Network Working Group S. Thomson
Request for Comments: 4862 Cisco
Obsoletes: 2462 T. Narten
Category: Standards Track IBM
T. Jinmei
Toshiba
September 2007
Network Working Group S. Thomson
Request for Comments: 4862 Cisco
Obsoletes: 2462 T. Narten
Category: Standards Track IBM
T. Jinmei
Toshiba
September 2007
IPv6 Stateless Address Autoconfiguration
IPv6无状态地址自动配置
Status of This Memo
关于下段备忘
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Abstract
摘要
This document specifies the steps a host takes in deciding how to autoconfigure its interfaces in IP version 6. The autoconfiguration process includes generating a link-local address, generating global addresses via stateless address autoconfiguration, and the Duplicate Address Detection procedure to verify the uniqueness of the addresses on a link.
本文档指定主机在决定如何在IP版本6中自动配置其接口时所采取的步骤。自动配置过程包括生成链路本地地址、通过无状态地址自动配置生成全局地址，以及验证链路上地址唯一性的重复地址检测过程。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 7
3. Design Goals . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Site Renumbering . . . . . . . . . . . . . . . . . . . . . 9
5. Protocol Specification . . . . . . . . . . . . . . . . . . . . 10
5.1. Node Configuration Variables . . . . . . . . . . . . . . . 10
5.2. Autoconfiguration-Related Structures . . . . . . . . . . . 11
5.3. Creation of Link-Local Addresses . . . . . . . . . . . . . 11
5.4. Duplicate Address Detection . . . . . . . . . . . . . . . 12
5.4.1. Message Validation . . . . . . . . . . . . . . . . . . 14
5.4.2. Sending Neighbor Solicitation Messages . . . . . . . . 14
5.4.3. Receiving Neighbor Solicitation Messages . . . . . . . 15
5.4.4. Receiving Neighbor Advertisement Messages . . . . . . 16
5.4.5. When Duplicate Address Detection Fails . . . . . . . . 17
5.5. Creation of Global Addresses . . . . . . . . . . . . . . . 17
5.5.1. Soliciting Router Advertisements . . . . . . . . . . . 18
5.5.2. Absence of Router Advertisements . . . . . . . . . . . 18
5.5.3. Router Advertisement Processing . . . . . . . . . . . 18
5.5.4. Address Lifetime Expiry . . . . . . . . . . . . . . . 20
5.6. Configuration Consistency . . . . . . . . . . . . . . . . 21
5.7. Retaining Configured Addresses for Stability . . . . . . . 22
6. Security Considerations . . . . . . . . . . . . . . . . . . . 22
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.1. Normative References . . . . . . . . . . . . . . . . . . . 23
8.2. Informative References . . . . . . . . . . . . . . . . . . 23
Appendix A. Loopback Suppression and Duplicate Address
Detection . . . . . . . . . . . . . . . . . . . . . . 25
Appendix B. Changes since RFC 1971 . . . . . . . . . . . . . . . 26
Appendix C. Changes since RFC 2462 . . . . . . . . . . . . . . . 27
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 7
3. Design Goals . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Site Renumbering . . . . . . . . . . . . . . . . . . . . . 9
5. Protocol Specification . . . . . . . . . . . . . . . . . . . . 10
5.1. Node Configuration Variables . . . . . . . . . . . . . . . 10
5.2. Autoconfiguration-Related Structures . . . . . . . . . . . 11
5.3. Creation of Link-Local Addresses . . . . . . . . . . . . . 11
5.4. Duplicate Address Detection . . . . . . . . . . . . . . . 12
5.4.1. Message Validation . . . . . . . . . . . . . . . . . . 14
5.4.2. Sending Neighbor Solicitation Messages . . . . . . . . 14
5.4.3. Receiving Neighbor Solicitation Messages . . . . . . . 15
5.4.4. Receiving Neighbor Advertisement Messages . . . . . . 16
5.4.5. When Duplicate Address Detection Fails . . . . . . . . 17
5.5. Creation of Global Addresses . . . . . . . . . . . . . . . 17
5.5.1. Soliciting Router Advertisements . . . . . . . . . . . 18
5.5.2. Absence of Router Advertisements . . . . . . . . . . . 18
5.5.3. Router Advertisement Processing . . . . . . . . . . . 18
5.5.4. Address Lifetime Expiry . . . . . . . . . . . . . . . 20
5.6. Configuration Consistency . . . . . . . . . . . . . . . . 21
5.7. Retaining Configured Addresses for Stability . . . . . . . 22
6. Security Considerations . . . . . . . . . . . . . . . . . . . 22
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.1. Normative References . . . . . . . . . . . . . . . . . . . 23
8.2. Informative References . . . . . . . . . . . . . . . . . . 23
Appendix A. Loopback Suppression and Duplicate Address
Detection . . . . . . . . . . . . . . . . . . . . . . 25
Appendix B. Changes since RFC 1971 . . . . . . . . . . . . . . . 26
Appendix C. Changes since RFC 2462 . . . . . . . . . . . . . . . 27
This document specifies the steps a host takes in deciding how to autoconfigure its interfaces in IP version 6 (IPv6). The autoconfiguration process includes generating a link-local address, generating global addresses via stateless address autoconfiguration, and the Duplicate Address Detection procedure to verify the uniqueness of the addresses on a link.
本文档指定主机在决定如何在IP版本6（IPv6）中自动配置其接口时所采取的步骤。自动配置过程包括生成链路本地地址、通过无状态地址自动配置生成全局地址，以及验证链路上地址唯一性的重复地址检测过程。
The IPv6 stateless autoconfiguration mechanism requires no manual configuration of hosts, minimal (if any) configuration of routers, and no additional servers. The stateless mechanism allows a host to generate its own addresses using a combination of locally available information and information advertised by routers. Routers advertise prefixes that identify the subnet(s) associated with a link, while hosts generate an "interface identifier" that uniquely identifies an interface on a subnet. An address is formed by combining the two. In the absence of routers, a host can only generate link-local addresses. However, link-local addresses are sufficient for allowing communication among nodes attached to the same link.
IPv6无状态自动配置机制不需要手动配置主机、最少（如果有）配置路由器，也不需要额外的服务器。无状态机制允许主机使用本地可用信息和路由器公布的信息的组合来生成自己的地址。路由器播发标识与链路关联的子网的前缀，而主机生成唯一标识子网上接口的“接口标识符”。一个地址是由两者结合而成的。在没有路由器的情况下，主机只能生成链路本地地址。然而，链路本地地址足以允许连接到同一链路的节点之间的通信。
The stateless approach is used when a site is not particularly concerned with the exact addresses hosts use, so long as they are unique and properly routable. On the other hand, Dynamic Host Configuration Protocol for IPv6 (DHCPv6) [RFC3315] is used when a site requires tighter control over exact address assignments. Both stateless address autoconfiguration and DHCPv6 may be used simultaneously.
当站点不特别关心主机使用的确切地址时，只要这些地址是唯一的并且可以正确路由，就可以使用无状态方法。另一方面，当站点需要更严格地控制确切的地址分配时，使用IPv6动态主机配置协议（DHCPv6）[RFC3315]。无状态地址自动配置和DHCPv6都可以同时使用。
IPv6 addresses are leased to an interface for a fixed (possibly infinite) length of time. Each address has an associated lifetime that indicates how long the address is bound to an interface. When a lifetime expires, the binding (and address) become invalid and the address may be reassigned to another interface elsewhere in the Internet. To handle the expiration of address bindings gracefully, an address goes through two distinct phases while assigned to an interface. Initially, an address is "preferred", meaning that its use in arbitrary communication is unrestricted. Later, an address becomes "deprecated" in anticipation that its current interface binding will become invalid. While an address is in a deprecated state, its use is discouraged, but not strictly forbidden. New communication (e.g., the opening of a new TCP connection) should use a preferred address when possible. A deprecated address should be used only by applications that have been using it and would have difficulty switching to another address without a service disruption.
IPv6地址租给接口的时间是固定的（可能是无限的）。每个地址都有一个关联的生存期，它指示地址绑定到接口的时间。当生存期到期时，绑定（和地址）将无效，并且该地址可能会重新分配到Internet其他位置的另一个接口。为了优雅地处理地址绑定的过期，地址在分配给接口时会经历两个不同的阶段。最初，地址是“首选”的，这意味着它在任意通信中的使用是不受限制的。稍后，一个地址会被“弃用”，因为它的当前接口绑定将变得无效。当地址处于不推荐状态时，不鼓励使用，但并非严格禁止。新的通信（例如，打开新的TCP连接）应尽可能使用首选地址。不推荐使用的地址只能由正在使用它的应用程序使用，并且在不中断服务的情况下很难切换到其他地址。
To ensure that all configured addresses are likely to be unique on a given link, nodes run a "duplicate address detection" algorithm on addresses before assigning them to an interface. The Duplicate Address Detection algorithm is performed on all addresses, independently of whether they are obtained via stateless autoconfiguration or DHCPv6. This document defines the Duplicate Address Detection algorithm.
为了确保所有配置的地址在给定链路上都可能是唯一的，节点在将地址分配给接口之前对地址运行“重复地址检测”算法。重复地址检测算法对所有地址执行，与它们是通过无状态自动配置还是通过DHCPv6获得无关。本文档定义了重复地址检测算法。
The autoconfiguration process specified in this document applies only to hosts and not routers. Since host autoconfiguration uses information advertised by routers, routers will need to be configured by some other means. However, it is expected that routers will generate link-local addresses using the mechanism described in this document. In addition, routers are expected to successfully pass the Duplicate Address Detection procedure described in this document on all addresses prior to assigning them to an interface.
本文档中指定的自动配置过程仅适用于主机，而不适用于路由器。由于主机自动配置使用路由器公布的信息，因此需要通过其他方式配置路由器。然而，预计路由器将使用本文档中描述的机制生成链路本地地址。此外，在将路由器分配给接口之前，路由器应成功通过本文档中描述的所有地址的重复地址检测程序。
Section 2 provides definitions for terminology used throughout this document. Section 3 describes the design goals that lead to the current autoconfiguration procedure. Section 4 provides an overview of the protocol, while Section 5 describes the protocol in detail.
第2节提供了本文件中所用术语的定义。第3节描述了导致当前自动配置过程的设计目标。第4节概述了协议，第5节详细介绍了协议。
IP - Internet Protocol Version 6. The terms IPv4 and IPv6 are used only in contexts where necessary to avoid ambiguity.
IP-互联网协议版本6。术语IPv4和IPv6仅在必要时用于避免歧义。
node - a device that implements IP.
节点-实现IP的设备。
router - a node that forwards IP packets not explicitly addressed to itself.
路由器-转发未明确寻址到自身的IP数据包的节点。
host - any node that is not a router.
