IPv6 Node Requirements Jisc Lumen House, Library Avenue Harwell Oxford, Didcot OX11 0SG United Kingdom tim.chown@jisc.ac.uk Intel Santa Clara, CAUSAjohn.loughney@gmail.comUniversity of New Hampshire, Interoperability Lab (UNH-IOL) DurhamNH United States twinters@iol.unh.edu
Internet
Internet Engineering Task ForceIPv6Internet Protocol Version 6Internet ProtocolIPThis document defines requirements for IPv6 nodes. It is
expected that IPv6 will be deployed in a wide range of devices and
situations. Specifying the requirements for IPv6 nodes allows
IPv6 to function well and interoperate in a large number of
situations and deployments.This document obsoletes RFC 6434, and in turn RFC 4294.This document defines common functionality required by both
IPv6 hosts and routers. Many IPv6 nodes will implement optional
or additional features, but this document collects and summarizes
requirements from other published Standards Track documents in one
place.This document tries to avoid discussion of protocol details
and references RFCs for this purpose. This document is intended
to be an applicability statement and to provide guidance as to which
IPv6 specifications should be implemented in the general case and
which specifications may be of interest to specific deployment
scenarios. This document does not update any individual protocol
document RFCs.Although this document points to different specifications, it
should be noted that in many cases, the granularity of a
particular requirement will be smaller than a single specification,
as many specifications define multiple, independent pieces, some
of which may not be mandatory. In addition, most specifications
define both client and server behavior in the same specification,
while many implementations will be focused on only one of those
roles. This document defines a minimal level of requirement needed
for a device to provide useful internet service and considers a
broad range of device types and deployment scenarios. Because of
the wide range of deployment scenarios, the minimal requirements
specified in this document may not be sufficient for all
deployment scenarios. It is perfectly reasonable (and indeed
expected) for other profiles to define additional or stricter
requirements appropriate for specific usage and deployment
environments. For example, this document does not mandate that all
clients support DHCP, but some deployment scenarios may deem
it appropriate to make such a requirement. For example,
government agencies in the USA have defined profiles for
specialized requirements for IPv6 in target environments (see
).As it is not always possible for an implementer to know the
exact usage of IPv6 in a node, an overriding requirement for IPv6
nodes is that they should adhere to Jon Postel's Robustness
Principle: "Be conservative in what you do, be liberal in what you accept
from others" . IPv6 covers many specifications. It is intended that IPv6
will be deployed in many different situations and environments.
Therefore, it is important to develop requirements for IPv6
nodes to ensure interoperability. This document assumes that all IPv6 nodes meet the minimum
requirements specified here.From the Internet Protocol, Version 6 (IPv6) Specification , we have
the following definitions: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.An IPv6 node must include support for one or more IPv6
link-layer specifications. Which link-layer specifications an
implementation should include will depend upon what link-layers
are supported by the hardware available on the system. It is
possible for a conformant IPv6 node to support IPv6 on some of its
interfaces and not on others. As IPv6 is run over new layer 2 technologies, it is expected
that new specifications will be issued. In the following, we list some of
the layer 2 technologies for which an IPv6 specification has been developed.
It is provided for informational purposes only and may
not be complete. Transmission of IPv6 Packets over Ethernet
Networks Transmission of IPv6 Packets over Frame
Relay Networks Specification Transmission of IPv6 Packets over IEEE 1394
Networks Transmission of IPv6, IPv4, and Address
Resolution Protocol (ARP) Packets over Fibre Channel
Transmission of IPv6 Packets over IEEE
802.15.4 Networks Transmission of IPv6 via the IPv6
Convergence Sublayer over IEEE 802.16 Networks
IP version 6 over PPP
In addition to traditional physical link-layers, it is also
possible to tunnel IPv6 over other protocols. Examples
include: Teredo: Tunneling IPv6 over UDP through
Network Address Translations (NATs) Section 3 of "Basic Transition Mechanisms for IPv6
Hosts and Routers" The Internet Protocol Version 6 is specified in . This specification MUST be supported.The node MUST follow the packet transmission rules in RFC 8200.All conformant IPv6 implementations MUST be
capable of sending and receiving IPv6 packets; forwarding
functionality MAY be supported.
Nodes MUST always be able to send, receive, and process
fragment headers. IPv6 nodes must not create
overlapping fragments. Also, when reassembling an IPv6
datagram, if one or more of its constituent fragments is
determined to be an overlapping fragment, the entire datagram
(and any constituent fragments) must be silently discarded.
See [RFC5722] for more information.
As recommended in , nodes MUST NOT
generate atomic fragments, i.e., where the fragment is a whole datagram.
As per , if a receiving node reassembling
a datagram encounters an atomic fragment,
it should be processed as a fully reassembled packet, and
any other fragments that match this packet should be processed independently.
To mitigate a variety of potential attacks,
nodes SHOULD avoid using predictable fragment Identification values
in Fragment Headers, as discussed in .
