Network Working Group O. Troan
Request for Comments: 3633 R. Droms
Category: Standards Track Cisco Systems
December 2003
Network Working Group O. Troan
Request for Comments: 3633 R. Droms
Category: Standards Track Cisco Systems
December 2003
IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6
动态主机配置协议（DHCP）版本6的IPv6前缀选项
Status of this Memo
本备忘录的状况
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。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2003). All Rights Reserved.
版权所有（C）互联网协会（2003年）。版权所有。
Abstract
摘要
The Prefix Delegation options provide a mechanism for automated delegation of IPv6 prefixes using the Dynamic Host Configuration Protocol (DHCP). This mechanism is intended for delegating a long-lived prefix from a delegating router to a requesting router, across an administrative boundary, where the delegating router does not require knowledge about the topology of the links in the network to which the prefixes will be assigned.
前缀委派选项提供了一种使用动态主机配置协议（DHCP）自动委派IPv6前缀的机制。此机制旨在跨管理边界将长寿命前缀从委派路由器委派给请求路由器，其中委派路由器不需要关于前缀将被分配到的网络中的链路拓扑的知识。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. DHCPv6 specification dependency . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Model and Applicability . . . . . . . . . . . . . . . . . . 3
5.1. Example network architecture . . . . . . . . . . . . . 4
6. Identity Association for Prefix Delegation . . . . . . . . . 5
7. Overview of DHCP with Prefix Delegation . . . . . . . . . . 6
8. Interface Selection . . . . . . . . . . . . . . . . . . . . 7
9. Identity Association for Prefix Delegation Option . . . . . 7
10. IA_PD Prefix option . . . . . . . . . . . . . . . . . . . . 9
11. Delegating Router Solicitation . . . . . . . . . . . . . . . 11
11.1. Requesting router behavior . . . . . . . . . . . . . . 11
11.2. Delegating router behavior . . . . . . . . . . . . . . 11
12. Requesting router initiated prefix delegation . . . . . . . 12
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. DHCPv6 specification dependency . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Model and Applicability . . . . . . . . . . . . . . . . . . 3
5.1. Example network architecture . . . . . . . . . . . . . 4
6. Identity Association for Prefix Delegation . . . . . . . . . 5
7. Overview of DHCP with Prefix Delegation . . . . . . . . . . 6
8. Interface Selection . . . . . . . . . . . . . . . . . . . . 7
9. Identity Association for Prefix Delegation Option . . . . . 7
10. IA_PD Prefix option . . . . . . . . . . . . . . . . . . . . 9
11. Delegating Router Solicitation . . . . . . . . . . . . . . . 11
11.1. Requesting router behavior . . . . . . . . . . . . . . 11
11.2. Delegating router behavior . . . . . . . . . . . . . . 11
12. Requesting router initiated prefix delegation . . . . . . . 12
12.1. Requesting router behavior . . . . . . . . . . . . . . 12
12.2. Delegating Router behavior . . . . . . . . . . . . . . 14
13. Prefix Delegation reconfiguration . . . . . . . . . . . . . 15
13.1. Delegating Router behavior . . . . . . . . . . . . . . 15
13.2. Requesting Router behavior . . . . . . . . . . . . . . 15
14. Relay agent behavior . . . . . . . . . . . . . . . . . . . . 15
15. Security Considerations . . . . . . . . . . . . . . . . . . 16
16. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16
17. Intellectual Property Statement. . . . . . . . . . . . . . . 17
18. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
18.1. Normative References . . . . . . . . . . . . . . . . . 17
18.2. Informative References . . . . . . . . . . . . . . . . 17
19. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
20. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 18
21. Full Copyright Statement . . . . . . . . . . . . . . . . . . 19
12.1. Requesting router behavior . . . . . . . . . . . . . . 12
12.2. Delegating Router behavior . . . . . . . . . . . . . . 14
13. Prefix Delegation reconfiguration . . . . . . . . . . . . . 15
13.1. Delegating Router behavior . . . . . . . . . . . . . . 15
13.2. Requesting Router behavior . . . . . . . . . . . . . . 15
14. Relay agent behavior . . . . . . . . . . . . . . . . . . . . 15
15. Security Considerations . . . . . . . . . . . . . . . . . . 16
16. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16
17. Intellectual Property Statement. . . . . . . . . . . . . . . 17
18. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
18.1. Normative References . . . . . . . . . . . . . . . . . 17
18.2. Informative References . . . . . . . . . . . . . . . . 17
19. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
20. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 18
21. Full Copyright Statement . . . . . . . . . . . . . . . . . . 19
This document describes new options for Dynamic Host Configuration Protocol (DHCP) that provide a mechanism for the delegation of IPv6 prefixes [1]. Through these options, a delegating router can delegate prefixes to authorized requesting routers.
本文档介绍了动态主机配置协议（DHCP）的新选项，该协议为IPv6前缀的委派提供了一种机制[1]。通过这些选项，委托路由器可以将前缀委托给授权的请求路由器。
The prefix delegation mechanism described in this document is intended for simple delegation of prefixes from a delegating router to requesting routers. It is appropriate for situations in which the delegating router does not have knowledge about the topology of the networks to which the requesting router is attached, and the delegating router does not require other information aside from the identity of the requesting router to choose a prefix for delegation. For example, these options would be used by a service provider to assign a prefix to a Customer Premise Equipment (CPE) device acting as a router between the subscriber's internal network and the service provider's core network.
本文档中描述的前缀委托机制旨在将前缀从委托路由器简单地委托给请求路由器。它适用于授权路由器不知道请求路由器所连接的网络拓扑，并且授权路由器不需要除了请求路由器的身份之外的其他信息来选择用于授权的前缀的情况。例如，服务提供商将使用这些选项为充当用户的内部网络和服务提供商的核心网络之间的路由器的客户前提设备（CPE）设备分配前缀。
Many applications expect stable addresses. Even though this mechanism makes automatic renumbering easier, it is expected that prefixes have a long lifespan. During renumbering it is expected that the old and the new prefix co-exist for some time.
许多应用程序需要稳定的地址。尽管这种机制使自动重新编号更容易，但前缀的使用寿命预计会更长。在重新编号期间，旧前缀和新前缀预计会共存一段时间。
The design of this prefix delegation mechanism meets the requirements for prefix delegation in Requirements for IPv6 prefix delegation [6].