主机-不是路由器的任何节点。
upper layer - a protocol layer immediately above IP. Examples are transport protocols such as TCP and UDP, control protocols such as ICMP, routing protocols such as OSPF, and Internet or lower-layer protocols being "tunneled" over (i.e., encapsulated in) IP such as IPX, AppleTalk, or IP itself.
上层-IP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）IP（如IPX、AppleTalk或IP本身）“隧道”的互联网或较低层协议。
link - a communication facility or medium over which nodes can communicate at the link layer, i.e., the layer immediately below IP. Examples are Ethernets (simple or bridged); PPP links; X.25, Frame Relay, or ATM networks; and Internet (or higher) layer "tunnels", such as tunnels over IPv4 or IPv6 itself. The protocol described in this document will be used on all types of links unless specified otherwise in the link-type-specific document describing how to operate IP on the link in line with [RFC4861].
链路-一种通信设施或介质，节点可通过该通信设施或介质在链路层（即IP下的一层）进行通信。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（或更高）层的“隧道”，如IPv4或IPv6本身上的隧道。本文件中描述的协议将用于所有类型的链路，除非链路类型特定文件中另有规定，该文件描述了如何根据[RFC4861]在链路上操作IP。
interface - a node's attachment to a link.
接口-节点与链接的附件。
packet - an IP header plus payload.
数据包-IP报头加上有效负载。
address - an IP-layer identifier for an interface or a set of interfaces.
地址-一个接口或一组接口的IP层标识符。
unicast address - an identifier for a single interface. A packet sent to a unicast address is delivered to the interface identified by that address.
单播地址-单个接口的标识符。发送到单播地址的数据包被发送到由该地址标识的接口。
multicast address - an identifier for a set of interfaces (typically belonging to different nodes). A packet sent to a multicast address is delivered to all interfaces identified by that address.
多播地址-一组接口（通常属于不同节点）的标识符。发送到多播地址的数据包被发送到该地址标识的所有接口。
anycast address - an identifier for a set of interfaces (typically belonging to different nodes). A packet sent to an anycast address is delivered to one of the interfaces identified by that address (the "nearest" one, according to the routing protocol's measure of distance). See [RFC4291].
选播地址-一组接口（通常属于不同节点）的标识符。发送到选播地址的数据包被发送到该地址标识的接口之一（根据路由协议的距离度量，“最近的”接口）。见[RFC4291]。
solicited-node multicast address - a multicast address to which Neighbor Solicitation messages are sent. The algorithm for computing the address is given in [RFC4291].
请求节点多播地址-向其发送邻居请求消息的多播地址。[RFC4291]中给出了计算地址的算法。
link-layer address - a link-layer identifier for an interface. Examples include IEEE 802 addresses for Ethernet links and E.164 addresses for Integrated Services Digital Network (ISDN) links.
链路层地址-接口的链路层标识符。示例包括以太网链路的IEEE 802地址和综合业务数字网（ISDN）链路的E.164地址。
link-local address - an address having link-only scope that can be used to reach neighboring nodes attached to the same link. All interfaces have a link-local unicast address.
链路本地地址-具有仅链路作用域的地址，可用于到达连接到同一链路的相邻节点。所有接口都有一个链路本地单播地址。
global address - an address with unlimited scope.
全局地址-具有无限范围的地址。
communication - any packet exchange among nodes that requires that the address of each node used in the exchange remain the same for the duration of the packet exchange. Examples are a TCP connection or a UDP request-response.
通信-节点之间的任何数据包交换，要求交换中使用的每个节点的地址在数据包交换期间保持不变。例如TCP连接或UDP请求响应。
tentative address - an address whose uniqueness on a link is being verified, prior to its assignment to an interface. A tentative address is not considered assigned to an interface in the usual sense. An interface discards received packets addressed to a tentative address, but accepts Neighbor Discovery packets related to Duplicate Address Detection for the tentative address.
暂定地址-在将其分配给接口之前，正在验证其在链接上的唯一性的地址。在通常意义上，临时地址不被视为分配给接口。接口丢弃发送到暂定地址的接收数据包，但接受与暂定地址的重复地址检测相关的邻居发现数据包。
preferred address - an address assigned to an interface whose use by upper-layer protocols is unrestricted. Preferred addresses may be used as the source (or destination) address of packets sent from (or to) the interface.
首选地址-分配给上层协议使用不受限制的接口的地址。优选地址可用作从接口发送（或发送到接口）的数据包的源（或目的地）地址。
deprecated address - An address assigned to an interface whose use is discouraged, but not forbidden. A deprecated address should no longer be used as a source address in new communications, but packets sent from or to deprecated addresses are delivered as expected. A deprecated address may continue to be used as a source address in communications where switching to a preferred address causes hardship to a specific upper-layer activity (e.g., an existing TCP connection).
不推荐使用的地址-分配给不鼓励使用但不禁止使用的接口的地址。不推荐使用的地址不应再用作新通信中的源地址，但从不推荐使用的地址发送或发送到不推荐使用的地址的数据包将按预期方式传递。不推荐使用的地址可以继续用作通信中的源地址，其中切换到首选地址会对特定上层活动（例如，现有TCP连接）造成困难。
valid address - a preferred or deprecated address. A valid address may appear as the source or destination address of a packet, and the Internet routing system is expected to deliver packets sent to a valid address to their intended recipients.
有效地址-首选或不推荐的地址。有效地址可能显示为数据包的源地址或目的地址，并且期望因特网路由系统将发送到有效地址的数据包传递给其预期的接收者。
invalid address - an address that is not assigned to any interface. A valid address becomes invalid when its valid lifetime expires. Invalid addresses should not appear as the destination or source address of a packet. In the former case, the Internet routing system will be unable to deliver the packet; in the latter case, the recipient of the packet will be unable to respond to it.
无效地址-未分配给任何接口的地址。有效地址在其有效生存期到期时变为无效。无效地址不应显示为数据包的目标或源地址。在前一种情况下，互联网路由系统将无法传送数据包；在后一种情况下，数据包的接收者将无法响应它。
preferred lifetime - the length of time that a valid address is preferred (i.e., the time until deprecation). When the preferred lifetime expires, the address becomes deprecated.
首选生存期-首选有效地址的时间长度（即，直到弃用的时间）。当首选生存期到期时，该地址将被弃用。
valid lifetime - the length of time an address remains in the valid state (i.e., the time until invalidation). The valid lifetime must be greater than or equal to the preferred lifetime. When the valid lifetime expires, the address becomes invalid.
有效生存期-地址保持有效状态的时间长度（即，直到失效的时间）。有效生存期必须大于或等于首选生存期。当有效生存期到期时，地址将无效。
interface identifier - a link-dependent identifier for an interface that is (at least) unique per link [RFC4291]. Stateless address autoconfiguration combines an interface identifier with a prefix to form an address. From address autoconfiguration's perspective, an interface identifier is a bit string of known length. The exact length of an interface identifier and the way it is created is defined in a separate link-type specific document that covers issues related to the transmission of IP over a particular link type (e.g., [RFC2464]). Note that the address architecture [RFC4291] also defines the length of the interface identifiers for some set of addresses, but the two sets of definitions must be consistent. In many cases, the identifier will be derived from the interface's link-layer address.
接口标识符-每个链路（至少）唯一的接口的链路相关标识符[RFC4291]。无状态地址自动配置将接口标识符与前缀组合在一起以形成地址。从地址自动配置的角度来看，接口标识符是一个已知长度的位字符串。接口标识符的确切长度及其创建方式在单独的链路类型特定文档中定义，该文档涵盖与通过特定链路类型传输IP相关的问题（例如，[RFC2464]）。请注意，地址体系结构[RFC4291]还为某些地址集定义了接口标识符的长度，但这两组定义必须一致。在许多情况下，标识符将从接口的链路层地址派生。
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in [RFC2119].
本文件中出现的关键词必须、不得、必需、应、不应、应、不应、建议、可和可选时，应按照[RFC2119]中的说明进行解释。
Note that this document intentionally limits the use of the keywords to the protocol specification (Section 5).
注意，本文件有意将关键字的使用限制在协议规范中（第5节）。
Stateless autoconfiguration is designed with the following goals in mind:
无状态自动配置的设计目标如下：
o Manual configuration of individual machines before connecting them to the network should not be required. Consequently, a mechanism is needed that allows a host to obtain or create unique addresses for each of its interfaces. Address autoconfiguration assumes that each interface can provide a unique identifier for that interface (i.e., an "interface identifier"). In the simplest case, an interface identifier consists of the interface's link-layer address. An interface identifier can be combined with a prefix to form an address.
o 在将单个机器连接到网络之前，不需要手动配置它们。因此，需要一种机制，允许主机为其每个接口获取或创建唯一地址。地址自动配置假定每个接口都可以为该接口提供唯一的标识符（即“接口标识符”）。在最简单的情况下，接口标识符由接口的链路层地址组成。接口标识符可以与前缀组合以形成地址。
o Small sites consisting of a set of machines attached to a single link should not require the presence of a DHCPv6 server or router as a prerequisite for communicating. Plug-and-play communication is achieved through the use of link-local addresses. Link-local addresses have a well-known prefix that identifies the (single) shared link to which a set of nodes attach. A host forms a link-local address by appending an interface identifier to the link-local prefix.
o 由连接到单个链路的一组机器组成的小型站点不应要求存在DHCPv6服务器或路由器作为通信的先决条件。即插即用通信是通过使用链路本地地址实现的。链路本地地址有一个众所周知的前缀，用于标识一组节点所连接的（单个）共享链路。主机通过将接口标识符附加到链接本地前缀来形成链接本地地址。
o A large site with multiple networks and routers should not require the presence of a DHCPv6 server for address configuration. In order to generate global addresses, hosts must determine the prefixes that identify the subnets to which they attach. Routers generate periodic Router Advertisements that include options listing the set of active prefixes on a link.
o 具有多个网络和路由器的大型站点不需要DHCPv6服务器来进行地址配置。为了生成全局地址，主机必须确定标识其连接到的子网的前缀。路由器定期生成路由器广告，其中包括列出链路上活动前缀集的选项。
o Address configuration should facilitate the graceful renumbering of a site's machines. For example, a site may wish to renumber all of its nodes when it switches to a new network service provider. Renumbering is achieved through the leasing of addresses to interfaces and the assignment of multiple addresses to the same interface. Lease lifetimes provide the mechanism through which a site phases out old prefixes. The assignment of multiple addresses to an interface provides for a transition
o 地址配置应该有助于站点机器的优雅重新编号。例如，当站点切换到新的网络服务提供商时，可能希望对其所有节点重新编号。重新编号是通过向接口租用地址和向同一接口分配多个地址来实现的。租约生命期提供了一种机制，站点通过该机制逐步淘汰旧前缀。将多个地址分配给一个接口可实现转换
period during which both a new address and the one being phased out work simultaneously.