All nodes SHOULD support the setting and use of the IPv6 Flow
Label field as defined in the IPv6 Flow Label specification
. Forwarding nodes such as routers and load distributors
MUST NOT depend only on Flow Label values being uniformly
distributed. It is RECOMMENDED that source hosts support the flow
label by setting the Flow Label field for all packets of a given
flow to the same value chosen from an approximation to a discrete
uniform distribution.
RFC 8200 specifies extension headers and the processing for
these headers.
Extension headers (except for the Hop-by-Hop Options header) are not
processed, inserted, or deleted by any node along a packet's delivery
path, until the packet reaches the node (or each of the set of nodes,
in the case of multicast) identified in the Destination Address field
of the IPv6 header.
Any unrecognized extension headers or options MUST be
processed as described in RFC 8200. Note that where
Section 4 of RFC 8200
refers to the action to be taken when a Next Header value
in the current header is not recognized by a node, that action
applies whether the value is an unrecognized Extension
Header or an unrecognized upper layer protocol (ULP). An IPv6 node MUST be able to process these headers. An
exception is Routing Header type 0 (RH0), which was deprecated
by due to security concerns and
which MUST be treated as an unrecognized routing type.
Further, adds specific requirements for
processing of Extension Headers, in particular that any forwarding
node along an IPv6 packet's path, which forwards the packet for
any reason, SHOULD do so regardless of any extension headers
that are present.
As per RFC 8200, when a node fragments an IPv6 datagram,
it MUST include the entire IPv6 Header Chain in the first fragment.
The Per-Fragment headers must
consist of the IPv6 header plus any extension headers that must be
processed by nodes en route to the destination,
that is, all headers up to and including the Routing
header if present, else the Hop-by-Hop Options header if present,
else no extension headers. On reassembly,
if the first fragment does not include all headers through an
Upper-Layer header, then that fragment should be discarded and
an ICMP Parameter Problem, Code 3, message should be sent to
the source of the fragment, with the Pointer field set to zero.
See for a discussion of why oversized
IPv6 Extension Header chains are avoided.
Defining new IPv6 extension headers is not recommended, unless there
are no existing IPv6 extension headers that can be used by specifying
a new option for that IPv6 extension header. A proposal to specify a
new IPv6 extension header must include a detailed technical
explanation of why an existing IPv6 extension header can not be used
for the desired new function, and in such cases need to follow the format
described in Section 8 of RFC 8200. For further background
reading on this topic, see .
As per RFC 8200, end hosts are expected to process all extension headers,
destination options, and hop-by-hop options in a packet. Given that
the only limit on the number and size of extension headers is the MTU,
the processing of received packets could be considerable. It is also
conceivable that a long chain of extension headers might be used as a
form of denial-of-service attack. Accordingly, a host may place limits
on the number and sizes of extension headers and options it is willing
to process.
A host MAY limit the number of consecutive PAD1 options in destination
options or hop-by-hop options to seven. In this case, if the more than
seven consecutive PAD1 options are present the packet should be
silently discarded. The rationale is that if padding of eight or more
bytes is required than the PADN option should be used.
A host MAY limit number of bytes in a PADN option to be less than
eight. In such a case, if a PADN option is present that has a length
greater than seven then the packet should be silently discarded. The
rationale for this guideline is that the purpose of padding is for
alignment and eight bytes is the maximum alignment used in IPv6.
A host MAY disallow unknown options in destination options or
hop-by-hop options. This should be configurable where the default is
to accept unknown options and process them per
. If a packet
with unknown options is received and the host is configured to
disallow them, then the packet should be silently discarded.
A host MAY impose a limit on the maximum number of non-padding options
allowed in a destination options and hop-by-hop extension headers. If
this feature is supported the maximum number should be configurable
and the default value SHOULD be set to eight. The limits for
destination options and hop-by-hop options may be separately
configurable. If a packet is received and the number of destination or
hop-by-hop optines exceeds the limit, then the packet should be
silently discarded.
A host MAY impose a limit on the maximum length of destination options
or hop-by-hop options extension header. This value should be
configurable and the default is to accept options of any length. If a
packet is received and the length of destination or hop-by-hop options
extension header exceeds the length limit, then the packet should be
silently discarded.
Neighbor Discovery is defined in ; the
definition was updated by . Neighbor Discovery
SHOULD be supported. RFC 4861 states:
Unless specified otherwise (in a document that covers operating IP
over a particular link type) this document applies to all link types.
However, because ND uses link-layer multicast for some of its
services, it is possible that on some link types (e.g., Non-Broadcast
Multi-Access (NBMA) links), alternative protocols or mechanisms to
implement those services will be specified (in the appropriate
document covering the operation of IP over a particular link type).
The services described in this document that are not directly
dependent on multicast, such as Redirects, next-hop determination,
Neighbor Unreachability Detection, etc., are expected to be provided
as specified in this document.
The details of how one uses ND on
NBMA links are addressed in .
