Internet Engineering Task Force (IETF) S. Deering
Request for Comments: 8200 Retired
STD: 86 R. Hinden
Obsoletes: 2460 Check Point Software
Category: Standards Track July 2017
ISSN: 2070-1721
Internet Engineering Task Force (IETF) S. Deering
Request for Comments: 8200 Retired
STD: 86 R. Hinden
Obsoletes: 2460 Check Point Software
Category: Standards Track July 2017
ISSN: 2070-1721
Internet Protocol, Version 6 (IPv6) Specification
互联网协议，版本6（IPv6）规范
Abstract
摘要
This document specifies version 6 of the Internet Protocol (IPv6). It obsoletes RFC 2460.
本文档指定了Internet协议（IPv6）的版本6。它淘汰了RFC2460。
Status of This Memo
关于下段备忘
This is an Internet Standards Track document.
这是一份互联网标准跟踪文件。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。有关互联网标准的更多信息，请参见RFC 7841第2节。
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.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc8200.
Copyright Notice
版权公告
Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2017 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.
本文件可能包含2008年11月10日之前发布或公开的IETF文件或IETF贡献中的材料。控制某些材料版权的人员可能未授予IETF信托允许在IETF标准流程之外修改此类材料的权利。在未从控制此类材料版权的人员处获得充分许可的情况下，不得在IETF标准流程之外修改本文件，也不得在IETF标准流程之外创建其衍生作品，除了将其格式化以RFC形式发布或将其翻译成英语以外的其他语言。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. IPv6 Header Format . . . . . . . . . . . . . . . . . . . . . 6
4. IPv6 Extension Headers . . . . . . . . . . . . . . . . . . . 7
4.1. Extension Header Order . . . . . . . . . . . . . . . . . 10
4.2. Options . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Hop-by-Hop Options Header . . . . . . . . . . . . . . . . 13
4.4. Routing Header . . . . . . . . . . . . . . . . . . . . . 14
4.5. Fragment Header . . . . . . . . . . . . . . . . . . . . . 15
4.6. Destination Options Header . . . . . . . . . . . . . . . 23
4.7. No Next Header . . . . . . . . . . . . . . . . . . . . . 24
4.8. Defining New Extension Headers and Options . . . . . . . 24
5. Packet Size Issues . . . . . . . . . . . . . . . . . . . . . 25
6. Flow Labels . . . . . . . . . . . . . . . . . . . . . . . . . 26
7. Traffic Classes . . . . . . . . . . . . . . . . . . . . . . . 26
8. Upper-Layer Protocol Issues . . . . . . . . . . . . . . . . . 27
8.1. Upper-Layer Checksums . . . . . . . . . . . . . . . . . . 27
8.2. Maximum Packet Lifetime . . . . . . . . . . . . . . . . . 28
8.3. Maximum Upper-Layer Payload Size . . . . . . . . . . . . 29
8.4. Responding to Packets Carrying Routing Headers . . . . . 29
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
10. Security Considerations . . . . . . . . . . . . . . . . . . . 30
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
11.1. Normative References . . . . . . . . . . . . . . . . . . 32
11.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A. Formatting Guidelines for Options . . . . . . . . . 36
Appendix B. Changes Since RFC 2460 . . . . . . . . . . . . . . . 39
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. IPv6 Header Format . . . . . . . . . . . . . . . . . . . . . 6
4. IPv6 Extension Headers . . . . . . . . . . . . . . . . . . . 7
4.1. Extension Header Order . . . . . . . . . . . . . . . . . 10
4.2. Options . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Hop-by-Hop Options Header . . . . . . . . . . . . . . . . 13
4.4. Routing Header . . . . . . . . . . . . . . . . . . . . . 14
4.5. Fragment Header . . . . . . . . . . . . . . . . . . . . . 15
4.6. Destination Options Header . . . . . . . . . . . . . . . 23
4.7. No Next Header . . . . . . . . . . . . . . . . . . . . . 24
4.8. Defining New Extension Headers and Options . . . . . . . 24
5. Packet Size Issues . . . . . . . . . . . . . . . . . . . . . 25
6. Flow Labels . . . . . . . . . . . . . . . . . . . . . . . . . 26
7. Traffic Classes . . . . . . . . . . . . . . . . . . . . . . . 26
8. Upper-Layer Protocol Issues . . . . . . . . . . . . . . . . . 27
8.1. Upper-Layer Checksums . . . . . . . . . . . . . . . . . . 27
8.2. Maximum Packet Lifetime . . . . . . . . . . . . . . . . . 28
8.3. Maximum Upper-Layer Payload Size . . . . . . . . . . . . 29
8.4. Responding to Packets Carrying Routing Headers . . . . . 29
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
10. Security Considerations . . . . . . . . . . . . . . . . . . . 30
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
11.1. Normative References . . . . . . . . . . . . . . . . . . 32
11.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A. Formatting Guidelines for Options . . . . . . . . . 36
Appendix B. Changes Since RFC 2460 . . . . . . . . . . . . . . . 39
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
IP version 6 (IPv6) is a new version of the Internet Protocol (IP), designed as the successor to IP version 4 (IPv4) [RFC791]. The changes from IPv4 to IPv6 fall primarily into the following categories:
IP版本6（IPv6）是Internet协议（IP）的新版本，设计为IP版本4（IPv4）的继承版本[RFC791]。从IPv4到IPv6的变化主要分为以下几类：
o Expanded Addressing Capabilities
o 扩展的寻址能力
IPv6 increases the IP address size from 32 bits to 128 bits, to support more levels of addressing hierarchy, a much greater number of addressable nodes, and simpler autoconfiguration of addresses. The scalability of multicast routing is improved by adding a "scope" field to multicast addresses. And a new type of address called an "anycast address" is defined; it is used to send a packet to any one of a group of nodes.
IPv6将IP地址大小从32位增加到128位，以支持更高级别的寻址层次结构、更多的可寻址节点以及更简单的地址自动配置。通过在多播地址中添加“scope”字段，提高了多播路由的可扩展性。定义了一种称为“选播地址”的新型地址；它用于向一组节点中的任何一个发送数据包。
o Header Format Simplification
o 标题格式简化
Some IPv4 header fields have been dropped or made optional, to reduce the common-case processing cost of packet handling and to limit the bandwidth cost of the IPv6 header.
一些IPv4报头字段已被删除或成为可选字段，以降低数据包处理的常见情况处理成本并限制IPv6报头的带宽成本。
o Improved Support for Extensions and Options
o 改进了对扩展和选项的支持
Changes in the way IP header options are encoded allows for more efficient forwarding, less stringent limits on the length of options, and greater flexibility for introducing new options in the future.
IP报头选项编码方式的改变允许更高效的转发，对选项长度的限制不那么严格，并且在将来引入新选项时具有更大的灵活性。
o Flow Labeling Capability
o 流标记能力
A new capability is added to enable the labeling of sequences of packets that the sender requests to be treated in the network as a single flow.
增加了一项新功能，可以对发送方请求在网络中作为单个流处理的数据包序列进行标记。
o Authentication and Privacy Capabilities
o 身份验证和隐私功能
Extensions to support authentication, data integrity, and (optional) data confidentiality are specified for IPv6.
为IPv6指定了支持身份验证、数据完整性和（可选）数据机密性的扩展。
This document specifies the basic IPv6 header and the initially defined IPv6 extension headers and options. It also discusses packet size issues, the semantics of flow labels and traffic classes, and the effects of IPv6 on upper-layer protocols. The format and semantics of IPv6 addresses are specified separately in [RFC4291]. The IPv6 version of ICMP, which all IPv6 implementations are required to include, is specified in [RFC4443].
本文档指定基本IPv6标头以及最初定义的IPv6扩展标头和选项。它还讨论了数据包大小问题、流标签和流量类的语义，以及IPv6对上层协议的影响。[RFC4291]中分别规定了IPv6地址的格式和语义。[RFC4443]中规定了ICMP的IPv6版本，所有IPv6实现都需要包括该版本。
The data transmission order for IPv6 is the same as for IPv4 as defined in Appendix B of [RFC791].
IPv6的数据传输顺序与[RFC791]附录B中定义的IPv4的数据传输顺序相同。
Note: As this document obsoletes [RFC2460], any document referenced in this document that includes pointers to RFC 2460 should be interpreted as referencing this document.
注：由于本文件淘汰了[RFC2460]，本文件中引用的任何文件，包括指向RFC 2460的指针，应解释为引用本文件。
node a device that implements IPv6.
节点实现IPv6的设备。
router a node that forwards IPv6 packets not explicitly addressed to itself. (See Note below.)
路由器转发未显式寻址到自身的IPv6数据包的节点。（见下文注释。）
host any node that is not a router. (See Note below.)
托管不是路由器的任何节点。（见下文注释。）
upper layer a protocol layer immediately above IPv6. Examples are transport protocols such as TCP and UDP, control protocols such as ICMP, routing protocols such as OSPF, and internet-layer or lower-layer protocols being "tunneled" over (i.e., encapsulated in) IPv6 such as Internetwork Packet Exchange (IPX), AppleTalk, or IPv6 itself.
上层IPv6之上的协议层。例如，传输协议（如TCP和UDP）、控制协议（如ICMP）、路由协议（如OSPF）以及通过（即封装在）IPv6（如互联网数据包交换（IPX）、AppleTalk或IPv6本身）“隧道”的互联网层或较低层协议。
link a communication facility or medium over which nodes can communicate at the link layer, i.e., the layer immediately below IPv6. Examples are Ethernets (simple or bridged); PPP links; X.25, Frame Relay, or ATM networks; and internet-layer or higher-layer "tunnels", such as tunnels over IPv4 or IPv6 itself.
链路节点可在链路层（即IPv6正下方的层）上进行通信的通信设施或介质。例如以太网络（简单或桥接）；PPP链接；X.25、帧中继或ATM网络；互联网层或更高层的“隧道”，如IPv4或IPv6本身上的隧道。
neighbors nodes attached to the same link.
连接到同一链路的邻居节点。
interface a node's attachment to a link.
将节点的附件连接到链接。
address an IPv6-layer identifier for an interface or a set of interfaces.
寻址一个或一组接口的IPv6层标识符。
packet an IPv6 header plus payload.
数据包包含IPv6标头和有效负载。
link MTU the maximum transmission unit, i.e., maximum packet size in octets, that can be conveyed over a link.
链路MTU——可通过链路传输的最大传输单元，即以八位字节为单位的最大数据包大小。
path MTU the minimum link MTU of all the links in a path between a source node and a destination node.
路径MTU源节点和目标节点之间路径中所有链路的最小链路MTU。
Note: it is possible for a device with multiple interfaces to be configured to forward non-self-destined packets arriving from some set (fewer than all) of its interfaces and to discard non-self-destined packets arriving from its other interfaces. Such a device must obey the protocol requirements for routers when receiving packets from, and interacting with neighbors over, the former (forwarding) interfaces. It must obey the protocol requirements for hosts when receiving packets from, and interacting with neighbors over, the latter (non-forwarding) interfaces.
注意：对于具有多个接口的设备，可以配置为转发从其某一组（少于所有）接口到达的非自定目的数据包，并丢弃从其其他接口到达的非自定目的数据包。当从前（转发）接口接收数据包并通过前（转发）接口与邻居交互时，此类设备必须遵守路由器的协议要求。当从邻居（非转发）接口接收数据包并通过邻居（非转发）接口与邻居交互时，它必须遵守主机的协议要求。
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Traffic Class | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | Next Header | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Traffic Class | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | Next Header | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Version 4-bit Internet Protocol version number = 6.
版本4位互联网协议版本号=6。
Traffic Class 8-bit Traffic Class field. See Section 7.
流量等级8位流量等级字段。见第7节。
Flow Label 20-bit flow label. See Section 6.
流量标签20位流量标签。见第6节。
Payload Length 16-bit unsigned integer. Length of the IPv6 payload, i.e., the rest of the packet following this IPv6 header, in octets. (Note that any extension headers (see Section 4) present are considered part of the payload, i.e., included in the length count.)
有效负载长度16位无符号整数。IPv6有效负载的长度，即该IPv6报头之后的数据包的剩余部分，以八位字节为单位。（请注意，存在的任何扩展标头（见第4节）都被视为有效载荷的一部分，即包含在长度计数中。）
Next Header 8-bit selector. Identifies the type of header immediately following the IPv6 header. Uses the same values as the IPv4 Protocol field [IANA-PN].
