Network Working Group C. Huitema
Request for Comments: 3068 Microsoft
Category: Standards Track June 2001
Network Working Group C. Huitema
Request for Comments: 3068 Microsoft
Category: Standards Track June 2001
An Anycast Prefix for 6to4 Relay Routers
6to4中继路由器的选播前缀
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 (2001). All Rights Reserved.
版权所有（C）互联网协会（2001年）。版权所有。
Abstract
摘要
This memo introduces a "6to4 anycast address" in order to simplify the configuration of 6to4 routers. It also defines how this address will be used by 6to4 relay routers, how the corresponding "6to4 anycast prefix" will be advertised in the IGP and in the EGP. The memo documents the reservation by IANA (Internet Assigned Numbers Authority) of the "6to4 relay anycast prefix."
本备忘录引入了“6to4选播地址”，以简化6to4路由器的配置。它还定义了6to4中继路由器将如何使用该地址，以及相应的“6to4选播前缀”将如何在IGP和EGP中公布。备忘录记录了IANA（互联网分配号码管理局）对“6to4中继选播前缀”的保留
1 Introduction
1导言
According to [RFC3056], there are two deployment options for a 6to4 routing domain, depending on whether or not the domain is using an IPv6 exterior routing protocol. If a routing protocol is used, then the 6to4 routers acquire routes to all existing IPv6 networks through the combination of EGP and IGP. If no IPv6 exterior routing protocol is used, the 6to4 routers using a given relay router each have a default IPv6 route pointing to the relay router. This second case is typically used by small networks; for these networks, finding and configuring the default route is in practice a significant hurdle. In addition, even when the managers of these networks find an available route, this route often points to a router on the other side of the Internet, leading to very poor performance.
根据[RFC3056]，6to4路由域有两种部署选项，具体取决于该域是否使用IPv6外部路由协议。如果使用路由协议，则6to4路由器通过EGP和IGP的组合获取到所有现有IPv6网络的路由。如果未使用IPv6外部路由协议，则使用给定中继路由器的6to4路由器都具有指向中继路由器的默认IPv6路由。第二种情况通常由小型网络使用；对于这些网络，查找和配置默认路由实际上是一个重大障碍。此外，即使这些网络的管理者找到了一条可用的路由，该路由也常常指向互联网另一端的路由器，导致性能非常差。
The operation of 6to4 routers requires either that the routers participate in IPv6 inter-domain routing, or that the routers be provisioned with a default route. This memo proposes a standard method to define the default route. It introduces the IANA assigned "6to4 Relay anycast prefix" from which 6to4 packets will be
6to4路由器的操作要求路由器参与IPv6域间路由，或者为路由器提供默认路由。本备忘录提出了定义默认路线的标准方法。它引入了IANA分配的“6to4中继选播前缀”，6to4数据包将从中传输
automatically routed to the nearest available router. It allows the managers of the 6to4 relay routers to control the sources authorized to use their resource. It makes it easy to set up a large number of 6to4 relay routers, thus enabling scalability.
自动路由到最近的可用路由器。它允许6to4中继路由器的管理员控制授权使用其资源的源。它可以方便地设置大量6to4中继路由器，从而实现可扩展性。
2 Definitions
2定义
This memo uses the definitions introduced in [RFC3056], in particular the definition of a 6to4 router and a 6to4 Relay Router. It adds the definition of the 6to4 Relay anycast prefix, 6to4 Relay anycast address, 6to4 IPv6 relay anycast address, and Equivalent IPv4 unicast address.
本备忘录使用了[RFC3056]中介绍的定义，特别是6to4路由器和6to4中继路由器的定义。它添加了6to4中继选播前缀、6to4中继选播地址、6to4 IPv6中继选播地址和等效IPv4单播地址的定义。
An IPv6 router supporting a 6to4 pseudo-interface. It is normally the border router between an IPv6 site and a wide-area IPv4 network.
支持6to4伪接口的IPv6路由器。它通常是IPv6站点和广域IPv4网络之间的边界路由器。
A 6to4 router configured to support transit routing between 6to4 addresses and native IPv6 addresses.
配置为支持6to4地址和本机IPv6地址之间的传输路由的6to4路由器。
An IPv4 address prefix used to advertise an IPv4 route to an available 6to4 Relay Router, as defined in this memo.
IPv4地址前缀，用于向可用的6to4中继路由器播发IPv4路由，如本备忘录中所定义。
The value of this prefix is 192.88.99.0/24
此前缀的值为192.88.99.0/24
An IPv4 address used to reach the nearest 6to4 Relay Router, as defined in this memo.
