scope of this document.An end-user network will likely support both IPv4 and IPv6. It is
not expected that an end user will change their existing network
topology with the introduction of IPv6. There are some differences in
how IPv6 works and is provisioned; these differences have implications
for the network architecture. A typical IPv4 end-user network consists
of a "plug and play" router with NAT functionality and a single link
behind it, connected to the service provider network.A typical IPv4 NAT deployment by default blocks all incoming
connections. Opening of ports is typically allowed using a Universal
Plug and Play Internet Gateway Device (UPnP IGD) or some other firewall control protocol.Another consequence of using private address space in the end-user
network is that it provides stable addressing; that is, it never changes
even when you change service providers, and the addresses are always
there even when the WAN interface is down or the customer edge router
has not yet been provisioned.Many existing routers support dynamic routing (which learns routes
from other routers), and advanced end-users can build arbitrary, complex
networks using manual configuration of address prefixes combined with a
dynamic routing protocol.The end-user network architecture for IPv6 should provide
equivalent or better capabilities and functionality than the current
IPv4 architecture.The end-user network is a stub network. Figure 1 illustrates the
model topology for the end-user network.This architecture describes the:Basic capabilities of an IPv6 CE routerProvisioning of the WAN interface connecting to the service
providerProvisioning of the LAN interfacesFor IPv6 multicast traffic, the IPv6 CE router may act as a
Multicast Listener Discovery (MLD) proxy and may support a dynamic multicast routing
protocol.The IPv6 CE router may be manually configured in an arbitrary
topology with a dynamic routing protocol. Automatic provisioning and
configuration is described for a single IPv6 CE router only.Link-local IPv6 addresses are used by hosts communicating on a single
link. Unique Local IPv6 Unicast Addresses (ULAs) are used
by hosts communicating within the end-user network across multiple
links, but without requiring the application to use a globally
routable address. The IPv6 CE router defaults to acting as the
demarcation point between two networks by providing a ULA boundary, a
multicast zone boundary, and ingress and egress traffic filters.At the time of this writing, several host implementations do not
handle the case where they have an IPv6 address configured and no
IPv6 connectivity, either because the address itself has a limited
topological reachability (e.g., ULA) or because the IPv6 CE router
is not connected to the IPv6 network on its WAN interface. To
support host implementations that do not handle multihoming in a
multi-prefix environment , the IPv6 CE router
should not, as detailed in the requirements below, advertise itself as a
default router on the LAN interface(s) when it does not have IPv6
connectivity on the WAN interface or when it is not provisioned with
IPv6 addresses. For local IPv6 communication, the mechanisms
specified in are used.ULA addressing is useful where the IPv6 CE router has multiple
LAN interfaces with hosts that need to communicate with each other.
If the IPv6 CE router has only a single LAN interface (IPv6 link),
then link-local addressing can be used instead.Coexistence with IPv4 requires any IPv6 CE router(s) on the LAN
to conform to these recommendations, especially requirements ULA-5
and L-4 below.The IPv6 CE router is responsible for implementing IPv6 routing;
that is, the IPv6 CE router must look up the IPv6 destination address
in its routing table to decide to which interface it should send the
packet.In this role, the IPv6 CE router is responsible for ensuring that
traffic using its ULA addressing does not go out the WAN interface
and does not originate from the WAN interface.An IPv6 CE router is an IPv6 node according to the IPv6 Node Requirements specification.The IPv6 CE router MUST implement ICMPv6 according to . In particular, point-to-point links MUST
be handled as described in Section 3.1 of .The IPv6 CE router MUST NOT forward any IPv6 traffic between
its LAN interface(s) and its WAN interface until the router has
successfully completed the IPv6 address and the delegated prefix
acquisition process.By default, an IPv6 CE router that has no default router(s) on
its WAN interface MUST NOT advertise itself as an IPv6 default