下一个标题8位选择器。标识紧跟在IPv6标头之后的标头类型。使用与IPv4协议字段[IANA-PN]相同的值。
Hop Limit 8-bit unsigned integer. Decremented by 1 by each node that forwards the packet. When forwarding, the packet is discarded if Hop Limit was zero when received or is decremented to zero. A node that is the destination of a packet should not discard a packet with Hop Limit equal to zero; it should process the packet normally.
跃点限制8位无符号整数。转发数据包的每个节点递减1。转发时，如果接收到的跃点限制为零或减小到零，则丢弃数据包。作为数据包目的地的节点不应丢弃跳数限制等于零的数据包；它应该正常处理数据包。
Source Address 128-bit address of the originator of the packet. See [RFC4291].
源地址数据包发起方的128位地址。见[RFC4291]。
Destination Address 128-bit address of the intended recipient of the packet (possibly not the ultimate recipient, if a Routing header is present). See [RFC4291] and Section 4.4.
目标地址数据包的预期收件人的128位地址（如果存在路由报头，则可能不是最终收件人）。参见[RFC4291]和第4.4节。
In IPv6, optional internet-layer information is encoded in separate 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 headers, each one identified by a distinct Next Header value.
在IPv6中，可选的internet层信息编码在单独的报头中，这些报头可以放在数据包中的IPv6报头和上层报头之间。有少量这样的扩展头，每个扩展头由一个不同的下一个头值标识。
Extension headers are numbered from IANA IP Protocol Numbers [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 an extension header [IANA-EH] indicates that the next item in the packet is the corresponding upper-layer header. A special "No Next Header" value is used if there is no upper-layer header.
扩展头根据IANA IP协议编号[IANA-PN]进行编号，这些编号与IPv4和IPv6使用的值相同。当处理分组中的下一个报头值序列时，不是扩展报头[IANA-EH]的第一个报头指示分组中的下一项是对应的上层报头。如果没有上层标头，则使用特殊的“无下一个标头”值。
As illustrated in these examples, an IPv6 packet may carry zero, one, or more extension headers, each identified by the Next Header field of the preceding header:
如这些示例中所示，IPv6数据包可携带零个、一个或多个扩展报头，每个扩展报头由前一报头的下一报头字段标识：
+---------------+------------------------
| IPv6 header | TCP header + data
| |
| Next Header = |
| TCP |
+---------------+------------------------
+---------------+------------------------
| IPv6 header | TCP header + data
| |
| Next Header = |
| TCP |
+---------------+------------------------
+---------------+----------------+------------------------
| IPv6 header | Routing header | TCP header + data
| | |
| Next Header = | Next Header = |
| Routing | TCP |
+---------------+----------------+------------------------
+---------------+----------------+------------------------
| IPv6 header | Routing header | TCP header + data
| | |
| Next Header = | Next Header = |
| Routing | TCP |
+---------------+----------------+------------------------
+---------------+----------------+-----------------+-----------------
| IPv6 header | Routing header | Fragment header | fragment of TCP
| | | | header + data
| Next Header = | Next Header = | Next Header = |
| Routing | Fragment | TCP |
+---------------+----------------+-----------------+-----------------
+---------------+----------------+-----------------+-----------------
| IPv6 header | Routing header | Fragment header | fragment of TCP
| | | | header + data
| Next Header = | Next Header = | Next Header = |
| Routing | Fragment | TCP |
+---------------+----------------+-----------------+-----------------
Extension headers (except for the Hop-by-Hop Options header) are not processed, inserted, or deleted by any node along a packet's delivery path, until the packet reaches the node (or each of the set of nodes, in the case of multicast) identified in the Destination Address field of the IPv6 header.
扩展标头（逐跳选项标头除外）不会由任何节点沿数据包的传递路径进行处理、插入或删除，直到数据包到达IPv6标头的目标地址字段中标识的节点（或多播情况下的每个节点集）。
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, until the packet reaches the node (or each of the set of nodes, in the case of multicast) identified in the Destination Address field of the IPv6 header. The Hop-by-Hop Options header, when present, must immediately follow the IPv6 header. Its presence is indicated by the value zero in the Next Header field of the IPv6 header.
逐跳选项报头不被插入或删除，但可由沿分组的递送路径的任何节点检查或处理，直到分组到达在IPv6报头的目的地地址字段中标识的节点（或在多播的情况下，每组节点）为止。“逐跳选项”标头（如果存在）必须紧跟在IPv6标头之后。它的存在由IPv6标头的下一个标头字段中的值零表示。
NOTE: While [RFC2460] required that all nodes must examine and 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-Hop Options header if explicitly configured to do so.
注意：虽然[RFC2460]要求所有节点必须检查和处理逐跳选项报头，但现在可以预期，如果明确配置为这样做，则沿着数据包传递路径的节点仅检查和处理逐跳选项报头。
At the destination node, normal demultiplexing on the Next Header field of the IPv6 header invokes the module to process the first extension header, or the upper-layer header if no extension header is present. The contents and semantics of each extension header determine whether or not to proceed to the next header. Therefore, extension headers must be processed strictly in the order they appear in the packet; a receiver must not, for example, scan through a packet looking for a particular kind of extension header and process that header prior to processing all preceding ones.
在目标节点，IPv6报头的下一个报头字段上的正常解复用调用模块来处理第一个扩展报头，如果不存在扩展报头，则调用上层报头。每个扩展头的内容和语义决定是否继续下一个头。因此，必须严格按照扩展头在数据包中出现的顺序进行处理；例如，接收方不得扫描数据包寻找特定类型的扩展报头，并在处理之前处理该报头。
If, as a result of processing a header, the destination node is required to proceed to the next header but the Next Header value in the current header is unrecognized by the node, it should discard the packet and send an ICMP Parameter Problem message to the source of the packet, with an ICMP Code value of 1 ("unrecognized Next Header type encountered") and the ICMP Pointer field containing the offset of the unrecognized value within the original packet. The same action should be taken if a node encounters a Next Header value of zero in any header other than an IPv6 header.
如果作为处理报头的结果，目标节点需要继续处理下一个报头，但节点无法识别当前报头中的下一个报头值，则它应丢弃该数据包，并向数据包源发送ICMP参数问题消息，ICMP代码值为1(“遇到无法识别的下一个标头类型”）和包含原始数据包中无法识别值的偏移量的ICMP指针字段。如果节点在除IPv6标头以外的任何标头中遇到下一个标头值为零，则应采取相同的操作。
Each extension header is an integer multiple of 8 octets long, in order to retain 8-octet alignment for subsequent headers. Multi-octet fields within each extension header are aligned on their natural boundaries, i.e., fields of width n octets are placed at an integer multiple of n octets from the start of the header, for n = 1, 2, 4, or 8.
每个扩展头是8个八位字节的整数倍，以便为后续头保留8个八位字节的对齐。每个扩展标头内的多个八位元字段在其自然边界上对齐，即，宽度为n个八位元的字段从标头开始以n个八位元的整数倍放置，n=1、2、4或8。
A full implementation of IPv6 includes implementation of the following extension headers:
IPv6的完整实现包括以下扩展头的实现：
Hop-by-Hop Options Fragment Destination Options Routing Authentication Encapsulating Security Payload
逐跳选项片段目标选项路由身份验证封装安全负载
The first four are specified in this document; the last two are specified in [RFC4302] and [RFC4303], respectively. The current list of IPv6 extension headers can be found at [IANA-EH].
前四项在本文件中规定；最后两个分别在[RFC4302]和[RFC4303]中指定。IPv6扩展头的当前列表可在[IANA-EH]中找到。
When more than one extension header is used in the same packet, it is recommended that those headers appear in the following order:
当在同一数据包中使用多个扩展标头时，建议这些标头按以下顺序显示：
IPv6 header Hop-by-Hop Options header Destination Options header (note 1) Routing header Fragment header Authentication header (note 2) Encapsulating Security Payload header (note 2) Destination Options header (note 3) Upper-Layer header
IPv6标头逐跳选项标头目的地选项标头（注1）路由标头片段标头身份验证标头（注2）封装安全有效负载标头（注2）目的地选项标头（注3）上层标头
note 1: for options to be processed by the first destination that appears in the IPv6 Destination Address field plus subsequent destinations listed in the Routing header.
注1：用于由IPv6目标地址字段中显示的第一个目标以及路由标头中列出的后续目标处理的选项。
note 2: additional recommendations regarding the relative order of the Authentication and Encapsulating Security Payload headers are given in [RFC4303].
注2:[RFC4303]中给出了有关身份验证和封装安全有效负载头的相对顺序的其他建议。
note 3: for options to be processed only by the final destination of the packet.
注3：对于仅由数据包最终目的地处理的选项。
Each extension header should occur at most once, except for the Destination Options header, which should occur at most twice (once before a Routing header and once before the upper-layer header).
每个扩展标头最多应出现一次，但Destination Options标头除外，该标头最多应出现两次（一次在路由标头之前，一次在上层标头之前）。
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 its own extension headers, which are separately subject to the same ordering recommendations.
如果上层报头是另一个IPv6报头（在IPv6被隧道覆盖或封装在IPv6中的情况下），则其后面可能会有其自己的扩展报头，这些扩展报头分别遵循相同的排序建议。
If and when other extension headers are defined, their ordering constraints relative to the above listed headers must be specified.
如果定义了其他扩展标头，则必须指定它们相对于上面列出的标头的顺序约束。
IPv6 nodes must accept and attempt to process extension headers in any order and occurring any number of times in the same packet, except for the Hop-by-Hop Options header, which is restricted to appear immediately after an IPv6 header only. Nonetheless, it is strongly advised that sources of IPv6 packets adhere to the above recommended order until and unless subsequent specifications revise that recommendation.
IPv6节点必须接受并尝试以任何顺序处理扩展标头，并在同一数据包中出现任意次数，但逐跳选项标头除外，该标头仅限于出现在IPv6标头之后。尽管如此，强烈建议IPv6数据包的源遵守上述建议的顺序，除非后续规范修改该建议。
Two of the currently defined extension headers specified in this document -- the Hop-by-Hop Options header and the Destination Options header -- carry a variable number of "options" that are type-length-value (TLV) encoded in the following format:
本文档中指定的两个当前定义的扩展标题（逐跳选项标题和目标选项标题）包含可变数量的“选项”，这些选项是按以下格式编码的类型长度值（TLV）：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| Option Type | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| Option Type | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
Option Type 8-bit identifier of the type of option.
选项类型选项类型的8位标识符。
Opt Data Len 8-bit unsigned integer. Length of the Option Data field of this option, in octets.
Opt Data Len 8位无符号整数。此选项的选项数据字段的长度，以八位字节为单位。
Option Data Variable-length field. Option-Type-specific data.
选项数据可变长度字段。选项类型特定的数据。
The sequence of options within a header must be processed strictly in the order they appear in the header; a receiver must not, for example, scan through the header looking for a particular kind of option and process that option prior to processing all preceding ones.
标题中的选项序列必须严格按照它们在标题中出现的顺序进行处理；例如，接收者不得扫描报头寻找特定类型的选项，并在处理之前处理该选项。
The Option Type identifiers are internally encoded such that their highest-order 2 bits specify the action that must be taken if the processing IPv6 node does not recognize the Option Type:
选项类型标识符进行内部编码，以便其最高阶2位指定在处理IPv6节点无法识别选项类型时必须采取的操作：
00 - skip over this option and continue processing the header.
00-跳过此选项并继续处理标题。
01 - discard the packet.
01-丢弃数据包。
10 - discard the packet and, regardless of whether or not the packet's Destination Address was a multicast address, send an ICMP Parameter Problem, Code 2, message to the packet's Source Address, pointing to the unrecognized Option Type.
10-丢弃数据包，无论数据包的目标地址是否为多播地址，都将ICMP参数问题代码2消息发送到数据包的源地址，指向无法识别的选项类型。
11 - discard the packet and, only if the packet's Destination Address was not a multicast address, send an ICMP Parameter Problem, Code 2, message to the packet's Source Address, pointing to the unrecognized Option Type.
11-丢弃数据包，仅当数据包的目标地址不是多播地址时，才将ICMP参数问题代码2消息发送到数据包的源地址，指向无法识别的选项类型。
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 packet's final destination. When an Authentication header is present
选项类型的第三高阶位指定该选项的选项数据是否可以在到数据包最终目的地的途中更改。当存在身份验证标头时
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 computing or verifying the packet's authenticating value.
在数据包中，对于其数据可能在途中更改的任何选项，在计算或验证数据包的身份验证值时，其整个选项数据字段必须视为零值八位字节。
0 - Option Data does not change en route
0-选项数据在途中不会更改
1 - Option Data may change en route
1-选项数据可能会在途中更改
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 particular option is identified by a full 8-bit Option Type, not just the low-order 5 bits of an Option Type.