用于到达最近的6to4中继路由器的IPv4地址，如本备忘录中所定义。
The address corresponds to host number 1 in the 6to4 Relay anycast prefix, 192.88.99.1.
该地址对应于6to4中继选播前缀192.88.99.1中的主机号1。
The IPv6 address derived from the 6to4 Relay anycast address according to the rules defined in 6to4, using a null prefix and a null host identifier.
根据6to4中定义的规则，使用空前缀和空主机标识符从6to4中继选播地址派生的IPv6地址。
The value of the address is "2002:c058:6301::".
地址的值为“2002:c058:6301:：”。
A regular IPv4 address associated with a specific 6to4 Relay Router. Packets sent to that address are treated by the 6to4 Relay Router as if they had been sent to the 6to4 Relay anycast address.
与特定6to4中继路由器关联的常规IPv4地址。发送到该地址的数据包被6to4中继路由器视为已发送到6to4中继选播地址。
3 Model, requirements
3.型号、要求
Operation of 6to4 routers in domains that don't run an IPv6 EGP requires that these routers be configured with a default route to the IPv6 Internet. This route will be expressed as a 6to4 address. The packets bound to this route will be encapsulated in IPv4 whose source will be an IPv4 address associated to the 6to4 router, and whose destination will be the IPv4 address that is extracted from the default route. We want to arrive at a model of operation in which the configuration is automatic.
在不运行IPv6 EGP的域中操作6to4路由器需要为这些路由器配置到IPv6 Internet的默认路由。此路由将表示为6to4地址。绑定到此路由的数据包将封装在IPv4中，其源将是与6to4路由器关联的IPv4地址，其目标将是从默认路由提取的IPv4地址。我们希望得到一种自动配置的操作模式。
It should also be easy to set up a large number of 6to4 relay routers, in order to cope with the demand. The discovery of the nearest relay router should be automatic; if a router fails, the traffic should be automatically redirected to the nearest available router. The managers of the 6to4 relay routers should be able to control the sources authorized to use their resource.
它也应该很容易建立大量的6to4中继路由器，以应付需求。最近的中继路由器的发现应该是自动的；如果路由器出现故障，流量应自动重定向到最近的可用路由器。6to4中继路由器的管理者应该能够控制授权使用其资源的源。
Anycast routing is known to cause operational issues: since the sending 6to4 router does not directly identify the specific 6to4 relay router to which it forwards the packets, it is hard to identify the responsible router in case of failure, in particular when the failure is transient or intermittent. Anycast solutions must thus include adequate monitoring of the routers performing the service, in order to promptly detect and correct failures, and also adequate fault isolation procedures, in order to find out the responsible element when needed, e.g., following a user's complaint.
众所周知，选播路由会导致操作问题：由于发送的6to4路由器不会直接识别它将数据包转发到的特定6to4中继路由器，因此在发生故障时，特别是当故障是暂时的或间歇性的时，很难识别负责的路由器。因此，选播解决方案必须包括对执行服务的路由器的充分监控，以便及时检测和纠正故障，以及充分的故障隔离程序，以便在需要时（例如，在用户投诉后）找出责任元件。
4 Description of the solution
4解决方案的说明
The 6to4 routers are configured with the default IPv6 route (::/0) pointing to the 6to4 IPv6 anycast address.
6to4路由器配置有指向6to4 IPv6选播地址的默认IPv6路由（：：/0）。
The 6to4 relay routers that follow the specification of this memo shall advertise the 6to4 anycast prefix, using the IGP of their IPv4 autonomous system, as if it where a connection to an external network.
遵循本备忘录规范的6to4中继路由器应使用其IPv4自治系统的IGP公布6to4选播前缀，就好像它连接到外部网络一样。
The 6to4 relay routers that advertise the 6to4 anycast prefix will receive packets bound to the 6to4 anycast address. They will relay these packets to the IPv6 Internet, as specified in [RFC3056].
播发6to4选播前缀的6to4中继路由器将接收绑定到6to4选播地址的数据包。他们将按照[RFC3056]中的规定，将这些数据包中继到IPv6 Internet。
Each 6to4 relay router that advertise the 6to4 anycast prefix MUST also provide an equivalent IPv4 unicast address. Packets sent to that unicast address will follow the same processing path as packets sent to the anycast address, i.e., be relayed to the IPv6 Internet.
