draft-ietf-6man-rfc2460bis-13.txt   rfc8200.txt 
Network Working Group S. Deering Internet Engineering Task Force (IETF) S. Deering
Internet-Draft Retired Request for Comments: 8200 Retired
Obsoletes: 2460 (if approved) R. Hinden STD: 86 R. Hinden
Intended status: Standards Track Check Point Software Obsoletes: 2460 Check Point Software
Expires: November 20, 2017 May 19, 2017 Category: Standards Track July 2017
ISSN: 2070-1721
Internet Protocol, Version 6 (IPv6) Specification Internet Protocol, Version 6 (IPv6) Specification
draft-ietf-6man-rfc2460bis-13
Abstract Abstract
This document specifies version 6 of the Internet Protocol (IPv6). This document specifies version 6 of the Internet Protocol (IPv6).
It obsoletes RFC2460 It obsoletes RFC 2460.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on November 20, 2017. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8200.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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modifications of such material outside the IETF Standards Process. modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. IPv6 Header Format . . . . . . . . . . . . . . . . . . . . . 5 3. IPv6 Header Format . . . . . . . . . . . . . . . . . . . . . 6
4. IPv6 Extension Headers . . . . . . . . . . . . . . . . . . . 6 4. IPv6 Extension Headers . . . . . . . . . . . . . . . . . . . 7
4.1. Extension Header Order . . . . . . . . . . . . . . . . . 8 4.1. Extension Header Order . . . . . . . . . . . . . . . . . 10
4.2. Options . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.2. Options . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Hop-by-Hop Options Header . . . . . . . . . . . . . . . . 12 4.3. Hop-by-Hop Options Header . . . . . . . . . . . . . . . . 13
4.4. Routing Header . . . . . . . . . . . . . . . . . . . . . 12 4.4. Routing Header . . . . . . . . . . . . . . . . . . . . . 14
4.5. Fragment Header . . . . . . . . . . . . . . . . . . . . . 14 4.5. Fragment Header . . . . . . . . . . . . . . . . . . . . . 15
4.6. Destination Options Header . . . . . . . . . . . . . . . 21 4.6. Destination Options Header . . . . . . . . . . . . . . . 23
4.7. No Next Header . . . . . . . . . . . . . . . . . . . . . 22 4.7. No Next Header . . . . . . . . . . . . . . . . . . . . . 24
4.8. Defining New Extension Headers and Options . . . . . . . 22 4.8. Defining New Extension Headers and Options . . . . . . . 24
5. Packet Size Issues . . . . . . . . . . . . . . . . . . . . . 23 5. Packet Size Issues . . . . . . . . . . . . . . . . . . . . . 25
6. Flow Labels . . . . . . . . . . . . . . . . . . . . . . . . . 24 6. Flow Labels . . . . . . . . . . . . . . . . . . . . . . . . . 26
7. Traffic Classes . . . . . . . . . . . . . . . . . . . . . . . 24 7. Traffic Classes . . . . . . . . . . . . . . . . . . . . . . . 26
8. Upper-Layer Protocol Issues . . . . . . . . . . . . . . . . . 24 8. Upper-Layer Protocol Issues . . . . . . . . . . . . . . . . . 27
8.1. Upper-Layer Checksums . . . . . . . . . . . . . . . . . . 25 8.1. Upper-Layer Checksums . . . . . . . . . . . . . . . . . . 27
8.2. Maximum Packet Lifetime . . . . . . . . . . . . . . . . . 26 8.2. Maximum Packet Lifetime . . . . . . . . . . . . . . . . . 28
8.3. Maximum Upper-Layer Payload Size . . . . . . . . . . . . 27 8.3. Maximum Upper-Layer Payload Size . . . . . . . . . . . . 29
8.4. Responding to Packets Carrying Routing Headers . . . . . 27 8.4. Responding to Packets Carrying Routing Headers . . . . . 29
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
10. Security Considerations . . . . . . . . . . . . . . . . . . . 28 10. Security Considerations . . . . . . . . . . . . . . . . . . . 30
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 11.1. Normative References . . . . . . . . . . . . . . . . . . 32
12.1. Normative References . . . . . . . . . . . . . . . . . . 30 11.2. Informative References . . . . . . . . . . . . . . . . . 33
12.2. Informative References . . . . . . . . . . . . . . . . . 31 Appendix A. Formatting Guidelines for Options . . . . . . . . . 36
Appendix A. Formatting Guidelines for Options . . . . . . . . . 33 Appendix B. Changes Since RFC 2460 . . . . . . . . . . . . . . . 39
Appendix B. Changes Since RFC2460 . . . . . . . . . . . . . . . 36 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42
B.1. Change History Since RFC2460 . . . . . . . . . . . . . . 39 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45
1. Introduction 1. Introduction
IP version 6 (IPv6) is a new version of the Internet Protocol (IP), IP version 6 (IPv6) is a new version of the Internet Protocol (IP),
designed as the successor to IP version 4 (IPv4) [RFC0791]. The designed as the successor to IP version 4 (IPv4) [RFC791]. The
changes from IPv4 to IPv6 fall primarily into the following changes from IPv4 to IPv6 fall primarily into the following
categories: categories:
o Expanded Addressing Capabilities o Expanded Addressing Capabilities
IPv6 increases the IP address size from 32 bits to 128 bits, to IPv6 increases the IP address size from 32 bits to 128 bits, to
support more levels of addressing hierarchy, a much greater support more levels of addressing hierarchy, a much greater
number of addressable nodes, and simpler auto-configuration of number of addressable nodes, and simpler autoconfiguration of
addresses. The scalability of multicast routing is improved by addresses. The scalability of multicast routing is improved by
adding a "scope" field to multicast addresses. And a new type adding a "scope" field to multicast addresses. And a new type
of address called an "anycast address" is defined, used to send of address called an "anycast address" is defined; it is used
a packet to any one of a group of nodes. to send a packet to any one of a group of nodes.
o Header Format Simplification o Header Format Simplification
Some IPv4 header fields have been dropped or made optional, to Some IPv4 header fields have been dropped or made optional, to
reduce the common-case processing cost of packet handling and reduce the common-case processing cost of packet handling and
to limit the bandwidth cost of the IPv6 header. to limit the bandwidth cost of the IPv6 header.
o Improved Support for Extensions and Options o Improved Support for Extensions and Options
Changes in the way IP header options are encoded allows for Changes in the way IP header options are encoded allows for
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A new capability is added to enable the labeling of sequences A new capability is added to enable the labeling of sequences
of packets that the sender requests to be treated in the of packets that the sender requests to be treated in the
network as a single flow. network as a single flow.
o Authentication and Privacy Capabilities o Authentication and Privacy Capabilities
Extensions to support authentication, data integrity, and Extensions to support authentication, data integrity, and
(optional) data confidentiality are specified for IPv6. (optional) data confidentiality are specified for IPv6.
This document specifies the basic IPv6 header and the initially- This document specifies the basic IPv6 header and the initially
defined IPv6 extension headers and options. It also discusses packet defined IPv6 extension headers and options. It also discusses packet
size issues, the semantics of flow labels and traffic classes, and size issues, the semantics of flow labels and traffic classes, and
the effects of IPv6 on upper-layer protocols. The format and the effects of IPv6 on upper-layer protocols. The format and
semantics of IPv6 addresses are specified separately in [RFC4291]. semantics of IPv6 addresses are specified separately in [RFC4291].
The IPv6 version of ICMP, which all IPv6 implementations are required The IPv6 version of ICMP, which all IPv6 implementations are required
to include, is specified in [RFC4443] to include, is specified in [RFC4443].
The data transmission order for IPv6 is the same as for IPv4 as The data transmission order for IPv6 is the same as for IPv4 as
defined in Appendix B of [RFC0791]. defined in Appendix B of [RFC791].
Note: As this document obsoletes [RFC2460], any document referenced Note: As this document obsoletes [RFC2460], any document referenced
in this document that includes pointers to RFC2460, should be in this document that includes pointers to RFC 2460 should be
interpreted as referencing this document. interpreted as referencing this document.
2. Terminology 2. Terminology
node a device that implements IPv6. node a device that implements IPv6.
router a node that forwards IPv6 packets not explicitly router a node that forwards IPv6 packets not explicitly
addressed to itself. [See Note below]. addressed to itself. (See Note below.)
host any node that is not a router. [See Note below]. host any node that is not a router. (See Note below.)
upper layer a protocol layer immediately above IPv6. Examples are upper layer a protocol layer immediately above IPv6. Examples are
transport protocols such as TCP and UDP, control transport protocols such as TCP and UDP, control
protocols such as ICMP, routing protocols such as OSPF, protocols such as ICMP, routing protocols such as OSPF,
and internet or lower-layer protocols being "tunneled" and internet-layer or lower-layer protocols being
over (i.e., encapsulated in) IPv6 such as IPX, "tunneled" over (i.e., encapsulated in) IPv6 such as
AppleTalk, or IPv6 itself. Internetwork Packet Exchange (IPX), AppleTalk, or IPv6
itself.
link a communication facility or medium over which nodes can link a communication facility or medium over which nodes can
communicate at the link layer, i.e., the layer communicate at the link layer, i.e., the layer
immediately below IPv6. Examples are Ethernets (simple immediately below IPv6. Examples are Ethernets (simple
or bridged); PPP links; X.25, Frame Relay, or ATM or bridged); PPP links; X.25, Frame Relay, or ATM
networks; and internet (or higher) layer "tunnels", such networks; and internet-layer or higher-layer "tunnels",
as tunnels over IPv4 or IPv6 itself. such as tunnels over IPv4 or IPv6 itself.
neighbors nodes attached to the same link. neighbors nodes attached to the same link.
interface a node's attachment to a link. interface a node's attachment to a link.
address an IPv6-layer identifier for an interface or a set of address an IPv6-layer identifier for an interface or a set of
interfaces. interfaces.
packet an IPv6 header plus payload. packet an IPv6 header plus payload.
link MTU the maximum transmission unit, i.e., maximum packet size link MTU the maximum transmission unit, i.e., maximum packet size
in octets, that can be conveyed over a link. in octets, that can be conveyed over a link.
path MTU the minimum link MTU of all the links in a path between path MTU the minimum link MTU of all the links in a path between
a source node and a destination node. a source node and a destination node.
Note: it is possible for a device with multiple interfaces to be Note: it is possible for a device with multiple interfaces to be
configured to forward non-self-destined packets arriving from some configured to forward non-self-destined packets arriving from some
set (fewer than all) of its interfaces, and to discard non-self- set (fewer than all) of its interfaces and to discard non-self-
destined packets arriving from its other interfaces. Such a device destined packets arriving from its other interfaces. Such a device
must obey the protocol requirements for routers when receiving must obey the protocol requirements for routers when receiving
packets from, and interacting with neighbors over, the former packets from, and interacting with neighbors over, the former
(forwarding) interfaces. It must obey the protocol requirements for (forwarding) interfaces. It must obey the protocol requirements for
hosts when receiving packets from, and interacting with neighbors hosts when receiving packets from, and interacting with neighbors
over, the latter (non-forwarding) interfaces. over, the latter (non-forwarding) interfaces.
3. IPv6 Header Format 3. IPv6 Header Format
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+ + + +
| | | |
+ Destination Address + + Destination Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Version 4-bit Internet Protocol version number = 6. Version 4-bit Internet Protocol version number = 6.
Traffic Class 8-bit traffic class field. See section 7. Traffic Class 8-bit Traffic Class field. See Section 7.
Flow Label 20-bit flow label. See section 6. Flow Label 20-bit flow label. See Section 6.
Payload Length 16-bit unsigned integer. Length of the IPv6 Payload Length 16-bit unsigned integer. Length of the IPv6
payload, i.e., the rest of the packet payload, i.e., the rest of the packet
following this IPv6 header, in octets. (Note following this IPv6 header, in octets. (Note
that any extension headers [Section 4] present that any extension headers (see Section 4)
are considered part of the payload, i.e., present are considered part of the payload,
included in the length count.) i.e., included in the length count.)
Next Header 8-bit selector. Identifies the type of header Next Header 8-bit selector. Identifies the type of header
immediately following the IPv6 header. Uses immediately following the IPv6 header. Uses
the same values as the IPv4 Protocol field the same values as the IPv4 Protocol field
[IANA-PN]. [IANA-PN].