Some detailed analysis of Neighbor Discovery follows:Router Discovery is how hosts locate routers that reside on
an attached link. Hosts MUST support Router Discovery
functionality.Prefix Discovery is how hosts discover the set of address
prefixes that define which destinations are on-link for an
attached link. Hosts MUST support Prefix Discovery.Hosts MUST also implement Neighbor Unreachability Detection
(NUD) for all paths between hosts and neighboring nodes. NUD is
not required for paths between routers. However, all nodes MUST
respond to unicast Neighbor Solicitation (NS) messages. discusses NUD, in particular cases
where it behaves too impatiently. It states that if a node
transmits more than a certain number of packets, then it
SHOULD use the exponential backoff of the retransmit timer,
up to a certain threshold point.
Hosts MUST support the sending of Router Solicitations and
the receiving of Router Advertisements. The ability to
understand individual Router Advertisement options is dependent
on supporting the functionality making use of the particular
option. discusses packet loss resliency
for Router Solicitations, and requires that nodes MUST use
a specific exponential backoff algorithm for RS retransmissions.
All nodes MUST support the sending and receiving of Neighbor
Solicitation (NS) and Neighbor Advertisement (NA) messages. NS
and NA messages are required for Duplicate Address Detection
(DAD).Hosts SHOULD support the processing of Redirect
functionality. Routers MUST support the sending of Redirects,
though not necessarily for every individual packet (e.g., due to
rate limiting). Redirects are only useful on networks supporting
hosts. In core networks dominated by routers, Redirects are
typically disabled. The sending of Redirects SHOULD be disabled
by default on backbone routers. They MAY be enabled by default
on routers intended to support hosts on edge networks. "IPv6 Host-to-Router Load Sharing" includes additional recommendations on how to select from a
set of available routers. SHOULD be supported.
SEND and Cryptographically Generated
Addresses (CGAs) provide a way to
secure the message exchanges of Neighbor Discovery. SEND
has the potential to address certain classes of spoofing
attacks, but it does not provide specific protection for threats
from off-link attackers.
There have been relatively few implementations of SEND
in common operating systems and platforms since its publication in 2005,
and thus deployment experience remains very limited to date.
At this time, support for SEND is considered optional. Due to the
complexity in deploying SEND, and its heavyweight provisioning,
its deployment is only
likely to be considered where nodes are operating in a
particularly strict security environment. Router Advertisements include an 8-bit field of single-bit
Router Advertisement flags. The Router Advertisement Flags
Option extends the number of available flag bits by 48 bits. At
the time of this writing, 6 of the original 8 single-bit flags have
been assigned, while 2 remain available for future
assignment. No flags have been defined that make use of the new
option, and thus, strictly speaking, there is no requirement to
implement the option today. However, implementations that are
able to pass unrecognized options to a higher-level entity that
may be able to understand them (e.g., a user-level process using
a "raw socket" facility) MAY take steps to handle the option in
anticipation of a future usage. "Path MTU Discovery for IP version 6" SHOULD be
supported. From : It is strongly recommended that IPv6 nodes implement
Path MTU Discovery , in order to
discover and
take advantage of path MTUs greater than 1280 octets.
However, a minimal IPv6 implementation (e.g., in a boot
ROM) may simply restrict itself to sending packets no
larger than 1280 octets, and omit implementation of Path
MTU Discovery. The rules in and
MUST be followed for packet
fragmentation and reassembly.
As described in RFC 8201,
nodes implementing Path MTU Discovery and sending packets larger than
the IPv6 minimum link MTU are susceptible to problematic connectivity
if ICMPv6 messages are blocked or not transmitted. For
example, this will result in connections that complete the TCP three-
way handshake correctly but then hang when data is transferred. This
state is referred to as a black-hole connection
. Path MTU
Discovery relies on ICMPv6 Packet Too Big (PTB) to determine the MTU
of the path (and thus these should not be filtered, as per the
recommendation in ).
An extension to Path MTU Discovery defined in RFC 8201 can be
found in , which defines a method for Packetization
Layer Path MTU Discovery (PLPMTUD) designed for use over paths where
delivery of ICMPv6 messages to a host is not assured.
While an IPv6 link MTU can be set to 1280 bytes,
it is recommended that for IPv6 UDP in particular,
which includes DNS operation, the sender use a
large MTU if they can, in order to avoid gratuitous
fragmentation-caused packet drops.
ICMPv6 MUST be supported. "Extended
ICMP to Support Multi-Part Messages"
MAY be supported."Default Router Preferences and More-Specific Routes" provides support for nodes attached to
multiple (different) networks, each providing routers that
advertise themselves as default routers via Router
Advertisements. In some scenarios, one router may provide
connectivity to destinations the other router does not, and
choosing the "wrong" default router can result in reachability
failures. In order to resolve this scenario IPv6 Nodes MUST implement
and SHOULD implement the Type C host role defined in RFC4191.