播发6to4选播前缀的每个6to4中继路由器还必须提供等效的IPv4单播地址。发送到该单播地址的数据包将遵循与发送到选播地址的数据包相同的处理路径，即，被中继到IPv6 Internet。
If the managers of an IPv4 autonomous domain that includes 6to4 relay routers want to make these routers available to neighbor ASes, they will advertise reachability of the 6to4 anycast prefix. When this advertisement is done using BGP, the initial AS path must contain the AS number of the announcing AS. The AS path should also include an indication of the actual router providing the service; there is a suggestion to perform this function by documenting the router's equivalent IPv4 address in the BGP aggregator attribute of the path; further work is needed on this point.
如果包含6to4中继路由器的IPv4自治域的管理者希望使这些路由器可用于邻居ASE，他们将公布6to4选播前缀的可达性。使用BGP完成此播发时，初始AS路径必须包含宣布AS的AS编号。AS路径还应包括提供服务的实际路由器的指示；建议通过在路径的BGP聚合器属性中记录路由器的等效IPv4地址来执行此功能；在这一点上还需要进一步的工作。
The path to the 6to4 anycast prefix may be propagated using standard EGP procedures. The whole v6 network will appear to v4 as a single multi-homed network, with multiple access points scattered over the whole Internet.
可以使用标准EGP过程传播到6to4选播前缀的路径。整个v6网络在v4看来将是一个单一的多主机网络，多个接入点分散在整个互联网上。
Any 6to4 relay router corresponding to this specification must include a monitoring function, to check that the 6to4 relay function is operational. The router must stop injecting the route leading to the 6to4 anycast prefix immediately if it detects that the relay function is not operational.
与本规范相对应的任何6to4中继路由器必须包括监控功能，以检查6to4中继功能是否正常工作。如果检测到中继功能不工作，路由器必须立即停止注入通向6to4选播前缀的路由。
The equivalent IPv4 address may be used to check remotely that a specific router is operational, e.g., by tunneling a test IPv6 packet through the router's equivalent unicast IPv4 address. When a domain deploys several 6to4 relay routers, it is possible to build a centralized monitoring function by using the list of equivalent IPv4 addresses of these routers.
等效IPv4地址可用于远程检查特定路由器是否可操作，例如，通过隧道将测试IPv6分组穿过路由器的等效单播IPv4地址。当一个域部署多个6to4中继路由器时，可以通过使用这些路由器的等效IPv4地址列表来构建集中监控功能。
When an error is reported, e.g., by a user, the domain manager should be able to find the specific 6to4 relay router that is causing the problem. The first step of fault isolation is to retrieve the equivalent unicast IPv4 address of the router used by the user. If the router is located within the domain, this information will have
当用户报告错误时，域管理器应该能够找到导致问题的特定6to4中继路由器。故障隔离的第一步是检索用户使用的路由器的等效单播IPv4地址。如果路由器位于域内，则此信息将
to be retrieved from the IGP tables. If the service is obtained through a peering agreement with another domain, the information will be retrieved from the EGP data, e.g., the BGP path attributes.
从IGP表中检索。如果服务是通过与另一个域的对等协议获得的，则将从EGP数据（例如BGP路径属性）中检索信息。
The second step is obviously to perform connectivity tests using the equivalent unicast IPv4 address.
第二步显然是使用等效的单播IPv4地址执行连接测试。
5 Discussion of the solution
5讨论解决办法
The initial surfacing of the proposal in the NGTRANS working group helped us discover a number of issues, such as scaling concerns, the size of the address prefix, the need for an AS number, and concerns about risking to stay too long in a transition state.
在NGTRANS工作组中初步提出该提案有助于我们发现一些问题，如扩展问题、地址前缀的大小、as号码的需要以及在过渡状态中停留时间过长的风险问题。
With the proposed scheme, it is easy to first deploy a small number of relay routers, which will carry the limited 6to4 traffic during the initial phases of IPv6 deployment. The routes to these routers will be propagated according to standard peering agreements.
利用所提出的方案，可以很容易地首先部署少量中继路由器，这些路由器将在IPv6部署的初始阶段承载有限的6to4流量。到这些路由器的路由将根据标准对等协议进行传播。
As the demand for IPv6 increases, we expect that more ISPs will deploy 6to4 relay routers. Standard IPv4 routing procedures will direct the traffic to the nearest relay router, assuring good performance.
随着IPv6需求的增加，我们预计更多的ISP将部署6to4中继路由器。标准的IPv4路由过程将把流量定向到最近的中继路由器，从而确保良好的性能。
The 6to4 routers send packets bound to the v6 Internet by tunneling them to the 6to4 anycast address. These packets will reach the closest 6to4 relay router provided by their ISP, or by the closest ISP according to inter-domain routing.