该前缀委托机制的设计满足IPv6前缀委托要求[6]中的前缀委托要求。
Note that this use of DHCP is not bound to the assignment of IP addresses or other configuration information to hosts, and that no mechanism is currently available to communicate delegated prefixes to a DHCP server that serves such a function. This may be an item of future work, should usage warrant.
请注意，DHCP的这种使用不受IP地址或其他配置信息分配给主机的限制，并且目前没有任何机制可用于将委派的前缀传递给提供这种功能的DHCP服务器。如果使用许可，这可能是未来工作的一项。
This document describes new DHCPv6 options for IPv6 prefix delegation. This document should be read in conjunction with the DHCPv6 specification, RFC 3315 [2], for a complete specification of the Prefix Delegation options and mechanism. Definitions for terms and acronyms not specifically defined in this document are defined in RFC 3315.
本文档介绍IPv6前缀委派的新DHCPv6选项。本文档应结合DHCPv6规范RFC 3315[2]阅读，以了解前缀委派选项和机制的完整规范。本文件中未明确定义的术语和首字母缩略词的定义见RFC 3315。
This document uses the terminology defined in RFC 2460 [1] and RFC 3315. In addition, this document uses the following terms:
本文件使用RFC 2460[1]和RFC 3315中定义的术语。此外，本文件使用以下术语：
requesting router: The router that acts as a DHCP client and is requesting prefix(es) to be assigned.
请求路由器：充当DHCP客户端并请求分配前缀的路由器。
delegating router: The router that acts as a DHCP server, and is responding to the prefix request.
委派路由器：充当DHCP服务器并响应前缀请求的路由器。
Identity Association for Prefix Delegation (IA_PD): A collection of prefixes assigned to the requesting router. Each IA_PD has an associated IAID. A requesting router may have more than one IA_PD assigned to it; for example, one for each of its interfaces.
前缀委派的身份关联（IA_PD）：分配给请求路由器的前缀集合。每个IAU PD都有一个关联的IAID。请求路由器可能有多个IA_PD分配给它；例如，每个接口对应一个。
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 BCP 14, RFC 2119 [3].
本文件中出现的关键词必须、不得、必需、应、不应、应、不应、建议、可能和可选时，应按照BCP 14、RFC 2119[3]中的说明进行解释。
The model of operation for prefix delegation is as follows. A delegating router is provided IPv6 prefixes to be delegated to requesting routers. Examples of ways in which the delegating router may be provided these prefixes are given in Section 12.2. A requesting router requests prefix(es) from the delegating router, as described in Section 12.1. The delegating router chooses prefix(es) for delegation, and responds with prefix(es) to the requesting router. The requesting router is then responsible for the delegated prefix(es). For example, the requesting router might assign a subnet from a delegated prefix to one of its interfaces, and begin sending router advertisements for the prefix on that link.
前缀委派的操作模型如下所示。委派路由器提供IPv6前缀以委派给请求路由器。第12.2节给出了授权路由器提供这些前缀的方式示例。请求路由器从委托路由器请求前缀，如第12.1节所述。委派路由器为委派选择前缀，并用前缀响应请求路由器。然后，请求路由器负责委托的前缀。例如，请求路由器可能会将一个子网从委派前缀分配给它的一个接口，并开始在该链路上发送前缀的路由器公告。
Each prefix has an associated valid and preferred lifetime, which constitutes an agreement about the length of time over which the requesting router is allowed to use the prefix. A requesting router can request an extension of the lifetimes on a delegated prefix and is required to terminate the use of a delegated prefix if the valid lifetime of the prefix expires.
每个前缀都有一个相关的有效和首选生存期，这构成了一个关于允许请求路由器使用前缀的时间长度的协议。请求路由器可以请求延长委托前缀的生存期，并且如果前缀的有效生存期到期，则需要终止委托前缀的使用。
This prefix delegation mechanism would be appropriate for use by an ISP to delegate a prefix to a subscriber, where the delegated prefix would possibly be subnetted and assigned to the links within the subscriber's network.
这种前缀委派机制适合ISP将前缀委派给订阅者，其中委派的前缀可能被分网并分配给订阅者网络内的链路。
Figure 1 illustrates a network architecture in which prefix delegation could be used.
图1说明了一种可以使用前缀委派的网络体系结构。
______________________ \
/ \ \
| ISP core network | \
\__________ ___________/ |
| |
+-------+-------+ |
| Aggregation | | ISP
| device | | network
| (delegating | |
| router) | |
+-------+-------+ |
| /
|DSL to subscriber /
|premises /
|
+------+------+ \
| CPE | \
| (requesting | \
| router) | |
+----+---+----+ |
| | | Subscriber
---+-------------+-----+- -+-----+-------------+--- | network
| | | | |
+----+-----+ +-----+----+ +----+-----+ +-----+----+ |
|Subscriber| |Subscriber| |Subscriber| |Subscriber| /
| PC | | PC | | PC | | PC | /
+----------+ +----------+ +----------+ +----------+ /
______________________ \
/ \ \
| ISP core network | \
\__________ ___________/ |
| |
+-------+-------+ |
| Aggregation | | ISP
| device | | network
| (delegating | |
| router) | |
+-------+-------+ |
| /
|DSL to subscriber /
|premises /
|
+------+------+ \
| CPE | \
| (requesting | \
| router) | |
+----+---+----+ |
| | | Subscriber
---+-------------+-----+- -+-----+-------------+--- | network
| | | | |
+----+-----+ +-----+----+ +----+-----+ +-----+----+ |
|Subscriber| |Subscriber| |Subscriber| |Subscriber| /
| PC | | PC | | PC | | PC | /
+----------+ +----------+ +----------+ +----------+ /
Figure 1: An example of prefix delegation.
图1：前缀委托的示例。
In this example, the delegating router is configured with a set of prefixes to be used for assignment to customers at the time of each customer's first connection to the ISP service. The prefix delegation process begins when the requesting router requests configuration information through DHCP. The DHCP messages from the requesting router are received by the delegating router in the aggregation device. When the delegating router receives the request, it selects an available prefix or prefixes for delegation to the requesting router. The delegating router then returns the prefix or prefixes to the requesting router.