Hop Limit 8-bit unsigned integer. Decremented by 1 by Hop Limit 8-bit unsigned integer. Decremented by 1 by
each node that forwards the packet. When each node that forwards the packet. When
forwarding, the packet is discarded if Hop forwarding, the packet is discarded if Hop
Limit was zero when received or is decremented Limit was zero when received or is decremented
to zero. A node that is the destination of a to zero. A node that is the destination of a
packet should not discard a packet with hop packet should not discard a packet with Hop
limit equal to zero, it should process the Limit equal to zero; it should process the
packet normally. packet normally.
Source Address 128-bit address of the originator of the Source Address 128-bit address of the originator of the
packet. See [RFC4291]. packet. See [RFC4291].
Destination Address 128-bit address of the intended recipient of Destination Address 128-bit address of the intended recipient of
the packet (possibly not the ultimate the packet (possibly not the ultimate
recipient, if a Routing header is present). recipient, if a Routing header is present).
See [RFC4291] and section 4.4. See [RFC4291] and Section 4.4.
4. IPv6 Extension Headers 4. IPv6 Extension Headers
In IPv6, optional internet-layer information is encoded in separate In IPv6, optional internet-layer information is encoded in separate
headers that may be placed between the IPv6 header and the upper- headers that may be placed between the IPv6 header and the upper-
layer header in a packet. There is a small number of such extension layer header in a packet. There is a small number of such extension
headers, each one identified by a distinct Next Header value. headers, each one identified by a distinct Next Header value.
Extension Headers are numbered from IANA IP Protocol Numbers Extension headers are numbered from IANA IP Protocol Numbers
[IANA-PN], the same values used for IPv4 and IPv6. When processing a [IANA-PN], the same values used for IPv4 and IPv6. When processing a
sequence of Next Header values in a packet, the first one that is not sequence of Next Header values in a packet, the first one that is not
an Extension Header [IANA-EH] indicates that the next item in the an extension header [IANA-EH] indicates that the next item in the
packet is the corresponding upper-layer header. A special "No Next packet is the corresponding upper-layer header. A special "No Next
Header" value is used if there is no upper-layer header. Header" value is used if there is no upper-layer header.
As illustrated in these examples, an IPv6 packet may carry zero, one, As illustrated in these examples, an IPv6 packet may carry zero, one,
or more extension headers, each identified by the Next Header field or more extension headers, each identified by the Next Header field
of the preceding header: of the preceding header:
+---------------+------------------------ +---------------+------------------------
| IPv6 header | TCP header + data | IPv6 header | TCP header + data
| | | |
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The Hop-by-Hop Options header is not inserted or deleted, but may be The Hop-by-Hop Options header is not inserted or deleted, but may be
examined or processed by any node along a packet's delivery path, examined or processed by any node along a packet's delivery path,
until the packet reaches the node (or each of the set of nodes, in 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 case of multicast) identified in the Destination Address field of
the IPv6 header. The Hop-by-Hop Options header, when present, must the IPv6 header. The Hop-by-Hop Options header, when present, must
immediately follow the IPv6 header. Its presence is indicated by the immediately follow the IPv6 header. Its presence is indicated by the
value zero in the Next Header field of the IPv6 header. value zero in the Next Header field of the IPv6 header.
NOTE: While [RFC2460] required that all nodes must examine and NOTE: While [RFC2460] required that all nodes must examine and
process the Hop-by-Hop Options header, it is now expected that nodes process the Hop-by-Hop Options header, it is now expected that nodes
along a packet's delivery path only examine and process the Hop-by- along a packet's delivery path only examine and process the
Hop Options header if explicitly configured to do so. Hop-by-Hop Options header if explicitly configured to do so.
At the Destination node, normal demultiplexing on the Next Header At the destination node, normal demultiplexing on the Next Header
field of the IPv6 header invokes the module to process the first field of the IPv6 header invokes the module to process the first
extension header, or the upper-layer header if no extension header is extension header, or the upper-layer header if no extension header is
present. The contents and semantics of each extension header present. The contents and semantics of each extension header
determine whether or not to proceed to the next header. Therefore, determine whether or not to proceed to the next header. Therefore,
extension headers must be processed strictly in the order they appear extension headers must be processed strictly in the order they appear
in the packet; a receiver must not, for example, scan through a in the packet; a receiver must not, for example, scan through a
packet looking for a particular kind of extension header and process packet looking for a particular kind of extension header and process
that header prior to processing all preceding ones. that header prior to processing all preceding ones.
If, as a result of processing a header, the destination node is If, as a result of processing a header, the destination node is
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recommended that those headers appear in the following order: recommended that those headers appear in the following order:
IPv6 header IPv6 header
Hop-by-Hop Options header Hop-by-Hop Options header
Destination Options header (note 1) Destination Options header (note 1)
Routing header Routing header
Fragment header Fragment header
Authentication header (note 2) Authentication header (note 2)
Encapsulating Security Payload header (note 2) Encapsulating Security Payload header (note 2)
Destination Options header (note 3) Destination Options header (note 3)
upper-layer header Upper-Layer header
note 1: for options to be processed by the first destination that note 1: for options to be processed by the first destination that
appears in the IPv6 Destination Address field plus appears in the IPv6 Destination Address field plus
subsequent destinations listed in the Routing header. subsequent destinations listed in the Routing header.
note 2: additional recommendations regarding the relative order of note 2: additional recommendations regarding the relative order of
the Authentication and Encapsulating Security Payload the Authentication and Encapsulating Security Payload
headers are given in [RFC4303]. headers are given in [RFC4303].
note 3: for options to be processed only by the final destination note 3: for options to be processed only by the final destination
of the packet. of the packet.
Each extension header should occur at most once, except for the Each extension header should occur at most once, except for the
Destination Options header which should occur at most twice (once Destination Options header, which should occur at most twice (once
before a Routing header and once before the upper-layer header). before a Routing header and once before the upper-layer header).
If the upper-layer header is another IPv6 header (in the case of IPv6 If the upper-layer header is another IPv6 header (in the case of IPv6
being tunneled over or encapsulated in IPv6), it may be followed by being tunneled over or encapsulated in IPv6), it may be followed by
its own extension headers, which are separately subject to the same its own extension headers, which are separately subject to the same
ordering recommendations. ordering recommendations.
If and when other extension headers are defined, their ordering If and when other extension headers are defined, their ordering
constraints relative to the above listed headers must be specified. constraints relative to the above listed headers must be specified.
IPv6 nodes must accept and attempt to process extension headers in IPv6 nodes must accept and attempt to process extension headers in
any order and occurring any number of times in the same packet, any order and occurring any number of times in the same packet,
except for the Hop-by-Hop Options header which is restricted to except for the Hop-by-Hop Options header, which is restricted to
appear immediately after an IPv6 header only. Nonetheless, it is appear immediately after an IPv6 header only. Nonetheless, it is
strongly advised that sources of IPv6 packets adhere to the above strongly advised that sources of IPv6 packets adhere to the above
recommended order until and unless subsequent specifications revise recommended order until and unless subsequent specifications revise
that recommendation. that recommendation.
4.2. Options 4.2. Options
Two of the currently-defined extension headers defined in this Two of the currently defined extension headers specified in this
document -- the Hop-by-Hop Options header and the Destination Options document -- the Hop-by-Hop Options header and the Destination Options
header -- carry a variable number of type-length-value (TLV) encoded header -- carry a variable number of "options" that are type-length-
"options", of the following format: value (TLV) encoded in the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| Option Type | Opt Data Len | Option Data | Option Type | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
Option Type 8-bit identifier of the type of option. Option Type 8-bit identifier of the type of option.
Opt Data Len 8-bit unsigned integer. Length of the Option Opt Data Len 8-bit unsigned integer. Length of the Option
Data field of this option, in octets. Data field of this option, in octets.
Option Data Variable-length field. Option-Type-specific Option Data Variable-length field. Option-Type-specific
data. data.
The sequence of options within a header must be processed strictly in The sequence of options within a header must be processed strictly in
the order they appear in the header; a receiver must not, for the order they appear in the header; a receiver must not, for
example, scan through the header looking for a particular kind of example, scan through the header looking for a particular kind of
option and process that option prior to processing all preceding option and process that option prior to processing all preceding
ones. ones.
The Option Type identifiers are internally encoded such that their The Option Type identifiers are internally encoded such that their
highest-order two bits specify the action that must be taken if the highest-order 2 bits specify the action that must be taken if the
processing IPv6 node does not recognize the Option Type: processing IPv6 node does not recognize the Option Type:
00 - skip over this option and continue processing the header. 00 - skip over this option and continue processing the header.
01 - discard the packet. 01 - discard the packet.
10 - discard the packet and, regardless of whether or not the 10 - discard the packet and, regardless of whether or not the
packet's Destination Address was a multicast address, send an packet's Destination Address was a multicast address, send an
ICMP Parameter Problem, Code 2, message to the packet's ICMP Parameter Problem, Code 2, message to the packet's
Source Address, pointing to the unrecognized Option Type. Source Address, pointing to the unrecognized Option Type.
11 - discard the packet and, only if the packet's Destination 11 - discard the packet and, only if the packet's Destination
Address was not a multicast address, send an ICMP Parameter Address was not a multicast address, send an ICMP Parameter
Problem, Code 2, message to the packet's Source Address, Problem, Code 2, message to the packet's Source Address,
pointing to the unrecognized Option Type. pointing to the unrecognized Option Type.
The third-highest-order bit of the Option Type specifies whether or The third-highest-order bit of the Option Type specifies whether or
not the Option Data of that option can change en-route to the not the Option Data of that option can change en route to the
packet's final destination. When an Authentication header is present packet's final destination. When an Authentication header is present
in the packet, for any option whose data may change en-route, its in the packet, for any option whose data may change en route, its
entire Option Data field must be treated as zero-valued octets when entire Option Data field must be treated as zero-valued octets when
computing or verifying the packet's authenticating value. computing or verifying the packet's authenticating value.
0 - Option Data does not change en-route 0 - Option Data does not change en route
1 - Option Data may change en-route 1 - Option Data may change en route
The three high-order bits described above are to be treated as part The three high-order bits described above are to be treated as part
of the Option Type, not independent of the Option Type. That is, a of the Option Type, not independent of the Option Type. That is, a
particular option is identified by a full 8-bit Option Type, not just particular option is identified by a full 8-bit Option Type, not just
the low-order 5 bits of an Option Type. the low-order 5 bits of an Option Type.
The same Option Type numbering space is used for both the Hop-by-Hop The same Option Type numbering space is used for both the Hop-by-Hop
Options header and the Destination Options header. However, the Options header and the Destination Options header. However, the
specification of a particular option may restrict its use to only one specification of a particular option may restrict its use to only one
of those two headers. of those two headers.
Individual options may have specific alignment requirements, to Individual options may have specific alignment requirements, to
ensure that multi-octet values within Option Data fields fall on ensure that multi-octet values within Option Data fields fall on
natural boundaries. The alignment requirement of an option is natural boundaries. The alignment requirement of an option is
specified using the notation xn+y, meaning the Option Type must specified using the notation xn+y, meaning the Option Type must
appear at an integer multiple of x octets from the start of the appear at an integer multiple of x octets from the start of the
header, plus y octets. For example: header, plus y octets. For example:
2n means any 2-octet offset from the start of the header. 2n means any 2-octet offset from the start of the header.
8n+2 means any 8-octet offset from the start of the header, plus 2 8n+2 means any 8-octet offset from the start of the header, plus
octets. 2 octets.
There are two padding options which are used when necessary to align There are two padding options that are used when necessary to align
subsequent options and to pad out the containing header to a multiple subsequent options and to pad out the containing header to a multiple
of 8 octets in length. These padding options must be recognized by of 8 octets in length. These padding options must be recognized by
all IPv6 implementations: all IPv6 implementations:
Pad1 option (alignment requirement: none) Pad1 option (alignment requirement: none)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| 0 | | 0 |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
NOTE! the format of the Pad1 option is a special case -- it does NOTE! the format of the Pad1 option is a special case -- it does
not have length and value fields. not have length and value fields.