router on its LAN interfaces. That is, the "Router Lifetime" field
is set to zero in all Router Advertisement messages it originates
.By default, if the IPv6 CE router is an advertising router and
loses its IPv6 default router(s) and/or detects loss of
connectivity on the WAN interface, it MUST explicitly invalidate
itself as an IPv6 default router on each of its advertising
interfaces by immediately transmitting one or more Router
Advertisement messages with the "Router Lifetime" field set to
zero .The IPv6 CE router will need to support connectivity to one or more
access network architectures. This document describes an IPv6 CE
router that is not specific to any particular architecture or service
provider and that supports all commonly used architectures.IPv6 Neighbor Discovery and DHCPv6 protocols operate over any type
of IPv6-supported link layer, and there is no need for a
link-layer-specific configuration protocol for IPv6 network-layer
configuration options as in, e.g., PPP IP Control Protocol (IPCP) for
IPv4. This section makes the assumption that the same mechanism will
work for any link layer, be it Ethernet, the Data Over Cable Service
Interface Specification (DOCSIS), PPP, or others.WAN-side requirements: When the router is attached to the WAN interface link, it MUST
act as an IPv6 host for the purposes of stateless or stateful interface address assignment.The IPv6 CE router MUST generate a link-local address and
finish Duplicate Address Detection according to prior to sending any Router Solicitations
on the interface. The source address used in the subsequent Router
Solicitation MUST be the link-local address on the WAN
interface.Absent other routing information, the IPv6 CE router MUST use
Router Discovery as specified in to
discover a default router(s) and install a default route(s) in its
routing table with the discovered router's address as the next
hop.The router MUST act as a requesting router for the purposes of
DHCPv6 prefix delegation ().The IPv6 CE router MUST use a persistent DHCP Unique Identifier
(DUID) for DHCPv6 messages. The DUID MUST NOT change between
network-interface resets or IPv6 CE router reboots.The WAN interface of the CE router SHOULD support a Port Control
Protocol (PCP) client as specified in for use
by applications on the CE router. The PCP client SHOULD follow the
procedure specified in Section 8.1 of to discover its PCP server.
This document takes no position on whether such functionality is
enabled by default or mechanisms by which users would configure
the functionality. Handling PCP requests from PCP clients in the
LAN side of the CE router is out of scope.Link-layer requirements: If the WAN interface supports Ethernet encapsulation, then the
IPv6 CE router MUST support IPv6 over Ethernet .If the WAN interface supports PPP encapsulation, the IPv6 CE
router MUST support IPv6 over PPP .If the WAN interface supports PPP encapsulation, in a
dual-stack environment with IPCP and IPV6CP running over one PPP
logical channel, the Network Control Protocols (NCPs) MUST be
treated as independent of each other and start and terminate
independently.Address assignment requirements:The IPv6 CE router MUST support Stateless Address
Autoconfiguration (SLAAC) .The IPv6 CE router MUST follow the recommendations in Section 4
of , and in particular the handling
of the L flag in the Router Advertisement Prefix Information
option.The IPv6 CE router MUST support DHCPv6
client behavior.The IPv6 CE router MUST be able to support the following DHCPv6
options: Identity Association for Non-temporary Address (IA_NA),
Reconfigure Accept ,
and DNS_SERVERS . The IPv6 CE router
SHOULD be able to support the DNS Search List (DNSSL) option as
specified in .The IPv6 CE router SHOULD implement the Network Time
Protocol (NTP) as specified in to provide
a time reference common to the service provider for other protocols, such
as DHCPv6, to use. If the CE router implements NTP, it requests the NTP
Server DHCPv6 option and uses the received
list of servers as primary time reference, unless explicitly configured
otherwise. LAN side support of NTP is out of scope for this document.If the IPv6 CE router receives a Router Advertisement message
(described in ) with the M flag set
to 1, the IPv6 CE router MUST do DHCPv6 address assignment
(request an IA_NA option).If the IPv6 CE router does not acquire a global IPv6 address(es)
from either SLAAC or DHCPv6, then it MUST create a global IPv6
address(es) from its delegated prefix(es) and configure those on