在此示例中，委托路由器配置有一组前缀，用于在每个客户第一次连接到ISP服务时分配给客户。当请求路由器通过DHCP请求配置信息时，前缀委派过程开始。来自请求路由器的DHCP消息由聚合设备中的委派路由器接收。当委托路由器接收到请求时，它会选择一个或多个可用的前缀来委托给请求路由器。然后，委托路由器将前缀返回给请求路由器。
The requesting router subnets the delegated prefix and assigns the longer prefixes to links in the subscriber's network. In a typical scenario based on the network shown in Figure 1, the requesting router subnets a single delegated /48 prefix into /64 prefixes and assigns one /64 prefix to each of the links in the subscriber network.
请求路由器将委派的前缀子网化，并将较长的前缀分配给订户网络中的链路。在基于图1所示网络的典型场景中，请求路由器将单个委派的/48前缀子网化为/64前缀，并将一个/64前缀分配给订户网络中的每个链路。
The prefix delegation options can be used in conjunction with other DHCP options carrying other configuration information to the requesting router. The requesting router may, in turn, then provide DHCP service to hosts attached to the internal network. For example, the requesting router may obtain the addresses of DNS and NTP servers from the ISP delegating router, and then pass that configuration information on to the subscriber hosts through a DHCP server in the requesting router.
前缀委派选项可与其他DHCP选项结合使用，将其他配置信息传送到请求路由器。然后，请求路由器可以向连接到内部网络的主机提供DHCP服务。例如，请求路由器可以从ISP委托路由器获得DNS和NTP服务器的地址，然后通过请求路由器中的DHCP服务器将该配置信息传递给订户主机。
An IA_PD is a construct through which a delegating router and a requesting router can identify, group and manage a set of related IPv6 prefixes. Each IA_PD consists of an IAID and associated configuration information. An IA_PD for prefixes is the equivalent of an IA (described in RFC 3315) for addresses.
IA_PD是授权路由器和请求路由器可以识别、分组和管理一组相关IPv6前缀的结构。每个IA_PD由一个IAID和相关配置信息组成。前缀的IA_PD相当于地址的IA（如RFC 3315所述）。
An IA_PD is different from an IA, in that it does not need to be associated with exactly one interface. One IA_PD can be associated with the requesting router, with a set of interfaces or with exactly one interface. A requesting router must create at least one distinct IA_PD. It may associate a distinct IA_PD with each of its downstream network interfaces and use that IA_PD to obtain a prefix for that interface from the delegating router.
IA_PD不同于IA，因为它不需要仅与一个接口关联。一个IA_PD可与请求路由器、一组接口或仅一个接口相关联。请求路由器必须至少创建一个不同的IA_PD。它可以将不同的IA_-PD与其每个下游网络接口相关联，并使用该IA_-PD从委派路由器获得该接口的前缀。
The IAID uniquely identifies the IA_PD and must be chosen to be unique among the IA_PD IAIDs on the requesting router. The IAID is chosen by the requesting router. For any given use of an IA_PD by the requesting router, the IAID for that IA_PD MUST be consistent across restarts of the requesting router. The requesting router may
IAID唯一标识IA_PD，并且必须选择为在请求路由器上的IA_PD IAID中唯一。IAID由请求路由器选择。对于请求路由器对IA_PD的任何给定使用，该IA_PD的IAID必须在请求路由器重启时保持一致。请求路由器可以
maintain consistency either by storing the IAID in non-volatile storage or by using an algorithm that will consistently produce the same IAID as long as the configuration of the requesting router has not changed. If the requesting router uses only one IAID, it can use a well-known value, e.g., zero.
通过将IAID存储在非易失性存储器中或通过使用一种算法来保持一致性，只要请求路由器的配置没有改变，该算法将始终如一地生成相同的IAID。如果请求路由器仅使用一个IAID，它可以使用已知值，例如零。
The configuration information in an IA_PD consists of one or more IPv6 prefixes along with the times T1 and T2 for the IA_PD. See section 9 for the representation of an IA_PD in a DHCP message.
IA_PD中的配置信息包括一个或多个IPv6前缀以及IA_PD的时间T1和T2。有关DHCP消息中IA_PD的表示，请参见第9节。
Prefix delegation with DHCP is independent of address assignment with DHCP. A requesting router can use DHCP for just prefix delegation or for prefix delegation along with address assignment and other configuration information.
使用DHCP的前缀委派独立于使用DHCP的地址分配。请求路由器可以仅将DHCP用于前缀委派或前缀委派以及地址分配和其他配置信息。
A requesting router first creates an IA_PD and assigns it an IAID. The requesting router then transmits a Solicit message containing an IA_PD option describing the IA_PD. Delegating routers that can delegate prefixes to the IA_PD respond to the requesting router with an Advertise message.
请求路由器首先创建一个IAU PD并为其分配一个IAID。然后，请求路由器发送包含描述IA_PD的IA_PD选项的请求消息。可以将前缀委托给IA_PD的委托路由器使用播发消息响应请求路由器。
The requesting router may include prefixes in the IA_PDs as a hint to the delegating router about specific prefixes for which the requesting router has a preference.
请求路由器可以在IA_PDs中包括前缀，作为关于请求路由器具有优先权的特定前缀的对委托路由器的提示。
When the requesting router has identified a delegating router, the requesting router uses a Request message to populate the IA_PDs with prefixes. The requesting router includes one or more IA_PD options in the Request message. The delegating router returns prefixes and other information about the IA_PDs to the requesting router in IA_PD options in a Reply message. The requesting router records the lifetimes for the delegated prefix(es) and uses the prefix(es) as described in the previous section.
当请求路由器识别出一个委托路由器时，请求路由器使用请求消息用前缀填充IA_PDs。请求路由器在请求消息中包括一个或多个IA_PD选项。授权路由器在回复消息中向请求路由器返回IA_PD选项中的前缀和其他IA_PD信息。请求路由器记录委派前缀的生存时间，并使用前一节中描述的前缀。
Before the valid lifetime on each delegated prefix expires, the requesting router includes the prefix in an IA_PD option sent in a Renew message to the delegating router. The delegating router responds by returning the prefix with updated lifetimes to the requesting router.
在每个委派前缀的有效生存期到期之前，请求路由器在向委派路由器发送的续订消息中的IA_PD选项中包含该前缀。委派路由器通过向请求路由器返回具有更新生存期的前缀来响应。
Delegated prefixes are not associated with a particular interface in the same way as addresses are for address assignment, and the rules described in section 16, "Client Source Address and Interface Selection" of RFC 3315 do not apply.