The Pad1 option is used to insert one octet of padding into the The Pad1 option is used to insert 1 octet of padding into the
Options area of a header. If more than one octet of padding is Options area of a header. If more than one octet of padding is
required, the PadN option, described next, should be used, rather required, the PadN option, described next, should be used, rather
than multiple Pad1 options. than multiple Pad1 options.
PadN option (alignment requirement: none) PadN option (alignment requirement: none)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| 1 | Opt Data Len | Option Data | 1 | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
skipping to change at page 12, line 14 skipping to change at page 13, line 23
Opt Data Len field contains the value N-2, and the Option Data Opt Data Len field contains the value N-2, and the Option Data
consists of N-2 zero-valued octets. consists of N-2 zero-valued octets.
Appendix A contains formatting guidelines for designing new options. Appendix A contains formatting guidelines for designing new options.
4.3. Hop-by-Hop Options Header 4.3. Hop-by-Hop Options Header
The Hop-by-Hop Options header is used to carry optional information The Hop-by-Hop Options header is used to carry optional information
that may be examined and processed by every node along a packet's that may be examined and processed by every node along a packet's
delivery path. The Hop-by-Hop Options header is identified by a Next delivery path. The Hop-by-Hop Options header is identified by a Next
Header value of 0 in the IPv6 header, and has the following format: Header value of 0 in the IPv6 header and has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | | | Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
. . . .
. Options . . Options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the type of header Next Header 8-bit selector. Identifies the type of header
immediately following the Hop-by-Hop Options immediately following the Hop-by-Hop Options
header. Uses the same values as the IPv4 header. Uses the same values as the IPv4
Protocol field [IANA-PN]. Protocol field [IANA-PN].
Hdr Ext Len 8-bit unsigned integer. Length of the Hop-by- Hdr Ext Len 8-bit unsigned integer. Length of the
Hop Options header in 8-octet units, not Hop-by-Hop Options header in 8-octet units,
including the first 8 octets. not including the first 8 octets.
Options Variable-length field, of length such that the Options Variable-length field, of length such that the
complete Hop-by-Hop Options header is an complete Hop-by-Hop Options header is an
integer multiple of 8 octets long. Contains integer multiple of 8 octets long. Contains
one or more TLV-encoded options, as described one or more TLV-encoded options, as described
in section 4.2. in Section 4.2.
The only hop-by-hop options defined in this document are the Pad1 and The only hop-by-hop options defined in this document are the Pad1 and
PadN options specified in section 4.2. PadN options specified in Section 4.2.
4.4. Routing Header 4.4. Routing Header
The Routing header is used by an IPv6 source to list one or more The Routing header is used by an IPv6 source to list one or more
intermediate nodes to be "visited" on the way to a packet's intermediate nodes to be "visited" on the way to a packet's
destination. This function is very similar to IPv4's Loose Source destination. This function is very similar to IPv4's Loose Source
and Record Route option. The Routing header is identified by a Next and Record Route option. The Routing header is identified by a Next
Header value of 43 in the immediately preceding header, and has the Header value of 43 in the immediately preceding header and has the
following format: following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left | | Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. type-specific data . . type-specific data .
. . . .
| | | |
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The currently defined IPv6 Routing Headers and their status can be The currently defined IPv6 Routing Headers and their status can be
found at [IANA-RH]. Allocation guidelines for IPv6 Routing Headers found at [IANA-RH]. Allocation guidelines for IPv6 Routing Headers
can be found in [RFC5871]. can be found in [RFC5871].
4.5. Fragment Header 4.5. Fragment Header
The Fragment header is used by an IPv6 source to send a packet larger The Fragment header is used by an IPv6 source to send a packet larger
than would fit in the path MTU to its destination. (Note: unlike than would fit in the path MTU to its destination. (Note: unlike
IPv4, fragmentation in IPv6 is performed only by source nodes, not by IPv4, fragmentation in IPv6 is performed only by source nodes, not by
routers along a packet's delivery path -- see section 5.) The routers along a packet's delivery path -- see Section 5.) The
Fragment header is identified by a Next Header value of 44 in the Fragment header is identified by a Next Header value of 44 in the
immediately preceding header, and has the following format: immediately preceding header and has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Reserved | Fragment Offset |Res|M| | Next Header | Reserved | Fragment Offset |Res|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification | | Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the initial header Next Header 8-bit selector. Identifies the initial header
type of the Fragmentable Part of the original type of the Fragmentable Part of the original
packet (defined below). Uses the same values packet (defined below). Uses the same values
skipping to change at page 15, line 40 skipping to change at page 17, line 16
"original packet", and it is considered to consist of three parts, as "original packet", and it is considered to consist of three parts, as
illustrated: illustrated:
original packet: original packet:
+------------------+-------------------------+---//----------------+ +------------------+-------------------------+---//----------------+
| Per-Fragment | Extension & Upper-Layer | Fragmentable | | Per-Fragment | Extension & Upper-Layer | Fragmentable |
| Headers | Headers | Part | | Headers | Headers | Part |
+------------------+-------------------------+---//----------------+ +------------------+-------------------------+---//----------------+
The Per-Fragment Headers must consist of the IPv6 header plus any The Per-Fragment headers must consist of the IPv6 header plus any
extension headers that must be processed by nodes en route to the extension headers that must be processed by nodes en route to the
destination, that is, all headers up to and including the Routing destination, that is, all headers up to and including the Routing
header if present, else the Hop-by-Hop Options header if present, header if present, else the Hop-by-Hop Options header if present,
else no extension headers. else no extension headers.
The Extension Headers are all other extension headers that are not The Extension headers are all other extension headers that are not
included in the Per-Fragment headers part of the packet. For this included in the Per-Fragment headers part of the packet. For this
purpose, the Encapsulating Security Payload (ESP) is not purpose, the Encapsulating Security Payload (ESP) is not
considered an extension header. The Upper-Layer Header is the considered an extension header. The Upper-Layer header is the
first upper-layer header that is not an IPv6 extension header. first upper-layer header that is not an IPv6 extension header.
Examples of upper-layer headers include TCP, UDP, IPv4, IPv6, Examples of upper-layer headers include TCP, UDP, IPv4, IPv6,
ICMPv6, and as noted ESP. ICMPv6, and as noted ESP.
The Fragmentable Part consists of the rest of the packet after the The Fragmentable Part consists of the rest of the packet after the
upper-layer header or after any header (i.e., initial IPv6 header upper-layer header or after any header (i.e., initial IPv6 header
or extension header) that contains a Next Header value of No Next or extension header) that contains a Next Header value of No Next
Header. Header.
The Fragmentable Part of the original packet is divided into The Fragmentable Part of the original packet is divided into
fragments. The lengths of the fragments must be chosen such that the fragments. The lengths of the fragments must be chosen such that the
skipping to change at page 16, line 16 skipping to change at page 17, line 38
ICMPv6, and as noted ESP. ICMPv6, and as noted ESP.
The Fragmentable Part consists of the rest of the packet after the The Fragmentable Part consists of the rest of the packet after the
upper-layer header or after any header (i.e., initial IPv6 header upper-layer header or after any header (i.e., initial IPv6 header
or extension header) that contains a Next Header value of No Next or extension header) that contains a Next Header value of No Next
Header. Header.
The Fragmentable Part of the original packet is divided into The Fragmentable Part of the original packet is divided into
fragments. The lengths of the fragments must be chosen such that the fragments. The lengths of the fragments must be chosen such that the
resulting fragment packets fit within the MTU of the path to the resulting fragment packets fit within the MTU of the path to the
packets' destination(s). Each complete fragment, except possibly the packet's destination(s). Each complete fragment, except possibly the
last ("rightmost") one, being an integer multiple of 8 octets long. last ("rightmost") one, is an integer multiple of 8 octets long.
The fragments are transmitted in separate "fragment packets" as The fragments are transmitted in separate "fragment packets" as
illustrated: illustrated:
original packet: original packet:
+-----------------+-----------------+--------+--------+-//-+--------+ +-----------------+-----------------+--------+--------+-//-+--------+
| Per-Fragment |Ext & Upper-Layer| first | second | | last | | Per-Fragment |Ext & Upper-Layer| first | second | | last |
| Headers | Headers |fragment|fragment|....|fragment| | Headers | Headers |fragment|fragment|....|fragment|
+-----------------+-----------------+--------+--------+-//-+--------+ +-----------------+-----------------+--------+--------+-//-+--------+
skipping to change at page 16, line 50 skipping to change at page 18, line 36
o o
o o
o o
+------------------+--------+----------+ +------------------+--------+----------+
| Per-Fragment |Fragment| last | | Per-Fragment |Fragment| last |
| Headers | Header | fragment | | Headers | Header | fragment |
+------------------+--------+----------+ +------------------+--------+----------+
The first fragment packet is composed of: The first fragment packet is composed of:
(1) The Per-Fragment Headers of the original packet, with the (1) The Per-Fragment headers of the original packet, with the
Payload Length of the original IPv6 header changed to contain the Payload Length of the original IPv6 header changed to contain
length of this fragment packet only (excluding the length of the the length of this fragment packet only (excluding the length
IPv6 header itself), and the Next Header field of the last header of the IPv6 header itself), and the Next Header field of the
of the Per-Fragment Headers changed to 44. last header of the Per-Fragment headers changed to 44.
(2) A Fragment header containing: (2) A Fragment header containing:
The Next Header value that identifies the first header after The Next Header value that identifies the first header
the Per-Fragment Headers of the original packet. after the Per-Fragment headers of the original packet.
A Fragment Offset containing the offset of the fragment, in A Fragment Offset containing the offset of the fragment,
8-octet units, relative to the start of the Fragmentable Part in 8-octet units, relative to the start of the
of the original packet. The Fragment Offset of the first Fragmentable Part of the original packet. The Fragment
("leftmost") fragment is 0. Offset of the first ("leftmost") fragment is 0.
An M flag value of 1 as this is the first fragment. An M flag value of 1 as this is the first fragment.
The Identification value generated for the original packet. The Identification value generated for the original
packet.
(3) Extension Headers, if any, and the Upper-Layer header. These (3) Extension headers, if any, and the Upper-Layer header. These
headers must be in the first fragment. Note: This restricts the headers must be in the first fragment. Note: This restricts
size of the headers through the Upper-Layer header to the MTU of the size of the headers through the Upper-Layer header to the
the path to the packets' destinations(s). MTU of the path to the packet's destinations(s).
(4) The first fragment. (4) The first fragment.
The subsequent fragment packets are composed of: The subsequent fragment packets are composed of:
(1) The Per-Fragment Headers of the original packet, with the (1) The Per-Fragment headers of the original packet, with the
Payload Length of the original IPv6 header changed to contain the Payload Length of the original IPv6 header changed to contain
length of this fragment packet only (excluding the length of the the length of this fragment packet only (excluding the length
IPv6 header itself), and the Next Header field of the last header of the IPv6 header itself), and the Next Header field of the
of the Per-Fragment Headers changed to 44. last header of the Per-Fragment headers changed to 44.
(2) A Fragment header containing: (2) A Fragment header containing:
The Next Header value that identifies the first header after The Next Header value that identifies the first header
the Per-Fragment Headers of the original packet. after the Per-Fragment headers of the original packet.
A Fragment Offset containing the offset of the fragment, in A Fragment Offset containing the offset of the fragment,
8-octet units, relative to the start of the Fragmentable part in 8-octet units, relative to the start of the
of the original packet. Fragmentable Part of the original packet.
An M flag value of 0 if the fragment is the last ("rightmost") An M flag value of 0 if the fragment is the last
one, else an M flag value of 1. ("rightmost") one, else an M flag value of 1.
The Identification value generated for the original packet. The Identification value generated for the original
packet.
(3) The fragment itself. (3) The fragment itself.
Fragments must not be created that overlap with any other fragments Fragments must not be created that overlap with any other fragments
created from the original packet. created from the original packet.