In multihomed scenarios, where a host has more than one prefix,
each allocated by an upstream network that is assumed to implement
BCP 38 ingress filtering, the host may have multiple routers to
choose from.
Hosts that may be deployed in such multihomed environments
SHOULD follow the guidance given in .
Nodes that need to join multicast groups MUST support MLDv2
. MLD is needed by any node that is
expected to receive and process multicast traffic and in particular
MLDv2 is required for support for source-specific multicast (SSM) as
per .
Previous versions of this document only required MLDv1
() to be implemented
on all nodes. Since participation of any
MLDv1-only nodes on a link require that all other nodeas on the link then
operate in version 1 compatibility mode, the requirement to support MLDv2
on all nodes was upgraded to a MUST. Further, SSM is now the preferred
multicast distribution method, rather than ASM.
Note that
Neighbor Discovery (as used on most link types -- see ) depends on multicast and requires that nodes join Solicited
Node multicast addresses.
An ECN-aware router may set a mark in the IP header in order to signal
impending congestion, rather than dropping a packet. The receiver of
the packet echoes the congestion indication to the sender, which can then
reduce its transmission rate as if it detected a dropped packet.
Nodes that may be deployed in environments where they would benefit
from such early congestion notification SHOULD implement
. In such cases, the updates presented in
may also be relevant.
The IPv6 Addressing Architecture
MUST be supported.The current IPv6 Address Architecture is based on a 64-bit boundary for subnet prefixes.
The reasoning behind this decision is documented in .
Implementations MUST also support the Multicast flag updates
documented in
Hosts may be configured with addresses through a variety of methods,
including SLAAC, DHCPv6, or manual configuration.
recommends that networks provide general-purpose end
hosts with multiple global IPv6 addresses when they attach, and it
describes the benefits of and the options for doing so. Routers SHOULD support
for assigning multiple address to a host. Host SHOULD support
assigning multiple addresses as described in .
Nodes SHOULD support the capability to be assigned a prefix per host as
documented in .
Such an approach can offer improved host
isolation and enhanced subscriber management on shared network segments.
Hosts MUST support IPv6 Stateless Address Autoconfiguration.
It is recommended, as described in , that unless there
is a specific requirement for MAC addresses to be embedded in
an IID, nodes follow the procedure in to generate SLAAC-based
addresses, rather than using .
Addresses generated through RFC7217 will be the same
whenever a given device (re)appears on the same subnet (with a
specific IPv6 prefix), but the IID will vary on each subnet visited.
Nodes that are routers MUST be able to generate link-local
addresses as described in .From RFC 4862:
The autoconfiguration process specified in this document
applies only to hosts and not routers. Since host
autoconfiguration uses information advertised by routers,
routers will need to be configured by some other means.
However, it is expected that routers will generate link-local
addresses using the mechanism described in this document. In
addition, routers are expected to successfully pass the
Duplicate Address Detection procedure described in this
document on all addresses prior to assigning them to an
interface.All nodes MUST implement Duplicate Address Detection. Quoting
from Section 5.4 of RFC 4862: Duplicate Address Detection MUST
be performed on all unicast addresses prior to assigning them
to an interface, regardless of whether they are obtained
through stateless autoconfiguration, DHCPv6, or manual
configuration, with the following [exceptions noted therein].
"Optimistic Duplicate Address Detection (DAD) for
IPv6" specifies a mechanism to reduce
delays associated with generating addresses via Stateless
Address Autoconfiguration . RFC 4429
was developed in conjunction with Mobile IPv6 in order to reduce
the time needed to acquire and configure addresses as devices
quickly move from one network to another, and it is desirable to
minimize transition delays. For general purpose devices, RFC 4429 remains optional at this time.
discusses enhanced DAD, and describes an
algorithm to automate the detection of looped back IPv6 ND messages
used by DAD. Nodes SHOULD implement this behaviour where such
detection is beneficial.
A node using Stateless Address
Autoconfiguration to form a globally
unique IPv6 address using its MAC address to generate the IID
will see that IID remain the same on any visited
network, even though the network prefix part changes.
Thus it is possible for 3rd party devices such nodes communicate
with to track the activities of the node as it moves
around the network. Privacy Extensions for Stateless Address
Autoconfiguration address this
concern by allowing nodes to configure an additional temporary address
where the IID is effectively randomly generated. Privacy addresses
are then used as source addresses for new communications initiated by the node.
General issues regarding privacy issues for IPv6 addressing are discussed in .
RFC 4941 SHOULD be supported. In some scenarios,
such as dedicated servers in a data
center, it provides limited or no benefit, or may complicate network management.
Thus devices implementing this specification MUST provide a way for the
end user to explicitly enable or disable the use of such temporary
addresses.
Note that RFC4941 can be used independently of traditional SLAAC, or
of RFC7217-based SLAAC.Implementers of RFC 4941 should be aware that certain
addresses are reserved and should not be chosen for use as
temporary addresses. Consult "Reserved IPv6 Interface
Identifiers" for more details.