委托前缀与特定接口的关联方式与地址分配的方式不同，RFC 3315第16节“客户机源地址和接口选择”中描述的规则不适用。
When a requesting router sends a DHCP message, it SHOULD be sent on the interface associated with the upstream router (ISP network). The upstream interface is typically determined by configuration. This rule applies even in the case where a separate IA_PD is used for each downstream interface.
当请求路由器发送DHCP消息时，它应该在与上游路由器（ISP网络）相关联的接口上发送。上游接口通常由配置决定。即使在每个下游接口使用单独IA_PD的情况下，该规则也适用。
When a requesting router sends a DHCP message directly to a delegating router using unicast (after receiving the Server Unicast option from that delegating router), the source address SHOULD be an address from the upstream interface and which is suitable for use by the delegating router in responding to the requesting router.
当请求路由器使用单播（从该委托路由器接收服务器单播选项后）直接向委托路由器发送DHCP消息时，源地址应为来自上游接口的地址，并且适合委托路由器在响应请求路由器时使用。
The IA_PD option is used to carry a prefix delegation identity association, the parameters associated with the IA_PD and the prefixes associated with it.
IA_PD选项用于携带前缀委派标识关联、与IA_PD关联的参数以及与之关联的前缀。
The format of the IA_PD option is:
IA_PD选项的格式为：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IA_PD | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. IA_PD-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IA_PD | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. IA_PD-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_IA_PD (25)
选项代码：选项A\U PD（25）
option-length: 12 + length of IA_PD-options field.
选项长度：12+IA_PD-options字段的长度。
IAID: The unique identifier for this IA_PD; the IAID must be unique among the identifiers for all of this requesting router's IA_PDs.
IAID：此IA_PD的唯一标识符；IAID在所有请求路由器的IA_PD的标识符中必须是唯一的。
T1: The time at which the requesting router should contact the delegating router from which the prefixes in the IA_PD were obtained to extend the lifetimes of the prefixes delegated to the IA_PD; T1 is a time duration relative to the current time expressed in units of seconds.
T1：请求路由器应联系授权路由器的时间，从该授权路由器获得IA_PD中的前缀，以延长授权给IA_PD的前缀的寿命；T1是相对于当前时间的持续时间，以秒为单位表示。
T2: The time at which the requesting router should contact any available delegating router to extend the lifetimes of the prefixes assigned to the IA_PD; T2 is a time duration relative to the current time expressed in units of seconds.
T2：请求路由器应联系任何可用的授权路由器以延长分配给IA_PD的前缀的生存期的时间；T2是相对于当前时间的持续时间，以秒为单位表示。
IA_PD-options: Options associated with this IA_PD.
IA_PD-options：与此IA_PD关联的选项。
The IA_PD-options field encapsulates those options that are specific to this IA_PD. For example, all of the IA_PD Prefix Options carrying the prefixes associated with this IA_PD are in the IA_PD-options field.
IA_PD-options字段封装了特定于此IA_PD的选项。例如，所有带有与此IA_PD关联的前缀的IA_PD前缀选项都位于IA_PD-Options字段中。
An IA_PD option may only appear in the options area of a DHCP message. A DHCP message may contain multiple IA_PD options.
IA_PD选项只能出现在DHCP消息的选项区域中。DHCP消息可能包含多个IA_PD选项。
The status of any operations involving this IA_PD is indicated in a Status Code option in the IA_PD-options field.
涉及此IA_PD的任何操作的状态在IA_PD-options字段中的状态代码选项中指示。
Note that an IA_PD has no explicit "lifetime" or "lease length" of its own. When the valid lifetimes of all of the prefixes in a IA_PD have expired, the IA_PD can be considered as having expired. T1 and T2 are included to give delegating routers explicit control over when a requesting router should contact the delegating router about a specific IA_PD.
请注意，IA_PD本身没有明确的“寿命”或“租赁期限”。当IA_PD中所有前缀的有效生存期已过期时，可以认为IA_PD已过期。T1和T2被包括在内，以便授权路由器明确控制请求路由器何时应就特定IA_PD联系授权路由器。
In a message sent by a requesting router to a delegating router, values in the T1 and T2 fields indicate the requesting router's preference for those parameters. The requesting router sets T1 and T2 to zero if it has no preference for those values. In a message sent by a delegating router to a requesting router, the requesting router MUST use the values in the T1 and T2 fields for the T1 and T2 parameters. The values in the T1 and T2 fields are the number of seconds until T1 and T2.
在请求路由器发送给委托路由器的消息中，T1和T2字段中的值表示请求路由器对这些参数的偏好。如果请求路由器对T1和T2值没有偏好，则将其设置为零。在委托路由器发送给请求路由器的消息中，请求路由器必须使用T1和T2字段中的值作为T1和T2参数。T1和T2字段中的值是T1和T2之前的秒数。
The delegating router selects the T1 and T2 times to allow the requesting router to extend the lifetimes of any prefixes in the
委派路由器选择T1和T2时间，以允许请求路由器延长系统中任何前缀的生存时间
IA_PD before the lifetimes expire, even if the delegating router is unavailable for some short period of time. Recommended values for T1 and T2 are .5 and .8 times the shortest preferred lifetime of the prefixes in the IA_PD that the delegating router is willing to extend, respectively. If the time at which the prefixes in an IA_PD are to be renewed is to be left to the discretion of the requesting router, the delegating router sets T1 and T2 to 0.
即使授权路由器在短时间内不可用，在生存期到期之前，IA_PD也是如此。T1和T2的建议值分别是授权路由器愿意延长的IA_PD中前缀的最短首选生存期的.5倍和.8倍。如果IA_PD中前缀的更新时间由请求路由器决定，则委托路由器将T1和T2设置为0。
If a delegating router receives an IA_PD with T1 greater than T2, and both T1 and T2 are greater than 0, the delegating router ignores the invalid values of T1 and T2 and processes the IA_PD as though the delegating router had set T1 and T2 to 0.
如果委派路由器接收到T1大于T2的IA_PD，并且T1和T2都大于0，则委派路由器将忽略T1和T2的无效值，并处理IA_PD，就像委派路由器已将T1和T2设置为0一样。
If a requesting router receives an IA_PD with T1 greater than T2, and both T1 and T2 are greater than 0, the client discards the IA_PD option and processes the remainder of the message as though the delegating router had not included the IA_PD option.