上述三个高阶位将被视为选项类型的一部分，而不是独立于选项类型。也就是说，特定选项由完整的8位选项类型标识，而不仅仅是选项类型的低阶5位。
The same Option Type numbering space is used for both the Hop-by-Hop Options header and the Destination Options header. However, the specification of a particular option may restrict its use to only one of those two headers.
相同的选项类型编号空间用于逐跳选项标题和目标选项标题。但是，特定选项的规范可能会将其使用限制为这两个标题中的一个。
Individual options may have specific alignment requirements, to ensure that multi-octet values within Option Data fields fall on natural boundaries. The alignment requirement of an option is specified using the notation xn+y, meaning the Option Type must appear at an integer multiple of x octets from the start of the header, plus y octets. For example:
单个选项可能有特定的对齐要求，以确保选项数据字段中的多个八位组值位于自然边界上。选项的对齐要求使用符号xn+y指定，这意味着选项类型必须以从标题开始的x个八位字节加上y个八位字节的整数倍显示。例如：
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 octets.
2n表示从报头开始的任何2个八位组偏移量。8n+2表示从报头开始的任何8个八位字节的偏移量加上2个八位字节。
There are two padding options that are used when necessary to align subsequent options and to pad out the containing header to a multiple of 8 octets in length. These padding options must be recognized by all IPv6 implementations:
有两个填充选项，用于在必要时对齐后续选项，并将包含的标题填充到8个八位字节的倍数。所有IPv6实施都必须识别这些填充选项：
Pad1 option (alignment requirement: none)
Pad1选项（对齐要求：无）
+-+-+-+-+-+-+-+-+
| 0 |
+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+
| 0 |
+-+-+-+-+-+-+-+-+
NOTE! the format of the Pad1 option is a special case -- it does not have length and value fields.
笔记Pad1选项的格式是一种特殊情况——它没有长度和值字段。
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 required, the PadN option, described next, should be used, rather than multiple Pad1 options.
Pad1选项用于在标头的选项区域中插入1个八位字节的填充。如果需要多个八位字节的填充，则应使用下面介绍的PadN选项，而不是多个Pad1选项。
PadN option (alignment requirement: none)
PadN选项（对齐要求：无）
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| 1 | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| 1 | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
The PadN option is used to insert two or more octets of padding into the Options area of a header. For N octets of padding, the Opt Data Len field contains the value N-2, and the Option Data consists of N-2 zero-valued octets.
PadN选项用于将两个或多个八位字节的填充插入标头的选项区域。对于N个八位字节的填充，Opt Data Len字段包含值N-2，选项数据由N-2个零值八位字节组成。
Appendix A contains formatting guidelines for designing new options.
附录A包含设计新选项的格式指南。
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 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:
Hop-by-Hop-Options报头用于携带可选信息，这些信息可由每个节点沿着数据包的传递路径进行检查和处理。逐跳选项标头由IPv6标头中的下一个标头值0标识，格式如下：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the type of header immediately following the Hop-by-Hop Options header. Uses the same values as the IPv4 Protocol field [IANA-PN].
下一个标题8位选择器。标识紧跟在逐跳选项标头之后的标头类型。使用与IPv4协议字段[IANA-PN]相同的值。
Hdr Ext Len 8-bit unsigned integer. Length of the Hop-by-Hop Options header in 8-octet units, not including the first 8 octets.
Hdr Ext Len 8位无符号整数。逐跳选项标头的长度，以8个八位字节为单位，不包括前8个八位字节。
Options Variable-length field, of length such that the complete Hop-by-Hop Options header is an integer multiple of 8 octets long. Contains one or more TLV-encoded options, as described in Section 4.2.
Options可变长度字段，其长度应确保完整的逐跳Options标头为8个八位字节长的整数倍。包含一个或多个TLV编码选项，如第4.2节所述。
The only hop-by-hop options defined in this document are the Pad1 and PadN options specified in Section 4.2.
本文件中定义的唯一逐跳选项是第4.2节中规定的Pad1和PadN选项。
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 destination. This function is very similar to IPv4's Loose Source and Record Route option. The Routing header is identified by a Next Header value of 43 in the immediately preceding header and has the following format:
IPv6源使用路由报头列出一个或多个中间节点，这些节点将在到达数据包目的地的途中“访问”。此功能与IPv4的松散源代码和记录路由选项非常相似。路由报头由前一报头中的下一报头值43标识，格式如下：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. type-specific data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. type-specific data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the type of header immediately following the Routing header. Uses the same values as the IPv4 Protocol field [IANA-PN].
下一个标题8位选择器。标识紧接路由标头之后的标头类型。使用与IPv4协议字段[IANA-PN]相同的值。
Hdr Ext Len 8-bit unsigned integer. Length of the Routing header in 8-octet units, not including the first 8 octets.
Hdr Ext Len 8位无符号整数。路由头的长度，以8个八位字节为单位，不包括前8个八位字节。
Routing Type 8-bit identifier of a particular Routing header variant.
路由类型特定路由头变量的8位标识符。
Segments Left 8-bit unsigned integer. Number of route segments remaining, i.e., number of explicitly listed intermediate nodes still to be visited before reaching the final destination.
段左8位无符号整数。剩余的路由段数，即在到达最终目的地之前仍要访问的明确列出的中间节点数。
type-specific data Variable-length field, of format determined by the Routing Type, and of length such that the complete Routing header is an integer multiple of 8 octets long.
特定于类型的数据可变长度字段，其格式由路由类型确定，长度应确保完整的路由头是8个八位字节的整数倍。
If, while processing a received packet, a node encounters a Routing header with an unrecognized Routing Type value, the required behavior of the node depends on the value of the Segments Left field, as follows:
如果在处理接收到的数据包时，节点遇到具有无法识别的路由类型值的路由报头，则节点所需的行为取决于Segments Left字段的值，如下所示：
If Segments Left is zero, the node must ignore the Routing header and proceed to process the next header in the packet, whose type is identified by the Next Header field in the Routing header.
如果剩余段为零，则节点必须忽略路由报头并继续处理数据包中的下一个报头，其类型由路由报头中的下一个报头字段标识。
If Segments Left is non-zero, the node must discard the packet and send an ICMP Parameter Problem, Code 0, message to the packet's Source Address, pointing to the unrecognized Routing Type.
如果剩余段不为零，则节点必须丢弃数据包，并向数据包的源地址发送ICMP参数问题代码0消息，指向无法识别的路由类型。
If, after processing a Routing header of a received packet, an intermediate node determines that the packet is to be forwarded onto a link whose link MTU is less than the size of the packet, the node must discard the packet and send an ICMP Packet Too Big message to the packet's Source Address.
如果在处理所接收分组的路由报头之后，中间节点确定该分组将被转发到链路MTU小于该分组大小的链路上，则该节点必须丢弃该分组并向该分组的源地址发送ICMP分组过大消息。
The currently defined IPv6 Routing Headers and their status can be found at [IANA-RH]. Allocation guidelines for IPv6 Routing Headers can be found in [RFC5871].
当前定义的IPv6路由头及其状态可在[IANA-RH]中找到。IPv6路由头的分配指南可在[RFC5871]中找到。
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 IPv4, fragmentation in IPv6 is performed only by source nodes, not by routers along a packet's delivery path -- see Section 5.) The Fragment header is identified by a Next Header value of 44 in the immediately preceding header and has the following format:
IPv6源使用片段头向其目的地发送比路径MTU中适合的数据包大的数据包。（注意：与IPv4不同，IPv6中的分段仅由源节点执行，而不是由沿数据包传递路径的路由器执行——请参见第5节。）分段标头由前一个标头中的下一个标头值44标识，格式如下：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Reserved | Fragment Offset |Res|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Reserved | Fragment Offset |Res|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the initial header type of the Fragmentable Part of the original packet (defined below). Uses the same values as the IPv4 Protocol field [IANA-PN].
下一个标题8位选择器。标识原始数据包（定义见下文）可分段部分的初始头类型。使用与IPv4协议字段[IANA-PN]相同的值。
Reserved 8-bit reserved field. Initialized to zero for transmission; ignored on reception.
保留8位保留字段。初始化为零以便传输；接待时被忽略。
Fragment Offset 13-bit unsigned integer. The offset, in 8-octet units, of the data following this header, relative to the start of the Fragmentable Part of the original packet.
片段偏移量13位无符号整数。该报头之后的数据相对于原始数据包的可分割部分的开始的偏移量，以8个八位字节为单位。
Res 2-bit reserved field. Initialized to zero for transmission; ignored on reception.
Res 2位保留字段。初始化为零以便传输；接待时被忽略。
M flag 1 = more fragments; 0 = last fragment.
M标志1=更多碎片；0=最后一个片段。
Identification 32 bits. See description below.
标识32位。见下面的描述。
In order to send a packet that is too large to fit in the MTU of the path to its destination, a source node may divide the packet into fragments and send each fragment as a separate packet, to be reassembled at the receiver.
为了发送太大而不适合其目的地的路径的MTU的分组，源节点可以将该分组分成片段，并将每个片段作为单独的分组发送，以在接收器处重新组装。
For every packet that is to be fragmented, the source node generates an Identification value. The Identification must be different than that of any other fragmented packet sent recently* with the same Source Address and Destination Address. If a Routing header is present, the Destination Address of concern is that of the final destination.
对于要分段的每个数据包，源节点生成一个标识值。该标识必须与最近发送的具有相同源地址和目标地址的任何其他碎片数据包的标识不同。如果存在路由标头，则关注的目的地地址是最终目的地的地址。
* "recently" means within the maximum likely lifetime of a packet, including transit time from source to destination and time spent awaiting reassembly with other fragments of the same packet. However, it is not required that a source node knows the maximum packet lifetime. Rather, it is assumed that the requirement can be met by implementing an algorithm that results in a low identification reuse frequency. Examples of algorithms that can meet this requirement are described in [RFC7739].
* “最近”是指在数据包的最大可能生存期内，包括从源到目的地的传输时间以及等待与同一数据包的其他片段重新组装所花费的时间。然而，不要求源节点知道最大数据包生存期。相反，假设可以通过实现导致低识别重用频率的算法来满足需求。[RFC7739]中描述了可满足此要求的算法示例。
The initial, large, unfragmented packet is referred to as the "original packet", and it is considered to consist of three parts, as illustrated:
初始的、大的、未分割的数据包被称为“原始数据包”，它被认为由三部分组成，如图所示：
original packet:
原始数据包：
+------------------+-------------------------+---//----------------+
| Per-Fragment | Extension & Upper-Layer | Fragmentable |
| Headers | Headers | Part |
+------------------+-------------------------+---//----------------+
+------------------+-------------------------+---//----------------+
| Per-Fragment | Extension & Upper-Layer | Fragmentable |
| Headers | Headers | Part |
+------------------+-------------------------+---//----------------+
The Per-Fragment headers must consist of the IPv6 header plus any extension headers that must be processed by nodes en route to the destination, that is, all headers up to and including the Routing header if present, else the Hop-by-Hop Options header if present, else no extension headers.
每个片段头必须由IPv6头加上节点在路由到目的地的过程中必须处理的任何扩展头组成，也就是说，路由头（如果存在）之前的所有头（包括路由头），否则逐跳选项头（如果存在），否则无扩展头。
The Extension headers are all other extension headers that are not included in the Per-Fragment headers part of the packet. For this purpose, the Encapsulating Security Payload (ESP) is not considered an extension header. The Upper-Layer header is the first upper-layer header that is not an IPv6 extension header. Examples of upper-layer headers include TCP, UDP, IPv4, IPv6, ICMPv6, and as noted ESP.
扩展头是数据包的每片段头部分中不包括的所有其他扩展头。为此，封装安全有效负载（ESP）不被视为扩展头。上层标头是不是IPv6扩展标头的第一个上层标头。上层头的示例包括TCP、UDP、IPv4、IPv6、ICMPv6和如前所述的ESP。
The Fragmentable Part consists of the rest of the packet after the upper-layer header or after any header (i.e., initial IPv6 header or extension header) that contains a Next Header value of No Next Header.
可分段部分由上层报头之后或任何报头（即初始IPv6报头或扩展报头）之后的数据包剩余部分组成，该报头包含无下一报头的下一报头值。
The Fragmentable Part of the original packet is divided into fragments. The lengths of the fragments must be chosen such that the resulting fragment packets fit within the MTU of the path to the packet's destination(s). Each complete fragment, except possibly the last ("rightmost") one, is an integer multiple of 8 octets long.