At the destination, fragment packets are reassembled into their At the destination, fragment packets are reassembled into their
original, unfragmented form, as illustrated: original, unfragmented form, as illustrated:
reassembled original packet: reassembled original packet:
+---------------+-----------------+---------+--------+-//--+--------+ +---------------+-----------------+---------+--------+-//--+--------+
| Per-Fragment |Ext & Upper-Layer| first | second | | last | | Per-Fragment |Ext & Upper-Layer| first | second | | last |
| Headers | Headers |frag data|fragment|.....|fragment| | Headers | Headers |frag data|fragment|.....|fragment|
+---------------+-----------------+---------+--------+-//--+--------+ +---------------+-----------------+---------+--------+-//--+--------+
The following rules govern reassembly: The following rules govern reassembly:
An original packet is reassembled only from fragment packets that An original packet is reassembled only from fragment packets that
have the same Source Address, Destination Address, and Fragment have the same Source Address, Destination Address, and Fragment
Identification. Identification.
The Per-Fragment Headers of the reassembled packet consists of all The Per-Fragment headers of the reassembled packet consists of all
headers up to, but not including, the Fragment header of the first headers up to, but not including, the Fragment header of the first
fragment packet (that is, the packet whose Fragment Offset is fragment packet (that is, the packet whose Fragment Offset is
zero), with the following two changes: zero), with the following two changes:
The Next Header field of the last header of the Per-Fragment The Next Header field of the last header of the Per-Fragment
Headers is obtained from the Next Header field of the first headers is obtained from the Next Header field of the first
fragment's Fragment header. fragment's Fragment header.
The Payload Length of the reassembled packet is computed from The Payload Length of the reassembled packet is computed from
the length of the Per-Fragment Headers and the length and the length of the Per-Fragment headers and the length and
offset of the last fragment. For example, a formula for offset of the last fragment. For example, a formula for
computing the Payload Length of the reassembled original packet computing the Payload Length of the reassembled original packet
is: is:
PL.orig = PL.first - FL.first - 8 + (8 * FO.last) + FL.last PL.orig = PL.first - FL.first - 8 + (8 * FO.last) + FL.last
where where
PL.orig = Payload Length field of reassembled packet. PL.orig = Payload Length field of reassembled packet.
PL.first = Payload Length field of first fragment packet. PL.first = Payload Length field of first fragment packet.
FL.first = length of fragment following Fragment header of FL.first = length of fragment following Fragment header of
first fragment packet. first fragment packet.
FO.last = Fragment Offset field of Fragment header of last FO.last = Fragment Offset field of Fragment header of last
fragment packet. fragment packet.
FL.last = length of fragment following Fragment header of FL.last = length of fragment following Fragment header of
last fragment packet. last fragment packet.
The Fragmentable Part of the reassembled packet is constructed The Fragmentable Part of the reassembled packet is constructed
from the fragments following the Fragment headers in each of from the fragments following the Fragment headers in each of
the fragment packets. The length of each fragment is computed the fragment packets. The length of each fragment is computed
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relative position in Fragmentable Part is computed from its relative position in Fragmentable Part is computed from its
Fragment Offset value. Fragment Offset value.
The Fragment header is not present in the final, reassembled The Fragment header is not present in the final, reassembled
packet. packet.
If the fragment is a whole datagram (that is, both the Fragment If the fragment is a whole datagram (that is, both the Fragment
Offset field and the M flag are zero), then it does not need Offset field and the M flag are zero), then it does not need
any further reassembly and should be processed as a fully any further reassembly and should be processed as a fully
reassembled packet (i.e., updating Next Header, adjust Payload reassembled packet (i.e., updating Next Header, adjust Payload
Length, removing the Fragmentation Header, etc.). Any other Length, removing the Fragment header, etc.). Any other
fragments that match this packet (i.e., the same IPv6 Source fragments that match this packet (i.e., the same IPv6 Source
Address, IPv6 Destination Address, and Fragment Identification) Address, IPv6 Destination Address, and Fragment Identification)
should be processed independently. should be processed independently.
The following error conditions may arise when reassembling fragmented The following error conditions may arise when reassembling fragmented
packets: packets:
o If insufficient fragments are received to complete reassembly o If insufficient fragments are received to complete reassembly
of a packet within 60 seconds of the reception of the first- of a packet within 60 seconds of the reception of the first-
arriving fragment of that packet, reassembly of that packet arriving fragment of that packet, reassembly of that packet
skipping to change at page 20, line 17 skipping to change at page 22, line 5
would exceed 65,535 octets, then that fragment must be would exceed 65,535 octets, then that fragment must be
discarded and an ICMP Parameter Problem, Code 0, message should discarded and an ICMP Parameter Problem, Code 0, message should
be sent to the source of the fragment, pointing to the Fragment be sent to the source of the fragment, pointing to the Fragment
Offset field of the fragment packet. Offset field of the fragment packet.
o If the first fragment does not include all headers through an o If the first fragment does not include all headers through an
Upper-Layer header, then that fragment should be discarded and Upper-Layer header, then that fragment should be discarded and
an ICMP Parameter Problem, Code 3, message should be sent to an ICMP Parameter Problem, Code 3, message should be sent to
the source of the fragment, with the Pointer field set to zero. the source of the fragment, with the Pointer field set to zero.
o If any of the fragments being reassembled overlaps with any o If any of the fragments being reassembled overlap with any
other fragments being reassembled for the same packet, other fragments being reassembled for the same packet,
reassembly of that packet must be abandoned and all the reassembly of that packet must be abandoned and all the
fragments that have been received for that packet must be fragments that have been received for that packet must be
discarded and no ICMP error messages should be sent. discarded, and no ICMP error messages should be sent.
It should be noted that fragments may be duplicated in the It should be noted that fragments may be duplicated in the
network. Instead of treating these exact duplicate fragments network. Instead of treating these exact duplicate fragments
as overlapping fragments, an implementation may choose to as overlapping fragments, an implementation may choose to
detect this case and drop exact duplicate fragments while detect this case and drop exact duplicate fragments while
keeping the other fragments belonging to the same packet. keeping the other fragments belonging to the same packet.
The following conditions are not expected to occur frequently, but The following conditions are not expected to occur frequently but are
are not considered errors if they do: not considered errors if they do:
The number and content of the headers preceding the Fragment The number and content of the headers preceding the Fragment
header of different fragments of the same original packet may header of different fragments of the same original packet may
differ. Whatever headers are present, preceding the Fragment differ. Whatever headers are present, preceding the Fragment
header in each fragment packet, are processed when the packets header in each fragment packet, are processed when the packets
arrive, prior to queueing the fragments for reassembly. Only arrive, prior to queueing the fragments for reassembly. Only
those headers in the Offset zero fragment packet are retained in those headers in the Offset zero fragment packet are retained in
the reassembled packet. the reassembled packet.
The Next Header values in the Fragment headers of different The Next Header values in the Fragment headers of different
skipping to change at page 21, line 10 skipping to change at page 23, line 10
the values from the Offset zero fragment is not sufficient. For the values from the Offset zero fragment is not sufficient. For
example, Section 5.3 of [RFC3168] describes how to combine the example, Section 5.3 of [RFC3168] describes how to combine the
Explicit Congestion Notification (ECN) bits from different Explicit Congestion Notification (ECN) bits from different
fragments to derive the ECN bits of the reassembled packet. fragments to derive the ECN bits of the reassembled packet.
4.6. Destination Options Header 4.6. Destination Options Header
The Destination Options header is used to carry optional information The Destination Options header is used to carry optional information
that need be examined only by a packet's destination node(s). The that need be examined only by a packet's destination node(s). The
Destination Options header is identified by a Next Header value of 60 Destination Options header is identified by a Next Header value of 60
in the immediately preceding header, and has the following format: in the immediately preceding header and has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | | | Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
. . . .
. Options . . Options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 21, line 35 skipping to change at page 23, line 35
Protocol field [IANA-PN]. Protocol field [IANA-PN].
Hdr Ext Len 8-bit unsigned integer. Length of the Hdr Ext Len 8-bit unsigned integer. Length of the
Destination Options header in 8-octet units, Destination Options header in 8-octet units,
not including the first 8 octets. not including the first 8 octets.
Options Variable-length field, of length such that the Options Variable-length field, of length such that the
complete Destination Options header is an complete Destination Options header is an
integer multiple of 8 octets long. Contains integer multiple of 8 octets long. Contains
one or more TLV-encoded options, as described one or more TLV-encoded options, as described
in section 4.2. in Section 4.2.
The only destination options defined in this document are the Pad1 The only destination options defined in this document are the Pad1
and PadN options specified in section 4.2. and PadN options specified in Section 4.2.
Note that there are two possible ways to encode optional destination Note that there are two possible ways to encode optional destination
information in an IPv6 packet: either as an option in the Destination information in an IPv6 packet: either as an option in the Destination
Options header, or as a separate extension header. The Fragment Options header or as a separate extension header. The Fragment
header and the Authentication header are examples of the latter header and the Authentication header are examples of the latter
approach. Which approach can be used depends on what action is approach. Which approach can be used depends on what action is
desired of a destination node that does not understand the optional desired of a destination node that does not understand the optional
information: information:
o If the desired action is for the destination node to discard o If the desired action is for the destination node to discard
the packet and, only if the packet's Destination Address is not the packet and, only if the packet's Destination Address is not
a multicast address, send an ICMP Unrecognized Type message to a multicast address, send an ICMP Unrecognized Type message to
the packet's Source Address, then the information may be the packet's Source Address, then the information may be
encoded either as a separate header or as an option in the encoded either as a separate header or as an option in the
Destination Options header whose Option Type has the value 11 Destination Options header whose Option Type has the value 11
in its highest-order two bits. The choice may depend on such in its highest-order 2 bits. The choice may depend on such
factors as which takes fewer octets, or which yields better factors as which takes fewer octets, or which yields better
alignment or more efficient parsing. alignment or more efficient parsing.
o If any other action is desired, the information must be encoded o If any other action is desired, the information must be encoded
as an option in the Destination Options header whose Option as an option in the Destination Options header whose Option
Type has the value 00, 01, or 10 in its highest-order two bits, Type has the value 00, 01, or 10 in its highest-order 2 bits,
specifying the desired action (see section 4.2). specifying the desired action (see Section 4.2).
4.7. No Next Header 4.7. No Next Header
The value 59 in the Next Header field of an IPv6 header or any The value 59 in the Next Header field of an IPv6 header or any
extension header indicates that there is nothing following that extension header indicates that there is nothing following that
header. If the Payload Length field of the IPv6 header indicates the header. If the Payload Length field of the IPv6 header indicates the
presence of octets past the end of a header whose Next Header field presence of octets past the end of a header whose Next Header field
contains 59, those octets must be ignored, and passed on unchanged if contains 59, those octets must be ignored and passed on unchanged if
the packet is forwarded. the packet is forwarded.
4.8. Defining New Extension Headers and Options 4.8. Defining New Extension Headers and Options
Defining new IPv6 extension headers is not recommended, unless there Defining new IPv6 extension headers is not recommended, unless there
are no existing IPv6 extension headers that can be used by specifying 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 a new option for that IPv6 extension header. A proposal to specify a
new IPv6 extension header must include a detailed technical new IPv6 extension header must include a detailed technical
explanation of why an existing IPv6 extension header can not be used explanation of why an existing IPv6 extension header can not be used
for the desired new function. See [RFC6564] for additional for the desired new function. See [RFC6564] for additional
background information. background information.
Note: New extension headers that require hop-by-hop behavior must not Note: New extension headers that require hop-by-hop behavior must not
be defined because, as specified in Section 4 of this document, the be defined because, as specified in Section 4 of this document, the
only Extension Header that has hop-by-hop behavior is the Hop-by-Hop only extension header that has hop-by-hop behavior is the Hop-by-Hop
Options header. Options header.
New hop-by-hop options are not recommended because nodes may be New hop-by-hop options are not recommended because nodes may be
configured to ignore the Hop-by-Hop Option header, drop packets configured to ignore the Hop-by-Hop Options header, drop packets
containing a hop-by-hop header, or assign packets containing a hop- containing a Hop-by-Hop Options header, or assign packets containing
by-hop header to a slow processing path. Designers considering a Hop-by-Hop Options header to a slow processing path. Designers
defining new hop-by-hop options need to be aware of this likely considering defining new hop-by-hop options need to be aware of this
behaviour. There has to be a very clear justification why any new likely behavior. There has to be a very clear justification why any
hop-by-hop option is needed before it is standardized. new hop-by-hop option is needed before it is standardized.