新地址和被逐步淘汰的地址同时工作的期间。
This section provides an overview of the typical steps that take place when an interface autoconfigures itself. Autoconfiguration is performed only on multicast-capable links and begins when a multicast-capable interface is enabled, e.g., during system startup. Nodes (both hosts and routers) begin the autoconfiguration process by generating a link-local address for the interface. A link-local address is formed by appending an identifier of the interface to the well-known link-local prefix [RFC4291].
本节概述了接口自动配置自身时发生的典型步骤。自动配置仅在支持多播的链路上执行，并在启用支持多播的接口时开始，例如在系统启动期间。节点（主机和路由器）通过为接口生成链路本地地址开始自动配置过程。链路本地地址通过将接口的标识符附加到众所周知的链路本地前缀[RFC4291]来形成。
Before the link-local address can be assigned to an interface and used, however, a node must attempt to verify that this "tentative" address is not already in use by another node on the link. Specifically, it sends a Neighbor Solicitation message containing the tentative address as the target. If another node is already using that address, it will return a Neighbor Advertisement saying so. If another node is also attempting to use the same address, it will send a Neighbor Solicitation for the target as well. The exact number of times the Neighbor Solicitation is (re)transmitted and the delay time between consecutive solicitations is link-specific and may be set by system management.
然而，在将链路本地地址分配给接口并使用之前，节点必须尝试验证链路上的另一个节点是否已经在使用该“暂定”地址。具体地说，它发送一个邻居请求消息，其中包含作为目标的暂定地址。如果另一个节点已经在使用该地址，它将返回一个邻居公告，这样说。如果另一个节点也试图使用相同的地址，它也将发送目标的邻居请求。邻居请求被（重新）传输的确切次数以及连续请求之间的延迟时间是特定于链路的，并且可以由系统管理设置。
If a node determines that its tentative link-local address is not unique, autoconfiguration stops and manual configuration of the interface is required. To simplify recovery in this case, it should be possible for an administrator to supply an alternate interface identifier that overrides the default identifier in such a way that the autoconfiguration mechanism can then be applied using the new (presumably unique) interface identifier. Alternatively, link-local and other addresses will need to be configured manually.
如果节点确定其临时链路本地地址不唯一，则自动配置将停止，需要手动配置接口。为了简化这种情况下的恢复，管理员应该可以提供一个替代接口标识符，该标识符覆盖默认标识符，从而可以使用新的（可能是唯一的）接口标识符应用自动配置机制。或者，需要手动配置链路本地地址和其他地址。
Once a node ascertains that its tentative link-local address is unique, it assigns the address to the interface. At this point, the node has IP-level connectivity with neighboring nodes. The remaining autoconfiguration steps are performed only by hosts; the (auto)configuration of routers is beyond the scope of this document.
一旦节点确定其临时链路本地地址是唯一的，它就会将该地址分配给接口。此时，节点与相邻节点具有IP级别的连接。其余的自动配置步骤仅由主机执行；路由器的（自动）配置超出了本文档的范围。
The next phase of autoconfiguration involves obtaining a Router Advertisement or determining that no routers are present. If routers are present, they will send Router Advertisements that specify what sort of autoconfiguration a host can do. Note that the DHCPv6 service for address configuration may still be available even if no routers are present.
自动配置的下一阶段涉及获取路由器广告或确定不存在路由器。如果存在路由器，它们将发送路由器广告，指定主机可以执行的自动配置类型。请注意，即使没有路由器，用于地址配置的DHCPv6服务也可能仍然可用。
Routers send Router Advertisements periodically, but the delay between successive advertisements will generally be longer than a host performing autoconfiguration will want to wait [RFC4861]. To obtain an advertisement quickly, a host sends one or more Router Solicitations to the all-routers multicast group.
路由器定期发送路由器广告，但连续广告之间的延迟通常比执行自动配置的主机需要等待的时间长[RFC4861]。为了快速获得广告，主机向all routers多播组发送一个或多个路由器请求。
Router Advertisements also contain zero or more Prefix Information options that contain information used by stateless address autoconfiguration to generate global addresses. It should be noted that a host may use both stateless address autoconfiguration and DHCPv6 simultaneously. One Prefix Information option field, the "autonomous address-configuration flag", indicates whether or not the option even applies to stateless autoconfiguration. If it does, additional option fields contain a subnet prefix, together with lifetime values, indicating how long addresses created from the prefix remain preferred and valid.
路由器广告还包含零个或多个前缀信息选项，这些选项包含无状态地址自动配置用于生成全局地址的信息。应该注意的是，主机可能同时使用无状态地址自动配置和DHCPv6。一个前缀信息选项字段“自治地址配置标志”指示该选项是否适用于无状态自动配置。如果是，其他选项字段将包含子网前缀以及生存期值，指示根据前缀创建的地址保持首选和有效的时间。
Because routers generate Router Advertisements periodically, hosts will continually receive new advertisements. Hosts process the information contained in each advertisement as described above, adding to and refreshing information received in previous advertisements.
由于路由器定期生成路由器播发，主机将不断接收新的播发。主机如上所述处理每个播发中包含的信息，添加并刷新以前播发中接收到的信息。
By default, all addresses should be tested for uniqueness prior to their assignment to an interface for safety. The test should individually be performed on all addresses obtained manually, via stateless address autoconfiguration, or via DHCPv6. To accommodate sites that believe the overhead of performing Duplicate Address Detection outweighs its benefits, the use of Duplicate Address Detection can be disabled through the administrative setting of a per-interface configuration flag.
默认情况下，为了安全起见，在将所有地址分配到接口之前，应测试其唯一性。应通过无状态地址自动配置或DHCPv6对手动获取的所有地址分别执行测试。为了适应认为执行重复地址检测的开销大于其好处的站点，可以通过管理设置每个接口配置标志来禁用重复地址检测的使用。
To speed the autoconfiguration process, a host may generate its link-local address (and verify its uniqueness) in parallel with waiting for a Router Advertisement. Because a router may delay responding to a Router Solicitation for a few seconds, the total time needed to complete autoconfiguration can be significantly longer if the two steps are done serially.
为了加快自动配置过程，主机可以在等待路由器公告的同时生成其链路本地地址（并验证其唯一性）。由于路由器可能会延迟响应路由器请求几秒钟，因此如果连续完成这两个步骤，则完成自动配置所需的总时间可能会显著延长。
Address leasing facilitates site renumbering by providing a mechanism to time-out addresses assigned to interfaces in hosts. At present, upper-layer protocols such as TCP provide no support for changing end-point addresses while a connection is open. If an end-point address becomes invalid, existing connections break and all
地址租赁通过提供一种机制来超时分配给主机中接口的地址，从而有助于站点重新编号。目前，上层协议（如TCP）不支持在连接打开时更改端点地址。如果一个端点地址变得无效，现有的连接将断开，并且所有
communication to the invalid address fails. Even when applications use UDP as a transport protocol, addresses must generally remain the same during a packet exchange.
与无效地址的通信失败。即使应用程序使用UDP作为传输协议，在数据包交换期间，地址通常也必须保持不变。
Dividing valid addresses into preferred and deprecated categories provides a way of indicating to upper layers that a valid address may become invalid shortly and that future communication using the address will fail, should the address's valid lifetime expire before communication ends. To avoid this scenario, higher layers should use a preferred address (assuming one of sufficient scope exists) to increase the likelihood that an address will remain valid for the duration of the communication. It is up to system administrators to set appropriate prefix lifetimes in order to minimize the impact of failed communication when renumbering takes place. The deprecation period should be long enough that most, if not all, communications are using the new address at the time an address becomes invalid.
将有效地址划分为首选和不推荐的类别，提供了一种向上层指示有效地址可能很快失效的方法，并且如果地址的有效生存期在通信结束之前过期，则使用该地址的未来通信将失败。为了避免这种情况，高层应该使用首选地址（假设存在一个足够的作用域），以增加地址在通信期间保持有效的可能性。由系统管理员设置适当的前缀生存期，以便在重新编号时将通信失败的影响降至最低。弃用期应足够长，以使大多数（如果不是全部）通信在地址无效时使用新地址。
The IP layer is expected to provide a means for upper layers (including applications) to select the most appropriate source address given a particular destination and possibly other constraints. An application may choose to select the source address itself before starting a new communication or may leave the address unspecified, in which case, the upper networking layers will use the mechanism provided by the IP layer to choose a suitable address on the application's behalf.
IP层有望为上层（包括应用程序）提供一种方法，以便在给定特定目的地和可能的其他约束条件下选择最合适的源地址。应用程序可以在开始新的通信之前选择源地址本身，或者可以不指定地址，在这种情况下，上层网络层将使用IP层提供的机制代表应用程序选择合适的地址。
Detailed address selection rules are beyond the scope of this document and are described in [RFC3484].
详细的地址选择规则超出了本文档的范围，请参见[RFC3484]。
Autoconfiguration is performed on a per-interface basis on multicast-capable interfaces. For multihomed hosts, autoconfiguration is performed independently on each interface. Autoconfiguration applies primarily to hosts, with two exceptions. Routers are expected to generate a link-local address using the procedure outlined below. In addition, routers perform Duplicate Address Detection on all addresses prior to assigning them to an interface.
自动配置是在支持多播的接口上基于每个接口执行的。对于多宿主主机，自动配置在每个接口上独立执行。自动配置主要适用于主机，但有两个例外。路由器应使用以下程序生成链路本地地址。此外，路由器在将所有地址分配给接口之前，对其执行重复地址检测。
A node MUST allow the following autoconfiguration-related variable to be configured by system management for each multicast-capable interface:
节点必须允许系统管理为每个支持多播的接口配置以下自动配置相关变量：
DupAddrDetectTransmits The number of consecutive Neighbor Solicitation messages sent while performing Duplicate Address Detection on a tentative address. A value of zero indicates that Duplicate Address Detection is not performed on tentative addresses. A value of one indicates a single transmission with no follow-up retransmissions.
DupAddrDetect传输在对临时地址执行重复地址检测时发送的连续邻居请求消息数。值为零表示不会对临时地址执行重复地址检测。值为1表示没有后续重传的单次传输。
Default: 1, but may be overridden by a link-type specific value in the document that covers issues related to the transmission of IP over a particular link type (e.g., [RFC2464]).
默认值：1，但可能会被文档中的链接类型特定值覆盖，该值涵盖与通过特定链接类型（例如[RFC2464]）传输IP相关的问题。
Autoconfiguration also assumes the presence of the variable RetransTimer as defined in [RFC4861]. For autoconfiguration purposes, RetransTimer specifies the delay between consecutive Neighbor Solicitation transmissions performed during Duplicate Address Detection (if DupAddrDetectTransmits is greater than 1), as well as the time a node waits after sending the last Neighbor Solicitation before ending the Duplicate Address Detection process.