DHCPv6 can be used to obtain and
configure addresses. In general, a network may provide for the
configuration of addresses through SLAAC,
DHCPv6, or both. There will be a wide range of IPv6 deployment
models and differences in address assignment requirements,
some of which may require DHCPv6 for stateful address assignment.
Consequently, all hosts SHOULD implement address configuration
via DHCPv6. In the absence of observed Router Advertisement messages, IPv6 nodes
MAY initiate DHCP to obtain IPv6 addresses
and other configuration information, as described in Section
5.5.2 of .Where devices are likely to be carried by users and attached
to multiple visisted networks, DHCPv6 client
anonymity profiles SHOULD be supported as described in
to minimise the disclosure of identifying information.
Section 5 of RFC7844 describes operational considerations on the use of
such anonymity profiles.IPv6 nodes will invariably have multiple addresses configured simultaneously,
and thus will need to choose which addresses to use for which communications.
The rules specified in the Default Address Selection for
IPv6 document MUST be implemented.
updates rule 5.5 from ; implementations
SHOULD implement this rule.DNS is described in , , , and . Not all nodes will need to resolve names;
those that will never need to resolve DNS names do not need to
implement resolver functionality. However, the ability to
resolve names is a basic infrastructure capability on which
applications rely, and most nodes will need to provide
support. All nodes SHOULD implement stub-resolver functionality, as in , Section
5.3.1, with support for:AAAA type Resource Records ;reverse addressing in ip6.arpa using PTR records ;Extension Mechanisms for DNS (EDNS0) to allow for DNS packet sizes larger than 512 octets.Those nodes are RECOMMENDED to support DNS security extensions .A6 Resource Records, which were only ever defined with Experimental status in ,
are now classified as Historic, as per . DHCP Specifies a mechanism for IPv6 nodes to obtain
address configuration information (see ) and to
obtain additional (non-address) configuration. If a host
implementation supports applications or other protocols that
require configuration that is only available via DHCP, hosts
SHOULD implement DHCP. For specialized devices on which no
such configuration need is present, DHCP may not be
necessary.An IPv6 node can use the subset of DHCP (described in
) to obtain other configuration
information.If an IPv6 node implements DHCP it MUST implement the DNS options
as most deployments will expect these options are available.There is no defined DHCPv6 Gateway option.Nodes using the Dynamic Host Configuration Protocol for
IPv6 (DHCPv6) are thus expected to determine their default router
information and on-link prefix information from received
Router Advertisements.
Router Advertisement Options have historically been limited to
those that are critical to basic IPv6 functionality. Originally,
DNS configuration was not included as an RA option, and DHCP
was the recommended way to obtain DNS configuration
information. Over time, the thinking surrounding such an
option has evolved. It is now generally recognized that few
nodes can function adequately without having access to a
working DNS resolver, and thus a
Standards Track document has been published to provide this
capability .Implementations MUST include support for the DNS RA option
. In IPv6, there are two main protocol mechanisms for
propagating configuration information to hosts: Router
Advertisements (RAs) and DHCP. RA options have been
restricted to those deemed essential for basic network
functioning and for which all nodes are configured with exactly
the same information. Examples include the Prefix Information
Options, the MTU option, etc. On the other hand, DHCP has
generally been preferred for configuration of more general
parameters and for parameters that may be client-specific.
Generally speaking, however, there has been a desire
to define only one mechanism for configuring a given option,
rather than defining multiple (different) ways of configuring
the same information.One issue with having multiple ways of configuring the same
information is that interoperability suffers if a host chooses one
mechanism but the
network operator chooses a different mechanism. For "closed"
environments, where the network operator
has significant influence over what devices connect to the
network and thus what configuration mechanisms they support, the
operator may be able to ensure that a particular mechanism is
supported by all connected hosts. In more open environments,
however, where arbitrary devices may connect (e.g., a WIFI
hotspot), problems can arise. To maximize interoperability in
such environments, hosts would need to implement multiple
configuration mechanisms to ensure interoperability. and
describe multicast DNS (mDNS) and
DNS-Based Service Discovery (DNS-SD) respectively.
These protocols, collectively commonly referred to as the
'Bonjour' protocols after their naming by Apple, provide
the means for devices to discover services within a local
link and, in the absence of a unicast DNS service, to
exchange naming information.
Where devices are to be deployed in networks where
service dicovery would be beneficial, e.g., for users
seeking to discover printers or display devices, mDNS and
DNS-SD SHOULD be supported.
The IETF dnssd WG is defining solutions for DNS-based
service discovery in multi-link networks.