如果请求路由器接收到T1大于T2的IA_PD，并且T1和T2都大于0，则客户端将丢弃IA_PD选项，并处理消息的其余部分，就像委托路由器未包含IA_PD选项一样。
The IA_PD Prefix option is used to specify IPv6 address prefixes associated with an IA_PD. The IA_PD Prefix option must be encapsulated in the IA_PD-options field of an IA_PD option.
IA_PD Prefix选项用于指定与IA_PD关联的IPv6地址前缀。IA_PD前缀选项必须封装在IA_PD选项的IA_PD-options字段中。
The format of the IA_PD Prefix option is:
IA_PD前缀选项的格式为：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IAPREFIX | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preferred-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-length | |
+-+-+-+-+-+-+-+-+ IPv6 prefix |
| (16 octets) |
| |
| |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | .
+-+-+-+-+-+-+-+-+ .
. IAprefix-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IAPREFIX | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preferred-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-length | |
+-+-+-+-+-+-+-+-+ IPv6 prefix |
| (16 octets) |
| |
| |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | .
+-+-+-+-+-+-+-+-+ .
. IAprefix-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_IAPREFIX (26)
选项代码：选项前缀（26）
option-length: 25 + length of IAprefix-options field
选项长度：25+前缀选项字段的长度
preferred-lifetime: The recommended preferred lifetime for the IPv6 prefix in the option, expressed in units of seconds. A value of 0xFFFFFFFF represents infinity.
首选生存期：选项中IPv6前缀的建议首选生存期，以秒为单位。0xFFFFFF的值表示无穷大。
valid-lifetime: The valid lifetime for the IPv6 prefix in the option, expressed in units of seconds. A value of 0xFFFFFFFF represents infinity.
有效生存期：选项中IPv6前缀的有效生存期，以秒为单位。0xFFFFFF的值表示无穷大。
prefix-length: Length for this prefix in bits
前缀长度：此前缀的长度（以位为单位）
IPv6-prefix: An IPv6 prefix
IPv6前缀：IPv6前缀
IAprefix-options: Options associated with this prefix
IAprefix选项：与此前缀关联的选项
In a message sent by a requesting router to a delegating router, the values in the fields can be used to indicate the requesting router's preference for those values. The requesting router may send a value of zero to indicate no preference. A requesting router may set the IPv6 prefix field to zero and a given value in the prefix-length field to indicate a preference for the size of the prefix to be delegated.
在请求路由器发送给委托路由器的消息中，字段中的值可用于指示请求路由器对这些值的偏好。请求路由器可发送值为零以指示没有偏好。请求路由器可以将IPv6前缀字段设置为零，并在前缀长度字段中设置给定值，以指示对要委派的前缀的大小的偏好。
In a message sent by a delegating router the preferred and valid lifetimes should be set to the values of AdvPreferredLifetime and AdvValidLifetime as specified in section 6.2.1, "Router Configuration Variables" of RFC 2461 [4], unless administratively configured.
在委派路由器发送的消息中，首选和有效的生存时间应设置为RFC 2461[4]第6.2.1节“路由器配置变量”中规定的AdvPreferredLifetime和AdvValidLifetime的值，除非进行了管理性配置。
A requesting router discards any prefixes for which the preferred lifetime is greater than the valid lifetime. A delegating router ignores the lifetimes set by the requesting router if the preferred lifetime is greater than the valid lifetime and ignores the values for T1 and T2 set by the requesting router if those values are greater than the preferred lifetime.
请求路由器丢弃首选生存期大于有效生存期的任何前缀。如果首选生存期大于有效生存期，则委派路由器忽略请求路由器设置的生存期；如果T1和T2的值大于首选生存期，则忽略请求路由器设置的这些值。
The values in the preferred and valid lifetimes are the number of seconds remaining for each lifetime.
首选和有效生存期中的值是每个生存期剩余的秒数。
An IA_PD Prefix option may appear only in an IA_PD option. More than one IA_PD Prefix Option can appear in a single IA_PD option.
IA_PD前缀选项只能出现在IA_PD选项中。一个IA_PD选项中可以出现多个IA_PD前缀选项。
The status of any operations involving this IA_PD Prefix option is indicated in a Status Code option in the IAprefix-options field.
涉及此IA_PD Prefix选项的任何操作的状态在IAprefix选项字段中的状态代码选项中指示。
The requesting router locates and selects a delegating router in the same way as described in section 17, "DHCP Server Solicitation" of RFC 3315. The details of the solicitation process are described in this section.
请求路由器以RFC 3315第17节“DHCP服务器请求”中描述的相同方式定位和选择委托路由器。本节介绍了招标过程的详细信息。
The requesting router creates and transmits a Solicit message as described in sections 17.1.1, "Creation of Solicit Messages" and 17.1.2, "Transmission of Solicit Messages" of RFC 3315. The requesting router creates an IA_PD and assigns it an IAID. The requesting router MUST include the IA_PD option in the Solicit message.
请求路由器按照RFC 3315第17.1.1节“请求消息的创建”和第17.1.2节“请求消息的传输”中的描述创建和传输请求消息。请求路由器创建一个IAU PD并为其分配一个IAID。请求路由器必须在请求消息中包含IA_PD选项。
The requesting router processes any received Advertise messages as described in section 17.1.3, "Receipt of Advertise Messages" of RFC 3315. The requesting router MAY choose to consider the presence of advertised prefixes in its decision about which delegating router to respond to.
请求路由器按照RFC 3315第17.1.3节“接收播发消息”中的说明处理任何接收到的播发消息。请求路由器可以选择考虑广告前缀的存在，在其决定哪个委托路由器响应。
The requesting router MUST ignore any Advertise message that includes a Status Code option containing the value NoPrefixAvail, with the exception that the requesting router MAY display the associated status message to the user.
请求路由器必须忽略任何包含包含值NoPrefixAvail的状态代码选项的播发消息，但请求路由器可能会向用户显示相关的状态消息除外。
The delegating router sends an Advertise message to the requesting router in the same way as described in section 17.2.2, "Creation and transmission of Advertise messages" of RFC 3315. If the message contains an IA_PD option and the delegating router is configured to delegate prefix(es) to the requesting router, the delegating router selects the prefix(es) to be delegated to the requesting router. The mechanism through which the delegating router selects prefix(es) for delegation is not specified in this document. Examples of ways in which the delegating router might select prefix(es) for a requesting router include: static assignment based on subscription to an ISP; dynamic assignment from a pool of available prefixes; selection based on an external authority such as a RADIUS server using the Framed-IPv6-Prefix option as described in RFC 3162 [5].