自动配置还假设存在[RFC4861]中定义的变量Renstimer。出于自动配置目的，Renstimer指定重复地址检测期间执行的连续邻居请求传输之间的延迟（如果DupAddrDetectTransmissions大于1），以及节点在发送最后一个邻居请求后在结束重复地址检测过程之前等待的时间。
Beyond the formation of a link-local address and use of Duplicate Address Detection, how routers (auto)configure their interfaces is beyond the scope of this document.
除了形成链路本地地址和使用重复地址检测之外，路由器（自动）如何配置其接口超出了本文档的范围。
A host maintains a list of addresses together with their corresponding lifetimes. The address list contains both autoconfigured addresses and those configured manually.
主机维护一个地址列表及其相应的生存期。地址列表包含自动配置的地址和手动配置的地址。
A node forms a link-local address whenever an interface becomes enabled. An interface may become enabled after any of the following events:
只要启用接口，节点就会形成链接本地地址。在发生以下任何事件后，接口可能会启用：
- The interface is initialized at system startup time.
- 接口在系统启动时初始化。
- The interface is reinitialized after a temporary interface failure or after being temporarily disabled by system management.
- 在临时接口出现故障或被系统管理暂时禁用后，将重新初始化接口。
- The interface attaches to a link for the first time. This includes the case where the attached link is dynamically changed due to a change of the access point of wireless networks.
- 该接口第一次连接到链接。这包括由于无线网络的接入点的改变而动态地改变所附链路的情况。
- The interface becomes enabled by system management after having been administratively disabled.
- 该接口在被管理禁用后由系统管理启用。
A link-local address is formed by combining the well-known link-local prefix FE80::0 [RFC4291] (of appropriate length) with an interface identifier as follows:
链路本地地址通过将众所周知的链路本地前缀FE80:：0[RFC4291]（适当长度）与接口标识符组合而形成，如下所示：
1. The left-most 'prefix length' bits of the address are those of the link-local prefix.
1. 地址最左边的“前缀长度”位是链接本地前缀的位。
2. The bits in the address to the right of the link-local prefix are set to all zeroes.
2. 链路本地前缀右侧地址中的位设置为全零。
3. If the length of the interface identifier is N bits, the right-most N bits of the address are replaced by the interface identifier.
3. 如果接口标识符的长度为N位，则地址最右边的N位将替换为接口标识符。
If the sum of the link-local prefix length and N is larger than 128, autoconfiguration fails and manual configuration is required. The length of the interface identifier is defined in a separate link-type-specific document, which should also be consistent with the address architecture [RFC4291] (see Section 2). These documents will carefully define the length so that link-local addresses can be autoconfigured on the link.
如果链路本地前缀长度与N之和大于128，则自动配置失败，需要手动配置。接口标识符的长度在单独的链路类型特定文档中定义，该文档还应与地址体系结构[RFC4291]一致（参见第2节）。这些文档将仔细定义长度，以便可以在链接上自动配置链接本地地址。
A link-local address has an infinite preferred and valid lifetime; it is never timed out.
链路本地地址具有无限的首选有效生存期；它从不超时。
Duplicate Address Detection MUST be performed on all unicast addresses prior to assigning them to an interface, regardless of whether they are obtained through stateless autoconfiguration, DHCPv6, or manual configuration, with the following exceptions:
在将所有单播地址分配给接口之前，必须对其执行重复地址检测，无论这些地址是通过无状态自动配置、DHCPv6还是手动配置获得的，但以下情况除外：
- An interface whose DupAddrDetectTransmits variable is set to zero does not perform Duplicate Address Detection.
- DupAddrDetectTransmists变量设置为零的接口不执行重复地址检测。
- Duplicate Address Detection MUST NOT be performed on anycast addresses (note that anycast addresses cannot syntactically be distinguished from unicast addresses).
- 不得对选播地址执行重复地址检测（请注意，选播地址在语法上无法与单播地址区分）。
- Each individual unicast address SHOULD be tested for uniqueness. Note that there are implementations deployed that only perform Duplicate Address Detection for the link-local address and skip the test for the global address that uses the same interface identifier as that of the link-local address. Whereas this document does not invalidate such implementations, this kind of
- 应测试每个单播地址的唯一性。请注意，部署的一些实现仅对链路本地地址执行重复地址检测，而对使用与链路本地地址相同的接口标识符的全局地址跳过测试。鉴于本文件并未使此类实现无效，此类
"optimization" is NOT RECOMMENDED, and new implementations MUST NOT do that optimization. This optimization came from the assumption that all of an interface's addresses are generated from the same identifier. However, the assumption does actually not stand; new types of addresses have been introduced where the interface identifiers are not necessarily the same for all unicast addresses on a single interface [RFC4941] [RFC3972]. Requiring that Duplicate Address Detection be performed for all unicast addresses will make the algorithm robust for the current and future special interface identifiers.
不建议使用“优化”，新的实现也不能进行这种优化。这种优化源于这样一种假设：一个接口的所有地址都是由同一个标识符生成的。然而，这一假设实际上并不成立；引入了新类型的地址，其中单个接口上的所有单播地址的接口标识符不一定相同[RFC4941][RFC3972]。要求对所有单播地址执行重复地址检测将使算法对当前和未来的特殊接口标识符具有鲁棒性。
The procedure for detecting duplicate addresses uses Neighbor Solicitation and Advertisement messages as described below. If a duplicate address is discovered during the procedure, the address cannot be assigned to the interface. If the address is derived from an interface identifier, a new identifier will need to be assigned to the interface, or all IP addresses for the interface will need to be manually configured. Note that the method for detecting duplicates is not completely reliable, and it is possible that duplicate addresses will still exist (e.g., if the link was partitioned while Duplicate Address Detection was performed).
检测重复地址的过程使用邻居请求和广告消息，如下所述。如果在过程中发现重复地址，则无法将该地址分配给接口。如果地址来自接口标识符，则需要为接口分配新的标识符，或者需要手动配置接口的所有IP地址。请注意，检测重复的方法并不完全可靠，并且可能仍然存在重复地址（例如，如果在执行重复地址检测时对链路进行了分区）。
An address on which the Duplicate Address Detection procedure is applied is said to be tentative until the procedure has completed successfully. A tentative address is not considered "assigned to an interface" in the traditional sense. That is, the interface must accept Neighbor Solicitation and Advertisement messages containing the tentative address in the Target Address field, but processes such packets differently from those whose Target Address matches an address assigned to the interface. Other packets addressed to the tentative address should be silently discarded. Note that the "other packets" include Neighbor Solicitation and Advertisement messages that have the tentative (i.e., unicast) address as the IP destination address and contain the tentative address in the Target Address field. Such a case should not happen in normal operation, though, since these messages are multicasted in the Duplicate Address Detection procedure.
在重复地址检测过程成功完成之前，对其应用重复地址检测过程的地址称为暂定地址。在传统意义上，临时地址不被视为“分配给接口”。也就是说，接口必须接受邻居请求和广告消息，这些消息包含目标地址字段中的暂定地址，但处理此类数据包的方式不同于其目标地址与分配给接口的地址匹配的数据包。其他发往暂定地址的数据包应该被悄悄地丢弃。注意，“其他分组”包括具有暂定（即，单播）地址作为IP目的地地址并且在目标地址字段中包含暂定地址的邻居请求和广告消息。但是，这种情况不应该发生在正常操作中，因为这些消息在重复地址检测过程中是多播的。
It should also be noted that Duplicate Address Detection must be performed prior to assigning an address to an interface in order to prevent multiple nodes from using the same address simultaneously. If a node begins using an address in parallel with Duplicate Address Detection, and another node is already using the address, the node performing Duplicate Address Detection will erroneously process traffic intended for the other node, resulting in such possible negative consequences as the resetting of open TCP connections.
还应注意，在将地址分配给接口之前，必须执行重复地址检测，以防止多个节点同时使用同一地址。如果一个节点开始使用与重复地址检测并行的地址，而另一个节点已经在使用该地址，则执行重复地址检测的节点将错误地处理用于另一个节点的通信量，从而导致可能的负面后果，如重设打开的TCP连接。
The following subsections describe specific tests a node performs to verify an address's uniqueness. An address is considered unique if none of the tests indicate the presence of a duplicate address within RetransTimer milliseconds after having sent DupAddrDetectTransmits Neighbor Solicitations. Once an address is determined to be unique, it may be assigned to an interface.
以下小节描述节点为验证地址唯一性而执行的特定测试。如果在发送DupAddrDetect邻居请求后的Renstimer毫秒内没有任何测试表明存在重复地址，则认为地址是唯一的。一旦确定地址是唯一的，就可以将其分配给接口。
A node MUST silently discard any Neighbor Solicitation or Advertisement message that does not pass the validity checks specified in [RFC4861]. A Neighbor Solicitation or Advertisement message that passes these validity checks is called a valid solicitation or valid advertisement, respectively.
节点必须以静默方式丢弃未通过[RFC4861]中指定的有效性检查的任何邻居请求或播发消息。通过这些有效性检查的邻居请求或播发消息分别称为有效请求或有效播发。
Before sending a Neighbor Solicitation, an interface MUST join the all-nodes multicast address and the solicited-node multicast address of the tentative address. The former ensures that the node receives Neighbor Advertisements from other nodes already using the address; the latter ensures that two nodes attempting to use the same address simultaneously should detect each other's presence.
在发送邻居请求之前，接口必须加入所有节点多播地址和临时地址的请求节点多播地址。前者确保该节点从已经使用该地址的其他节点接收邻居播发；后者确保两个试图同时使用同一地址的节点能够检测到对方的存在。
To check an address, a node sends DupAddrDetectTransmits Neighbor Solicitations, each separated by RetransTimer milliseconds. The solicitation's Target Address is set to the address being checked, the IP source is set to the unspecified address, and the IP destination is set to the solicited-node multicast address of the target address.
为了检查地址，节点发送DupAddrDetect发送邻居请求，每个请求之间用Renstimer毫秒分隔。请求的目标地址设置为正在检查的地址，IP源设置为未指定的地址，IP目的地设置为目标地址的请求节点多播地址。
If the Neighbor Solicitation is going to be the first message sent from an interface after interface (re)initialization, the node SHOULD delay joining the solicited-node multicast address by a random delay between 0 and MAX_RTR_SOLICITATION_DELAY as specified in [RFC4861]. This serves to alleviate congestion when many nodes start up on the link at the same time, such as after a power failure, and may help to avoid race conditions when more than one node is trying to solicit for the same address at the same time.
如果邻居请求将是接口（重新）初始化后从接口发送的第一条消息，则节点应按照[RFC4861]中的规定，将加入请求节点多播地址的时间延迟为0到MAX_RTR_requisition_delay之间的随机延迟。这有助于在多个节点同时在链路上启动时（例如在电源故障后）缓解拥塞，并有助于避免多个节点同时尝试请求相同地址时出现争用情况。
Even if the Neighbor Solicitation is not going to be the first message sent, the node SHOULD delay joining the solicited-node multicast address by a random delay between 0 and MAX_RTR_SOLICITATION_DELAY if the address being checked is configured by a router advertisement message sent to a multicast address. The delay will avoid similar congestion when multiple nodes are going to configure addresses by receiving the same single multicast router advertisement.