one of its internal virtual network interfaces, unless configured
to require a global IPv6 address on the WAN interface.The CE router MUST support the SOL_MAX_RT
option
and request the SOL_MAX_RT option in an Option Request Option (ORO).As a router, the IPv6 CE router MUST follow the weak host (Weak
End System) model . When originating packets
from an interface, it will use a source address from another one
of its interfaces if the outgoing interface does not have an
address of suitable scope.The IPv6 CE router SHOULD implement the Information Refresh
Time option and associated client behavior as specified in .Prefix delegation requirements: The IPv6 CE router MUST support DHCPv6 prefix delegation
requesting router behavior as specified in (Identity Association for Prefix Delegation (IA_PD) option).The IPv6 CE router MAY indicate as a hint to the delegating
router the size of the prefix it requires. If so, it MUST ask for
a prefix large enough to assign one /64 for each of its
interfaces, rounded up to the nearest nibble, and SHOULD be
configurable to ask for more.The IPv6 CE router MUST be prepared to accept a delegated
prefix size different from what is given in the hint. If the
delegated prefix is too small to address all of its interfaces,
the IPv6 CE router SHOULD log a system management error. covers the recommendations for service
providers for prefix allocation sizes.By default, the IPv6 CE router MUST initiate DHCPv6 prefix
delegation when either the M or O flags are set to 1 in a received
Router Advertisement (RA) message. Behavior of the CE router to
use DHCPv6 prefix delegation when the CE router has not received
any RA or received an RA with the M and the O bits set to zero is
out of scope for this document.Any packet received by the CE router with a destination
address in the prefix(es) delegated to the CE router but
not in the set of prefixes assigned by the CE router to the
LAN must be dropped. In other words, the next hop for the
prefix(es) delegated to the CE router should be the null
destination. This is necessary to prevent forwarding loops
when some addresses covered by the aggregate are not
reachable .The IPv6 CE router SHOULD send an ICMPv6 Destination
Unreachable message in accordance with
Section 3.1 of back to the source of the packet, if the
packet is to be dropped due to this rule.If the IPv6 CE router requests both an IA_NA and an IA_PD
option in DHCPv6, it MUST accept an IA_PD option in DHCPv6
Advertise/Reply messages, even if the message does not contain any
addresses, unless configured to only obtain its WAN IPv6 address
via DHCPv6; see .By default, an IPv6 CE router MUST NOT initiate any dynamic
routing protocol on its WAN interface.The IPv6 CE router SHOULD support the Prefix Exclude option.The IPv6 CE router distributes configuration information obtained
during WAN interface provisioning to IPv6 hosts and assists IPv6 hosts
in obtaining IPv6 addresses. It also supports connectivity of these
devices in the absence of any working WAN interface.An IPv6 CE router is expected to support an IPv6 end-user network
and IPv6 hosts that exhibit the following characteristics:Link-local addresses may be insufficient for allowing IPv6
applications to communicate with each other in the end-user
network. The IPv6 CE router will need to enable this communication
by providing globally scoped unicast addresses or ULAs , whether or not WAN connectivity
exists.IPv6 hosts should be capable of using SLAAC and may be capable
of using DHCPv6 for acquiring their addresses.IPv6 hosts may use DHCPv6 for other configuration information,
such as the DNS_SERVERS option for acquiring DNS information.Unless otherwise specified, the following requirements apply to the
IPv6 CE router's LAN interfaces only.ULA requirements:The IPv6 CE router SHOULD be capable of generating a ULA prefix
.An IPv6 CE router with a ULA prefix MUST maintain this prefix
consistently across reboots.The value of the ULA prefix SHOULD be configurable.By default, the IPv6 CE router MUST act as a site border router
according to Section 4.3 of and
filter packets with local IPv6 source or destination addresses
accordingly.An IPv6 CE router MUST NOT advertise itself as a default router
with a Router Lifetime greater than zero whenever all of its
configured and delegated prefixes are ULA prefixes.LAN requirements:The IPv6 CE router MUST support router behavior according to
Neighbor Discovery for IPv6 .The IPv6 CE router MUST assign a separate /64 from its