委托路由器以RFC 3315第17.2.2节“广告消息的创建和传输”中所述的相同方式向请求路由器发送广告消息。如果消息包含IA_PD选项，并且委派路由器配置为将前缀委派给请求路由器，委派路由器将选择要委派给请求路由器的前缀。本文档中未指定委派路由器为委派选择前缀的机制。授权路由器可以为请求路由器选择前缀的方式的示例包括：基于对ISP的订阅的静态分配；来自可用前缀池的动态分配；基于外部授权的选择，例如使用RFC 3162[5]中所述的Framed-IPv6-Prefix选项的RADIUS服务器。
If the requesting router includes an IA_PD Prefix option in the IA_PD option in its Solicit message, the delegating router MAY choose to use the information in that option to select the prefix(es) or prefix size to be delegated to the requesting router.
如果请求路由器在其请求消息中的IA_PD选项中包括IA_PD Prefix选项，则委托路由器可以选择使用该选项中的信息来选择要委托给请求路由器的前缀或前缀大小。
The delegating router sends an Advertise message to the requesting router in the same way as described in section, "Creation and transmission of Advertise messages" of RFC 3315. The delegating router MUST include an IA_PD option, identifying any prefix(es) that the delegating router will delegate to the requesting router.
委托路由器以与RFC 3315的“广告消息的创建和传输”部分中描述的相同方式向请求路由器发送广告消息。委派路由器必须包括IA_PD选项，标识委派路由器将委派给请求路由器的任何前缀。
If the delegating router will not assign any prefixes to any IA_PDs in a subsequent Request from the requesting router, the delegating router MUST send an Advertise message to the requesting router that includes the IA_PD with no prefixes in the IA_PD and a Status Code option in the IA_PD containing status code NoPrefixAvail and a status message for the user, a Server Identifier option with the delegating router's DUID and a Client Identifier option with the requesting router's DUID.
如果授权路由器在来自请求路由器的后续请求中不会向任何IA_PDs分配任何前缀，委派路由器必须向请求路由器发送播发消息，该消息包括IA_PD中没有前缀的IA_PD和IA_PD中包含状态代码NoPrefixAvail的状态代码选项以及用户的状态消息，具有委托路由器DUID的服务器标识符选项和具有请求路由器DUID的客户端标识符选项。
A requesting router uses the same message exchanges as described in section 18, "DHCP Client-Initiated Configuration Exchange" of RFC 3315 to obtain or update prefix(es) from a delegating router. The requesting router and the delegating router use the IA_PD Prefix option to exchange information about prefix(es) in much the same way IA Address options are used for assigned addresses.
请求路由器使用RFC 3315第18节“DHCP客户端启动的配置交换”中所述的相同消息交换，从委派路由器获取或更新前缀。请求路由器和委派路由器使用IA_PD Prefix选项交换有关前缀的信息，方式与IA Address选项用于分配地址的方式大致相同。
The requesting router uses a Request message to populate IA_PDs with prefixes. The requesting router includes one or more IA_PD options in the Request message. The delegating router then returns the prefixes for the IA_PDs to the requesting router in IA_PD options in a Reply message.
请求路由器使用请求消息以前缀填充IA_PDs。请求路由器在请求消息中包括一个或多个IA_PD选项。然后，授权路由器将IA_PD的前缀返回给应答消息中IA_PD选项中的请求路由器。
The requesting router includes IA_PD options in any Renew, or Rebind messages sent by the requesting router. The IA_PD option includes all of the prefixes the requesting router currently has associated with that IA_PD.
请求路由器在请求路由器发送的任何续订或重新绑定消息中包含IA_PD选项。IA_PD选项包括请求路由器当前与该IA_PD关联的所有前缀。
In some circumstances the requesting router may need verification that the delegating router still has a valid binding for the requesting router. Examples of times when a requesting router may ask for such verification include:
在某些情况下，请求路由器可能需要验证委托路由器是否仍然具有请求路由器的有效绑定。请求路由器可能要求此类验证的时间示例包括：
o The requesting router reboots.
o 请求路由器重新启动。
o The requesting router's upstream link flaps.
o 请求路由器的上行链路。
o The requesting router is physically disconnected from a wired connection.
o 请求路由器从有线连接上物理断开。
If such verification is needed the requesting router MUST initiate a Rebind/Reply message exchange as described in section 18.1.4, "Creation and Transmission of Rebind Messages" of RFC 3315, with the exception that the retransmission parameters should be set as for the Confirm message, described in section 18.1.2, "Creation and Transmission of Confirm Messages" of RFC 3315. The requesting router includes any IA_PDs, along with prefixes associated with those IA_PDs in its Rebind message.
如果需要此类验证，请求路由器必须按照RFC 3315第18.1.4节“重新绑定消息的创建和传输”中的说明启动重新绑定/回复消息交换，但第18.1.2节中所述的确认消息应设置重新传输参数，RFC 3315的“确认消息的创建和传输”。请求路由器包括任何IA_PD，以及在其重新绑定消息中与这些IA_PD关联的前缀。
Each prefix has valid and preferred lifetimes whose durations are specified in the IA_PD Prefix option for that prefix. The requesting router uses Renew and Rebind messages to request the extension of the lifetimes of a delegated prefix.
每个前缀都有有效的首选生存期，其持续时间在该前缀的IA_PD prefix选项中指定。请求路由器使用Renew和Rebind消息请求延长委派前缀的生存期。
The requesting router uses a Release message to return a delegated prefix to a delegating router. The prefixes to be released MUST be included in the IA_PDs.
请求路由器使用释放消息将委派前缀返回给委派路由器。要发布的前缀必须包含在IA_PDs中。
The Confirm and Decline message types are not used with Prefix Delegation.
确认和拒绝消息类型不与前缀委派一起使用。
Upon the receipt of a valid Reply message, for each IA_PD the requesting router assigns a subnet from each of the delegated prefixes to each of the links to which the associated interfaces are attached, with the following exception: the requesting router MUST NOT assign any delegated prefixes or subnets from the delegated prefix(es) to the link through which it received the DHCP message from the delegating router.