即使邻居请求不是发送的第一条消息，如果要检查的地址是由发送到多播地址的路由器广告消息配置的，则节点也应延迟加入请求的节点多播地址，延迟为0到MAX_RTR_请求_延迟之间的随机延迟。当多个节点要通过接收同一个多播路由器广告来配置地址时，延迟将避免类似的拥塞。
Note that when a node joins a multicast address, it typically sends a Multicast Listener Discovery (MLD) report message [RFC2710] [RFC3810] for the multicast address. In the case of Duplicate Address Detection, the MLD report message is required in order to inform MLD-snooping switches, rather than routers, to forward multicast packets. In the above description, the delay for joining the multicast address thus means delaying transmission of the corresponding MLD report message. Since the MLD specifications do not request a random delay to avoid race conditions, just delaying Neighbor Solicitation would cause congestion by the MLD report messages. The congestion would then prevent the MLD-snooping switches from working correctly and, as a result, prevent Duplicate Address Detection from working. The requirement to include the delay for the MLD report in this case avoids this scenario. [RFC3590] also talks about some interaction issues between Duplicate Address Detection and MLD, and specifies which source address should be used for the MLD report in this case.
请注意，当节点加入多播地址时，它通常会为多播地址发送多播侦听器发现（MLD）报告消息[RFC2710][RFC3810]。在重复地址检测的情况下，需要MLD报告消息来通知MLD窥探交换机而不是路由器转发多播数据包。在上述描述中，加入多播地址的延迟因此意味着延迟相应MLD报告消息的传输。由于MLD规范不请求随机延迟以避免竞争条件，因此仅延迟邻居请求将导致MLD报告消息的拥塞。然后，拥塞将阻止MLD窥探交换机正常工作，从而阻止重复地址检测工作。在这种情况下，包含MLD报告延迟的要求避免了这种情况。[RFC3590]还讨论了重复地址检测和MLD之间的一些交互问题，并指定在这种情况下MLD报告应使用哪个源地址。
In order to improve the robustness of the Duplicate Address Detection algorithm, an interface MUST receive and process datagrams sent to the all-nodes multicast address or solicited-node multicast address of the tentative address during the delay period. This does not necessarily conflict with the requirement that joining the multicast group be delayed. In fact, in some cases it is possible for a node to start listening to the group during the delay period before MLD report transmission. It should be noted, however, that in some link-layer environments, particularly with MLD-snooping switches, no multicast reception will be available until the MLD report is sent.
为了提高重复地址检测算法的鲁棒性，接口必须在延迟期间接收和处理发送到临时地址的所有节点多播地址或请求节点多播地址的数据报。这并不一定与延迟加入多播组的要求相冲突。事实上，在某些情况下，节点可能在MLD报告传输之前的延迟期间开始侦听组。但是，应该注意的是，在某些链路层环境中，特别是使用MLD窥探交换机时，在发送MLD报告之前，将无法进行多播接收。
On receipt of a valid Neighbor Solicitation message on an interface, node behavior depends on whether or not the target address is tentative. If the target address is not tentative (i.e., it is assigned to the receiving interface), the solicitation is processed as described in [RFC4861]. If the target address is tentative, and the source address is a unicast address, the solicitation's sender is performing address resolution on the target; the solicitation should be silently ignored. Otherwise, processing takes place as described below. In all cases, a node MUST NOT respond to a Neighbor Solicitation for a tentative address.
在接口上收到有效的邻居请求消息时，节点行为取决于目标地址是否为暂定地址。如果目标地址不是暂定的（即分配给接收接口），则按照[RFC4861]中所述处理请求。如果目标地址是暂定的，而源地址是单播地址，则请求的发送方正在目标上执行地址解析；这种恳求应该被默默地忽略。否则，将按如下所述进行处理。在所有情况下，节点都不得响应邻居请求临时地址。
If the source address of the Neighbor Solicitation is the unspecified address, the solicitation is from a node performing Duplicate Address Detection. If the solicitation is from another node, the tentative address is a duplicate and should not be used (by either node). If the solicitation is from the node itself (because the node loops back multicast packets), the solicitation does not indicate the presence of a duplicate address.
如果邻居请求的源地址是未指定的地址，则请求来自执行重复地址检测的节点。如果请求来自另一个节点，则暂定地址是重复的，不应（由任一节点）使用。如果请求来自节点本身（因为节点循环回多播数据包），则请求不表示存在重复地址。
Implementer's Note: many interfaces provide a way for upper layers to selectively enable and disable the looping back of multicast packets. The details of how such a facility is implemented may prevent Duplicate Address Detection from working correctly. See Appendix A for further discussion.
实现者注意：许多接口为上层提供了一种方法，可以有选择地启用和禁用多播数据包的环回。有关如何实现此类功能的详细信息可能会阻止重复地址检测正常工作。进一步讨论见附录A。
The following tests identify conditions under which a tentative address is not unique:
以下测试确定了临时地址不唯一的条件：
- If a Neighbor Solicitation for a tentative address is received before one is sent, the tentative address is a duplicate. This condition occurs when two nodes run Duplicate Address Detection simultaneously, but transmit initial solicitations at different times (e.g., by selecting different random delay values before joining the solicited-node multicast address and transmitting an initial solicitation).
- 如果在发送临时地址之前收到邻居请求，则临时地址是重复的。当两个节点同时运行重复地址检测，但在不同时间发送初始请求（例如，通过在加入请求的节点多播地址并发送初始请求之前选择不同的随机延迟值）时，会发生这种情况。
- If the actual number of Neighbor Solicitations received exceeds the number expected based on the loopback semantics (e.g., the interface does not loop back the packet, yet one or more solicitations was received), the tentative address is a duplicate. This condition occurs when two nodes run Duplicate Address Detection simultaneously and transmit solicitations at roughly the same time.
- 如果收到的邻居请求的实际数量超过了基于环回语义的预期数量（例如，接口没有环回数据包，但收到了一个或多个请求），则暂定地址是重复的。当两个节点同时运行重复地址检测并大致同时发送请求时，就会出现这种情况。
On receipt of a valid Neighbor Advertisement message on an interface, node behavior depends on whether the target address is tentative or matches a unicast or anycast address assigned to the interface:
在接口上接收到有效的邻居播发消息时，节点行为取决于目标地址是暂定地址还是与分配给接口的单播或选播地址匹配：
1. If the target address is tentative, the tentative address is not unique.
1. 如果目标地址是暂定地址，则暂定地址不是唯一的。
2. If the target address matches a unicast address assigned to the receiving interface, it would possibly indicate that the address is a duplicate but it has not been detected by the Duplicate Address Detection procedure (recall that Duplicate Address Detection is not completely reliable). How to handle such a case is beyond the scope of this document.
2. 如果目标地址与分配给接收接口的单播地址相匹配，则可能表明该地址是重复的，但重复地址检测程序未检测到该地址（回想一下，重复地址检测并不完全可靠）。如何处理此类案件超出了本文件的范围。
3. Otherwise, the advertisement is processed as described in [RFC4861].
3. 否则，按照[RFC4861]中所述处理广告。
A tentative address that is determined to be a duplicate as described above MUST NOT be assigned to an interface, and the node SHOULD log a system management error.
如上所述确定为重复的暂定地址不得分配给接口，节点应记录系统管理错误。
If the address is a link-local address formed from an interface identifier based on the hardware address, which is supposed to be uniquely assigned (e.g., EUI-64 for an Ethernet interface), IP operation on the interface SHOULD be disabled. By disabling IP operation, the node will then:
如果该地址是由基于硬件地址的接口标识符形成的链路本地地址，该地址应被唯一分配（例如，以太网接口的EUI-64），则应禁用接口上的IP操作。通过禁用IP操作，节点将：
- not send any IP packets from the interface,
- 不从接口发送任何IP数据包，
- silently drop any IP packets received on the interface, and
- 以静默方式丢弃接口上接收到的任何IP数据包，以及
- not forward any IP packets to the interface (when acting as a router or processing a packet with a Routing header).
- 不将任何IP数据包转发到接口（当充当路由器或处理带有路由报头的数据包时）。
In this case, the IP address duplication probably means duplicate hardware addresses are in use, and trying to recover from it by configuring another IP address will not result in a usable network. In fact, it probably makes things worse by creating problems that are harder to diagnose than just disabling network operation on the interface; the user will see a partially working network where some things work, and other things do not.
在这种情况下，IP地址复制可能意味着重复的硬件地址正在使用中，试图通过配置另一个IP地址从中恢复不会产生可用的网络。事实上，它可能会造成比仅禁用接口上的网络操作更难诊断的问题，从而使情况变得更糟；用户将看到一个部分工作的网络，其中一些东西工作，而另一些东西不工作。
On the other hand, if the duplicate link-local address is not formed from an interface identifier based on the hardware address, which is supposed to be uniquely assigned, IP operation on the interface MAY be continued.
另一方面，如果重复链路本地地址不是由基于硬件地址的接口标识符形成的（假定该硬件地址是唯一分配的），则可以继续该接口上的IP操作。
Note: as specified in Section 2, "IP" means "IPv6" in the above description. While the background rationale about hardware address is independent of particular network protocols, its effect on other protocols is beyond the scope of this document.
注：如第2节所述，“IP”在上述描述中是指“IPv6”。虽然硬件地址的背景原理与特定网络协议无关，但其对其他协议的影响超出了本文档的范围。
Global addresses are formed by appending an interface identifier to a prefix of appropriate length. Prefixes are obtained from Prefix Information options contained in Router Advertisements. Creation of global addresses as described in this section SHOULD be locally configurable. However, the processing described below MUST be enabled by default.
全局地址是通过将接口标识符附加到适当长度的前缀来形成的。前缀是从路由器广告中包含的前缀信息选项中获取的。本节所述的全局地址的创建应该是本地可配置的。但是，默认情况下必须启用下面描述的处理。
Router Advertisements are sent periodically to the all-nodes multicast address. To obtain an advertisement quickly, a host sends out Router Solicitations as described in [RFC4861].
路由器广告会定期发送到所有节点的多播地址。为了快速获得广告，主机发送路由器请求，如[RFC4861]所述。
Even if a link has no routers, the DHCPv6 service to obtain addresses may still be available, and hosts may want to use the service. From the perspective of autoconfiguration, a link has no routers if no Router Advertisements are received after having sent a small number of Router Solicitations as described in [RFC4861].