原始数据包的可分割部分被划分为多个片段。必须选择片段的长度，以使生成的片段数据包适合到数据包目的地的路径的MTU。每个完整的片段，可能除了最后一个（“最右边的”）片段外，都是8个八位字节长的整数倍。
The fragments are transmitted in separate "fragment packets" as illustrated:
片段在单独的“片段包”中传输，如图所示：
original packet:
原始数据包：
+-----------------+-----------------+--------+--------+-//-+--------+
| Per-Fragment |Ext & Upper-Layer| first | second | | last |
| Headers | Headers |fragment|fragment|....|fragment|
+-----------------+-----------------+--------+--------+-//-+--------+
+-----------------+-----------------+--------+--------+-//-+--------+
| Per-Fragment |Ext & Upper-Layer| first | second | | last |
| Headers | Headers |fragment|fragment|....|fragment|
+-----------------+-----------------+--------+--------+-//-+--------+
fragment packets:
片段数据包：
+------------------+---------+-------------------+----------+
| Per-Fragment |Fragment | Ext & Upper-Layer | first |
| Headers | Header | Headers | fragment |
+------------------+---------+-------------------+----------+
+------------------+---------+-------------------+----------+
| Per-Fragment |Fragment | Ext & Upper-Layer | first |
| Headers | Header | Headers | fragment |
+------------------+---------+-------------------+----------+
+------------------+--------+-------------------------------+
| Per-Fragment |Fragment| second |
| Headers | Header | fragment |
+------------------+--------+-------------------------------+
o
o
o
+------------------+--------+----------+
| Per-Fragment |Fragment| last |
| Headers | Header | fragment |
+------------------+--------+----------+
+------------------+--------+-------------------------------+
| Per-Fragment |Fragment| second |
| Headers | Header | fragment |
+------------------+--------+-------------------------------+
o
o
o
+------------------+--------+----------+
| Per-Fragment |Fragment| last |
| Headers | Header | fragment |
+------------------+--------+----------+
The first fragment packet is composed of:
第一个片段数据包由以下部分组成：
(1) The Per-Fragment headers of the original packet, with the Payload Length of the original IPv6 header changed to contain the length of this fragment packet only (excluding the length of the IPv6 header itself), and the Next Header field of the last header of the Per-Fragment headers changed to 44.
(1) 原始数据包的每片段报头，原始IPv6报头的有效负载长度更改为仅包含此片段数据包的长度（不包括IPv6报头本身的长度），每片段报头最后一个报头的下一个报头字段更改为44。
(2) A Fragment header containing:
(2) 包含以下内容的片段标头：
The Next Header value that identifies the first header after the Per-Fragment headers of the original packet.
下一个标头值，用于标识原始数据包的每片段标头之后的第一个标头。
A Fragment Offset containing the offset of the fragment, in 8-octet units, relative to the start of the Fragmentable Part of the original packet. The Fragment Offset of the first ("leftmost") fragment is 0.
包含片段偏移量的片段偏移量，以8个八位字节为单位，相对于原始数据包的可分段部分的开始。第一个（“最左边”）片段的片段偏移量为0。
An M flag value of 1 as this is the first fragment.
M标志值为1，因为这是第一个片段。
The Identification value generated for the original packet.
为原始数据包生成的标识值。
(3) Extension headers, if any, and the Upper-Layer header. These headers must be in the first fragment. Note: This restricts the size of the headers through the Upper-Layer header to the MTU of the path to the packet's destinations(s).
(3) 扩展标头（如果有）和上层标头。这些头必须在第一个片段中。注意：这限制了通过上层报头到数据包目的地路径MTU的报头的大小。
(4) The first fragment.
(4) 第一个片段。
The subsequent fragment packets are composed of:
后续片段数据包由以下部分组成：
(1) The Per-Fragment headers of the original packet, with the Payload Length of the original IPv6 header changed to contain the length of this fragment packet only (excluding the length of the IPv6 header itself), and the Next Header field of the last header of the Per-Fragment headers changed to 44.
(1) 原始数据包的每片段报头，原始IPv6报头的有效负载长度更改为仅包含此片段数据包的长度（不包括IPv6报头本身的长度），每片段报头最后一个报头的下一个报头字段更改为44。
(2) A Fragment header containing:
(2) 包含以下内容的片段标头：
The Next Header value that identifies the first header after the Per-Fragment headers of the original packet.
下一个标头值，用于标识原始数据包的每片段标头之后的第一个标头。
A Fragment Offset containing the offset of the fragment, in 8-octet units, relative to the start of the Fragmentable Part of the original packet.
包含片段偏移量的片段偏移量，以8个八位字节为单位，相对于原始数据包的可分段部分的开始。
An M flag value of 0 if the fragment is the last ("rightmost") one, else an M flag value of 1.
如果片段是最后一个（“最右边”）片段，则M标志值为0，否则M标志值为1。
The Identification value generated for the original packet.
为原始数据包生成的标识值。
(3) The fragment itself.
(3) 碎片本身。
Fragments must not be created that overlap with any other fragments created from the original packet.
不得创建与从原始数据包创建的任何其他片段重叠的片段。
At the destination, fragment packets are reassembled into their original, unfragmented form, as illustrated:
在目的地，片段数据包被重新组装成其原始的未片段形式，如图所示：
reassembled original packet:
重新组装的原始数据包：
+---------------+-----------------+---------+--------+-//--+--------+
| Per-Fragment |Ext & Upper-Layer| first | second | | last |
| Headers | Headers |frag data|fragment|.....|fragment|
+---------------+-----------------+---------+--------+-//--+--------+
+---------------+-----------------+---------+--------+-//--+--------+
| Per-Fragment |Ext & Upper-Layer| first | second | | last |
| Headers | Headers |frag data|fragment|.....|fragment|
+---------------+-----------------+---------+--------+-//--+--------+
The following rules govern reassembly:
以下规则适用于重新组装：
An original packet is reassembled only from fragment packets that have the same Source Address, Destination Address, and Fragment Identification.
原始数据包仅从具有相同源地址、目标地址和片段标识的片段数据包重新组装。
The Per-Fragment headers of the reassembled packet consists of all headers up to, but not including, the Fragment header of the first fragment packet (that is, the packet whose Fragment Offset is zero), with the following two changes:
重新组装的数据包的每片段报头包括第一个片段数据包的片段报头（即片段偏移量为零的数据包）之前的所有报头，但不包括这些报头，其中有以下两个变化：
The Next Header field of the last header of the Per-Fragment headers is obtained from the Next Header field of the first fragment's Fragment header.
每个片段头的最后一个头的下一个头字段来自第一个片段的片段头的下一个头字段。
The Payload Length of the reassembled packet is computed from the length of the Per-Fragment headers and the length and offset of the last fragment. For example, a formula for computing the Payload Length of the reassembled original packet is:
重新组装的数据包的有效负载长度是根据每个片段头的长度以及最后一个片段的长度和偏移量来计算的。例如，用于计算重新组装的原始分组的有效载荷长度的公式为：
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 PL.orig = Payload Length field of reassembled packet. PL.first = Payload Length field of first fragment packet. FL.first = length of fragment following Fragment header of first fragment packet. FO.last = Fragment Offset field of Fragment header of last fragment packet. FL.last = length of fragment following Fragment header of last fragment packet.
其中PL.orig=重新组装的数据包的有效载荷长度字段。PL.first=第一个片段数据包的有效负载长度字段。FL.first=第一个片段数据包的片段头之后的片段长度。FO.last=最后一个片段数据包的片段头的片段偏移量字段。FL.last=最后一个片段数据包的片段头之后的片段长度。
The Fragmentable Part of the reassembled packet is constructed from the fragments following the Fragment headers in each of the fragment packets. The length of each fragment is computed by subtracting from the packet's Payload Length the length of the headers between the IPv6 header and fragment itself; its
重新组装的数据包的可分段部分由每个片段数据包中片段头之后的片段构成。通过从数据包的有效负载长度中减去IPv6报头和片段本身之间的报头长度来计算每个片段的长度；它的
relative position in Fragmentable Part is computed from its Fragment Offset value.
根据碎片偏移值计算可碎片零件中的相对位置。
The Fragment header is not present in the final, reassembled packet.
片段头不存在于最终重新组装的数据包中。
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 any further reassembly and should be processed as a fully reassembled packet (i.e., updating Next Header, adjust Payload Length, removing the Fragment header, etc.). Any other fragments that match this packet (i.e., the same IPv6 Source Address, IPv6 Destination Address, and Fragment Identification) should be processed independently.
如果片段是一个完整的数据报（即，片段偏移字段和M标志均为零），则它不需要进一步重新组装，应作为完全重新组装的数据包进行处理（即，更新下一个报头、调整有效负载长度、移除片段报头等）。应独立处理与此数据包匹配的任何其他片段（即，相同的IPv6源地址、IPv6目标地址和片段标识）。
The following error conditions may arise when reassembling fragmented packets:
重新组装碎片数据包时可能出现以下错误情况：
o If insufficient fragments are received to complete reassembly of a packet within 60 seconds of the reception of the first-arriving fragment of that packet, reassembly of that packet must be abandoned and all the fragments that have been received for that packet must be discarded. If the first fragment (i.e., the one with a Fragment Offset of zero) has been received, an ICMP Time Exceeded -- Fragment Reassembly Time Exceeded message should be sent to the source of that fragment.
o 如果在收到第一个到达的数据包片段后的60秒内没有收到足够的片段来完成数据包的重新组装，则必须放弃该数据包的重新组装，并且必须丢弃为该数据包接收的所有片段。如果已接收到第一个片段（即片段偏移量为零的片段），则应向该片段的源发送ICMP Time EXCENDED--片段重组时间EXCENDED消息。
o If the length of a fragment, as derived from the fragment packet's Payload Length field, is not a multiple of 8 octets and the M flag of that fragment is 1, then that fragment must be discarded and an ICMP Parameter Problem, Code 0, message should be sent to the source of the fragment, pointing to the Payload Length field of the fragment packet.
o 如果从片段数据包的有效负载长度字段派生的片段长度不是8个八位字节的倍数，并且该片段的M标志为1，则必须丢弃该片段，并且ICMP参数问题代码0消息应发送到片段源，指向片段数据包的有效负载长度字段。
o If the length and offset of a fragment are such that the Payload Length of the packet reassembled from that fragment would exceed 65,535 octets, then that fragment must be discarded and an ICMP Parameter Problem, Code 0, message should be sent to the source of the fragment, pointing to the Fragment Offset field of the fragment packet.
o 如果片段的长度和偏移量使从该片段重新组装的数据包的有效负载长度超过65535个八位字节，则必须丢弃该片段，并将ICMP参数问题代码0消息发送到片段源，指向片段数据包的片段偏移量字段。
o If the first fragment does not include all headers through an Upper-Layer header, then that fragment should be discarded and an ICMP Parameter Problem, Code 3, message should be sent to the source of the fragment, with the Pointer field set to zero.
o 如果第一个片段不包括通过上层标头的所有标头，则应丢弃该片段，并将ICMP参数问题（代码3）消息发送到片段源，指针字段设置为零。
o If any of the fragments being reassembled overlap with any other fragments being reassembled for the same packet, reassembly of that packet must be abandoned and all the fragments that have been received for that packet must be discarded, and no ICMP error messages should be sent.
o 如果重新组装的任何片段与为同一数据包重新组装的任何其他片段重叠，则必须放弃该数据包的重新组装，并且必须丢弃为该数据包接收的所有片段，并且不应发送ICMP错误消息。
It should be noted that fragments may be duplicated in the network. Instead of treating these exact duplicate fragments as overlapping fragments, an implementation may choose to detect this case and drop exact duplicate fragments while keeping the other fragments belonging to the same packet.
应该注意的是，片段可能在网络中重复。与将这些完全重复的片段视为重叠片段不同，实现可以选择检测这种情况并丢弃完全重复的片段，同时保留属于同一数据包的其他片段。
The following conditions are not expected to occur frequently but are not considered errors if they do:
以下情况预计不会频繁发生，但如果发生，则不视为错误：
The number and content of the headers preceding the Fragment header of different fragments of the same original packet may differ. Whatever headers are present, preceding the Fragment header in each fragment packet, are processed when the packets arrive, prior to queueing the fragments for reassembly. Only those headers in the Offset zero fragment packet are retained in the reassembled packet.
相同原始分组的不同片段的片段报头之前的报头的数量和内容可能不同。在每个片段数据包中，在片段报头之前存在的任何报头都会在数据包到达时进行处理，然后再将片段排队进行重新组装。重新组装的数据包中只保留偏移量为零的片段数据包中的那些头。
The Next Header values in the Fragment headers of different fragments of the same original packet may differ. Only the value from the Offset zero fragment packet is used for reassembly.