6to4路由器通过隧道将绑定到v6 Internet的数据包发送到6to4选播地址。这些数据包将到达其ISP提供的最近的6to4中继路由器，或根据域间路由由最近的ISP提供。
The routes to the relay routers will be propagated according to standard IPv4 routing rules. This ensures automatic discovery.
到中继路由器的路由将根据标准IPv4路由规则进行传播。这确保了自动发现。
If a 6to4 relay router somehow breaks, or loses connectivity to the v6 Internet, it will cease to advertise reachability of the 6to4 anycast prefix. At that point, the local IGP will automatically compute a route towards the "next best" 6to4 relay router. We expect that adequate monitoring tools will be used to guarantee timely discovery of connectivity losses.
如果6to4中继路由器以某种方式中断或失去与v6 Internet的连接，它将停止公布6to4选播前缀的可达性。在这一点上，本地IGP将自动计算到“下一个最佳”6to4中继路由器的路由。我们希望使用足够的监控工具，以确保及时发现连接丢失。
Only those ASes that run 6to4 relay routers and are willing to provide access to the v6 network announce a path to the 6to4 anycast prefix. They can use the existing structure of peering and transit agreements to control to whom they are willing to provide service, and possibly to charge for the service.
只有那些运行6to4中继路由器并愿意提供对v6网络的访问的ASE才会宣布到6to4选播前缀的路径。他们可以使用现有的对等和传输协议结构来控制他们愿意向谁提供服务，并可能对服务收费。
In theory, a single IP address, a.k.a. a /32 prefix, would be sufficient: all IGPs, and even BGP, can carry routes that are arbitrarily specific. In practice, however, such routes are almost guaranteed not to work.
理论上，一个IP地址，即a/32前缀就足够了：所有IGP，甚至BGP，都可以承载任意特定的路由。然而，在实践中，这类路线几乎肯定不起作用。
The size of the routing table is of great concern for the managers of Internet "default free" networks: they don't want to waste a routing entry, which is an important resource, for the sole benefit of a small number of Internet nodes. Many have put in place filters that automatically drop the routes that are too specific; most of these filters are expressed as a function of the length of the address prefix, such as "my network will not accept advertisements for a network that is smaller than a /24." The actual limit may vary from network to network, and also over time.
路由表的大小是Internet“无默认”网络管理者非常关心的问题：他们不想为了少数Internet节点的唯一利益而浪费一个重要的路由条目。许多公司已经安装了过滤器，可以自动删除过于具体的路线；大多数过滤器都表示为地址前缀长度的函数，例如“我的网络不接受小于a/24的网络的广告”。实际限制可能因网络而异，也可能随时间而变化。
It could indeed be argued that using a large network is a waste of the precious addressing resource. However, this is a waste for the good cause of actually moving to IPv6, i.e., providing a real relief to the address exhaustion problem.
确实可以说，使用大型网络是对宝贵寻址资源的浪费。然而，这是一种浪费，因为实际上需要迁移到IPv6，即真正缓解地址耗尽问题。
A first version of this memo suggested the use of a specific AS number to designate a virtual AS containing all the 6to4 relay routers. The rationale was to facilitate the registration of the access point in databases such as the RADB routing registry [RADB]. Further analysis has shown that this was not required for practical operation.
此备忘录的第一个版本建议使用特定的AS编号来指定包含所有6to4中继路由器的虚拟AS。其基本原理是便于在数据库（如RADB路由注册表[RADB]）中注册接入点。进一步分析表明，实际操作不需要这样做。
Some have expressed a concern that, while the assignment of an anycast address to 6to4 access routers would make life a bit easier, it would also tend to leave things in a transition state in perpetuity. In fact, we believe that the opposite is true.
一些人表示担心，虽然将选播地址分配给6to4访问路由器会让生活变得更轻松，但它也会让事情永远处于过渡状态。事实上，我们认为情况恰恰相反。
A condition for easy migration out of the "tunnelling" state is that it be easy to have connectivity to the "real" IPv6 network; this means that people trust that opting for a real IPv6 address will not somehow result in lower performances. So the anycast proposal actually ensures that we don't stay in a perpetual transition.