即使链路没有路由器，获取地址的DHCPv6服务也可能仍然可用，主机可能希望使用该服务。从自动配置的角度来看，如[RFC4861]所述，如果发送少量路由器请求后未收到路由器广告，则链路没有路由器。
Note that it is possible that there is no router on the link in this sense, but there is a node that has the ability to forward packets. In this case, the forwarding node's address must be manually configured in hosts to be able to send packets off-link, since the only mechanism to configure the default router's address automatically is the one using Router Advertisements.
请注意，在这种意义上，链路上可能没有路由器，但有一个节点具有转发数据包的能力。在这种情况下，必须在主机中手动配置转发节点的地址，以便能够从链路发送数据包，因为自动配置默认路由器地址的唯一机制是使用路由器广告的机制。
For each Prefix-Information option in the Router Advertisement:
对于路由器公告中的每个前缀信息选项：
a) If the Autonomous flag is not set, silently ignore the Prefix Information option.
a) 如果未设置自治标志，则默认忽略前缀信息选项。
b) If the prefix is the link-local prefix, silently ignore the Prefix Information option.
b) 如果前缀是链接本地前缀，则默认忽略前缀信息选项。
c) If the preferred lifetime is greater than the valid lifetime, silently ignore the Prefix Information option. A node MAY wish to log a system management error in this case.
c) 如果首选生存期大于有效生存期，则默认忽略前缀信息选项。在这种情况下，节点可能希望记录系统管理错误。
d) If the prefix advertised is not equal to the prefix of an address configured by stateless autoconfiguration already in the list of addresses associated with the interface (where "equal" means the two prefix lengths are the same and the first prefix-length bits of the prefixes are identical), and if the Valid Lifetime is not 0, form an address (and add it to the list) by combining the advertised prefix with an interface identifier of the link as follows:
d) 如果前缀的第一个前缀长度与地址的第一个前缀长度不相同，则“自动配置”的前缀长度与地址的第一个前缀长度不相同（并将其添加到列表中）通过将播发前缀与链接的接口标识符组合，如下所示：
| 128 - N bits | N bits |
+---------------------------------------+------------------------+
| link prefix | interface identifier |
+----------------------------------------------------------------+
| 128 - N bits | N bits |
+---------------------------------------+------------------------+
| link prefix | interface identifier |
+----------------------------------------------------------------+
If the sum of the prefix length and interface identifier length does not equal 128 bits, the Prefix Information option MUST be ignored. An implementation MAY wish to log a system management error in this case. The length of the interface identifier is defined in a separate link-type specific document, which should also be consistent with the address architecture [RFC4291] (see Section 2).
如果前缀长度和接口标识符长度之和不等于128位，则必须忽略前缀信息选项。在这种情况下，实现可能希望记录系统管理错误。接口标识符的长度在单独的链路类型特定文档中定义，该文档还应与地址体系结构[RFC4291]一致（参见第2节）。
It is the responsibility of the system administrator to ensure that the lengths of prefixes contained in Router Advertisements are consistent with the length of interface identifiers for that link type. It should be noted, however, that this does not mean the advertised prefix length is meaningless. In fact, the advertised length has non-trivial meaning for on-link determination in [RFC4861] where the sum of the prefix length and the interface identifier length may not be equal to 128. Thus, it should be safe to validate the advertised prefix length here, in order to detect and avoid a configuration error specifying an invalid prefix length in the context of address autoconfiguration.
系统管理员负责确保路由器播发中包含的前缀长度与该链路类型的接口标识符长度一致。然而，应该注意的是，这并不意味着广告的前缀长度是没有意义的。事实上，在[RFC4861]中，在前缀长度和接口标识符长度之和可能不等于128的情况下，广告长度对于链路上确定具有非平凡的意义。因此，在这里验证播发的前缀长度应该是安全的，以便在地址自动配置的上下文中检测并避免指定无效前缀长度的配置错误。
Note that a future revision of the address architecture [RFC4291] and a future link-type-specific document, which will still be consistent with each other, could potentially allow for an interface identifier of length other than the value defined in the current documents. Thus, an implementation should not assume a particular constant. Rather, it should expect any lengths of interface identifiers.
请注意，地址体系结构[RFC4291]的未来版本和未来链接类型特定文档（它们仍将相互一致）可能允许使用长度不同于当前文档中定义的值的接口标识符。因此，实现不应假定特定的常量。相反，它应该期望任何长度的接口标识符。
If an address is formed successfully and the address is not yet in the list, the host adds it to the list of addresses assigned to the interface, initializing its preferred and valid lifetime values from the Prefix Information option. Note that the check against the prefix performed at the beginning of this step cannot always detect the address conflict in the list. It could be possible that an address already in the list, configured either manually or by DHCPv6, happens to be identical to the newly created address, whereas such a case should be atypical.
如果一个地址已成功形成，但该地址尚未在列表中，则主机会将其添加到分配给接口的地址列表中，并从前缀信息选项初始化其首选和有效的生存期值。请注意，在本步骤开始时对前缀执行的检查不能始终检测到列表中的地址冲突。列表中已经存在的地址（手动配置或由DHCPv6配置）可能恰好与新创建的地址相同，而这种情况应该是非典型的。
e) If the advertised prefix is equal to the prefix of an address configured by stateless autoconfiguration in the list, the preferred lifetime of the address is reset to the Preferred Lifetime in the received advertisement. The specific action to perform for the valid lifetime of the address depends on the Valid Lifetime in the received advertisement and the remaining time to the valid lifetime expiration of the previously autoconfigured address. We call the remaining time "RemainingLifetime" in the following discussion:
e) 如果播发前缀等于列表中无状态自动配置配置的地址前缀，则地址的首选生存期将重置为接收到的播发中的首选生存期。在地址的有效生存期内要执行的特定操作取决于接收到的播发中的有效生存期以及到先前自动配置的地址的有效生存期到期的剩余时间。在以下讨论中，我们将剩余时间称为“剩余寿命”：
1. If the received Valid Lifetime is greater than 2 hours or greater than RemainingLifetime, set the valid lifetime of the corresponding address to the advertised Valid Lifetime.
1. 如果收到的有效生存期大于2小时或大于RemainingLifetime，请将相应地址的有效生存期设置为公布的有效生存期。
2. If RemainingLifetime is less than or equal to 2 hours, ignore the Prefix Information option with regards to the valid lifetime, unless the Router Advertisement from which this option was obtained has been authenticated (e.g., via Secure Neighbor Discovery [RFC3971]). If the Router Advertisement was authenticated, the valid lifetime of the corresponding address should be set to the Valid Lifetime in the received option.
2. 如果RemainingLifetime小于或等于2小时，则忽略有关有效生存期的前缀信息选项，除非获得此选项的路由器公告已通过身份验证（例如，通过安全邻居发现[RFC3971]）。如果路由器公告已通过身份验证，则相应地址的有效生存期应设置为received选项中的有效生存期。
3. Otherwise, reset the valid lifetime of the corresponding address to 2 hours.
3. 否则，将相应地址的有效生存期重置为2小时。
The above rules address a specific denial-of-service attack in which a bogus advertisement could contain prefixes with very small Valid Lifetimes. Without the above rules, a single unauthenticated advertisement containing bogus Prefix Information options with short Valid Lifetimes could cause all of a node's addresses to expire prematurely. The above rules ensure that legitimate advertisements (which are sent periodically) will "cancel" the short Valid Lifetimes before they actually take effect.
上述规则针对一种特定的拒绝服务攻击，其中虚假广告可能包含有效寿命非常短的前缀。如果没有包含上述未经验证的有效节点前缀信息的短伪地址，则可能会导致包含上述未经验证的所有伪地址信息的单个伪地址提前过期。上述规则确保合法广告（定期发送）在实际生效之前将“取消”短暂的有效生存期。
Note that the preferred lifetime of the corresponding address is always reset to the Preferred Lifetime in the received Prefix Information option, regardless of whether the valid lifetime is also reset or ignored. The difference comes from the fact that the possible attack for the preferred lifetime is relatively minor. Additionally, it is even undesirable to ignore the preferred lifetime when a valid administrator wants to deprecate a particular address by sending a short preferred lifetime (and the valid lifetime is ignored by accident).
请注意，在接收的前缀信息选项中，相应地址的首选生存期始终重置为首选生存期，无论有效生存期是否也重置或忽略。不同之处在于，首选生命周期内可能发生的攻击相对较小。此外，当有效管理员希望通过发送较短的首选生存期（并且由于意外而忽略了有效生存期）来拒绝使用特定地址时，甚至不希望忽略首选生存期。
A preferred address becomes deprecated when its preferred lifetime expires. A deprecated address SHOULD continue to be used as a source address in existing communications, but SHOULD NOT be used to initiate new communications if an alternate (non-deprecated) address of sufficient scope can easily be used instead.
当首选地址的首选生存期到期时，它将被弃用。不推荐使用的地址应继续用作现有通信中的源地址，但如果可以轻松使用具有足够范围的备用（非不推荐使用的）地址，则不应用于启动新通信。
Note that the feasibility of initiating new communication using a non-deprecated address may be an application-specific decision, as only the application may have knowledge about whether the (now) deprecated address was (or still is) in use by the application. For
请注意，使用未弃用的地址启动新通信的可行性可能是应用程序特定的决定，因为只有应用程序可能知道（现在）弃用的地址是否已被应用程序使用（或仍在使用）。对于
example, if an application explicitly specifies that the protocol stack use a deprecated address as a source address, the protocol stack must accept that; the application might request it because that IP address is used in higher-level communication and there might be a requirement that the multiple connections in such a grouping use the same pair of IP addresses.
例如，如果应用程序明确指定协议栈使用不推荐的地址作为源地址，则协议栈必须接受该地址；应用程序可能会请求它，因为该IP地址用于更高级别的通信，并且可能需要这样一个分组中的多个连接使用同一对IP地址。
IP and higher layers (e.g., TCP, UDP) MUST continue to accept and process datagrams destined to a deprecated address as normal since a deprecated address is still a valid address for the interface. In the case of TCP, this means TCP SYN segments sent to a deprecated address are responded to using the deprecated address as a source address in the corresponding SYN-ACK (if the connection would otherwise be allowed).
IP和更高的层（例如TCP、UDP）必须继续正常地接受和处理发送到不推荐的地址的数据报，因为不推荐的地址仍然是接口的有效地址。对于TCP，这意味着发送到不推荐使用的地址的TCP SYN段将在相应的SYN-ACK中使用不推荐使用的地址作为源地址进行响应（如果不允许连接）。
An implementation MAY prevent any new communication from using a deprecated address, but system management MUST have the ability to disable such a facility, and the facility MUST be disabled by default.
实现可能会阻止任何新通信使用不推荐的地址，但系统管理必须能够禁用此类设施，并且默认情况下必须禁用该设施。
Other subtle cases should also be noted about source address selection. For example, the above description does not clarify which address should be used between a deprecated, smaller-scope address and a non-deprecated, sufficient scope address. The details of the address selection including this case are described in [RFC3484] and are beyond the scope of this document.