同一原始分组的不同片段的片段报头中的下一报头值可能不同。只有来自偏移量零片段数据包的值用于重新组装。
Other fields in the IPv6 header may also vary across the fragments being reassembled. Specifications that use these fields may provide additional instructions if the basic mechanism of using the values from the Offset zero fragment is not sufficient. For example, Section 5.3 of [RFC3168] describes how to combine the Explicit Congestion Notification (ECN) bits from different fragments to derive the ECN bits of the reassembled packet.
IPv6标头中的其他字段也可能因重新组装的片段而异。如果使用偏移量零片段中的值的基本机制不够，则使用这些字段的规范可能会提供额外的说明。例如，[RFC3168]的第5.3节描述了如何组合来自不同片段的显式拥塞通知（ECN）位，以导出重新组装的数据包的ECN位。
The Destination Options header is used to carry optional information 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 in the immediately preceding header and has the following format:
Destination Options报头用于承载仅需要由数据包的目的地节点检查的可选信息。目标选项标头由前一个标头中的下一个标头值60标识，格式如下：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the type of header immediately following the Destination Options header. Uses the same values as the IPv4 Protocol field [IANA-PN].
下一个标题8位选择器。标识紧跟在目标选项标头之后的标头类型。使用与IPv4协议字段[IANA-PN]相同的值。
Hdr Ext Len 8-bit unsigned integer. Length of the Destination Options header in 8-octet units, not including the first 8 octets.
Hdr Ext Len 8位无符号整数。目标选项标头的长度，以8个八位字节为单位，不包括前8个八位字节。
Options Variable-length field, of length such that the complete Destination Options header is an integer multiple of 8 octets long. Contains one or more TLV-encoded options, as described in Section 4.2.
Options可变长度字段，其长度应确保完整的目标选项标头为8个八位字节长的整数倍。包含一个或多个TLV编码选项，如第4.2节所述。
The only destination options defined in this document are the Pad1 and PadN options specified in Section 4.2.
本文件中定义的唯一目的地选项是第4.2节中规定的Pad1和PadN选项。
Note that there are two possible ways to encode optional destination information in an IPv6 packet: either as an option in the Destination Options header or as a separate extension header. The Fragment header and the Authentication header are examples of the latter approach. Which approach can be used depends on what action is desired of a destination node that does not understand the optional information:
请注意，在IPv6数据包中编码可选目标信息有两种可能的方法：作为目标选项标头中的选项或作为单独的扩展标头。片段头和身份验证头是后一种方法的示例。可以使用哪种方法取决于不了解可选信息的目标节点需要采取什么行动：
o If the desired action is for the destination node to discard the packet and, only if the packet's Destination Address is not a multicast address, send an ICMP Unrecognized Type message to the packet's Source Address, then the information may be encoded either as a separate header or as an option in the
o 如果所需的操作是目的地节点丢弃该分组，并且仅当该分组的目的地地址不是多播地址时，才向该分组的源地址发送ICMP未识别类型的消息，则该信息可以被编码为单独的报头，或者作为该报头中的一个选项
Destination Options header whose Option Type has the value 11 in its highest-order 2 bits. The choice may depend on such factors as which takes fewer octets, or which yields better alignment or more efficient parsing.
目标选项标头，其选项类型在其最高顺序2位中的值为11。选择可能取决于这样的因素，例如需要更少的八位字节，或者产生更好的对齐或更有效的解析。
o If any other action is desired, the information must be encoded as an option in the Destination Options header whose Option Type has the value 00, 01, or 10 in its highest-order 2 bits, specifying the desired action (see Section 4.2).
o 如果需要任何其他操作，则必须将信息编码为目标选项标题中的选项，其选项类型的最高2位值为00、01或10，指定所需操作（参见第4.2节）。
The value 59 in the Next Header field of an IPv6 header or any extension header indicates that there is nothing following that 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 contains 59, those octets must be ignored and passed on unchanged if the packet is forwarded.
IPv6标头或任何扩展标头的下一个标头字段中的值59表示该标头后面没有任何内容。如果IPv6报头的有效负载长度字段指示在下一个报头字段包含59个字节的报头末尾之后存在八位字节，则必须忽略这些八位字节，并在转发数据包时保持不变。
Defining new IPv6 extension headers is not recommended, unless there are no existing IPv6 extension headers that can be used by specifying a new option for that IPv6 extension header. A proposal to specify a new IPv6 extension header must include a detailed technical explanation of why an existing IPv6 extension header can not be used for the desired new function. See [RFC6564] for additional background information.
不建议定义新的IPv6扩展标头，除非通过为该IPv6扩展标头指定新选项，没有可使用的现有IPv6扩展标头。指定新IPv6扩展标头的提案必须包括详细的技术说明，说明现有IPv6扩展标头无法用于所需新功能的原因。更多背景信息，请参见[RFC6564]。
Note: New extension headers that require hop-by-hop behavior must not 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 Options header.
注意：不能定义需要逐跳行为的新扩展标头，因为如本文档第4节所述，具有逐跳行为的唯一扩展标头是逐跳选项标头。
New hop-by-hop options are not recommended because nodes may be configured to ignore the Hop-by-Hop Options header, drop packets containing a Hop-by-Hop Options header, or assign packets containing a Hop-by-Hop Options header to a slow processing path. Designers considering defining new hop-by-hop options need to be aware of this likely behavior. There has to be a very clear justification why any new hop-by-hop option is needed before it is standardized.
不建议使用新的逐跳选项，因为节点可能被配置为忽略逐跳选项标头，丢弃包含逐跳选项标头的数据包，或将包含逐跳选项标头的数据包分配给慢速处理路径。考虑定义新的逐跳选项的设计师需要了解这种可能的行为。在标准化之前，必须有一个非常明确的理由说明为什么需要任何新的逐跳选项。
Instead of defining new extension headers, it is recommended that the Destination Options header is used to carry optional information that must be examined only by a packet's destination node(s), because they provide better handling and backward compatibility.
建议使用Destination Options报头来携带可选信息，而不是定义新的扩展报头，这些信息必须仅由数据包的目标节点检查，因为它们提供了更好的处理和向后兼容性。
If new extension headers are defined, they need to use the following format:
如果定义了新的扩展标头，则需要使用以下格式：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Header-Specific Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Header-Specific Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the type of header immediately following the extension header. Uses the same values as the IPv4 Protocol field [IANA-PN].
下一个标题8位选择器。标识紧跟在扩展标头之后的标头类型。使用与IPv4协议字段[IANA-PN]相同的值。
Hdr Ext Len 8-bit unsigned integer. Length of the Destination Options header in 8-octet units, not including the first 8 octets.
Hdr Ext Len 8位无符号整数。目标选项标头的长度，以8个八位字节为单位，不包括前8个八位字节。
Header Specific Data Variable-length field. Fields specific to the extension header.
标题特定的数据可变长度字段。特定于扩展标题的字段。
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 any link that cannot convey a 1280-octet packet in one piece, link-specific fragmentation and reassembly must be provided at a layer below IPv6.
IPv6要求Internet中的每条链路都有1280个八位字节或更大的MTU。这称为IPv6最小链路MTU。在任何不能完整传输1280个八位组数据包的链路上，必须在IPv6下的一层提供特定于链路的分段和重组。
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 recommended that they be configured with an MTU of 1500 octets or greater, to accommodate possible encapsulations (i.e., tunneling) without incurring IPv6-layer fragmentation.
具有可配置MTU的链路（例如，PPP链路[RFC1661]）必须配置为具有至少1280个八位字节的MTU；建议将其配置为1500个八位字节或更大的MTU，以适应可能的封装（即隧道），而不会导致IPv6层碎片。
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.
从节点直接连接到的每个链路，节点必须能够接受与该链路的MTU一样大的数据包。
It is strongly recommended that IPv6 nodes implement Path MTU Discovery [RFC8201], in order to discover and take advantage of path MTUs greater than 1280 octets. However, a minimal IPv6 implementation (e.g., in a boot ROM) may simply restrict itself to sending packets no larger than 1280 octets, and omit implementation of Path MTU Discovery.
强烈建议IPv6节点实现路径MTU发现[RFC8201]，以便发现并利用大于1280个八位字节的路径MTU。然而，最小IPv6实现（例如，在引导ROM中）可能仅限于发送不大于1280个八位字节的数据包，而忽略路径MTU发现的实现。
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 have it reassembled at the destination(s). However, the use of such fragmentation is discouraged in any application that is able to adjust its packets to fit the measured path MTU (i.e., down to 1280 octets).
为了发送大于路径MTU的数据包，节点可以使用IPv6片段头在源处对数据包进行片段化，并在目的地重新组装数据包。然而，在任何能够调整其分组以适合测量路径MTU（即，低至1280个八位字节）的应用程序中，不鼓励使用这种分段。
A node must be able to accept a fragmented packet that, after reassembly, is as large as 1500 octets. A node is permitted to accept fragmented packets that reassemble to more than 1500 octets. An upper-layer protocol or application that depends on IPv6 fragmentation to send packets larger than the MTU of a path should not send packets larger than 1500 octets unless it has assurance that the destination is capable of reassembling packets of that larger size.
一个节点必须能够接受一个碎片数据包，在重新组装后，这个碎片数据包的大小可达1500个八位组。允许一个节点接受碎片数据包，这些碎片数据包重新组合到1500个八位组以上。依赖IPv6碎片发送大于路径MTU的数据包的上层协议或应用程序不应发送大于1500个八位字节的数据包，除非其确保目的地能够重新组合该较大的数据包。
The 20-bit Flow Label field in the IPv6 header is used by a source to label sequences of packets to be treated in the network as a single flow.
IPv6报头中的20位流标签字段由源用于标记要在网络中作为单个流处理的数据包序列。
The current definition of the IPv6 Flow Label can be found in [RFC6437].
IPv6流标签的当前定义可在[RFC6437]中找到。
The 8-bit Traffic Class field in the IPv6 header is used by the network for traffic management. The value of the Traffic Class bits in a received packet or fragment might be different from the value sent by the packet's source.
IPv6标头中的8位流量类别字段由网络用于流量管理。接收到的数据包或片段中的流量类位的值可能与数据包源发送的值不同。
The current use of the Traffic Class field for Differentiated Services and Explicit Congestion Notification is specified in [RFC2474] and [RFC3168].
[RFC2474]和[RFC3168]中规定了区分服务和显式拥塞通知的当前使用流量类别字段。
Any transport or other upper-layer protocol that includes the addresses from the IP header in its checksum computation must be modified for use over IPv6, to include the 128-bit IPv6 addresses instead of 32-bit IPv4 addresses. In particular, the following illustration shows the TCP and UDP "pseudo-header" for IPv6:
任何在校验和计算中包含IP报头地址的传输协议或其他上层协议都必须进行修改，以便在IPv6上使用，以包含128位IPv6地址，而不是32位IPv4地址。特别是，下图显示了IPv6的TCP和UDP“伪标头”：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Upper-Layer Packet Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| zero | Next Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Upper-Layer Packet Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| zero | Next Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o If the IPv6 packet contains a Routing header, the Destination Address used in the pseudo-header is that of the final destination. At the originating node, that address will be in the last element of the Routing header; at the recipient(s), that address will be in the Destination Address field of the IPv6 header.
o 如果IPv6数据包包含路由报头，则伪报头中使用的目的地地址是最终目的地的地址。在发起节点，该地址将位于路由报头的最后一个元素中；在收件人处，该地址将位于IPv6标头的目标地址字段中。
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 differ from the Next Header value in the IPv6 header if there are extension headers between the IPv6 header and the upper-layer header.
o 伪报头中的下一个报头值标识上层协议（例如，TCP为6，UDP为17）。如果IPv6标头和上层标头之间存在扩展标头，则它将不同于IPv6标头中的下一个标头值。
o The Upper-Layer Packet Length in the pseudo-header is the length of the upper-layer header and data (e.g., TCP header plus TCP data). Some upper-layer protocols carry their own length information (e.g., the Length field in the UDP header); for such protocols, that is the length used in the pseudo-header. Other protocols (such as TCP) do not carry their own length information, in which case the length used in the pseudo-header is the Payload Length from the IPv6 header, minus the length of any extension headers present between the IPv6 header and the upper-layer header.