收到有效回复消息后，对于每个IA_PD，请求路由器将从每个委派前缀分配一个子网到关联接口连接到的每个链路，但以下例外：请求路由器不得从委派前缀分配任何委派前缀或子网到从委派路由器接收DHCP消息的链路。
When a requesting router subnets a delegated prefix, it must assign additional bits to the prefix to generate unique, longer prefixes. For example, if the requesting router in Figure 1 were delegated 3FFE:FFFF:0::/48, it might generate 3FFE:FFFF:0:1::/64 and 3FFE:FFFF:0:2::/64 for assignment to the two links in the subscriber network. If the requesting router were delegated 3FFE:FFFF:0::/48 and 3FFE:FFFF:5::/48, it might assign 3FFE:FFFF:0:1::/64 and 3FFE:FFFF:5:1::/64 to one of the links, and 3FFE:FFFF:0:2::/64 and 3FFE:FFFF:5:2::/64 for assignment to the other link.
当一个请求路由器将一个委派的前缀子网化时，它必须为该前缀分配额外的位以生成唯一的、更长的前缀。例如，如果图1中的请求路由器被委派3FFE:FFFF:0:：/48，它可能会生成3FFE:FFFF:0:1:：/64和3FFE:FFFF:0:2:：/64以分配给订户网络中的两个链路。如果请求的路由器被委派3FFE:FFFF:0:：/48和3FFE:FFFF:5:：/48，则它可能会将3FFE:FFFF:0:1:：/64和3FFE:FFFF:5:1:：/64分配给其中一个链路，并将3FFE:FFFF:0:2:：/64和3FFE:FFFF:5:2:：/64分配给另一个链路。
If the requesting router assigns a delegated prefix to a link to which the router is attached, and begins to send router advertisements for the prefix on the link, the requesting router MUST set the valid lifetime in those advertisements to be no later than the valid lifetime specified in the IA_PD Prefix option. A requesting router MAY use the preferred lifetime specified in the IA_PD Prefix option.
如果请求路由器向路由器所连接的链路分配委派前缀，并开始发送链路上前缀的路由器播发，则请求路由器必须将这些播发中的有效生存期设置为不晚于IA_PD prefix选项中指定的有效生存期。请求路由器可以使用IA_PD前缀选项中指定的首选生存期。
Handling of Status Codes options in received Reply messages is described in section 18.1.8, "Receipt of Reply Messages" of RFC 3315. The NoPrefixAvail Status Code is handled in the same manner as the NoAddrsAvail Status Code.
RFC 3315第18.1.8节“回复消息的接收”中描述了接收回复消息中状态代码选项的处理。NoPrefixAvail状态代码的处理方式与NoAddrsAvail状态代码相同。
When a delegating router receives a Request message from a requesting router that contains an IA_PD option, and the delegating router is authorized to delegate prefix(es) to the requesting router, the delegating router selects the prefix(es) to be delegated to the requesting router. The mechanism through which the delegating router selects prefix(es) for delegation is not specified in this document. Section 11.2 gives examples of ways in which a delegating router might select the prefix(es) to be delegated to a requesting router.
当委派路由器从包含IA_PD选项的请求路由器接收到请求消息，并且委派路由器被授权将前缀委派给请求路由器时，委派路由器选择要委派给请求路由器的前缀。本文档中未指定委派路由器为委派选择前缀的机制。第11.2节给出了授权路由器选择要授权给请求路由器的前缀的方式示例。
A delegating router examines the prefix(es) identified in IA_PD Prefix options (in an IA_PD option) in Renew and Rebind messages and responds according to the current status of the prefix(es). The delegating router returns IA_PD Prefix options (within an IA_PD option) with updated lifetimes for each valid prefix in the message from the requesting router. If the delegating router finds that any of the prefixes are not in the requesting router's binding entry, the delegating router returns the prefix to the requesting router with lifetimes of 0.
委派路由器检查续订和重新绑定消息中IA_PD前缀选项（IA_PD选项）中标识的前缀，并根据前缀的当前状态进行响应。委派路由器返回IA_PD前缀选项（在IA_PD选项内），其中包含来自请求路由器的消息中每个有效前缀的更新生存期。如果委托路由器发现任何前缀不在请求路由器的绑定条目中，则委托路由器将前缀返回给请求路由器，其生存期为0。
The delegating router behaves as follows when it cannot find a binding for the requesting router's IA_PD:
当委托路由器找不到请求路由器的IA_PD的绑定时，其行为如下：
Renew message: If the delegating router cannot find a binding for the requesting router's IA_PD the delegating router returns the IA_PD containing no prefixes with a Status Code option set to NoBinding in the Reply message.
续订消息：如果委托路由器找不到请求路由器的IA_PD的绑定，则委托路由器返回IA_PD，该IA_PD不包含前缀，且回复消息中的状态代码选项设置为NoBinding。
Rebind message: If the delegating router cannot find a binding for the requesting router's IA_PD and the delegating router determines that the prefixes in the IA_PD are not appropriate for the link to which the requesting router's interface is attached according to the delegating routers explicit configuration, the delegating router MAY send a Reply message to the requesting router containing the IA_PD with the lifetimes of the prefixes in the IA_PD set to zero. This Reply constitutes an explicit notification to the requesting router that the prefixes in the IA_PD are no longer valid. If the delegating router is
重新绑定消息：如果委托路由器无法找到请求路由器的IA_PD的绑定，并且根据委托路由器的显式配置，委托路由器确定IA_PD中的前缀不适合请求路由器接口连接到的链路，委派路由器可向请求路由器发送包含IA_PD的应答消息，且IA_PD中前缀的寿命设置为零。此回复构成对请求路由器的明确通知，即IA_PD中的前缀不再有效。如果委托路由器是
unable to determine if the prefix is not appropriate for the link, the Rebind message is discarded.
无法确定前缀是否不适合链接，将丢弃重新绑定消息。
A delegating router may mark any prefix(es) in IA_PD Prefix options in a Release message from a requesting router as "available", dependent on the mechanism used to acquire the prefix, e.g., in the case of a dynamic pool.
授权路由器可将来自请求路由器的释放消息中的IA_PD prefix options中的任何前缀标记为“可用”，这取决于用于获取前缀的机制，例如，在动态池的情况下。
The delegating router MUST include an IA_PD Prefix option or options (in an IA_PD option) in Reply messages sent to a requesting router.
委派路由器必须在发送到请求路由器的回复消息中包含一个或多个IA_PD前缀选项（在IA_PD选项中）。
This section describes prefix delegation in Reconfigure message exchanges.