Instead of defining new Extension Headers, it is recommended that the Instead of defining new extension headers, it is recommended that the
Destination Options header is used to carry optional information that Destination Options header is used to carry optional information that
must be examined only by a packet's destination node(s), because they must be examined only by a packet's destination node(s), because they
provide better handling and backward compatibility. provide better handling and backward compatibility.
If new Extension Headers are defined, they need to use the following If new extension headers are defined, they need to use the following
format: format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | | | Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
. . . .
. Header Specific Data . . Header-Specific Data .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the type of Next Header 8-bit selector. Identifies the type of
header immediately following the extension header immediately following the extension
header. Uses the same values as the IPv4 header. Uses the same values as the IPv4
Protocol field [IANA-PN]. Protocol field [IANA-PN].
Hdr Ext Len 8-bit unsigned integer. Length of the Hdr Ext Len 8-bit unsigned integer. Length of the
Destination Options header in 8-octet units, Destination Options header in 8-octet units,
not including the first 8 octets. not including the first 8 octets.
Header Specific Data Variable-length field. Fields specific to Header Specific Data Variable-length field. Fields specific to
the extension header. the extension header.
5. Packet Size Issues 5. Packet Size Issues
IPv6 requires that every link in the internet have an MTU of 1280 IPv6 requires that every link in the Internet have an MTU of 1280
octets or greater. This is known as the IPv6 minimum link MTU. On octets or greater. This is known as the IPv6 minimum link MTU. On
any link that cannot convey a 1280-octet packet in one piece, link- any link that cannot convey a 1280-octet packet in one piece, link-
specific fragmentation and reassembly must be provided at a layer specific fragmentation and reassembly must be provided at a layer
below IPv6. below IPv6.
Links that have a configurable MTU (for example, PPP links [RFC1661]) Links that have a configurable MTU (for example, PPP links [RFC1661])
must be configured to have an MTU of at least 1280 octets; it is must be configured to have an MTU of at least 1280 octets; it is
recommended that they be configured with an MTU of 1500 octets or recommended that they be configured with an MTU of 1500 octets or
greater, to accommodate possible encapsulations (i.e., tunneling) greater, to accommodate possible encapsulations (i.e., tunneling)
without incurring IPv6-layer fragmentation. without incurring IPv6-layer fragmentation.
From each link to which a node is directly attached, the node must be From each link to which a node is directly attached, the node must be
able to accept packets as large as that link's MTU. able to accept packets as large as that link's MTU.
It is strongly recommended that IPv6 nodes implement Path MTU It is strongly recommended that IPv6 nodes implement Path MTU
Discovery [RFC1981], in order to discover and take advantage of path Discovery [RFC8201], in order to discover and take advantage of path
MTUs greater than 1280 octets. However, a minimal IPv6 MTUs greater than 1280 octets. However, a minimal IPv6
implementation (e.g., in a boot ROM) may simply restrict itself to implementation (e.g., in a boot ROM) may simply restrict itself to
sending packets no larger than 1280 octets, and omit implementation sending packets no larger than 1280 octets, and omit implementation
of Path MTU Discovery. of Path MTU Discovery.
In order to send a packet larger than a path's MTU, a node may use In order to send a packet larger than a path's MTU, a node may use
the IPv6 Fragment header to fragment the packet at the source and the IPv6 Fragment header to fragment the packet at the source and
have it reassembled at the destination(s). However, the use of such have it reassembled at the destination(s). However, the use of such
fragmentation is discouraged in any application that is able to fragmentation is discouraged in any application that is able to
adjust its packets to fit the measured path MTU (i.e., down to 1280 adjust its packets to fit the measured path MTU (i.e., down to 1280
skipping to change at page 25, line 42 skipping to change at page 27, line 45
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o If the IPv6 packet contains a Routing header, the Destination o If the IPv6 packet contains a Routing header, the Destination
Address used in the pseudo-header is that of the final Address used in the pseudo-header is that of the final
destination. At the originating node, that address will be in destination. At the originating node, that address will be in
the last element of the Routing header; at the recipient(s), the last element of the Routing header; at the recipient(s),
that address will be in the Destination Address field of the that address will be in the Destination Address field of the
IPv6 header. IPv6 header.
o The Next Header value in the pseudo-header identifies the o The Next Header value in the pseudo-header identifies the
upper-layer protocol (e.g., 6 for TCP, or 17 for UDP). It will upper-layer protocol (e.g., 6 for TCP or 17 for UDP). It will
differ from the Next Header value in the IPv6 header if there differ from the Next Header value in the IPv6 header if there
are extension headers between the IPv6 header and the upper- are extension headers between the IPv6 header and the upper-
layer header. layer header.
o The Upper-Layer Packet Length in the pseudo-header is the o The Upper-Layer Packet Length in the pseudo-header is the
length of the upper-layer header and data (e.g., TCP header length of the upper-layer header and data (e.g., TCP header
plus TCP data). Some upper-layer protocols carry their own plus TCP data). Some upper-layer protocols carry their own
length information (e.g., the Length field in the UDP header); length information (e.g., the Length field in the UDP header);
for such protocols, that is the length used in the pseudo- for such protocols, that is the length used in the pseudo-
header. Other protocols (such as TCP) do not carry their own header. Other protocols (such as TCP) do not carry their own
skipping to change at page 26, line 19 skipping to change at page 28, line 23
the length of any extension headers present between the IPv6 the length of any extension headers present between the IPv6
header and the upper-layer header. header and the upper-layer header.
o Unlike IPv4, the default behavior when UDP packets are o Unlike IPv4, the default behavior when UDP packets are
originated by an IPv6 node is that the UDP checksum is not originated by an IPv6 node is that the UDP checksum is not
optional. That is, whenever originating a UDP packet, an IPv6 optional. That is, whenever originating a UDP packet, an IPv6
node must compute a UDP checksum over the packet and the node must compute a UDP checksum over the packet and the
pseudo-header, and, if that computation yields a result of pseudo-header, and, if that computation yields a result of
zero, it must be changed to hex FFFF for placement in the UDP zero, it must be changed to hex FFFF for placement in the UDP
header. IPv6 receivers must discard UDP packets containing a header. IPv6 receivers must discard UDP packets containing a
zero checksum, and should log the error. zero checksum and should log the error.
o As an exception to the default behaviour, protocols that use o As an exception to the default behavior, protocols that use UDP
UDP as a tunnel encapsulation may enable zero-checksum mode for as a tunnel encapsulation may enable zero-checksum mode for a
a specific port (or set of ports) for sending and/or receiving. specific port (or set of ports) for sending and/or receiving.
Any node implementing zero-checksum mode must follow the Any node implementing zero-checksum mode must follow the
requirements specified in "Applicability Statement for the Use requirements specified in "Applicability Statement for the Use
of IPv6 UDP Datagrams with Zero Checksums" [RFC6936]. of IPv6 UDP Datagrams with Zero Checksums" [RFC6936].
The IPv6 version of ICMP [RFC4443] includes the above pseudo-header The IPv6 version of ICMP [RFC4443] includes the above pseudo-header
in its checksum computation; this is a change from the IPv4 version in its checksum computation; this is a change from the IPv4 version
of ICMP, which does not include a pseudo-header in its checksum. The of ICMP, which does not include a pseudo-header in its checksum. The
reason for the change is to protect ICMP from misdelivery or reason for the change is to protect ICMP from misdelivery or
corruption of those fields of the IPv6 header on which it depends, corruption of those fields of the IPv6 header on which it depends,
which, unlike IPv4, are not covered by an internet-layer checksum. which, unlike IPv4, are not covered by an internet-layer checksum.
The Next Header field in the pseudo-header for ICMP contains the The Next Header field in the pseudo-header for ICMP contains the
value 58, which identifies the IPv6 version of ICMP. value 58, which identifies the IPv6 version of ICMP.
8.2. Maximum Packet Lifetime 8.2. Maximum Packet Lifetime
Unlike IPv4, IPv6 nodes are not required to enforce maximum packet Unlike IPv4, IPv6 nodes are not required to enforce maximum packet
lifetime. That is the reason the IPv4 "Time to Live" field was lifetime. That is the reason the IPv4 "Time-to-Live" field was
renamed "Hop Limit" in IPv6. In practice, very few, if any, IPv4 renamed "Hop Limit" in IPv6. In practice, very few, if any, IPv4
implementations conform to the requirement that they limit packet implementations conform to the requirement that they limit packet
lifetime, so this is not a change in practice. Any upper-layer lifetime, so this is not a change in practice. Any upper-layer
protocol that relies on the internet layer (whether IPv4 or IPv6) to protocol that relies on the internet layer (whether IPv4 or IPv6) to
limit packet lifetime ought to be upgraded to provide its own limit packet lifetime ought to be upgraded to provide its own
mechanisms for detecting and discarding obsolete packets. mechanisms for detecting and discarding obsolete packets.
8.3. Maximum Upper-Layer Payload Size 8.3. Maximum Upper-Layer Payload Size
When computing the maximum payload size available for upper-layer When computing the maximum payload size available for upper-layer
data, an upper-layer protocol must take into account the larger size data, an upper-layer protocol must take into account the larger size
of the IPv6 header relative to the IPv4 header. For example, in of the IPv6 header relative to the IPv4 header. For example, in
IPv4, TCP's MSS option is computed as the maximum packet size (a IPv4, TCP's Maximum Segment Size (MSS) option is computed as the
default value or a value learned through Path MTU Discovery) minus 40 maximum packet size (a default value or a value learned through Path
octets (20 octets for the minimum-length IPv4 header and 20 octets MTU Discovery) minus 40 octets (20 octets for the minimum-length IPv4
for the minimum-length TCP header). When using TCP over IPv6, the header and 20 octets for the minimum-length TCP header). When using
MSS must be computed as the maximum packet size minus 60 octets, TCP over IPv6, the MSS must be computed as the maximum packet size
because the minimum-length IPv6 header (i.e., an IPv6 header with no minus 60 octets, because the minimum-length IPv6 header (i.e., an
extension headers) is 20 octets longer than a minimum-length IPv4 IPv6 header with no extension headers) is 20 octets longer than a
header. minimum-length IPv4 header.
8.4. Responding to Packets Carrying Routing Headers 8.4. Responding to Packets Carrying Routing Headers
When an upper-layer protocol sends one or more packets in response to When an upper-layer protocol sends one or more packets in response to
a received packet that included a Routing header, the response a received packet that included a Routing header, the response
packet(s) must not include a Routing header that was automatically packet(s) must not include a Routing header that was automatically
derived by "reversing" the received Routing header UNLESS the derived by "reversing" the received Routing header UNLESS the
integrity and authenticity of the received Source Address and Routing integrity and authenticity of the received Source Address and Routing
header have been verified (e.g., via the use of an Authentication header have been verified (e.g., via the use of an Authentication
header in the received packet). In other words, only the following header in the received packet). In other words, only the following
skipping to change at page 27, line 46 skipping to change at page 29, line 46
configuration). configuration).
o Response packets that carry Routing headers that were derived o Response packets that carry Routing headers that were derived
by reversing the Routing header of the received packet IF AND by reversing the Routing header of the received packet IF AND
ONLY IF the integrity and authenticity of the Source Address ONLY IF the integrity and authenticity of the Source Address
and Routing header from the received packet have been verified and Routing header from the received packet have been verified
by the responder. by the responder.
9. IANA Considerations 9. IANA Considerations
RFC2460 is referenced in a number of IANA registries. These include: RFC 2460 is referenced in a number of IANA registries. These
include:
o Internet Protocol Version 6 (IPv6) Parameters [IANA-6P] o Internet Protocol Version 6 (IPv6) Parameters [IANA-6P]
o Assigned Internet Protocol Numbers [IANA-PN]
o Assigned Internet Protocol Numbers [IANA-PN]
o ONC RPC Network Identifiers (netids) [IANA-NI] o ONC RPC Network Identifiers (netids) [IANA-NI]
o Technical requirements for authoritative name servers [IANA-NS]
o Network Layer Protocol Identifiers (NLPIDs) of Interest o Network Layer Protocol Identifiers (NLPIDs) of Interest
[IANA-NL] [IANA-NL]
o Protocol Registries [IANA-PR] o Protocol Registries [IANA-PR]
o Structure of Management Information (SMI) Numbers (MIB Module The IANA has updated these references to point to this document.