关于源地址选择，还应注意其他微妙的情况。例如，上面的描述并没有说明在不推荐使用的较小作用域地址和未推荐使用的足够作用域地址之间应该使用哪个地址。[RFC3484]中描述了包括本案例在内的地址选择细节，超出了本文档的范围。
An address (and its association with an interface) becomes invalid when its valid lifetime expires. An invalid address MUST NOT be used as a source address in outgoing communications and MUST NOT be recognized as a destination on a receiving interface.
地址（及其与接口的关联）在其有效生存期到期时变为无效。无效地址不得用作传出通信中的源地址，也不得被识别为接收接口上的目标地址。
It is possible for hosts to obtain address information using both stateless autoconfiguration and DHCPv6 since both may be enabled at the same time. It is also possible that the values of other configuration parameters, such as MTU size and hop limit, will be learned from both Router Advertisements and DHCPv6. If the same configuration information is provided by multiple sources, the value of this information should be consistent. However, it is not considered a fatal error if information received from multiple sources is inconsistent. Hosts accept the union of all information received via Neighbor Discovery and DHCPv6.
主机可以同时使用无状态自动配置和DHCPv6来获取地址信息，因为这两者都可以同时启用。还可能从路由器广告和DHCPv6中学习其他配置参数的值，例如MTU大小和跃点限制。如果多个来源提供相同的配置信息，则此信息的值应一致。但是，如果从多个来源收到的信息不一致，则不认为是致命错误。主机接受通过邻居发现和DHCPv6接收的所有信息的联合。
If inconsistent information is learned from different sources, an implementation may want to give information learned securely precedence over information learned without protection. For
如果从不同的来源获取不一致的信息，则实现可能希望安全获取的信息优先于无保护获取的信息。对于
instance, Section 8 of [RFC3971] discusses how to deal with information learned through Secure Neighbor Discovery conflicting with information learned through plain Neighbor Discovery. The same discussion can apply to the preference between information learned through plain Neighbor Discovery and information learned via secured DHCPv6, and so on.
例如，[RFC3971]第8节讨论了如何处理通过安全邻居发现获得的信息与通过普通邻居发现获得的信息冲突。同样的讨论也适用于通过普通邻居发现获得的信息与通过安全DHCPv6获得的信息之间的偏好，等等。
In any case, if there is no security difference, the most recently obtained values SHOULD have precedence over information learned earlier.
在任何情况下，如果没有安全性差异，则最近获取的值应优先于先前获取的信息。
An implementation that has stable storage may want to retain addresses in the storage when the addresses were acquired using stateless address autoconfiguration. Assuming the lifetimes used are reasonable, this technique implies that a temporary outage (less than the valid lifetime) of a router will never result in losing a global address of the node even if the node were to reboot. When this technique is used, it should also be noted that the expiration times of the preferred and valid lifetimes must be retained, in order to prevent the use of an address after it has become deprecated or invalid.
具有稳定存储的实现可能希望在使用无状态地址自动配置获取地址时将地址保留在存储中。假设使用的生存期是合理的，这种技术意味着路由器的临时中断（小于有效生存期）永远不会导致丢失节点的全局地址，即使节点要重新启动。使用此技术时，还应注意，必须保留首选和有效生存期的过期时间，以防止在地址被弃用或无效后使用该地址。
Further details on this kind of extension are beyond the scope of this document.
关于这种扩展的更多细节超出了本文件的范围。
Stateless address autoconfiguration allows a host to connect to a network, configure an address, and start communicating with other nodes without ever registering or authenticating itself with the local site. Although this allows unauthorized users to connect to and use a network, the threat is inherently present in the Internet architecture. Any node with a physical attachment to a network can generate an address (using a variety of ad hoc techniques) that provides connectivity.
无状态地址自动配置允许主机连接到网络、配置地址并开始与其他节点通信，而无需向本地站点注册或验证自身。尽管这允许未经授权的用户连接和使用网络，但这种威胁在互联网体系结构中固有存在。任何与网络有物理连接的节点都可以生成提供连接的地址（使用各种临时技术）。
The use of stateless address autoconfiguration and Duplicate Address Detection opens up the possibility of several denial-of-service attacks. For example, any node can respond to Neighbor Solicitations for a tentative address, causing the other node to reject the address as a duplicate. A separate document [RFC3756] discusses details about these attacks, which can be addressed with the Secure Neighbor Discovery protocol [RFC3971]. It should also be noted that [RFC3756] points out that the use of IP security is not always feasible depending on network environments.
无状态地址自动配置和重复地址检测的使用增加了多次拒绝服务攻击的可能性。例如，任何节点都可以响应邻居请求临时地址，从而导致另一个节点拒绝该地址作为副本。另一份文件[RFC3756]讨论了有关这些攻击的详细信息，可通过安全邻居发现协议[RFC3971]解决。还应注意的是，[RFC3756]指出，根据网络环境的不同，IP安全的使用并不总是可行的。
Thomas Narten and Susan Thompson were the authors of RFCs 1971 and 2462. For this revision of the RFC, Tatuya Jinmei was the sole editor.
Thomas Narten和Susan Thompson分别是1971年和2462年RFCs的作者。对于RFC的这次修订，Tatuya Jinmei是唯一的编辑。
The authors of RFC 2461 would like to thank the members of both the IPNG (which is now IPV6) and ADDRCONF working groups for their input. In particular, thanks to Jim Bound, Steve Deering, Richard Draves, and Erik Nordmark. Thanks also goes to John Gilmore for alerting the WG of the "0 Lifetime Prefix Advertisement" denial-of-service attack vulnerability; this document incorporates changes that address this vulnerability.
RFC2461的作者要感谢IPNG（现在是IPV6）和ADDRCONF工作组的成员的投入。特别要感谢吉姆·邦德、史蒂夫·迪林、理查德·德拉维斯和埃里克·诺德马克。还感谢John Gilmore提醒工作组注意“0终身前缀广告”拒绝服务攻击漏洞；本文档包含了解决此漏洞的更改。
A number of people have contributed to identifying issues with RFC 2461 and to proposing resolutions to the issues as reflected in this version of the document. In addition to those listed above, the contributors include Jari Arkko, James Carlson, Brian E. Carpenter, Gregory Daley, Elwyn Davies, Ralph Droms, Jun-ichiro Itojun Hagino, Christian Huitema, Suresh Krishnan, Soohong Daniel Park, Markku Savela, Pekka Savola, Hemant Singh, Bernie Volz, Margaret Wasserman, and Vlad Yasevich.
许多人为确定RFC 2461中的问题做出了贡献，并就本版本文件中反映的问题提出了解决方案。除了上面列出的那些，贡献者还包括贾里·阿尔科、詹姆斯·卡尔森、布赖恩·E·卡彭特、格雷戈里·戴利、埃尔文·戴维斯、拉尔夫·德罗姆斯、伊藤俊一郎·哈吉诺、克里斯蒂安·惠特马、苏雷什·克里希南、苏洪·丹尼尔·帕克、马克库·萨维拉、佩卡·萨沃拉、赫曼·辛格、伯尼·沃尔兹、玛格丽特·瓦瑟曼和弗拉德·亚舍维奇。
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998.
[RFC2464]克劳福德，M.，“通过以太网传输IPv6数据包”，RFC2464，1998年12月。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006.
[RFC4291]Hinden，R.和S.Deering，“IP版本6寻址体系结构”，RFC 42912006年2月。
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007.
[RFC4861]Narten，T.，Nordmark，E.，Simpson，W.，和H.Soliman，“IP版本6（IPv6）的邻居发现”，RFC 48612007年9月。
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3315]Droms，R.，Bound，J.，Volz，B.，Lemon，T.，Perkins，C.，和M.Carney，“IPv6的动态主机配置协议（DHCPv6）”，RFC3315，2003年7月。
[RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC3484]Draves，R.，“互联网协议版本6（IPv6）的默认地址选择”，RFC 3484，2003年2月。
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, September 2007.
[RFC4941]Narten，T.，Draves，R.，和S.Krishnan，“IPv6中无状态地址自动配置的隐私扩展”，RFC 49412007年9月。
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", RFC 3972, March 2005.
[RFC3972]Aura，T.，“加密生成地址（CGA）”，RFC 39722005年3月。
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, October 1999.
[RFC2710]Deering，S.，Fenner，W.，和B.Haberman，“IPv6的多播侦听器发现（MLD）”，RFC 2710，1999年10月。
[RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
[RFC3810]Vida，R.和L.Costa，“IPv6多播侦听器发现版本2（MLDv2）”，RFC 3810，2004年6月。
[RFC3590] Haberman, B., "Source Address Selection for the Multicast Listener Discovery (MLD) Protocol", RFC 3590, September 2003.
[RFC3590]Haberman，B.，“多播侦听器发现（MLD）协议的源地址选择”，RFC 35902003年9月。
[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005.
[RFC3971]Arkko，J.，Kempf，J.，Zill，B.，和P.Nikander，“安全邻居发现（SEND）”，RFC 39712005年3月。
[RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor Discovery (ND) Trust Models and Threats", RFC 3756, May 2004.
[RFC3756]Nikander，P.，Kempf，J.，和E.Nordmark，“IPv6邻居发现（ND）信任模型和威胁”，RFC 37562004年5月。
[RFC1112] Deering, S., "Host extensions for IP multicasting", STD 5, RFC 1112, August 1989.
[RFC1112]Deering，S.，“IP多播的主机扩展”，STD 5，RFC11121989年8月。
[IEEE802.11] IEEE, "Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications", ANSI/IEEE STd 802.11, August 1999.
[IEEE802.11]IEEE，“无线局域网介质访问控制（MAC）和物理层（PHY）规范”，ANSI/IEEE标准802.11，1999年8月。
Determining whether a received multicast solicitation was looped back to the sender or actually came from another node is implementation-dependent. A problematic case occurs when two interfaces attached to the same link happen to have the same identifier and link-layer address, and they both send out packets with identical contents at roughly the same time (e.g., Neighbor Solicitations for a tentative address as part of Duplicate Address Detection messages). Although a receiver will receive both packets, it cannot determine which packet was looped back and which packet came from the other node simply by comparing packet contents (i.e., the contents are identical). In this particular case, it is not necessary to know precisely which packet was looped back and which was sent by another node; if one receives more solicitations than were sent, the tentative address is a duplicate. However, the situation may not always be this straightforward.