delegated prefix(es) (and ULA prefix if configured to provide ULA
addressing) for each of its LAN interfaces.An IPv6 CE router MUST advertise itself as a router for the
delegated prefix(es) (and ULA prefix if configured to provide ULA
addressing) using the "Route Information Option" specified in
Section 2.3 of . This advertisement
is independent of having or not having IPv6 connectivity on the
WAN interface.An IPv6 CE router MUST NOT advertise itself as a default router
with a Router Lifetime greater than
zero if it has no prefixes configured or delegated to it.The IPv6 CE router MUST make each LAN interface an advertising
interface according to .In Router Advertisement messages (), the Prefix Information
option's A and L flags MUST be set to 1 by default.The A and L flags' () settings SHOULD be user configurable.The IPv6 CE router MUST support a DHCPv6 server capable of IPv6
address assignment according to OR
a stateless DHCPv6 server according to on its LAN interfaces.Unless the IPv6 CE router is configured to support the DHCPv6
IA_NA option, it SHOULD set the M flag to zero and the O flag to 1 in
its Router Advertisement messages .The IPv6 CE router MUST support providing DNS information in
the DHCPv6 DNS_SERVERS and DOMAIN_LIST options .The IPv6 CE router MUST support providing DNS information in
the Router Advertisement Recursive DNS Server (RDNSS)
and DNS Search List options. Both options are specified
in .The IPv6 CE router SHOULD make available a subset of DHCPv6
options (as listed in Section 5.3 of ) received from the DHCPv6 client on its
WAN interface to its LAN-side DHCPv6 server.If the delegated prefix changes, i.e., the current prefix is
replaced with a new prefix without any overlapping time period,
then the IPv6 CE router MUST immediately advertise the old prefix
with a Preferred Lifetime of zero and a Valid Lifetime of either
a) zero or b) the lower of the current Valid Lifetime and two
hours (which must be decremented in real time) in a Router
Advertisement message as described in Section 5.5.3, (e) of .The IPv6 CE router MUST send an ICMPv6 Destination Unreachable
message, code 5 (Source address failed ingress/egress policy) for
packets forwarded to it that use an address from a prefix that has
been invalidated.The IPv6 CE router SHOULD provide HNCP (Home Networking Control Protocol)
services, as specified in .464XLAT is a technique
to provide IPv4 access service to IPv6-only edge networks
without encapsulation.The CE router SHOULD support CLAT functionality. If 464XLAT is
supported, it MUST be implemented according to .
The following CE Requirements also apply:464XLAT requirements: The IPv6 CE router MUST perform IPv4 Network Address
Translation (NAT) on IPv4 traffic translated using the CLAT, unless
a dedicated /64 prefix has been acquired using DHCPv6-PD
.The CE router MUST implement in order
to discover the PLAT-side translation IPv4 and IPv6 prefix(es)/suffix(es).
In environments with PCP support, the CE SHOULD follow
to learn the PLAT-side translation
IPv4 and IPv6 prefix(es)/suffix(es) used by an upstream PCP-controlled
NAT64 device. Alternatively SHOULD support
draft-li-intarea-nat64-prefix-dhcp-option.The CE router MUST implement a DNS proxy as described in
.The CE router MUST support the DHCPv4-over-DHCPv6 (DHCP 4o6) transport
described in .6in4 specifies a tunneling mechanism
to allow end-users to manually configure IPv6 support
via a service provider's IPv4 network infrastructure.The CE router MAY support 6in4 functionality. If 6rd is implemented,
6in4 MUST be supported as well. If 6in4 is supported, it MUST be implemented
according to . The following CE Requirements
also apply:6in4 requirements: The IPv6 CE router SHOULD support 6in4 automated configuration by means
of the 6rd DHCPv4 Option 212. If the CE router has obtained an IPv4
network address through some other means such as PPP, it SHOULD
use the DHCPINFORM request message to
request the 6rd DHCPv4 Option. The IPv6 CE router MAY use other mechanisms
to configure 6in4 parameters. Such mechanisms are outside the scope of
this document.If the IPv6 CE router is capable of automated configuration
of IPv4 through IPCP (i.e., over a PPP connection), it MUST
support user-entered configuration of 6in4.If the CE router supports configuration mechanisms other than the 6rd
DHCPv4 Option 212 (user-entered, TR-069 , etc.),
the CE router MUST support 6in4 in "hub and spoke" mode. 6in4 in "hub and
spoke" requires all IPv6 traffic to go to the 6rd Border Relay.