Registrations) [IANA-MI]
The IANA should update these references to point to this document.
10. Security Considerations 10. Security Considerations
IPv6, from the viewpoint of the basic format and transmission of IPv6, from the viewpoint of the basic format and transmission of
packets, has security properties that are similar to IPv4. These packets, has security properties that are similar to IPv4. These
security issues include: security issues include:
o Eavesdropping, On-path elements can observe the whole packet o Eavesdropping, where on-path elements can observe the whole
(including both contents and metadata) of each IPv6 datagram. packet (including both contents and metadata) of each IPv6
o Replay, where attacker records a sequence of packets off of the datagram.
wire and plays them back to the party which originally received o Replay, where the attacker records a sequence of packets off of
them. the wire and plays them back to the party that originally
received them.
o Packet insertion, where the attacker forges a packet with some o Packet insertion, where the attacker forges a packet with some
chosen set of properties and injects it into the network. chosen set of properties and injects it into the network.
o Packet deletion, where the attacker remove a packet from the o Packet deletion, where the attacker removes a packet from the
wire. wire.
o Packet modification, where the attacker removes a packet from o Packet modification, where the attacker removes a packet from
the wire, modifies it, and re-injects it into the network. the wire, modifies it, and reinjects it into the network.
o Man in the Middle attacks, where the attacker subverts the o Man-in-the-middle (MITM) attacks, where the attacker subverts
communication stream in order to pose as the sender to receiver the communication stream in order to pose as the sender to
and the receiver to the sender. receiver and the receiver to the sender.
o Denial of Service Attacks, where the attacker sends large o Denial-of-service (DoS) attacks, where the attacker sends large
amounts of legitimate traffic to a destination to overwhelm it. amounts of legitimate traffic to a destination to overwhelm it.
IPv6 packets can be protected from eavesdropping, replay, packet IPv6 packets can be protected from eavesdropping, replay, packet
insertion, packet modification, and man in the middle attacks by use insertion, packet modification, and MITM attacks by use of the
of the "Security Architecture for the Internet Protocol" [RFC4301]. "Security Architecture for the Internet Protocol" [RFC4301]. In
In addition, upper-layer protocols such as TLS or SSH can be used to addition, upper-layer protocols such as Transport Layer Security
protect the application layer traffic running on top of IPv6. (TLS) or Secure Shell (SSH) can be used to protect the application-
layer traffic running on top of IPv6.
There is not any mechanism to protect against "denial of service There is not any mechanism to protect against DoS attacks. Defending
attacks". Defending against these type of attacks is outside the against these type of attacks is outside the scope of this
scope of this specification. specification.
IPv6 addresses are significantly larger than IPv4 address making it IPv6 addresses are significantly larger than IPv4 addresses making it
much harder to scan the address space across the Internet and even on much harder to scan the address space across the Internet and even on
a single network link (e.g., Local Area Network). See [RFC7707] for a single network link (e.g., Local Area Network). See [RFC7707] for
more information. more information.
IPv6 addresses of nodes are expected to be more visible on the IPv6 addresses of nodes are expected to be more visible on the
Internet as compared with IPv4 since the use of address translation Internet as compared with IPv4 since the use of address translation
technology is reduced. This creates some additional privacy issues technology is reduced. This creates some additional privacy issues
such as making it easier to distinguish endpoints. See [RFC7721] for such as making it easier to distinguish endpoints. See [RFC7721] for
more information. more information.
The design of IPv6 extension headers architecture, while adding a lot The design of IPv6 extension header architecture, while adding a lot
of flexibility, also creates new security challenges. As noted of flexibility, also creates new security challenges. As noted
below, issues relating the fragment extension header have been below, issues relating to the Fragment extension header have been
resolved, but it's clear that for any new extension header designed resolved, but it's clear that for any new extension header designed
in the future, the security implications need to be examined in the future, the security implications need to be examined
throughly, and this needs to include how the new extension header thoroughly, and this needs to include how the new extension header
works with existing extension headers. See [RFC7045] for more works with existing extension headers. See [RFC7045] for more
information. information.
This version of the IPv6 specification resolves a number of security This version of the IPv6 specification resolves a number of security
issues that were found with the previous version [RFC2460] of the issues that were found with the previous version [RFC2460] of the
IPv6 specification. These include: IPv6 specification. These include:
o Revised the text to handle the case of fragments that are whole o Revised the text to handle the case of fragments that are whole
datagrams (i.e., both the Fragment Offset field and the M flag datagrams (i.e., both the Fragment Offset field and the M flag
are zero). If received they should be processed as a are zero). If received, they should be processed as a
reassembled packet. Any other fragments that match should be reassembled packet. Any other fragments that match should be
processed independently. The Fragment creation process was processed independently. The Fragment creation process was
modified to not create whole datagram fragments (Fragment modified to not create whole datagram fragments (Fragment
Offset field and the M flag are zero). See [RFC6946] and Offset field and the M flag are zero). See [RFC6946] and
[RFC8021] for more information. [RFC8021] for more information.
o Removed the paragraph in Section 5 that required including a
Fragment header to outgoing packets if an ICMP Packet Too Big
message reporting a Next-Hop MTU is less than 1280. See
[RFC6946] for more information.
o Changed the text to require that IPv6 nodes must not create o Changed the text to require that IPv6 nodes must not create
overlapping fragments. Also, when reassembling an IPv6 overlapping fragments. Also, when reassembling an IPv6
datagram, if one or more its constituent fragments is datagram, if one or more of its constituent fragments is
determined to be an overlapping fragment, the entire datagram determined to be an overlapping fragment, the entire datagram
(and any constituent fragments) must be silently discarded. (and any constituent fragments) must be silently discarded.
Includes clarification that no ICMP error message should be Includes clarification that no ICMP error message should be
sent if overlapping fragments are received. See [RFC5722] for sent if overlapping fragments are received. See [RFC5722] for
more information. more information.
0 Revised the text to require that all headers through the first o Revised the text to require that all headers through the first
Upper-Layer Header are in the first fragment. See [RFC6946] upper-layer header are in the first fragment. See [RFC7112]
for more information.
o Removed the paragraph in Section 5 that required including a
fragment header to outgoing packets if a ICMP Packet Too Big
message reporting a Next-Hop MTU less than 1280. See [RFC7112]
for more information. for more information.
o Incorporated the updates from [RFC5095] and [RFC5871] to remove o Incorporated the updates from [RFC5095] and [RFC5871] to remove
the description of the RH0 Routing Header, that the allocations the description of the Routing Header type 0 (RH0), that the
guidelines for routing headers are specified in RFC5871, and allocations guidelines for Routing headers are specified in RFC
removed RH0 Routing Header from the list of required extension 5871, and removed RH0 from the list of required extension
headers. headers.
Security issues relating to other parts of IPv6 including addressing, Security issues relating to other parts of IPv6 including addressing,
ICMPv6, Path MTU Discovery, etc., are discussed in the appropriate ICMPv6, Path MTU Discovery, etc., are discussed in the appropriate
specifications. specifications.
11. Acknowledgments 11. References
The authors gratefully acknowledge the many helpful suggestions of
the members of the IPng working group, the End-to-End Protocols
research group, and the Internet Community At Large.
The authors would also like to acknowledge the authors of the
updating RFCs that were incorporated in this version of the document
to move the IPv6 specification to Internet Standard. They are Joe
Abley, Shane Amante, Jari Arkko, Manav Bhatia, Ronald P. Bonica,
Scott Bradner, Brian Carpenter, P.F. Chimento, Marshall Eubanks,
Fernando Gont, James Hoagland, Sheng Jiang, Erik Kline, Suresh
Krishnan, Vishwas Manral, George Neville-Neil, Jarno Rajahalme, Pekka
Savola, Magnus Westerlund, and James Woodyatt.
12. References
12.1. Normative References 11.1. Normative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, DOI [RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791,
10.17487/RFC0791, September 1981, DOI 10.17487/RFC0791, September 1981,
<http://www.rfc-editor.org/info/rfc791>. <http://www.rfc-editor.org/info/rfc791>.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS "Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, DOI Field) in the IPv4 and IPv6 Headers", RFC 2474,
10.17487/RFC2474, December 1998, DOI 10.17487/RFC2474, December 1998,
<http://www.rfc-editor.org/info/rfc2474>. <http://www.rfc-editor.org/info/rfc2474>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP", RFC of Explicit Congestion Notification (ECN) to IP",
3168, DOI 10.17487/RFC3168, September 2001, RFC 3168, DOI 10.17487/RFC3168, September 2001,
<http://www.rfc-editor.org/info/rfc3168>. <http://www.rfc-editor.org/info/rfc3168>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>. 2006, <http://www.rfc-editor.org/info/rfc4291>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", RFC 4443, DOI Protocol Version 6 (IPv6) Specification", STD 89,
10.17487/RFC4443, March 2006, RFC 4443, DOI 10.17487/RFC4443, March 2006,
<http://www.rfc-editor.org/info/rfc4443>. <http://www.rfc-editor.org/info/rfc4443>.
[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
"IPv6 Flow Label Specification", RFC 6437, DOI 10.17487/ "IPv6 Flow Label Specification", RFC 6437,
RFC6437, November 2011, DOI 10.17487/RFC6437, November 2011,
<http://www.rfc-editor.org/info/rfc6437>. <http://www.rfc-editor.org/info/rfc6437>.
12.2. Informative References 11.2. Informative References
[IANA-6P] "Internet Protocol Version 6 (IPv6) Parameters", [Err2541] RFC Errata, Erratum ID 2541, RFC 2460.
<https://www.iana.org/assignments/ipv6-parameters/
ipv6-parameters.xhtml>.
[IANA-EH] "IPv6 Extension Header Types", [Err4279] RFC Errata, Erratum ID 4279, RFC 2460.
<https://www.iana.org/assignments/ipv6-parameters/ipv6-
parameters.xhtml#extension-header>.
[IANA-MI] "Structure of Management Information (SMI) Numbers (MIB [Err4657] RFC Errata, Erratum ID 4657, RFC 2460.
Module Registrations)", < http://www.iana.org/assignments/
smi-numbers/smi-numbers.xhtml>.
[IANA-NI] "ONC RPC Network Identifiers (netids)", [Err4662] RFC Errata, Erratum ID 4662, RFC 2460.
<http://www.iana.org/assignments/rpc-netids/
rpc-netids.xhtml>.
[IANA-NL] "Network Layer Protocol Identifiers (NLPIDs) of Interest", [IANA-6P] IANA, "Internet Protocol Version 6 (IPv6) Parameters",
<http://www.iana.org/assignments/nlpids/nlpids.xhtml>. <https://www.iana.org/assignments/ipv6-parameters>.
[IANA-NS] "Technical requirements for authoritative name servers", [IANA-EH] IANA, "IPv6 Extension Header Types",
<https://www.iana.org/help/nameserver-requirements>. <https://www.iana.org/assignments/ipv6-parameters>.
[IANA-PN] "Assigned Internet Protocol Numbers", [IANA-NI] IANA, "ONC RPC Network Identifiers (netids)",
<https://www.iana.org/assignments/protocol-numbers/ <https://www.iana.org/assignments/rpc-netids>.
protocol-numbers.xhtml>.
[IANA-PR] "Protocol Registries", <https://www.iana.org/protocols>. [IANA-NL] IANA, "Network Layer Protocol Identifiers (NLPIDs) of
Interest", <https://www.iana.org/assignments/nlpids>.
[IANA-RH] "IANA Routing Types Parameter Registry", [IANA-PN] IANA, "Protocol Numbers",
<https://www.iana.org/assignments/ipv6-parameters/ <https://www.iana.org/assignments/protocol-numbers>.
ipv6-parameters.xhtml#ipv6-parameters-3>.
[RFC1661] Simpson, W., Ed., "The Point-to-Point Protocol (PPP)", STD [IANA-PR] IANA, "Protocol Registries", <https://www.iana.org/
51, RFC 1661, DOI 10.17487/RFC1661, July 1994, protocols>.
<http://www.rfc-editor.org/info/rfc1661>.
[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery [IANA-RH] IANA, "Routing Types", <https://www.iana.org/assignments/
for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August ipv6-parameters>.
1996, <http://www.rfc-editor.org/info/rfc1981>.