IPv6 nodes MAY support IPv4.If an IPv6 node implements dual stack and tunneling, then
MUST be supported.Software that allows users and operators to input IPv6
addresses in text form SHOULD support "A Recommendation for
IPv6 Address Text Representation" .There are a number of IPv6-related APIs. This document does
not mandate the use of any, because the choice of API does not
directly relate to on-the-wire behavior of
protocols. Implementers, however, would be advised to consider
providing a common API or reviewing existing APIs for the type
of functionality they provide to applications. "Basic Socket Interface Extensions for IPv6"
provides IPv6 functionality used by
typical applications. Implementers should note that RFC3493 has
been picked up and further standardized by the Portable Operating System
Interface (POSIX) ."Advanced Sockets Application Program Interface (API) for
IPv6" provides access to
advanced IPv6 features needed by diagnostic and other
more specialized applications. "IPv6 Socket API for Source Address Selection"
provides facilities that allow an
application to override the default Source Address Selection
rules of . "Socket Interface Extensions for Multicast Source Filters"
provides support for expressing source
filters on multicast group memberships. "Extension to Sockets API for Mobile IPv6"
provides application support for
accessing and enabling Mobile IPv6 features.Mobile IPv6 and associated
specifications
allow a node to change its point of attachment within the
Internet, while maintaining (and using) a permanent address. All
communication using the permanent address continues to proceed as
expected even as the node moves around. The definition of Mobile
IP includes requirements for the following types of nodes: - mobile nodes - correspondent nodes with support for route optimization - home agents - all IPv6 routers At the present time, Mobile IP has seen only limited
implementation and no significant deployment, partly because it
originally assumed an IPv6-only environment rather than a mixed
IPv4/IPv6 Internet. Recently, additional work has been done to
support mobility in mixed-mode IPv4 and IPv6
networks . More usage and deployment experience is needed with mobility
before any specific approach can be recommended for broad
implementation in all hosts and routers. Consequently, , , and associated
standards such as are considered a MAY
at this time. IPv6 for 3GPP lists a snapshot of required
IPv6 Functionalities at the time the document was published that would
need to be implemented, going above
and beyond the recommendations in this document. Additionally a 3GPP IPv6 Host MAY implement
for delivering IPv6 prefixes on the LAN link. This section describes the specification for security for IPv6
nodes. Achieving security in practice is a complex undertaking.
Operational procedures, protocols, key distribution mechanisms,
certificate management approaches, etc., are all components that
impact the level of security actually achieved in practice. More
importantly, deficiencies or a poor fit in any one individual
component can significantly reduce the overall effectiveness of a
particular security approach. IPsec either can provide end-to-end security between nodes or
or can provide channel security (for example, via a site-to-site IPsec
VPN), making it possible to provide secure communication for all (or a subset
of) communication flows at the IP layer between pairs of internet
nodes. IPsec has two standard operating modes, Tunnel-mode and Transport-mode.
In Tunnel-mode, IPsec provides network-layer security and protects an entire IP packet
by encapsulating the orginal IP packet and then pre-pending a new IP header.
In Transport-mode, IPsec provides security for the transport-layer (and above) by
encapsulating only the transport-layer (and above) portion of the IP packet (i.e., without adding
a 2nd IP header). Although IPsec can be used with manual keying in some cases,
such usage has limited applicability and is not recommended.
A range of security technologies and approaches proliferate
today (e.g., IPsec, Transport Layer Security (TLS), Secure SHell (SSH), SSL VPNS, etc.)
No one approach has emerged as
an ideal technology for all needs and environments. Moreover, IPsec
is not viewed as the ideal security technology in all cases and is
unlikely to displace the others. Previously, IPv6 mandated implementation of IPsec and
recommended the key management approach of IKE. This document
updates that recommendation by making support of the IPsec
Architecture a SHOULD for all IPv6 nodes.
Note that
the IPsec Architecture requires (e.g., Section 4.5 of RFC 4301) the
implementation of both manual and automatic key management.
Currently, the default automated key management protocol to
implement is IKEv2 . This document recognizes that there exists a range of device
types and environments where approaches to security other than
IPsec can be justified. For example, special-purpose devices may
support only a very limited number or type of applications, and an
application-specific security approach may be sufficient for
limited management or configuration capabilities. Alternatively,
some devices may run on extremely constrained hardware (e.g.,
sensors) where the full IPsec Architecture is not justified.
Because most common platforms now support IPv6 and have it
enabled by default, IPv6 security is an issue for networks
that are ostensibly IPv4-only; see
for guidance on this area.
"Security Architecture for the Internet Protocol"
SHOULD be supported by all IPv6
nodes. Note that the IPsec Architecture requires (e.g., Section 4.5 of
) the implementation of both manual and automatic key
management. Currently, the default automated key management
protocol to implement is IKEv2. As required in , IPv6
nodes implementing the IPsec Architecture MUST implement ESP
and MAY implement AH
.
The current set of mandatory-to-implement algorithms for the
IPsec Architecture are defined in "Cryptographic
Algorithm Implementation Requirements For ESP and AH"
. IPv6 nodes implementing the IPsec
Architecture MUST conform to the requirements in .