In effect, this requirement removes the "direct connect to 6rd"
route defined in Section 7.1.1 of .A CE router MUST allow 6in4 and native IPv6 WAN interfaces
to be active alone as well as simultaneously in order to support
coexistence of the two technologies during an incremental transition
period such as a transition from 6in4 to native IPv6.
Each packet sent on a 6in4 or native WAN interface MUST be directed
such that its source IP address is derived from the delegated prefix
associated with the particular interface from which the packet
is being sent (Section 4.3 of ).The CE router MUST allow different as well as identical delegated prefixes
to be configured via each (6in4 or native) WAN interface.
In the event that forwarding rules produce a tie between 6in4 and
native IPv6, by default, the IPv6 CE router MUST prefer native IPv6.
6rd specifies an automatic
tunneling mechanism tailored to advance deployment of IPv6 to end users
via a service provider's IPv4 network infrastructure. Key
aspects include automatic IPv6 prefix delegation to sites, stateless
operation, simple provisioning, and service that is equivalent to
native IPv6 at the sites that are served by the mechanism. It is
expected that such traffic is forwarded over the CE router's native
IPv4 WAN interface and not encapsulated in another tunnel.The CE router MAY support 6rd functionality. If 6rd is
supported, it MUST be implemented according to . The following CE Requirements also
apply:6rd requirements: The IPv6 CE router MUST support 6rd configuration via the 6rd
DHCPv4 Option 212. If the CE router has obtained an IPv4
network address through some other means such as PPP, it SHOULD
use the DHCPINFORM request message to
request the 6rd DHCPv4 Option. The IPv6 CE router MAY use other mechanisms
to configure 6rd parameters. Such mechanisms are outside the scope of
this document.If the IPv6 CE router is capable of automated configuration
of IPv4 through IPCP (i.e., over a PPP connection), it MUST
support user-entered configuration of 6rd.If the CE router supports configuration mechanisms other than the 6rd
DHCPv4 Option 212 (user-entered, TR-069 , etc.),
the CE router MUST support 6rd in "hub and spoke" mode. 6rd in "hub and
spoke" requires all IPv6 traffic to go to the 6rd Border Relay.
In effect, this requirement removes the "direct connect to 6rd"
route defined in Section 7.1.1 of .A CE router MUST allow 6rd and native IPv6 WAN interfaces
to be active alone as well as simultaneously in order to support
coexistence of the two technologies during an incremental transition
period such as a transition from 6rd to native IPv6.
Each packet sent on a 6rd or native WAN interface MUST be directed
such that its source IP address is derived from the delegated prefix
associated with the particular interface from which the packet
is being sent (Section 4.3 of ).The CE router MUST allow different as well as identical delegated prefixes
to be configured via each (6rd or native) WAN interface.
In the event that forwarding rules produce a tie between 6rd and
native IPv6, by default, the IPv6 CE router MUST prefer native IPv6.
Dual-Stack Lite enables both
continued support for IPv4 services and incentives for the
deployment of IPv6. It also de&nbhy;couples IPv6 deployment in the
service provider network from the rest of the Internet, making
incremental deployment easier. Dual-Stack Lite enables a broadband
service provider to share IPv4 addresses among customers by
combining two well-known technologies: IP in IP (IPv4-in-IPv6) and
Network Address Translation (NAT). It is expected that DS-Lite
traffic is forwarded over the CE router's native IPv6 WAN interface,
and not encapsulated in another tunnel.The IPv6 CE router SHOULD implement DS-Lite functionality. If
DS&nbhy;Lite is supported, it MUST be implemented according to . This document takes no position on
simultaneous operation of Dual-Stack Lite and native IPv4. The
following CE router requirements also apply:DS-Lite requirements: The CE router MUST support configuration of DS-Lite via the
DS-Lite DHCPv6 option .