[RFC1661] Simpson, W., Ed., "The Point-to-Point Protocol (PPP)",
STD 51, RFC 1661, DOI 10.17487/RFC1661, July 1994,
<http://www.rfc-editor.org/info/rfc1661>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>. December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <http://www.rfc-editor.org/info/rfc4301>. December 2005, <http://www.rfc-editor.org/info/rfc4301>.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302, DOI [RFC4302] Kent, S., "IP Authentication Header", RFC 4302,
10.17487/RFC4302, December 2005, DOI 10.17487/RFC4302, December 2005,
<http://www.rfc-editor.org/info/rfc4302>. <http://www.rfc-editor.org/info/rfc4302>.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
4303, DOI 10.17487/RFC4303, December 2005, RFC 4303, DOI 10.17487/RFC4303, December 2005,
<http://www.rfc-editor.org/info/rfc4303>. <http://www.rfc-editor.org/info/rfc4303>.
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
of Type 0 Routing Headers in IPv6", RFC 5095, DOI of Type 0 Routing Headers in IPv6", RFC 5095,
10.17487/RFC5095, December 2007, DOI 10.17487/RFC5095, December 2007,
<http://www.rfc-editor.org/info/rfc5095>. <http://www.rfc-editor.org/info/rfc5095>.
[RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments", [RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments",
RFC 5722, DOI 10.17487/RFC5722, December 2009, RFC 5722, DOI 10.17487/RFC5722, December 2009,
<http://www.rfc-editor.org/info/rfc5722>. <http://www.rfc-editor.org/info/rfc5722>.
[RFC5871] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for [RFC5871] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for
the IPv6 Routing Header", RFC 5871, DOI 10.17487/RFC5871, the IPv6 Routing Header", RFC 5871, DOI 10.17487/RFC5871,
May 2010, <http://www.rfc-editor.org/info/rfc5871>. May 2010, <http://www.rfc-editor.org/info/rfc5871>.
[RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and [RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and
M. Bhatia, "A Uniform Format for IPv6 Extension Headers", M. Bhatia, "A Uniform Format for IPv6 Extension Headers",
RFC 6564, DOI 10.17487/RFC6564, April 2012, RFC 6564, DOI 10.17487/RFC6564, April 2012,
<http://www.rfc-editor.org/info/rfc6564>. <http://www.rfc-editor.org/info/rfc6564>.
[RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement
for the Use of IPv6 UDP Datagrams with Zero Checksums", for the Use of IPv6 UDP Datagrams with Zero Checksums",
RFC 6936, DOI 10.17487/RFC6936, April 2013, RFC 6936, DOI 10.17487/RFC6936, April 2013,
<http://www.rfc-editor.org/info/rfc6936>. <http://www.rfc-editor.org/info/rfc6936>.
[RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", RFC [RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments",
6946, DOI 10.17487/RFC6946, May 2013, RFC 6946, DOI 10.17487/RFC6946, May 2013,
<http://www.rfc-editor.org/info/rfc6946>. <http://www.rfc-editor.org/info/rfc6946>.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
of IPv6 Extension Headers", RFC 7045, DOI 10.17487/ of IPv6 Extension Headers", RFC 7045,
RFC7045, December 2013, DOI 10.17487/RFC7045, December 2013,
<http://www.rfc-editor.org/info/rfc7045>. <http://www.rfc-editor.org/info/rfc7045>.
[RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of [RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of
Oversized IPv6 Header Chains", RFC 7112, DOI 10.17487/ Oversized IPv6 Header Chains", RFC 7112,
RFC7112, January 2014, DOI 10.17487/RFC7112, January 2014,
<http://www.rfc-editor.org/info/rfc7112>. <http://www.rfc-editor.org/info/rfc7112>.
[RFC7707] Gont, F. and T. Chown, "Network Reconnaissance in IPv6 [RFC7707] Gont, F. and T. Chown, "Network Reconnaissance in IPv6
Networks", RFC 7707, DOI 10.17487/RFC7707, March 2016, Networks", RFC 7707, DOI 10.17487/RFC7707, March 2016,
<http://www.rfc-editor.org/info/rfc7707>. <http://www.rfc-editor.org/info/rfc7707>.
[RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
Considerations for IPv6 Address Generation Mechanisms", Considerations for IPv6 Address Generation Mechanisms",
RFC 7721, DOI 10.17487/RFC7721, March 2016, RFC 7721, DOI 10.17487/RFC7721, March 2016,
<http://www.rfc-editor.org/info/rfc7721>. <http://www.rfc-editor.org/info/rfc7721>.
[RFC7739] Gont, F., "Security Implications of Predictable Fragment [RFC7739] Gont, F., "Security Implications of Predictable Fragment
Identification Values", RFC 7739, DOI 10.17487/RFC7739, Identification Values", RFC 7739, DOI 10.17487/RFC7739,
February 2016, <http://www.rfc-editor.org/info/rfc7739>. February 2016, <http://www.rfc-editor.org/info/rfc7739>.
[RFC8021] Gont, F., Liu, W., and T. Anderson, "Generation of IPv6 [RFC8021] Gont, F., Liu, W., and T. Anderson, "Generation of IPv6
Atomic Fragments Considered Harmful", RFC 8021, DOI Atomic Fragments Considered Harmful", RFC 8021,
10.17487/RFC8021, January 2017, DOI 10.17487/RFC8021, January 2017,
<http://www.rfc-editor.org/info/rfc8021>. <http://www.rfc-editor.org/info/rfc8021>.
[RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, "Path
MTU Discovery for IP version 6", STD 87, RFC 8201,
DOI 10.17487/RFC8201, July 2017,
<http://www.rfc-editor.org/info/rfc8201>.
Appendix A. Formatting Guidelines for Options Appendix A. Formatting Guidelines for Options
This appendix gives some advice on how to lay out the fields when This appendix gives some advice on how to lay out the fields when
designing new options to be used in the Hop-by-Hop Options header or designing new options to be used in the Hop-by-Hop Options header or
the Destination Options header, as described in section 4.2. These the Destination Options header, as described in Section 4.2. These
guidelines are based on the following assumptions: guidelines are based on the following assumptions:
o One desirable feature is that any multi-octet fields within the o One desirable feature is that any multi-octet fields within the
Option Data area of an option be aligned on their natural Option Data area of an option be aligned on their natural
boundaries, i.e., fields of width n octets should be placed at boundaries, i.e., fields of width n octets should be placed at
an integer multiple of n octets from the start of the Hop-by- an integer multiple of n octets from the start of the
Hop or Destination Options header, for n = 1, 2, 4, or 8. Hop-by-Hop or Destination Options header, for n = 1, 2, 4, or
8.
o Another desirable feature is that the Hop-by-Hop or Destination o Another desirable feature is that the Hop-by-Hop or Destination
Options header take up as little space as possible, subject to Options header take up as little space as possible, subject to
the requirement that the header be an integer multiple of 8 the requirement that the header be an integer multiple of 8
octets long. octets long.
o It may be assumed that, when either of the option-bearing o It may be assumed that, when either of the option-bearing
headers are present, they carry a very small number of options, headers are present, they carry a very small number of options,
usually only one. usually only one.
skipping to change at page 36, line 41 skipping to change at page 39, line 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | 0 | Option Type=X |Opt Data Len=12| | 0 | 0 | Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field | | 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ 8-octet field + + 8-octet field +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Appendix B. Changes Since RFC2460 Appendix B. Changes Since RFC 2460
This memo has the following changes from RFC2460. This memo has the following changes from RFC 2460.
o Removed IP Next Generation from the Abstract. o Removed IP Next Generation from the Abstract.
o Added text in Section 1 that the Data Transmission Order is the o Added text in Section 1 that the data transmission order is the
same as IPv4 as defined in RFC791. same as IPv4 as defined in RFC 791.
o Clarified the text in Section 3 about decrementing the hop limit. o Clarified the text in Section 3 about decrementing the Hop Limit.
o Clarification that extension headers (except for the hop-by-hop o Clarified that extension headers (except for the Hop-by-Hop
options header) are not processed, inserted, or deleted by any Options header) are not processed, inserted, or deleted by any
node along a packet's delivery path. node along a packet's delivery path.
o Changed requirement for the Hop-by-Hop Options header to a may, o Changed requirement for the Hop-by-Hop Options header to a "may",
and added a note to indicate what is expected regarding the Hop- and added a note to indicate what is expected regarding the
by-Hop Options header. Hop-by-Hop Options header.
o Added paragraph to Section 4 to clarify how Extension Headers are o Added a paragraph to Section 4 to clarify how extension headers
numbered and which are upper-layer headers. are numbered and which are upper-layer headers.
o Add reference to the end of Section 4 to IPv6 Extension Header o Added a reference to the end of Section 4 to the "IPv6 Extension
IANA registry. Header Types" IANA registry.
o Incorporate the updates from RFC5095 and RFC5871 to remove the o Incorporated the updates from RFCs 5095 and 5871 to remove the
description of the RH0 Routing Header, that the allocations description of RH0, that the allocations guidelines for routing
guidelines for routing headers are specified in RFC5871, and headers are specified in RFC 5871, and removed RH0 from the list
removed RH0 Routing Header from the list of required extension of required extension headers.
headers.
o Revised Section 4.5 on IPv6 Fragmentation based on updates from o Revised Section 4.5 on IPv6 fragmentation based on updates from
RFC5722, RFC6946 RFC7112, and RFC8021. This include: RFCs 5722, 6946, 7112, and 8021. This includes:
- Revised the text to handle the case of fragments that are whole - Revised the text to handle the case of fragments that are whole
datagrams (i.e., both the Fragment Offset field and the M flag datagrams (i.e., both the Fragment Offset field and the M flag
are zero). If received they should be processed as a are zero). If received, they should be processed as a
reassembled packet. Any other fragments that match should be reassembled packet. Any other fragments that match should be
processed independently. The revised Fragment creation process processed independently. The revised Fragment creation process
was modified to not create whole datagram fragments (Fragment was modified to not create whole datagram fragments (Fragment
Offset field and the M flag are zero). Offset field and the M flag are zero).
- Changed the text to require that IPv6 nodes must not create - Changed the text to require that IPv6 nodes must not create
overlapping fragments. Also, when reassembling an IPv6 overlapping fragments. Also, when reassembling an IPv6
datagram, if one or more its constituent fragments is datagram, if one or more its constituent fragments is
determined to be an overlapping fragment, the entire datagram determined to be an overlapping fragment, the entire datagram
(and any constituent fragments) must be silently discarded. (and any constituent fragments) must be silently discarded.
Includes a clarification that no ICMP error message should be Includes a clarification that no ICMP error message should be
sent if overlapping fragments are received. sent if overlapping fragments are received.
- Revised the text to require that all headers through the first - Revised the text to require that all headers through the first
Upper-Layer Header are in the first fragment. This changed the Upper-Layer header are in the first fragment. This changed the
text describing how packets are fragmented and reassembled, and text describing how packets are fragmented and reassembled and
added a new error case. added a new error case.
- Added text to Fragment Header process on handling exact - Added text to the Fragment header process on handling exact
duplicate fragments. duplicate fragments.
- Updated the Fragmentation header text to correct the inclusion - Updated the Fragmentation header text to correct the inclusion
of AH and note no next header case. of an Authentication Header (AH) and noted No Next Header case.
- Change terminology in Fragment header section from - Changed terminology in the Fragment header section from
"Unfragmentable Headers" to "Per-Fragment Headers". "Unfragmentable Headers" to "Per-Fragment headers".
- Removed the paragraph in Section 5 that required including a - Removed the paragraph in Section 5 that required including a
fragment header to outgoing packets if a ICMP Packet Too Big Fragment header to outgoing packets if an ICMP Packet Too Big
message reporting a Next-Hop MTU less than 1280. message reports a Next-Hop MTU less than 1280.