本节介绍重新配置消息交换中的前缀委派。
The delegating router initiates a configuration message exchange with a requesting router, as described in section 19, "DHCP Server-Initiated Configuration Exchange" of RFC 3315, by sending a Reconfigure message (acting as a DHCP server) to the requesting router, as described in section 19.1, "Server Behavior" of RFC 3315. The delegating router specifies the IA_PD option in the Option Request option to cause the requesting router to include an IA_PD option to obtain new information about delegated prefix(es).
如RFC 3315第19节“DHCP服务器启动的配置交换”中所述，授权路由器通过向请求路由器发送重新配置消息（充当DHCP服务器）来启动与请求路由器的配置消息交换，如RFC 3315第19.1节“服务器行为”中所述。委派路由器在选项请求选项中指定IA_PD选项，以使请求路由器包括IA_PD选项，以获取有关委派前缀的新信息。
The requesting router responds to a Reconfigure message, acting as a DHCP client, received from a delegating router as described in section 19.4, "Client Behavior" of RFC 3315. The requesting router MUST include the IA_PD Prefix option(s) (in an IA_PD option) for prefix(es) that have been delegated to the requesting router by the delegating router from which the Reconfigure message was received.
如RFC 3315第19.4节“客户端行为”所述，请求路由器响应从委派路由器接收的作为DHCP客户端的重新配置消息。请求路由器必须包括IA_PD前缀选项（在IA_PD选项中），用于接收重新配置消息的委托路由器已委托给请求路由器的前缀。
A relay agent forwards messages containing Prefix Delegation options in the same way as described in section 20, "Relay Agent Behavior" of RFC 3315.
中继代理转发包含前缀委派选项的消息的方式与RFC 3315第20节“中继代理行为”中描述的相同。
If a delegating router communicates with a requesting router through a relay agent, the delegating router may need a protocol or other out-of-band communication to add routing information for delegated prefixes into the provider edge router.
如果委派路由器通过中继代理与请求路由器通信，则委派路由器可能需要协议或其他带外通信，以将委派前缀的路由信息添加到提供商边缘路由器中。
Security considerations in DHCP are described in section 23, "Security Considerations" of RFC 3315.
RFC 3315第23节“安全注意事项”描述了DHCP中的安全注意事项。
A rogue delegating router can issue bogus prefixes to a requesting router. This may cause denial of service due to unreachability.
恶意委托路由器可以向请求路由器发出虚假前缀。这可能会由于无法访问而导致拒绝服务。
A malicious requesting router may be able to mount a denial of service attack by repeated requests for delegated prefixes that exhaust the delegating router's available prefixes.
恶意请求路由器可能通过重复请求委托前缀（耗尽委托路由器的可用前缀）来发起拒绝服务攻击。
To guard against attacks through prefix delegation, requesting routers and delegating routers SHOULD use DHCP authentication as described in section 21, "Authentication of DHCP messages" of RFC 3315. For point to point links, where one trusts that there is no man in the middle, or one trusts layer two authentication, DHCP authentication or IPsec may not be necessary. Because a requesting router and delegating routers must each have at least one assigned IPv6 address, the routers may be able to use IPsec for authentication of DHCPv6 messages. The details of using IPsec for DHCPv6 are under development.
为了防止通过前缀委派的攻击，请求路由器和委派路由器应使用RFC 3315第21节“DHCP消息的身份验证”中所述的DHCP身份验证。对于点对点链接，其中一个信任中间没有人，或者一个信任层二认证，DHCP认证或IPSec可能不是必需的。由于请求路由器和委派路由器必须各自具有至少一个分配的IPv6地址，因此路由器可能能够使用IPsec对DHCPv6消息进行身份验证。DHCPv6使用IPsec的详细信息正在开发中。
Networks configured with delegated prefixes should be configured to preclude intentional or inadvertent inappropriate advertisement of these prefixes.
配置了委派前缀的网络应配置为防止有意或无意地不当公布这些前缀。
IANA has assigned option codes to:
IANA已将选项代码分配给：
OPTION_IA_PD (25)
方案（25）
OPTION_IAPREFIX (26)
选项(26)
from the option-code space as defined in section 24.3, "DHCP Options" of RFC 3315.
来自RFC 3315第24.3节“DHCP选项”中定义的选项代码空间。
IANA has assigned status code 6 to:
IANA已将状态代码6分配给：
NoPrefixAvail: Delegating router has no prefixes available to assign to the IAPD(s)
NoPrefixAvail:委派路由器没有可分配给IAPD的前缀
from the status-code space as defined in section 24.4, "Status Codes" of RFC 3315.
来自RFC 3315第24.4节“状态代码”中定义的状态代码空间。
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[1] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998.
[1] Deering，S.和R.Hinden，“互联网协议，第6版（IPv6）规范”，RFC 2460，1998年12月。
[2] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003.
[2] 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。
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[3] Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[4] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998.
[4] Narten，T.，Nordmark，E.和W.Simpson，“IP版本6（IPv6）的邻居发现”，RFC24611998年12月。
[5] Aboba, B., Zorn, G. and D. Mitton, "RADIUS and IPv6", RFC 3162, August 2001.
[5] Aboba，B.，Zorn，G.和D.Mitton，“RADIUS和IPv6”，RFC3162001年8月。
[6] Miyakawa, S. and R. Droms, "Requirements for IPv6 prefix delegation", Work in Progress, August 2003.
[6] Miyakawa，S.和R.Droms，“IPv6前缀授权的要求”，正在进行的工作，2003年8月。
Thanks for the input and review by (in alphabetical order) Steve Deering, Dave Forster, Brian Haberman, Tatuya Jinmei, Shin Miyakawa, Pekka Savola, Bernie Volz, Trevor Warwick and Toshi Yamasaki.
感谢Steve Deering、Dave Forster、Brian Haberman、Tatuya Jinmei、Shin Miyakawa、Pekka Savola、Bernie Volz、Trevor Warwick和Toshi Yamasaki（按字母顺序）的输入和评论。
Ole Troan Cisco Systems 250 Longwater Avenue Reading RG2 6GB United Kingdom
Ole Troan Cisco Systems 250 Longwater Avenue Reading RG2 6GB英国
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EMail: ot@cisco.com
Phone: +44 20 8824 8666
EMail: ot@cisco.com
Ralph Droms Cisco Systems 1414 Massachusetts Avenue Boxborough, MA 01719 USA
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EMail: rdroms@cisco.com
Phone: +1 978 936 1674
EMail: rdroms@cisco.com
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Acknowledgement
确认
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