The IPv6 CE router MAY use other mechanisms to configure
DS-Lite parameters. Such mechanisms are outside the scope
of this document.The CE router MUST support the DHCPv6 S46 priority
option described in .The CE router MUST support the DHCPv4-over-DHCPv6 (DHCP 4o6) transport
described in .The IPv6 CE router MUST NOT perform IPv4 Network Address
Translation (NAT) on IPv4 traffic encapsulated using
DS-Lite.If the IPv6 CE router is configured with an IPv4 address on
its WAN interface, then the IPv6 CE router SHOULD disable the
DS-Lite Basic Bridging BroadBand (B4) element.Lw4o6 specifies an extension to DS-Lite,
which moves the NAPT function from the DS-Lite tunnel concentrator to the
tunnel client located in the IPv6 CE router, removing the requirement for a CGN
function in the tunnel concentrator and reducing the amount of centralized
state.The IPv6 CE router SHOULD implement lw4o6 functionality. If DS-Lite is
implemented, lw4o6 MUST be supported as well. If lw4o6 is supported, it MUST
be implemented according to . This document takes
no position on simultaneous operation of lw4o6 and native IPv4. The following
CE router Requirements also apply:Lw4o6 requirements: The CE router MUST support configuration of lw4o6 via the
lw4o6 DHCPv6 options .
The IPv6 CE router MAY use other mechanisms to configure
lw4o6 parameters. Such mechanisms are outside the scope
of this document.The CE router MUST support the DHCPv6 S46 priority
option described in .The CE router MUST support the DHCPv4-over-DHCPv6 (DHCP 4o6) transport
described in .The IPv6 CE router MUST perform IPv4 Network Address
Translation (NAT) on IPv4 traffic encapsulated using lw4o6.If the IPv6 CE router is configured with an IPv4 address on
its WAN interface, then the IPv6 CE router SHOULD disable the
Lightweight Basic Bridging BroadBand (B4) element.MAP-E is a mechanism for transporting IPv4
packets across an IPv6 network using IP encapsulation, including a generic
mechanism for mapping between IPv6 addresses and IPv4 addresses as well as
transport-layer ports.The CE router SHOULD support MAP-E functionality. If MAP-E is
supported, it MUST be implemented according to .
The following CE Requirements also apply:MAP-E requirements: The CE router MUST support configuration of MAP-E via the
MAP-E DHCPv6 options .
The IPv6 CE router MAY use other mechanisms to configure
MAP-E parameters. Such mechanisms are outside the scope
of this document.The CE router MUST support the DHCPv6 S46 priority
option described in .The CE router MUST support the DHCPv4-over-DHCPv6 (DHCP 4o6) transport
described in .The IPv6 CE router MUST perform IPv4 Network Address
Translation (NAT) on IPv4 traffic encapsulated using MAP-E.MAP-T is a mechanism similar to MAP-E,
differing from it in that MAP-T uses IPv4-IPv6 translation, rather than
encapsulation, as the form of IPv6 domain transport.The CE router SHOULD support MAP-T functionality. If MAP-T is
supported, it MUST be implemented according to .
The following CE Requirements also apply:MAP-T requirements: The CE router MUST support configuration of MAP-T via the
MAP-E DHCPv6 options .
The IPv6 CE router MAY use other mechanisms to configure
MAP-E parameters. Such mechanisms are outside the scope
of this document.The CE router MUST support the DHCPv6 S46 priority
option described in .The CE router MUST support the DHCPv4-over-DHCPv6 (DHCP 4o6) transport
described in .The IPv6 CE router MUST perform IPv4 Network Address
Translation (NAT) on IPv4 traffic translated using MAP-T.Actual deployments support IPv4 multicast for services such as
IPTV. In the transition phase it is expected that multicast services
will still be provided using IPv4 to the customer LANs.In order to support the delivery of IPv4 multicast services to IPv4
clients over an IPv6 multicast network, the CE router SHOULD support
and .It is considered a best practice to filter obviously malicious
traffic (e.g., spoofed packets, "Martian" addresses, etc.). Thus, the
IPv6 CE router ought to support basic stateless egress and ingress
filters. The CE router is also expected to offer mechanisms to filter
traffic entering the customer network; however, the method by which
vendors implement configurable packet filtering is beyond the scope of
this document.Security requirements:The IPv6 CE router SHOULD support . In particular, the IPv6 CE router SHOULD
support functionality sufficient for implementing the set of
recommendations in , Section 4.