- Changed the text to clarify MTU restriction and 8-byte - Changed the text to clarify MTU restriction and 8-byte
restrictions, and noting the restriction on headers in first restrictions, and noted the restriction on headers in the first
fragment. fragment.
o In Section 4.5 added clarification noting that some fields in the o In Section 4.5, added clarification noting that some fields in the
IPv6 header may also vary across the fragments being reassembled IPv6 header may also vary across the fragments being reassembled,
and that other specifications may provide additional instructions and that other specifications may provide additional instructions
for how they should be reassembled. For example, Section 5.3 of for how they should be reassembled. See, for example, Section 5.3
[RFC3168]. of [RFC3168].
o Incorporated the update from RFC6564 to add a new Section 4.8 that o Incorporated the update from RFC 6564 to add a new Section 4.8
describes recommendations for defining new Extension headers and that describes recommendations for defining new extension headers
options. and options.
o Added text to Section 5 to define "IPv6 minimum link MTU". o Added text to Section 5 to define "IPv6 minimum link MTU".
o Simplify the text in Section 6 about Flow Labels and remove o Simplified the text in Section 6 about Flow Labels and removed
Appendix A, and instead point to the current specifications of the what was Appendix A ("Semantics and Usage of the Flow Label
IPv6 Flow Label field as defined in [RFC6437] and the Traffic Field"); instead, pointed to the current specifications of the
Class as defined in [RFC2474] and [RFC3168]. IPv6 Flow Label field in [RFC6437] and the Traffic Class field in
[RFC2474] and [RFC3168].
o Incorporate the update in made by RFC6935 "UDP Checksums for o Incorporated the update made by RFC 6935 ("IPv6 and UDP Checksums
Tunneled Packets" in Section 8. Added an exception to the default for Tunneled Packets") in Section 8. Added an exception to the
behaviour for the handling of handling UDP packets with zero default behavior for the handling of UDP packets with zero
checksums for tunnels. checksums for tunnels.
o Add instruction to Section 9 "IANA Considerations" to change o Added instruction to Section 9, "IANA Considerations", to change
references to RFC2460 to this document references to RFC 2460 to this document.
o Revised and expanded Section 10 "Security Considerations". o Revised and expanded Section 10, "Security Considerations".
o Add a paragraph to the acknowledgement section acknowledging the o Added a paragraph to the Acknowledgments section acknowledging the
authors of the updating documents authors of the updating documents.
o Update references to current versions and assign references to o Updated references to current versions and assigned references to
normative and informative. normative and informative.
o Changes to resolve the open Errata on RFC2460. These are: o Made changes to resolve the errata on RFC 2460. These are:
Errata ID: 2541: This errata notes that RFC2460 didn't update
RFC2205 when the length of the Flow Label was changed from 24
to 20 bits from RFC1883. This issue was resolved in RFC6437
where the Flow Label is defined. This draft now references
RFC6437. No change is required.
Errata ID: 4279: This errata noted that the specification
doesn't handle the case of a forwarding node receiving a packet
with a zero Hop Limit. This is fixed in Section 3 of this
draft.
Errata ID: 2843: This errata is marked rejected. No change was
made.
B.1. Change History Since RFC2460
NOTE TO RFC EDITOR: Please remove this subsection prior to RFC
Publication
This section describes change history made in each Internet Draft
that went into producing this version. The numbers identify the
Internet-Draft version in which the change was made.
Working Group Internet Drafts
13) Added link to reference to RFC6564 in Section 4.8.
13) Added text to Section 5 to define "IPv6 minimum link MTU".
13) Editorial changes.
12) Editorial changes (remove old duplicate paragraph).
11) In Section 4.5 added clarification noting that some fields in
the IPv6 header may also vary across the fragments being
reassembled and that other specifications may provide
additional instructions for how they should be reassembled.
For example, Section 5.3 of [RFC3168].
11) In Section 4 restructured text including separated behaviors
of extension headers and the hop-by-hop option header,
removed "examine" from first paragraph about extension
headers, and removed reference to RFC7045 because "examine"
was removed (RFC7045 is referenced in Security
Considerations). Also removed "including the source and
destination nodes" from paragraph about the hop-by-hop
options header.
11) Revised Section 4.8 to make it closer to the update done by
RFC6554 that updated it and reordered the paragraphs.
11) Reordered items in Appendix B "Changes Since RFC2460" to
match the order of the document.
11) Editorial changes.
10) Revised and expanded Security Consideration Section based on
IESG Discuss comments.
10) Editorial changes.
09) Based on results of IETF last call, changed text in Section 4
to add clarification that extension headers are not examined,
processed, inserted, or deleted by any node along a packet's
delivery path.
09) Changed reference from draft-ietf-6man-rfc4291bis to RFC4291
because the bis draft won't be advanced as the same time.
09) Revised "Changes since RFC2460" Section to have a summary of
changes since RFC2460 and a separate subsection with a change
history of each Internet Draft. This subsection will be
removed when the RFC is published.
09) Editorial changes.
08) Revised header insertion text in Section 4 based on the
results of w.g. survey that concluded to describe the
problems with header insertion.
08) Editorial changes.
07) Expanded Security Considerations section to include both
IPsec and encryption at higher levels in the protocol stack
as ways to mitigate IP level security issues.
07) Added paragraph to Section 4 to clarify how Extension Headers
are numbered and which are upper-layer headers.
07) Moved the text regarding network duplicated fragments to the
received fragment error section.
07) Added clarification that no ICMP error message should be sent
if overlapping fragments are received.
07) Revised the text in Section 4.8 regarding new hop-by-hop
options and new Extension headers to be closer to the -05
version.
07) Added additional registries to the IANA Considerations
section that IANA needs to update.
07) Editorial changes.
06) Added the Routing Header to the list required extension
headers that a full implementation includes.
06) Moved the text in Section 4.5 regarding the handling of
received overlapping fragments to the list of error
conditions
06) Rewrote the text in Section 4.8 "Defining New Extension
Headers and Options" to be clearer and remove redundant text.
06) Editorial changes.
05) Changed requirement for the Hop-by-Hop Options header from a
should to a may, and added a note to indicate what is
expected.
05) Corrected reference to point to draft-ietf-6man-rfc4291bis
instead of draft-hinden-6man-rfc4291bis.
05) Change to text regarding not inserting extension headers to
cite using encapsulation as an example.
04) Changed text discussing Fragment ID selection to refer to
RFC7739 for example algorithms.
04) Editorial changes.
03) Clarified the text about decrementing the hop limit.
03) Removed IP Next Generation from the Abstract.
03) Add reference to the end of Section 4 to IPv6 Extension
Header IANA registry.
03) Editorial changes.
02) Added text to Section 4.8 "Defining New Extension Headers and
Options" clarifying why no new hop by hop extension headers
should be defined.
02) Added text to Fragment Header process on handling exact
duplicate fragments.
02) Editorial changes.
01) Added text that Extension headers must never be inserted by
any node other than the source of the packet.
01) Change "must" to "should" in Section 4.3 on the Hop-by-Hop
header.
01) Added text that the Data Transmission Order is the same as
IPv4 as defined in RFC791.
01) Updated the Fragmentation header text to correct the
inclusion of AH and note no next header case.
01) Change terminology in Fragment header section from
"Unfragmentable Headers" to "Per-Fragment Headers".
01) Removed paragraph in Section 5 that required including a
fragment header to outgoing packets if a ICMP Packet Too Big
message reporting a Next-Hop MTU less than 1280. This is
based on the update in RFC8021.
01) Changed to Fragmentation Header section to clarify MTU
restriction and 8-byte restrictions, and noting the
restriction on headers in first fragment.
01) Editorial changes.
00) Add instruction to the IANA to change references to RFC2460
to this document
00) Add a paragraph to the acknowledgement section acknowledging
the authors of the updating documents
00) Remove old paragraph in Section 4 that should have been
removed when incorporating the update from RFC7045.
00) Editorial changes.
Individual Internet Drafts
07) Update references to current versions and assign references
to normative and informative.
07) Editorial changes.
06) The purpose of this draft is to incorporate the updates
dealing with Extension headers as defined in RFC6564,
RFC7045, and RFC7112. The changes include:
RFC6564: Added new Section 4.8 that describe
recommendations for defining new Extension headers and
options
RFC7045: The changes were to add a reference to RFC7045,
change the requirement for processing the hop-by-hop
option to a should, and added a note that due to
performance restrictions some nodes won't process the Hop-
by-Hop Option header.
RFC7112: The changes were to revise the Fragmentation
Section (Section 4.5) to require that all headers through
the first Upper-Layer Header are in the first fragment.
This changed the text describing how packets are
fragmented and reassembled and added a new error case.
06) Editorial changes.
05) The purpose of this draft is to incorporate the updates
dealing with fragmentation as defined in RFC5722 and RFC6946.
Note: The issue relating to the handling of exact duplicate
fragments identified on the mailing list is left open.
05) Fix text in the end of Section 4 to correct the number of
extension headers defined in this document.
05) Editorial changes.
04) The purpose of this draft is to update the document to
incorporate the update made by RFC6935 "UDP Checksums for
Tunneled Packets".
04) Remove Routing (Type 0) header from the list of required
extension headers.
04) Editorial changes.
03) The purpose of this draft is to update the document for the Erratum ID 2541 [Err2541]: This erratum notes that RFC 2460
deprecation of the RH0 Routing Header as specified in RFC5095 didn't update RFC 2205 when the length of the flow label was
and the allocations guidelines for routing headers as changed from 24 to 20 bits from RFC 1883. This issue was
specified in RFC5871. Both of these RFCs updated RFC2460. resolved in RFC 6437 where the flow label is defined. This
specification now references RFC 6437. No change is required.
02) The purpose of this version of the draft is to update the Erratum ID 4279 [Err4279]: This erratum noted that the
document to resolve the open Errata on RFC2460. specification doesn't handle the case of a forwarding node
receiving a packet with a zero Hop Limit. This is fixed in
Section 3 of this specification.
Errata ID: 2541: This errata notes that RFC2460 didn't Erratum ID 4657 [Err4657]: This erratum proposed text that
update RFC2205 when the length of the Flow Label was extension headers must never be inserted by any node other than
changed from 24 to 20 bits from RFC1883. This issue was the source of the packet. This was resolved in Section 4,
resolved in RFC6437 where the Flow Label is defined. This "IPv6 Extension Headers".
draft now references RFC6437. No change is required.
Errata ID: 4279: This errata noted that the specification Erratum ID 4662 [Err4662]: This erratum proposed text that
doesn't handle the case of a forwarding node receiving a extension headers, with one exception, are not examined,
packet with a zero Hop Limit. This is fixed in Section 3 processed, modified, inserted, or deleted by any node along a
of this draft. Note: No change was made regarding host packet's delivery path. This was resolved in Section 4, "IPv6
behaviour. Extension Headers".
Errata ID: 2843: This errata is marked rejected. No Erratum ID 2843: This erratum is marked "Rejected". No change
change is required. was made.
02) Editorial changes to the Flow Label and Traffic Class text. Acknowledgments
01) The purpose of this version of the draft is to update the The authors gratefully acknowledge the many helpful suggestions of
document to point to the current specifications of the IPv6 the members of the IPng Working Group, the End-to-End Protocols
Flow Label field as defined in [RFC6437] and the Traffic research group, and the Internet community at large.
Class as defined in [RFC2474] and [RFC3168].
00) The purpose of this version is to establish a baseline from The authors would also like to acknowledge the authors of the
RFC2460. The only intended changes are formatting (XML is updating RFCs that were incorporated in this document to move the
slightly different from .nroff), differences between an RFC IPv6 specification to Internet Standard. They are Joe Abley, Shane
and Internet Draft, fixing a few ID Nits, and updates to the Amante, Jari Arkko, Manav Bhatia, Ronald P. Bonica, Scott Bradner,
authors information. There should not be any content changes Brian Carpenter, P.F. Chimento, Marshall Eubanks, Fernando Gont,
to the specification. James Hoagland, Sheng Jiang, Erik Kline, Suresh Krishnan, Vishwas
Manral, George Neville-Neil, Jarno Rajahalme, Pekka Savola, Magnus
Westerlund, and James Woodyatt.
Authors' Addresses Authors' Addresses
Stephen E. Deering Stephen E. Deering
Retired Retired
Vancouver, British Columbia Vancouver, British Columbia
Canada Canada
Robert M. Hinden Robert M. Hinden
Check Point Software Check Point Software
959 Skyway Road 959 Skyway Road
San Carlos, CA 94070 San Carlos, CA 94070
USA United States of America
Email: bob.hinden@gmail.com Email: bob.hinden@gmail.com
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