确定接收到的多播请求是循环回发送方还是实际来自另一个节点取决于实现。当连接到同一链路的两个接口恰好具有相同的标识符和链路层地址，并且它们都在大致相同的时间发送具有相同内容的数据包（例如，作为重复地址检测消息的一部分，邻居请求临时地址）时，就会出现问题。尽管接收器将接收这两个数据包，但它不能仅仅通过比较数据包内容（即，内容相同）来确定哪个数据包被环回，哪个数据包来自另一个节点。在这种特殊情况下，不需要精确地知道哪个包被循环回，哪个包被另一个节点发送；如果收到的邀请函多于发送的邀请函，则暂定地址为重复地址。然而，情况可能并不总是如此简单。
The IPv4 multicast specification [RFC1112] recommends that the service interface provide a way for an upper-layer protocol to inhibit local delivery of packets sent to a multicast group that the sending host is a member of. Some applications know that there will be no other group members on the same host, and suppressing loopback prevents them from having to receive (and discard) the packets they themselves send out. A straightforward way to implement this facility is to disable loopback at the hardware level (if supported by the hardware), with packets looped back (if requested) by software. On interfaces in which the hardware itself suppresses loopbacks, a node running Duplicate Address Detection simply counts the number of Neighbor Solicitations received for a tentative address and compares them with the number expected. If there is a mismatch, the tentative address is a duplicate.
IPv4多播规范[RFC1112]建议服务接口为上层协议提供一种方式，以禁止发送到发送主机所属的多播组的数据包的本地传递。一些应用程序知道在同一主机上不会有其他组成员，而抑制环回可以防止它们不得不接收（和丢弃）自己发送的数据包。实现此功能的一种简单方法是在硬件级别（如果硬件支持）禁用环回，并通过软件环回数据包（如果请求）。在硬件本身抑制环回的接口上，运行重复地址检测的节点只需计算为暂定地址接收的邻居请求的数量，并将其与预期数量进行比较。如果存在不匹配，则暂定地址为重复地址。
In those cases where the hardware cannot suppress loopbacks, however, one possible software heuristic to filter out unwanted loopbacks is to discard any received packet whose link-layer source address is the same as the receiving interface's. There is even a link-layer specification that requires that any such packets be discarded [IEEE802.11]. Unfortunately, use of that criteria also results in the discarding of all packets sent by another node using the same link-layer address. Duplicate Address Detection will fail on interfaces that filter received packets in this manner:
然而，在硬件无法抑制环回的情况下，过滤掉不需要的环回的一种可能的软件启发式方法是丢弃链路层源地址与接收接口相同的任何接收数据包。甚至还有一个链路层规范要求丢弃任何此类数据包[IEEE802.11]。不幸的是，使用该标准还导致丢弃使用相同链路层地址的另一节点发送的所有数据包。重复地址检测将在以这种方式过滤接收数据包的接口上失败：
o If a node performing Duplicate Address Detection discards received packets that have the same source link-layer address as the receiving interface, it will also discard packets from other nodes that also use the same link-layer address, including Neighbor Advertisement and Neighbor Solicitation messages required to make
o 如果执行重复地址检测的节点丢弃与接收接口具有相同源链路层地址的接收数据包，则它还将丢弃来自同样使用相同链路层地址的其他节点的数据包，包括进行重复地址检测所需的邻居播发和邻居请求消息
Duplicate Address Detection work correctly. This particular problem can be avoided by temporarily disabling the software suppression of loopbacks while a node performs Duplicate Address Detection, if it is possible to disable the suppression.
重复地址检测工作正常。如果可以禁用环回抑制，则可以通过在节点执行重复地址检测时临时禁用环回软件抑制来避免此特定问题。
o If a node that is already using a particular IP address discards received packets that have the same link-layer source address as the interface, it will also discard Duplicate Address Detection-related Neighbor Solicitation messages sent by another node that also use the same link-layer address. Consequently, Duplicate Address Detection will fail, and the other node will configure a non-unique address. Since it is generally impossible to know when another node is performing Duplicate Address Detection, this scenario can be avoided only if software suppression of loopback is permanently disabled.
o 如果已经使用特定IP地址的节点丢弃接收到的与接口具有相同链路层源地址的数据包，则它还将丢弃由另一个也使用相同链路层地址的节点发送的与重复地址检测相关的邻居请求消息。因此，重复地址检测将失败，而另一个节点将配置非唯一地址。由于通常不可能知道另一个节点何时执行重复地址检测，因此只有在永久禁用环回软件抑制的情况下才能避免这种情况。
Thus, to perform Duplicate Address Detection correctly in the case where two interfaces are using the same link-layer address, an implementation must have a good understanding of the interface's multicast loopback semantics, and the interface cannot discard received packets simply because the source link-layer address is the same as the interface's. It should also be noted that a link-layer specification can conflict with the condition necessary to make Duplicate Address Detection work.
因此，要在两个接口使用相同链路层地址的情况下正确执行重复地址检测，实现必须很好地理解接口的多播环回语义，接口不能仅仅因为源链路层地址与接口地址相同而丢弃接收到的数据包。还应注意，链路层规范可能与使重复地址检测工作的必要条件相冲突。
o Changed document to use term "interface identifier" rather than "interface token" for consistency with other IPv6 documents.
o 将文档更改为使用术语“接口标识符”而不是“接口令牌”，以与其他IPv6文档保持一致。
o Clarified definition of deprecated address to make clear it is OK to continue sending to or from deprecated addresses.
o 澄清了不推荐使用的地址的定义，以明确是否可以继续向不推荐使用的地址发送邮件或从中发送邮件。
o Added rules to Section 5.5.3 Router Advertisement processing to address potential denial-of-service attack when prefixes are advertised with very short Lifetimes.
o 在第5.5.3节路由器公告处理中添加了规则，以解决前缀以极短生命周期公告时可能发生的拒绝服务攻击。
o Clarified wording in Section 5.5.4 to make clear that all upper layer protocols must process (i.e., send and receive) packets sent to deprecated addresses.
o 澄清了第5.5.4节中的措辞，以明确所有上层协议必须处理（即发送和接收）发送到不推荐地址的数据包。
Major changes that can affect existing implementations:
可能影响现有实施的主要更改：
o Specified that a node performing Duplicate Address Detection delay joining the solicited-node multicast group, not just delay sending Neighbor Solicitations, explaining the detailed reason.
o 指定执行重复地址检测的节点延迟加入请求节点多播组，而不仅仅延迟发送邻居请求，解释了详细原因。
o Added a requirement for a random delay before sending Neighbor Solicitations for Duplicate Address Detection if the address being checked is configured by a multicasted Router Advertisements.
o 增加了在发送邻居请求以检测重复地址之前的随机延迟要求，前提是检查的地址是由多播路由器配置的。
o Clarified that on failure of Duplicate Address Detection, IP network operation should be disabled and that the rule should apply when the hardware address is supposed to be unique.
o 阐明在重复地址检测失败时，应禁用IP网络操作，并且当硬件地址应是唯一的时，应应用该规则。
Major clarifications:
主要澄清：
o Clarified how the length of interface identifiers should be determined, described the relationship with the prefix length advertised in Router Advertisements, and avoided using a particular length hard-coded in this document.
o 阐明了应如何确定接口标识符的长度，描述了与路由器公告中公布的前缀长度的关系，并避免使用本文档中硬编码的特定长度。
o Clarified the processing of received neighbor advertisements while performing Duplicate Address Detection.
o 阐明了在执行重复地址检测时对接收到的邻居播发的处理。
o Removed the text regarding the M and O flags, considering the maturity of implementations and operational experiences. ManagedFlag and OtherConfigFlag were removed accordingly. (Note that this change does not mean the use of these flags is deprecated.)
o 考虑到实现的成熟度和操作经验，删除了有关M和O标志的文本。ManagedFlag和OtherConfigFlag已相应删除。（请注意，此更改并不意味着不推荐使用这些标志。）
o Avoided the wording of "stateful configuration", which is known to be quite confusing, and simply used "DHCPv6" wherever appropriate.
o 避免了“有状态配置”的措辞，这是众所周知的非常混乱的，并在适当的情况下简单地使用“DHCPv6”。
o Recommended to perform Duplicate Address Detection for all unicast addresses more strongly, considering a variety of different interface identifiers, while keeping care of existing implementations.
o 考虑到各种不同的接口标识符，建议更强烈地对所有单播地址执行重复地址检测，同时保留现有实现。
o Clarified wording in Section 5.5.4 to make clear that a deprecated address specified by an application can be used for any communication.
o 澄清了第5.5.4节中的措辞，以明确应用程序指定的弃用地址可用于任何通信。
o Clarified the prefix check described in Section 5.5.3 using more appropriate terms and that the check is done against the prefixes of addresses configured by stateless autoconfiguration.
o 使用更合适的术语阐明了第5.5.3节中描述的前缀检查，并且检查是针对无状态自动配置配置的地址前缀进行的。
o Changed the references to the IP security Authentication Header to references to RFC 3971 (Secure Neighbor Discovery). Also revised the Security Considerations section with a reference to RFC 3756.
o 将对IP安全身份验证标头的引用更改为对RFC 3971（安全邻居发现）的引用。还修订了安全注意事项一节，参考RFC 3756。
o Added a note when an implementation uses stable storage for autoconfigured addresses.
o 添加了一个注意事项，当实现为自动配置的地址使用稳定存储时。
o Added consideration about preference between inconsistent information sets, one from a secured source and the other learned without protection.
o 增加了对不一致信息集之间偏好的考虑，一个来自安全来源，另一个在没有保护的情况下学习。
Other miscellaneous clarifications:
其他杂项澄清：
o Removed references to site-local and revised wording around the keyword.
o 删除了对站点本地的引用，并修改了关键字周围的措辞。
o Removed redundant code in denial-of-service protection in Section 5.5.3.
o 删除了第5.5.3节中拒绝服务保护中的冗余代码。
o Clarified that a unicasted Neighbor Solicitation or Advertisement should be discarded while performing Duplicate Address Detection.
o 阐明在执行重复地址检测时应丢弃单播邻居请求或播发。
o Noted in Section 5.3 that an interface can be considered as becoming enabled when a wireless access point changes.
o 在第5.3节中指出，当无线接入点发生变化时，可以认为接口已启用。
Authors' Addresses
作者地址
Susan Thomson Cisco Systems
苏珊·汤姆森思科系统公司
EMail: sethomso@cisco.com
EMail: sethomso@cisco.com
Thomas Narten IBM Corporation P.O. Box 12195 Research Triangle Park, NC 27709-2195 USA
美国北卡罗来纳州三角研究园12195号邮政信箱托马斯·纳顿IBM公司，邮编：27709-2195
Phone: +1 919-254-7798
EMail: narten@us.ibm.com
Phone: +1 919-254-7798
EMail: narten@us.ibm.com
Tatuya Jinmei Corporate Research & Development Center, Toshiba Corporation 1 Komukai Toshiba-cho, Saiwai-ku Kawasaki-shi, Kanagawa 212-8582 Japan
Tatuya Jinmei公司研发中心，东芝公司1 Komukai Toshiba cho，日本神奈川市川崎市西围区212-8582
Phone: +81 44-549-2230
EMail: jinmei@isl.rdc.toshiba.co.jp
Phone: +81 44-549-2230
EMail: jinmei@isl.rdc.toshiba.co.jp
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