o 伪报头中的上层数据包长度是上层报头和数据（例如，TCP报头加TCP数据）的长度。一些上层协议携带自己的长度信息（例如，UDP报头中的长度字段）；对于此类协议，这是伪报头中使用的长度。其他协议（如TCP）不携带自己的长度信息，在这种情况下，伪报头中使用的长度是来自IPv6报头的有效负载长度减去IPv6报头和上层报头之间存在的任何扩展报头的长度。
o Unlike IPv4, the default behavior when UDP packets are originated by an IPv6 node is that the UDP checksum is not optional. That is, whenever originating a UDP packet, an IPv6 node must compute a UDP checksum over the packet and the pseudo-header, and, if that computation yields a result of zero, it must be changed to hex FFFF for placement in the UDP header. IPv6 receivers must discard UDP packets containing a zero checksum and should log the error.
o 与IPv4不同，IPv6节点发起UDP数据包时的默认行为是UDP校验和不是可选的。也就是说，每当发起UDP数据包时，IPv6节点必须计算该数据包和伪报头上的UDP校验和，如果该计算结果为零，则必须将其更改为十六进制FFFF以放置在UDP报头中。IPv6接收器必须丢弃包含零校验和的UDP数据包，并应记录错误。
o As an exception to the default behavior, protocols that use UDP as a tunnel encapsulation may enable zero-checksum mode for a specific port (or set of ports) for sending and/or receiving. Any node implementing zero-checksum mode must follow the requirements specified in "Applicability Statement for the Use of IPv6 UDP Datagrams with Zero Checksums" [RFC6936].
o 作为默认行为的一个例外，使用UDP作为隧道封装的协议可以为发送和/或接收的特定端口（或一组端口）启用零校验和模式。任何实现零校验和模式的节点必须遵守“使用零校验和的IPv6 UDP数据报的适用性声明”[RFC6936]中规定的要求。
The IPv6 version of ICMP [RFC4443] includes the above pseudo-header 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 reason for the change is to protect ICMP from misdelivery or corruption of those fields of the IPv6 header on which it depends, which, unlike IPv4, are not covered by an internet-layer checksum. The Next Header field in the pseudo-header for ICMP contains the value 58, which identifies the IPv6 version of ICMP.
IPv6版本的ICMP[RFC4443]在校验和计算中包含上述伪报头；这是对IPv4版本ICMP的更改，该版本的校验和中不包含伪报头。更改的原因是保护ICMP不受其所依赖的IPv6报头字段的误发或损坏，与IPv4不同，这些字段不受internet层校验和的覆盖。ICMP伪标头中的下一个标头字段包含值58，该值标识ICMP的IPv6版本。
Unlike IPv4, IPv6 nodes are not required to enforce maximum packet lifetime. That is the reason the IPv4 "Time-to-Live" field was renamed "Hop Limit" in IPv6. In practice, very few, if any, IPv4 implementations conform to the requirement that they limit packet lifetime, so this is not a change in practice. Any upper-layer protocol that relies on the internet layer (whether IPv4 or IPv6) to limit packet lifetime ought to be upgraded to provide its own mechanisms for detecting and discarding obsolete packets.
与IPv4不同，IPv6节点不需要强制执行最大数据包生存期。这就是IPv4“生存时间”字段在IPv6中重命名为“跃点限制”的原因。实际上，很少有IPv4实现符合限制数据包生存期的要求，因此这在实践中不是一个变化。任何依赖互联网层（IPv4或IPv6）来限制数据包生存期的上层协议都应该升级，以提供自己的机制来检测和丢弃过时的数据包。
When computing the maximum payload size available for upper-layer data, an upper-layer protocol must take into account the larger size of the IPv6 header relative to the IPv4 header. For example, in IPv4, TCP's Maximum Segment Size (MSS) option is computed as the maximum packet size (a default value or a value learned through Path MTU Discovery) minus 40 octets (20 octets for the minimum-length IPv4 header and 20 octets for the minimum-length TCP header). When using TCP over IPv6, the MSS must be computed as the maximum packet size minus 60 octets, because the minimum-length IPv6 header (i.e., an IPv6 header with no extension headers) is 20 octets longer than a minimum-length IPv4 header.
在计算上层数据可用的最大有效负载大小时，上层协议必须考虑IPv6报头相对于IPv4报头的较大大小。例如，在IPv4中，TCP的最大段大小（MSS）选项计算为最大数据包大小（默认值或通过路径MTU发现学习的值）减去40个八位字节（最小长度IPv4报头为20个八位字节，最小长度TCP报头为20个八位字节）。在IPv6上使用TCP时，MSS必须计算为最大数据包大小减去60个八位字节，因为最小长度IPv6报头（即没有扩展报头的IPv6报头）比最小长度IPv4报头长20个八位字节。
When an upper-layer protocol sends one or more packets in response to a received packet that included a Routing header, the response packet(s) must not include a Routing header that was automatically derived by "reversing" the received Routing header UNLESS the integrity and authenticity of the received Source Address and Routing header have been verified (e.g., via the use of an Authentication header in the received packet). In other words, only the following kinds of packets are permitted in response to a received packet bearing a Routing header:
当上层协议发送一个或多个数据包以响应包含路由报头的接收数据包时，响应数据包不得包含通过“反向”自动导出的路由报头接收到的路由报头，除非已验证接收到的源地址和路由报头的完整性和真实性（例如，通过在接收到的分组中使用认证报头）。换句话说，仅允许以下类型的分组响应于承载路由报头的接收分组：
o Response packets that do not carry Routing headers.
o 不携带路由头的响应数据包。
o Response packets that carry Routing headers that were NOT derived by reversing the Routing header of the received packet (for example, a Routing header supplied by local configuration).
o 带有路由头的响应数据包，该路由头不是通过反转接收数据包的路由头（例如，由本地配置提供的路由头）而派生的。
o Response packets that carry Routing headers that were derived by reversing the Routing header of the received packet IF AND ONLY IF the integrity and authenticity of the Source Address and Routing header from the received packet have been verified by the responder.
o 当且仅当响应者已验证来自接收数据包的源地址和路由报头的完整性和真实性时，携带路由报头的响应数据包，该路由报头通过反转接收数据包的路由报头而派生。
RFC 2460 is referenced in a number of IANA registries. These include:
RFC 2460在许多IANA注册中引用。这些措施包括：
o Internet Protocol Version 6 (IPv6) Parameters [IANA-6P]
o 互联网协议版本6（IPv6）参数[IANA-6P]
o Assigned Internet Protocol Numbers [IANA-PN]
o 分配的互联网协议编号[IANA-PN]
o ONC RPC Network Identifiers (netids) [IANA-NI]
o ONC RPC网络标识符（NetID）[IANA-NI]
o Network Layer Protocol Identifiers (NLPIDs) of Interest [IANA-NL]
o 感兴趣的网络层协议标识符（NLPID）[IANA-NL]
o Protocol Registries [IANA-PR]
o 协议登记处[IANA-PR]
The IANA has updated these references to point to this document.
IANA更新了这些参考文献，以指向本文件。
IPv6, from the viewpoint of the basic format and transmission of packets, has security properties that are similar to IPv4. These security issues include:
从数据包的基本格式和传输角度来看，IPv6具有类似于IPv4的安全特性。这些安全问题包括：
o Eavesdropping, where on-path elements can observe the whole packet (including both contents and metadata) of each IPv6 datagram. o Replay, where the attacker records a sequence of packets off of the wire and plays them back to the party that originally received them. o Packet insertion, where the attacker forges a packet with some chosen set of properties and injects it into the network. o Packet deletion, where the attacker removes a packet from the wire. o Packet modification, where the attacker removes a packet from the wire, modifies it, and reinjects it into the network. o Man-in-the-middle (MITM) attacks, where the attacker subverts the communication stream in order to pose as the sender to receiver and the receiver to the sender. o Denial-of-service (DoS) attacks, where the attacker sends large amounts of legitimate traffic to a destination to overwhelm it.
o 窃听，其中路径元素可以观察每个IPv6数据报的整个数据包（包括内容和元数据）。o Replay，即攻击者从线路上记录一系列数据包，并将其回放给最初接收数据包的一方。o数据包插入，即攻击者伪造具有某些选定属性集的数据包，并将其注入网络。o数据包删除，即攻击者从线路上删除数据包。o数据包修改，即攻击者从线路上删除数据包，对其进行修改，然后将其重新注入网络。o中间人（MITM）攻击，攻击者破坏通信流，以充当发送方对接收方和接收方对发送方的角色。o拒绝服务（DoS）攻击，即攻击者向目的地发送大量合法流量以压倒目的地。
IPv6 packets can be protected from eavesdropping, replay, packet insertion, packet modification, and MITM attacks by use of the "Security Architecture for the Internet Protocol" [RFC4301]. In addition, upper-layer protocols such as Transport Layer Security (TLS) or Secure Shell (SSH) can be used to protect the application-layer traffic running on top of IPv6.
通过使用“互联网协议安全架构”[RFC4301]，可以保护IPv6数据包免受窃听、重播、数据包插入、数据包修改和MITM攻击。此外，传输层安全（TLS）或安全外壳（SSH）等上层协议可用于保护在IPv6上运行的应用层通信。
There is not any mechanism to protect against DoS attacks. Defending against these type of attacks is outside the scope of this specification.
没有任何机制可以防止DoS攻击。防御此类攻击不在本规范的范围内。
IPv6 addresses are significantly larger than IPv4 addresses making it 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 more information.
IPv6地址比IPv4地址大得多，这使得在Internet上甚至在单个网络链路（例如局域网）上扫描地址空间变得更加困难。有关更多信息，请参阅[RFC7707]。
IPv6 addresses of nodes are expected to be more visible on the Internet as compared with IPv4 since the use of address translation technology is reduced. This creates some additional privacy issues such as making it easier to distinguish endpoints. See [RFC7721] for more information.
由于减少了地址转换技术的使用，与IPv4相比，IPv6节点地址在Internet上的可视性更高。这会产生一些额外的隐私问题，例如更容易区分端点。有关更多信息，请参阅[RFC7721]。
The design of IPv6 extension header architecture, while adding a lot of flexibility, also creates new security challenges. As noted below, issues relating to the Fragment extension header have been resolved, but it's clear that for any new extension header designed in the future, the security implications need to be examined thoroughly, and this needs to include how the new extension header works with existing extension headers. See [RFC7045] for more information.
IPv6扩展头架构的设计在增加了很多灵活性的同时，也带来了新的安全挑战。如下所述，与片段扩展头相关的问题已经解决，但很明显，对于将来设计的任何新扩展头，都需要彻底检查安全性影响，这需要包括新扩展头如何与现有扩展头一起工作。有关更多信息，请参阅[RFC7045]。
This version of the IPv6 specification resolves a number of security issues that were found with the previous version [RFC2460] of the IPv6 specification. These include:
此版本的IPv6规范解决了先前版本[RFC2460]的IPv6规范中发现的许多安全问题。这些措施包括：
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 are zero). If received, they should be processed as a reassembled packet. Any other fragments that match should be processed independently. The Fragment creation process was modified to not create whole datagram fragments (Fragment Offset field and the M flag are zero). See [RFC6946] and [RFC8021] for more information.
o 修改文本以处理作为完整数据报的片段（即，片段偏移量字段和M标志均为零）。如果收到，应将其作为重新组装的数据包进行处理。匹配的任何其他片段都应单独处理。片段创建过程被修改为不创建整个数据报片段（片段偏移字段和M标志为零）。有关更多信息，请参阅[RFC6946]和[RFC8021]。
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 删除了第5节中的段落，该段落要求在报告下一跳MTU小于1280的ICMP数据包过大消息时，在传出数据包中包含一个片段头。有关更多信息，请参阅[RFC6946]。
o Changed the text to require that IPv6 nodes must not create overlapping fragments. Also, when reassembling an IPv6 datagram, if one or more of its constituent fragments is determined to be an overlapping fragment, the entire datagram (and any constituent fragments) must be silently discarded. Includes clarification that no ICMP error message should be sent if overlapping fragments are received. See [RFC5722] for more information.
o 将文本更改为要求IPv6节点不得创建重叠片段。此外，在重新组装IPv6数据报时，如果确定其一个或多个组成片段是重叠片段，则必须悄悄地丢弃整个数据报（以及任何组成片段）。包括澄清，如果收到重叠片段，则不应发送ICMP错误消息。有关更多信息，请参阅[RFC5722]。
o Revised the text to require that all headers through the first upper-layer header are in the first fragment. See [RFC7112] for more information.
o 修改文本，要求通过第一个上层标题的所有标题都位于第一个片段中。有关更多信息，请参阅[RFC7112]。
o Incorporated the updates from [RFC5095] and [RFC5871] to remove the description of the Routing Header type 0 (RH0), that the allocations guidelines for Routing headers are specified in RFC 5871, and removed RH0 from the list of required extension headers.
o 合并了[RFC5095]和[RFC5871]的更新，以删除路由头类型0（RH0）的描述，路由头的分配指南在RFC 5871中指定，并从所需扩展头列表中删除RH0。
Security issues relating to other parts of IPv6 including addressing, ICMPv6, Path MTU Discovery, etc., are discussed in the appropriate specifications.