Preferred cryptographic algorithms often change more
frequently than security protocols. Therefore, implementations
MUST allow for migration to new algorithms, as RFC 8221 is
replaced or updated in the future. The current set of mandatory-to-implement algorithms for
IKEv2 are defined in "Cryptographic Algorithms for Use in the
Internet Key Exchange Version 2 (IKEv2)"
. IPv6 nodes implementing IKEv2 MUST
conform to the requirements in and/or any future
updates or replacements to .
This section defines general host considerations for IPv6 nodes
that act as routers. Currently, this section does not discuss
detailed routing-specific requirements. For the case of typical home routers,
defines basic requirements for customer edge routers.
The IPv6 Router Alert Option is
an optional IPv6 Hop-by-Hop Header that is used in conjunction
with some protocols (e.g., RSVP or
Multicast Listener Discovery (MLDv2) ). The Router Alert option will
need to be implemented whenever such protocols that mandate its
use are implemented. See .Sending Router Advertisements and processing Router
Solicitations MUST be supported. Section 7 of includes some mobility-specific
extensions to Neighbor Discovery. Routers SHOULD implement
Sections 7.3 and 7.5, even if they do not implement Home
Agent functionality. A single DHCP server ( or ) can provide configuration information to
devices directly attached to a shared link, as well as to
devices located elsewhere within a site. Communication between
a client and a DHCP server located on different links requires
the use of DHCP relay agents on routers. In simple deployments, consisting of a single router and
either a single LAN or multiple LANs attached to the single
router, together with a WAN connection, a DHCP server
embedded within the router is one common deployment scenario
(e.g., ). There is no need
for relay agents in such scenarios. In more complex deployment scenarios, such as within
enterprise or service provider networks, the use of DHCP
requires some level of configuration, in order to configure
relay agents, DHCP servers, etc. In such environments, the
DHCP server might even be run on a traditional server, rather
than as part of a router. Because of the wide range of deployment scenarios, support
for DHCP server functionality on routers is optional. However,
routers targeted for deployment within more complex scenarios
(as described above) SHOULD support relay agent functionality.
Note that "Basic Requirements for IPv6 Customer Edge Routers"
requires implementation of a DHCPv6
server function in IPv6 Customer Edge (CE) routers.
Forwarding nodes MUST conform to BCP 198
and thus IPv6 implementations of nodes that may forward packets
MUST conform to the rules specified in Section 5.1 of .
The target for this document is general IPv6 nodes. In this Section, we briefly
discuss considerations for constrained devices.
In the case of constrained nodes,
with limited CPU, memory, bandwidth or power, support for certain IPv6 functionality may need
to be considered due to those limitations. While the requirements of this document are
RECOMMENDED for all nodes, including constrained nodes, compromises may need to be
made in certain cases. Where such compromises are made, the interoperability of devices
should be strongly considered, paticularly where this may impact other nodes on the same
link, e.g., only supporting MLDv1 will affect other nodes.
The IETF 6LowPAN (IPv6 over Low Power LWPAN) WG defined six RFCs, including a general
overview and problem statement (, the means by which IPv6 packets
are transmitted over IEEE 802.15.4 networks
and ND optimisations for that medium .
If an IPv6 node is concerned about the impact of IPv6 message power consumption, it
SHOULD want to implement the recommendations in .
Network management MAY be supported by IPv6 nodes. However,
for IPv6 nodes that are embedded devices, network management may
be the only possible way of controlling these nodes.Existing network management protocols include SNMP , NETCONF
and RESTCONF . clarifies the obsoleted status of
various IPv6-specific MIB modules.
The following two MIB modules SHOULD be supported by nodes that
support a Simple Network Management Protocol (SNMP) agent.The IP Forwarding Table MIB SHOULD be supported by nodes that support an
SNMP agent.The IP MIB SHOULD be supported by nodes
that support an SNMP agent.The Interface MIB SHOULD be supported by nodes the support
an SNMP agent.The following YANG data models SHOULD be supported by nodes that support a
NETCONF or RESTCONF agent. The IP Management YANG Model SHOULD be supported
by nodes that support NETCONF or RESTCONF. The Interface Management YANG Model SHOULD be supported
by nodes that support NETCONF or RESTCONF.This document does not directly affect the security of the
Internet, beyond the security considerations associated with the
individual protocols. Security is also discussed in above.This document does not require any IANA actions.For this version of the IPv6 Node Requirements document, the
authors would like to thank
Brian Carpenter, Dave Thaler,
Tom Herbert, Erik Kline, Mohamed Boucadair, and Michayla Newcombe
for their contributions. Ed Jankiewicz and Thomas Narten were named authors of the previous iteration of this document, RFC6434.
For this version of the document, the authors
thanked Hitoshi Asaeda, Brian Carpenter, Tim Chown, Ralph
Droms, Sheila Frankel, Sam Hartman, Bob Hinden, Paul Hoffman, Pekka
Savola, Yaron Sheffer, and Dave Thaler.