This document takes no position on whether such functionality is
enabled by default or mechanisms by which users would configure
it.The IPv6 CE router SHOULD support ingress filtering in
accordance with BCP 38 . Note that
this requirement was downgraded from a MUST from RFC 6204 due
to the difficulty of implementation in the CE router and the feature's
redundancy with upstream router ingress filtering.If the IPv6 CE router firewall is configured to filter incoming
tunneled data, the firewall SHOULD provide the capability to
filter decapsulated packets from a tunnel.Thanks to Mohamed Boucadair for his review and comments.This document is an update of RFC7084, whose original authors were: Hemant Singh,
Wes Beebee, Chris Donley and Barbara Stark. The rest of the text on this section and
the Contributors section, are the original acknowledgements and Contributors
sections of the earlier version of this document.Thanks to the following people (in alphabetical order) for their
guidance and feedback:Mikael Abrahamsson, Tore Anderson, Merete Asak, Rajiv Asati, Scott
Beuker, Mohamed Boucadair, Rex Bullinger, Brian Carpenter, Tassos
Chatzithomaoglou, Lorenzo Colitti, Remi Denis-Courmont, Gert Doering,
Alain Durand, Katsunori Fukuoka, Brian Haberman, Tony Hain, Thomas Herbst,
Ray Hunter, Joel Jaeggli, Kevin Johns, Erik Kline, Stephen Kramer, Victor Kuarsingh,
Francois-Xavier Le Bail, Arifumi Matsumoto, David Miles, Shin Miyakawa,
Jean-Francois Mule, Michael Newbery, Carlos Pignataro, John Pomeroy,
Antonio Querubin, Daniel Roesen, Hiroki Sato, Teemu Savolainen, Matt
Schmitt, David Thaler, Mark Townsley, Sean Turner, Bernie Volz, Dan Wing,
Timothy Winters, James Woodyatt, Carl Wuyts, and Cor Zwart.This document is based in part on CableLabs' eRouter specification.
The authors wish to acknowledge the additional contributors from the
eRouter team:Ben Bekele, Amol Bhagwat, Ralph Brown, Eduardo Cardona, Margo Dolas,
Toerless Eckert, Doc Evans, Roger Fish, Michelle Kuska, Diego Mazzola,
John McQueen, Harsh Parandekar, Michael Patrick, Saifur Rahman, Lakshmi
Raman, Ryan Ross, Ron da Silva, Madhu Sudan, Dan Torbet, and Greg
White.The following people have participated as co-authors or provided
substantial contributions to this document: Ralph Droms, Kirk Erichsen,
Fred Baker, Jason Weil, Lee Howard, Jean-Francois Tremblay, Yiu Lee,
John Jason Brzozowski, and Heather Kirksey. Thanks to Ole Troan for
editorship in the original RFC 6204 document.One of the apparent main issues for vendors to include new functionalities,
such as support for new transition mechanisms, is the lack of space in the flash
(or equivalent) memory. However, it has been confirmed from existing open source
implementations (OpenWRT/LEDE), that adding the support for the new transitions
mechanisms, requires around 10-12 Kbytes (because most of the code is shared
among several transition mechanisms), which typically means about 0,15% of the
existing code size in popular CEs in the market.It is also clear that the new requirements don't have extra cost in terms of
RAM memory, neither other hardware requirements such as more powerful CPUs.The other issue seems to be the cost of developing the code for those new
functionalities. However at the time of writing this document, it has been
confirmed that there are several open source versions of the required code for
supporting the new transition mechanisms, so the development cost is negligent,
and only integration and testing cost may become a minor issue.The -bis version of this document has some minor text edits here and there.
Significant updates are:New section "Usage Scenarios".Added support of HNCP () in LAN (L-15).Added support of 464XLAT ().Added support of lw4o6 ().Added support of MAP-E () and MAP-T ().As the main scope of this document is the IPv6-only CE (IPv6-only in the WAN link),
the support of 6rd () has been changed to MAY.
6in4 () support has been included as well in case 6rd
is supported, as it doesn't require additional code.New section "IPv4 Multicast Support".CPE WAN Management Protocol Broadband ForumInternetGatewayDevice:2 Device Template Version 1.01