与IPv6其他部分相关的安全问题，包括寻址、ICMPv6、路径MTU发现等，将在相应的规范中讨论。
[RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791, DOI 10.17487/RFC0791, September 1981, <http://www.rfc-editor.org/info/rfc791>.
[RFC791]Postel，J.，“互联网协议”，STD 5，RFC 791，DOI 10.17487/RFC07911981年9月<http://www.rfc-editor.org/info/rfc791>.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, DOI 10.17487/RFC2474, December 1998, <http://www.rfc-editor.org/info/rfc2474>.
[RFC2474]Nichols，K.，Blake，S.，Baker，F.，和D.Black，“IPv4和IPv6报头中区分服务字段（DS字段）的定义”，RFC 2474，DOI 10.17487/RFC2474，1998年12月<http://www.rfc-editor.org/info/rfc2474>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, DOI 10.17487/RFC3168, September 2001, <http://www.rfc-editor.org/info/rfc3168>.
[RFC3168]Ramakrishnan，K.，Floyd，S.，和D.Black，“向IP添加显式拥塞通知（ECN）”，RFC 3168，DOI 10.17487/RFC3168，2001年9月<http://www.rfc-editor.org/info/rfc3168>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2006, <http://www.rfc-editor.org/info/rfc4291>.
[RFC4291]Hinden，R.和S.Deering，“IP版本6寻址体系结构”，RFC 4291，DOI 10.17487/RFC42912006年2月<http://www.rfc-editor.org/info/rfc4291>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", STD 89, RFC 4443, DOI 10.17487/RFC4443, March 2006, <http://www.rfc-editor.org/info/rfc4443>.
[RFC4443]Conta，A.，Deering，S.和M.Gupta，Ed.“互联网协议版本6（IPv6）规范的互联网控制消息协议（ICMPv6）”，STD 89，RFC 4443，DOI 10.17487/RFC4443，2006年3月<http://www.rfc-editor.org/info/rfc4443>.
[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, "IPv6 Flow Label Specification", RFC 6437, DOI 10.17487/RFC6437, November 2011, <http://www.rfc-editor.org/info/rfc6437>.
[RFC6437]Amante，S.，Carpenter，B.，Jiang，S.，和J.Rajahalme，“IPv6流标签规范”，RFC 6437，DOI 10.17487/RFC6437，2011年11月<http://www.rfc-editor.org/info/rfc6437>.
[Err2541] RFC Errata, Erratum ID 2541, RFC 2460.
[Err2541]RFC勘误表，勘误表ID 2541，RFC 2460。
[Err4279] RFC Errata, Erratum ID 4279, RFC 2460.
[Err4279]RFC勘误表，勘误表ID 4279，RFC 2460。
[Err4657] RFC Errata, Erratum ID 4657, RFC 2460.
[Err4657]RFC勘误表，勘误表ID 4657，RFC 2460。
[Err4662] RFC Errata, Erratum ID 4662, RFC 2460.
[Err4662]RFC勘误表，勘误表ID 4662，RFC 2460。
[IANA-6P] IANA, "Internet Protocol Version 6 (IPv6) Parameters", <https://www.iana.org/assignments/ipv6-parameters>.
[IANA-6P]IANA，“互联网协议版本6（IPv6）参数”<https://www.iana.org/assignments/ipv6-parameters>.
[IANA-EH] IANA, "IPv6 Extension Header Types", <https://www.iana.org/assignments/ipv6-parameters>.
[IANA-EH]IANA，“IPv6扩展头类型”<https://www.iana.org/assignments/ipv6-parameters>.
[IANA-NI] IANA, "ONC RPC Network Identifiers (netids)", <https://www.iana.org/assignments/rpc-netids>.
[IANA-NI]IANA，“ONC RPC网络标识符（NetID）”<https://www.iana.org/assignments/rpc-netids>.
[IANA-NL] IANA, "Network Layer Protocol Identifiers (NLPIDs) of Interest", <https://www.iana.org/assignments/nlpids>.
[IANA-NL]IANA，“感兴趣的网络层协议标识符（NLPID）”<https://www.iana.org/assignments/nlpids>.
[IANA-PN] IANA, "Protocol Numbers", <https://www.iana.org/assignments/protocol-numbers>.
[IANA-PN]IANA，“协议编号”<https://www.iana.org/assignments/protocol-numbers>.
[IANA-PR] IANA, "Protocol Registries", <https://www.iana.org/ protocols>.
[IANA-PR]IANA，“协议注册”<https://www.iana.org/ 协议>。
[IANA-RH] IANA, "Routing Types", <https://www.iana.org/assignments/ ipv6-parameters>.
[IANA-RH]IANA，“路由类型”<https://www.iana.org/assignments/ ipv6参数>。
[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>.
[RFC1661]辛普森，W.，编辑，“点对点协议（PPP）”，STD 51，RFC 1661，DOI 10.17487/RFC16611994年7月<http://www.rfc-editor.org/info/rfc1661>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC2460]Deering，S.和R.Hinden，“互联网协议，第6版（IPv6）规范”，RFC 2460，DOI 10.17487/RFC2460，1998年12月<http://www.rfc-editor.org/info/rfc2460>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, December 2005, <http://www.rfc-editor.org/info/rfc4301>.
[RFC4301]Kent，S.和K.Seo，“互联网协议的安全架构”，RFC 4301，DOI 10.17487/RFC4301，2005年12月<http://www.rfc-editor.org/info/rfc4301>.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302, DOI 10.17487/RFC4302, December 2005, <http://www.rfc-editor.org/info/rfc4302>.
[RFC4302]Kent，S.，“IP认证头”，RFC 4302，DOI 10.17487/RFC4302，2005年12月<http://www.rfc-editor.org/info/rfc4302>.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303, DOI 10.17487/RFC4303, December 2005, <http://www.rfc-editor.org/info/rfc4303>.
[RFC4303]Kent，S.，“IP封装安全有效载荷（ESP）”，RFC 4303，DOI 10.17487/RFC4303，2005年12月<http://www.rfc-editor.org/info/rfc4303>.
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation of Type 0 Routing Headers in IPv6", RFC 5095, DOI 10.17487/RFC5095, December 2007, <http://www.rfc-editor.org/info/rfc5095>.
[RFC5095]Abley，J.，Savola，P.，和G.Neville Neil，“IPv6中0型路由头的弃用”，RFC 5095，DOI 10.17487/RFC5095，2007年12月<http://www.rfc-editor.org/info/rfc5095>.
[RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments", RFC 5722, DOI 10.17487/RFC5722, December 2009, <http://www.rfc-editor.org/info/rfc5722>.
[RFC5722]Krishnan，S.，“重叠IPv6片段的处理”，RFC 5722，DOI 10.17487/RFC5722，2009年12月<http://www.rfc-editor.org/info/rfc5722>.
[RFC5871] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for the IPv6 Routing Header", RFC 5871, DOI 10.17487/RFC5871, May 2010, <http://www.rfc-editor.org/info/rfc5871>.
[RFC5871]Arkko，J.和S.Bradner，“IPv6路由报头的IANA分配指南”，RFC 5871，DOI 10.17487/RFC5871，2010年5月<http://www.rfc-editor.org/info/rfc5871>.
[RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and M. Bhatia, "A Uniform Format for IPv6 Extension Headers", RFC 6564, DOI 10.17487/RFC6564, April 2012, <http://www.rfc-editor.org/info/rfc6564>.
[RFC6564]Krishnan，S.，Woodyatt，J.，Kline，E.，Hoagland，J.，和M.Bhatia，“IPv6扩展头的统一格式”，RFC 6564，DOI 10.17487/RFC6564，2012年4月<http://www.rfc-editor.org/info/rfc6564>.
[RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement for the Use of IPv6 UDP Datagrams with Zero Checksums", RFC 6936, DOI 10.17487/RFC6936, April 2013, <http://www.rfc-editor.org/info/rfc6936>.
[RFC6936]Fairhurst，G.和M.Westerlund，“使用具有零校验和的IPv6 UDP数据报的适用性声明”，RFC 6936，DOI 10.17487/RFC6936，2013年4月<http://www.rfc-editor.org/info/rfc6936>.
[RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", RFC 6946, DOI 10.17487/RFC6946, May 2013, <http://www.rfc-editor.org/info/rfc6946>.
[RFC6946]Gont，F.，“IPv6原子片段的处理”，RFC 6946，DOI 10.17487/RFC6946，2013年5月<http://www.rfc-editor.org/info/rfc6946>.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing of IPv6 Extension Headers", RFC 7045, DOI 10.17487/RFC7045, December 2013, <http://www.rfc-editor.org/info/rfc7045>.
[RFC7045]Carpenter，B.和S.Jiang，“IPv6扩展头的传输和处理”，RFC 7045，DOI 10.17487/RFC70452013年12月<http://www.rfc-editor.org/info/rfc7045>.
[RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of Oversized IPv6 Header Chains", RFC 7112, DOI 10.17487/RFC7112, January 2014, <http://www.rfc-editor.org/info/rfc7112>.
[RFC7112]Gont，F.，Manral，V.，和R.Bonica，“超大IPv6头链的影响”，RFC 7112，DOI 10.17487/RFC7112，2014年1月<http://www.rfc-editor.org/info/rfc7112>.
[RFC7707] Gont, F. and T. Chown, "Network Reconnaissance in IPv6 Networks", RFC 7707, DOI 10.17487/RFC7707, March 2016, <http://www.rfc-editor.org/info/rfc7707>.
[RFC7707]Gont，F.和T.Chown，“IPv6网络中的网络侦察”，RFC 7707，DOI 10.17487/RFC7707，2016年3月<http://www.rfc-editor.org/info/rfc7707>.
[RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy Considerations for IPv6 Address Generation Mechanisms", RFC 7721, DOI 10.17487/RFC7721, March 2016, <http://www.rfc-editor.org/info/rfc7721>.
[RFC7721]Cooper，A.，Gont，F.，和D.Thaler，“IPv6地址生成机制的安全和隐私考虑”，RFC 7721，DOI 10.17487/RFC7721，2016年3月<http://www.rfc-editor.org/info/rfc7721>.
[RFC7739] Gont, F., "Security Implications of Predictable Fragment Identification Values", RFC 7739, DOI 10.17487/RFC7739, February 2016, <http://www.rfc-editor.org/info/rfc7739>.
[RFC7739]Gont，F.，“可预测碎片识别值的安全影响”，RFC 7739，DOI 10.17487/RFC7739，2016年2月<http://www.rfc-editor.org/info/rfc7739>.
[RFC8021] Gont, F., Liu, W., and T. Anderson, "Generation of IPv6 Atomic Fragments Considered Harmful", RFC 8021, DOI 10.17487/RFC8021, January 2017, <http://www.rfc-editor.org/info/rfc8021>.
[RFC8021]Gont，F.，Liu，W.和T.Anderson，“被认为有害的IPv6原子碎片的产生”，RFC 8021，DOI 10.17487/RFC8021，2017年1月<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>.
[RFC8201]McCann，J.，Deering，S.，Mogul，J.，和R.Hinden，“IP版本6的路径MTU发现”，STD 87，RFC 8201，DOI 10.17487/RFC8201，2017年7月<http://www.rfc-editor.org/info/rfc8201>.