The original version of this document (RFC 4294) was written by
the IPv6 Node Requirements design team, which had the following members:
Jari Arkko,
Marc Blanchet,
Samita Chakrabarti,
Alain Durand,
Gerard Gastaud,
Jun-ichiro Itojun Hagino,
Atsushi Inoue,
Masahiro Ishiyama,
John Loughney,
Rajiv Raghunarayan,
Shoichi Sakane,
Dave Thaler, and Juha Wiljakka.
The authors would like to thank Ran Atkinson, Jim Bound, Brian Carpenter, Ralph Droms,
Christian Huitema, Adam Machalek, Thomas Narten, Juha Ollila, and Pekka Savola for their comments.
Thanks to Mark Andrews for comments and corrections on DNS text. Thanks to Alfred Hoenes for tracking
the updates to various RFCs.
There have been many editorial clarifications as well as
significant additions and updates. While this section highlights
some of the changes, readers should not rely on this section for a
comprehensive list of all changes. Restructured sectionsAdded 6LoWPAN to link layers as it has some deployment.Removed DOD IPv6 Profile as it hasn't been updated.Updated to MLDv2 support to a MUST since nodes are restricted if MLDv1 is used.Require DNS RA Options so SLAAC-only devices can get DNS, RFC8106 is a MUST.Require RFC3646 DNS Options for DHCPv6 implementations.Added RESTCONF and NETCONF as possible options to Network management.Added section on constrained devices.Added text on RFC7934, address availability to hosts (SHOULD).Added text on RFC7844, anonymity profiles for DHCPv6 clients.mDNS and DNS-SD added as updated service discovery.Added RFC8028 as a SHOULD as a method for solving multi-prefix networkAdded ECN RFC3168 as a SHOULD, since recent reports have shown this as useful,
and added a note on RFC8311, which is related.Added reference to RFC7123 for Security over IPv4-only networksRemoved Jumbograms RFC2675 as they aren't deployed.Updated Obseleted RFCs to the new version of the RFC including 2460, 1981, 7321, 4307Added RFC7772 for power comsumptions considerationsAdded why /64 boundries for more detail - RFC 7421Added a Unique IPv6 Prefix per Host to support currently deployed IPv6 networksClarified RFC7066 was snapshot for 3GPPUpdated 4191 as a MUST, SHOULD for Type C Host as it helps solve multi-prefix problemRemoved IPv6 over ATM since there aren't many deploymentsAdded a note in Section 6.6 for RFC6724 Section 5.5/Added MUST for BCP 198 for forwarding IPv6 packetsAdded reference to RFC8064 for stable address creation.Added text on protection from excessive EH optionsAdded text on dangers of 1280 MTU UDP, esp. wrt DNS trafficAdded text to clarify RFC8200 behaviour for unrecognized EHs or unrecognized ULPsRemoved dated email addresses from design team acknowledgements for RFC 4294.
There have been many editorial clarifications as well as
significant additions and updates. While this section highlights
some of the changes, readers should not rely on this section for a
comprehensive list of all changes. Updated the Introduction to indicate that this document is an
applicability statement and is aimed at
general nodes. Significantly updated the section on Mobility protocols,
adding references and downgrading previous SHOULDs to MAYs.Changed Sub-IP Layer section to just list relevant RFCs, and
added some more RFCs. Added section on SEND (it is a MAY).Revised section on Privacy Extensions to add more
nuance to recommendation.Completely revised IPsec/IKEv2 section, downgrading overall
recommendation to a SHOULD.Upgraded recommendation of DHCPv6 to SHOULD.Added background section on DHCP versus RA options, added
SHOULD recommendation for DNS configuration via RAs (RFC6106), and cleaned up DHCP recommendations. Added recommendation that routers implement Sections 7.3 and
7.5 of .Added pointer to subnet clarification document .Added text that "IPv6 Host-to-Router Load Sharing"
SHOULD be implemented.Added reference to (Overlapping Fragments),
and made it a MUST to implement.Made "A Recommendation for IPv6 Address Text Representation"
a SHOULD. Removed mention of "DNAME" from the discussion about
.Numerous updates to reflect newer versions of IPv6
documents, including , ,
, and .Removed discussion of "Managed" and "Other" flags in
RAs. There is no consensus at present on how to process these
flags, and discussion of their semantics was removed in the most
recent update of Stateless Address Autoconfiguration . Added many more references to optional IPv6 documents. Made "A Recommendation for IPv6 Address Text Representation"
a SHOULD. Added reference to (Overlapping Fragments),
and made it a
MUST to implement. Updated MLD section to include reference to Lightweight MLD
. Added SHOULD recommendation for "Default Router Preferences
and More-Specific Routes" .Made "IPv6 Flow Label Specification" a SHOULD.IEEE Std. 1003.1-2008 Standard for Information
Technology -- Portable Operating System Interface
(POSIX), ISO/IEC 9945:2009IEEEA Profile for IPv6 in the U.S. Government - Version 1.0
National Institute of Standards and Technology