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 the Destination Options header, as described in Section 4.2. These guidelines are based on the following assumptions:
如第4.2节所述，本附录给出了在设计用于逐跳选项标题或目的地选项标题的新选项时如何布局字段的一些建议。这些指南基于以下假设：
o One desirable feature is that any multi-octet fields within the Option Data area of an option be aligned on their natural 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-Hop or Destination Options header, for n = 1, 2, 4, or 8.
o 一个可取的特征是，选项的选项数据区域内的任何多个八位字节字段应在其自然边界上对齐，即，宽度为n个八位字节的字段应放置在距离逐跳或目标选项报头开始的n个八位字节的整数倍处，即n=1、2、4或8。
o Another desirable feature is that the Hop-by-Hop or Destination Options header take up as little space as possible, subject to the requirement that the header be an integer multiple of 8 octets long.
o 另一个可取的特征是逐跳或目的地选项报头占用尽可能少的空间，但报头必须是8个八位字节长的整数倍。
o It may be assumed that, when either of the option-bearing headers are present, they carry a very small number of options, usually only one.
o 可以假设，当存在任何一个带有选项的标题时，它们携带的选项数量非常少，通常只有一个。
These assumptions suggest the following approach to laying out the fields of an option: order the fields from smallest to largest, with no interior padding, then derive the alignment requirement for the entire option based on the alignment requirement of the largest field (up to a maximum alignment of 8 octets). This approach is illustrated in the following examples:
这些假设建议采用以下方法来布置选项的字段：将字段从最小到最大排序，无内部填充，然后根据最大字段的对齐要求（最多8个八位字节的最大对齐）推导整个选项的对齐要求。以下示例说明了该方法：
Example 1
例1
If an option X required two data fields, one of length 8 octets and one of length 4 octets, it would be laid out as follows:
如果选项X需要两个数据字段，一个长度为8个八位字节，另一个长度为4个八位字节，则其布局如下：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Its alignment requirement is 8n+2, to ensure that the 8-octet field starts at a multiple-of-8 offset from the start of the enclosing header. A complete Hop-by-Hop or Destination Options header containing this one option would look as follows:
其对齐要求为8n+2，以确保8位字节字段从封闭标头开始的8倍偏移开始。包含这一选项的完整逐跳或目标选项标题如下所示：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=1 | Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=1 | Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Example 2
例2
If an option Y required three data fields, one of length 4 octets, one of length 2 octets, and one of length 1 octet, it would be laid out as follows:
如果选项Y需要三个数据字段，一个长度为4个八位字节，一个长度为2个八位字节，一个长度为1个八位字节，则其布局如下：
+-+-+-+-+-+-+-+-+
| Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+
| Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Its alignment requirement is 4n+3, to ensure that the 4-octet field starts at a multiple-of-4 offset from the start of the enclosing header. A complete Hop-by-Hop or Destination Options header containing this one option would look as follows:
其对齐要求为4n+3，以确保4-octet字段从封闭标头开始的4倍偏移量开始。包含这一选项的完整逐跳或目标选项标题如下所示：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=1 | Pad1 Option=0 | Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=2 | 0 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=1 | Pad1 Option=0 | Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=2 | 0 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Example 3
例3
A Hop-by-Hop or Destination Options header containing both options X and Y from Examples 1 and 2 would have one of the two following formats, depending on which option appeared first:
包含示例1和2中的选项X和Y的逐跳或目标选项标题将具有以下两种格式之一，具体取决于最先出现的选项：
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=3 | Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=1 | 0 | Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=2 | 0 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=3 | Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=1 | 0 | Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=2 | 0 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=3 | Pad1 Option=0 | Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=4 | 0 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | 0 | Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=3 | Pad1 Option=0 | Option Type=Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Opt Data Len=7 | 1-octet field | 2-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PadN Option=1 |Opt Data Len=4 | 0 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | 0 | Option Type=X |Opt Data Len=12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4-octet field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 8-octet field +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This memo has the following changes from RFC 2460.
本备忘录与RFC 2460相比有以下变化。
o Removed IP Next Generation from the Abstract.
o 从摘要中删除了IP下一代。
o Added text in Section 1 that the data transmission order is the same as IPv4 as defined in RFC 791.
o 在第1节中添加了数据传输顺序与RFC 791中定义的IPv4相同的文本。
o Clarified the text in Section 3 about decrementing the Hop Limit.
o 澄清了第3节中关于降低跃点限制的文本。
o Clarified that extension headers (except for the Hop-by-Hop Options header) are not processed, inserted, or deleted by any node along a packet's delivery path.
o 阐明了扩展标头（逐跳选项标头除外）不会由数据包传递路径上的任何节点处理、插入或删除。
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-by-Hop Options header.
o 将逐跳选项标题的要求更改为“可能”，并添加了一个注释，以指示有关逐跳选项标题的预期内容。
o Added a paragraph to Section 4 to clarify how extension headers are numbered and which are upper-layer headers.
o 在第4节中添加了一段，以澄清扩展标题是如何编号的，以及哪些是上层标题。
o Added a reference to the end of Section 4 to the "IPv6 Extension Header Types" IANA registry.
o 在IANA注册表的“IPv6扩展头类型”中添加了对第4节末尾的引用。
o Incorporated the updates from RFCs 5095 and 5871 to remove the description of RH0, that the allocations guidelines for routing headers are specified in RFC 5871, and removed RH0 from the list of required extension headers.
o 合并了来自RFC 5095和5871的更新，以删除RH0的描述，在RFC 5871中指定了路由标头的分配指南，并从所需扩展标头列表中删除了RH0。
o Revised Section 4.5 on IPv6 fragmentation based on updates from RFCs 5722, 6946, 7112, and 8021. This includes:
o 根据RFCs 5722、6946、7112和8021的更新，修订了关于IPv6分段的第4.5节。这包括：
- Revised the text to handle the case of fragments that are whole datagrams (i.e., both the Fragment Offset field and the M flag are zero). If received, they should be processed as a reassembled packet. Any other fragments that match should be processed independently. The revised Fragment creation process was modified to not create whole datagram fragments (Fragment Offset field and the M flag are zero).
- 修改文本以处理作为完整数据报的片段（即，片段偏移量字段和M标志均为零）。如果收到，应将其作为重新组装的数据包进行处理。匹配的任何其他片段都应单独处理。修改后的片段创建过程被修改为不创建整个数据报片段（片段偏移字段和M标志为零）。
- Changed the text to require that IPv6 nodes must not create overlapping fragments. Also, when reassembling an IPv6 datagram, if one or more its constituent fragments is determined to be an overlapping fragment, the entire datagram (and any constituent fragments) must be silently discarded. Includes a clarification that no ICMP error message should be sent if overlapping fragments are received.
- 将文本更改为要求IPv6节点不得创建重叠片段。此外，在重新组装IPv6数据报时，如果确定其一个或多个组成片段是重叠片段，则必须悄悄地丢弃整个数据报（以及任何组成片段）。包括一项澄清，即如果收到重叠片段，则不应发送ICMP错误消息。
- Revised the text 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.
- 修改文本，要求通过第一个上层标题的所有标题都位于第一个片段中。这改变了描述数据包如何分段和重新组装的文本，并添加了一个新的错误案例。
- Added text to the Fragment header process on handling exact duplicate fragments.
- 在处理完全重复的片段时，向片段头进程添加了文本。
- Updated the Fragmentation header text to correct the inclusion of an Authentication Header (AH) and noted No Next Header case.
- 更新了分段标头文本以更正包含的身份验证标头（AH），并注意到没有下一个标头案例。
- Changed terminology in the Fragment header section from "Unfragmentable Headers" to "Per-Fragment headers".
- 将片段头部分中的术语从“不可分割头”更改为“每个片段头”。
- Removed the paragraph in Section 5 that required including a Fragment header to outgoing packets if an ICMP Packet Too Big message reports a Next-Hop MTU less than 1280.
- 删除了第5节中的段落，该段落要求在ICMP数据包过大消息报告下一跳MTU小于1280时，在传出数据包中包含一个片段头。
- Changed the text to clarify MTU restriction and 8-byte restrictions, and noted the restriction on headers in the first fragment.
- 更改文本以澄清MTU限制和8字节限制，并注意到第一个片段中对标题的限制。
o 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. See, for example, Section 5.3 of [RFC3168].
o 在第4.5节中，添加了说明，注意到IPv6标头中的某些字段也可能因重新组装的片段而异，其他规范可能会提供有关如何重新组装的附加说明。例如，参见[RFC3168]第5.3节。
o Incorporated the update from RFC 6564 to add a new Section 4.8 that describes recommendations for defining new extension headers and options.
o 合并了RFC 6564的更新，以添加新的第4.8节，该节描述了定义新扩展头和选项的建议。
o Added text to Section 5 to define "IPv6 minimum link MTU".
o 在第5节中添加了定义“IPv6最小链路MTU”的文本。
o Simplified the text in Section 6 about Flow Labels and removed what was Appendix A ("Semantics and Usage of the Flow Label Field"); instead, pointed to the current specifications of the IPv6 Flow Label field in [RFC6437] and the Traffic Class field in [RFC2474] and [RFC3168].
o 简化了第6节中关于流量标签的文本，删除了附录A（“流量标签字段的语义和用法”）；相反，指向[RFC6437]中IPv6流标签字段的当前规范以及[RFC2474]和[RFC3168]中的流量类字段。
o Incorporated the update made by RFC 6935 ("IPv6 and UDP Checksums for Tunneled Packets") in Section 8. Added an exception to the default behavior for the handling of UDP packets with zero checksums for tunnels.
o 将RFC 6935（隧道数据包的IPv6和UDP校验和）所做的更新并入第8节。为处理隧道校验和为零的UDP数据包的默认行为添加了一个异常。
o Added instruction to Section 9, "IANA Considerations", to change references to RFC 2460 to this document.
o 增加了第9节“IANA注意事项”的说明，将RFC 2460的参考更改为本文件。
o Revised and expanded Section 10, "Security Considerations".
o 修订和扩大了第10节“安全考虑”。
o Added a paragraph to the Acknowledgments section acknowledging the authors of the updating documents.
o 在确认部分添加了一段，确认更新文档的作者。
o Updated references to current versions and assigned references to normative and informative.
o 更新了对当前版本的引用，并指定了对规范性和信息性版本的引用。
o Made changes to resolve the errata on RFC 2460. These are:
o 对RFC 2460上的勘误表进行了更改。这些是：
Erratum ID 2541 [Err2541]: This erratum notes that RFC 2460 didn't update RFC 2205 when the length of the flow label was changed from 24 to 20 bits from RFC 1883. This issue was resolved in RFC 6437 where the flow label is defined. This specification now references RFC 6437. No change is required.
勘误表ID 2541[Err2541]：此勘误表注意到，当流量标签的长度从RFC 1883的24位更改为20位时，RFC 2460没有更新RFC 2205。该问题在RFC 6437中得到解决，其中定义了流量标签。本规范现在参考RFC 6437。不需要更改。
Erratum ID 4279 [Err4279]: This erratum 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 specification.
勘误表ID 4279[Err4279]：该勘误表指出，该规范不处理转发节点接收具有零跳限制的数据包的情况。本规范第3节对此进行了固定。
Erratum ID 4657 [Err4657]: This erratum proposed text that extension headers must never be inserted by any node other than the source of the packet. This was resolved in Section 4, "IPv6 Extension Headers".
勘误表ID4657[Err4657]：这个勘误表建议的文本是，除了数据包的源之外，任何节点都不能插入扩展头。这在第4节“IPv6扩展头”中得到了解决。
Erratum ID 4662 [Err4662]: This erratum proposed text that extension headers, with one exception, are not examined, processed, modified, inserted, or deleted by any node along a packet's delivery path. This was resolved in Section 4, "IPv6 Extension Headers".
勘误表ID 4662[Err4662]：此勘误表建议的文本是，除了一个例外，扩展头不会被数据包传递路径上的任何节点检查、处理、修改、插入或删除。这在第4节“IPv6扩展头”中得到了解决。
Erratum ID 2843: This erratum is marked "Rejected". No change was made.
勘误表ID 2843：此勘误表标记为“已拒绝”。没有改变。
Acknowledgments
致谢
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.
作者非常感谢IPng工作组、端到端协议研究组和整个互联网社区成员提出的许多有益建议。
The authors would also like to acknowledge the authors of the updating RFCs that were incorporated in this 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.
作者还想感谢更新RFC的作者，这些RFC包含在本文档中，用于将IPv6规范转变为互联网标准。他们是乔·阿贝利、谢恩·阿曼特、贾里·阿尔科、马纳夫·巴蒂亚、罗纳德·博尼卡、斯科特·布拉德纳、布赖恩·卡彭特、P.F.奇门托、马歇尔·尤班克斯、费尔南多·贡特、詹姆斯·霍格兰、盛江、埃里克·克莱恩、苏雷什·克里希南、维斯瓦斯·曼拉尔、乔治·内维尔·尼尔、贾诺·拉贾哈尔梅、佩卡·萨沃拉、马格纳斯·韦斯特隆德和詹姆斯·伍迪亚特。
Authors' Addresses
作者地址
Stephen E. Deering Retired Vancouver, British Columbia Canada
斯蒂芬·迪林退休于加拿大不列颠哥伦比亚省温哥华
Robert M. Hinden Check Point Software 959 Skyway Road San Carlos, CA 94070 United States of America
美国加利福尼亚州圣卡洛斯市Skyway路959号Robert M.Hinden检查点软件94070
Email: bob.hinden@gmail.com
Email: bob.hinden@gmail.com