轻松迁移出“隧道”状态的条件是，可以轻松连接到“真正的”IPv6网络；这意味着人们相信选择真正的IPv6地址不会以某种方式导致性能降低。因此，选播方案实际上确保了我们不会永远处于过渡期。
6 Future Work
6今后的工作
Using a default route to reach the IPv6 Internet has a potential drawback: the chosen relay may not be on the most direct path to the target v6 address. In fact, one might argue that, in the early phase of deployment, a relay close to the 6to4 site would probably not be the site's ISP or the native destination's ISP...it would probably be some third party ISP's relay which would be used for transit and may have lousy connectivity. Using the relay closest to the native destination would more closely match the v4 route, and quite possibly provide a higher degree of reliability. A potential way to deal with this issue is to use a "redirection" procedure, by which the 6to4 router learns the most appropriate route for a specific destination. This is left for further study.
使用默认路由到达IPv6 Internet有一个潜在的缺点：所选中继可能不在目标v6地址的最直接路径上。事实上，有人可能会说，在部署的早期阶段，靠近6to4站点的中继可能不是站点的ISP或本机目的地的ISP……它可能是某个第三方ISP的中继，用于传输，并且可能具有糟糕的连接。使用距离本机目的地最近的中继将更接近v4路由，并且很可能提供更高程度的可靠性。处理此问题的一种潜在方法是使用“重定向”过程，通过该过程，6to4路由器为特定目的地学习最合适的路由。这有待进一步研究。
The practical operation of the 6to4 relay routers requires the development of monitoring and testing tools, and the elaboration of gradual management practices. While this document provides general guidelines for the design of tools and practice, we expect that the actual deployment will be guided by operational experience.
6to4中继路由器的实际操作需要开发监控和测试工具，并制定逐步的管理实践。虽然本文件提供了工具和实践设计的一般指南，但我们希望实际部署将以操作经验为指导。
7 Security Considerations
7安全考虑
The generic security risks of 6to4 tunneling and the appropriate protections are discussed in [RFC3056]. The anycast technique introduces an additional risk, that a rogue router or a rogue AS would introduce a bogus route to the 6to4 anycast prefix, and thus divert the traffic. IPv4 network managers have to guarantee the integrity of their routing to the 6to4 anycast prefix in much the same way that they guarantee the integrity of the generic v4 routing.
[RFC3056]中讨论了6to4隧道的一般安全风险和适当的保护措施。选播技术引入了一个额外的风险，即流氓路由器或流氓AS将向6to4选播前缀引入虚假路由，从而转移流量。IPv4网络管理器必须保证其到6to4选播前缀的路由的完整性，其方式与保证通用v4路由的完整性大致相同。
8 IANA Considerations
8 IANA考虑因素
The purpose of this memo is to document the allocation by IANA of an IPv4 prefix dedicated to the 6to4 gateways to the native v6 Internet; there is no need for any recurring assignment.
本备忘录的目的是记录IANA将专用于6to4网关的IPv4前缀分配给本机v6 Internet的情况；不需要任何定期任务。
The following notice is copied from RFC 2026 [Bradner, 1996], Section 10.4, and describes the position of the IETF concerning intellectual property claims made against this document.
以下通知摘自RFC 2026[Bradner，1996]第10.4节，描述了IETF对本文件提出的知识产权索赔的立场。
The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use other technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF Secretariat.
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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director.
IETF邀请任何相关方提请其注意任何版权、专利或专利申请，或其他可能涉及实施本标准所需技术的专有权利。请将信息发送给IETF执行董事。
10 Acknowledgements
10致谢
The discussion presented here was triggered by a note that Brad Huntting sent to the NGTRANS and IPNG working groups. The note revived previous informal discussions, for which we have to acknowledge the members of the NGTRANS and IPNG working groups, in particular Scott Bradner, Randy Bush, Brian Carpenter, Steve Deering, Bob Fink, Tony Hain, Bill Manning, Keith Moore, Andrew Partan and Dave Thaler.
布拉德·亨廷（Brad Hunting）发给NGTRANS和IPNG工作组的一份通知引发了这里的讨论。该说明恢复了以前的非正式讨论，为此，我们必须感谢NGTRANS和IPNG工作组的成员，特别是斯科特·布拉德纳、兰迪·布什、布赖恩·卡彭特、史蒂夫·迪林、鲍勃·芬克、托尼·海恩、比尔·曼宁、基思·摩尔、安德鲁·帕坦和戴夫·泰勒。
11 References
11参考文献
[RFC3056] Carpenter, B. and K. Moore "Connection of IPv6 Domains via IPv4 Clouds", RFC 3056, February 2001.
[RFC3056]Carpenter，B.和K.Moore，“通过IPv4云连接IPv6域”，RFC 3056，2001年2月。
[RADB] Introducing the RADB. Merit Networks, http://www.radb.net/docs/intro.html.
[RADB]介绍RADB。价值网络，http://www.radb.net/docs/intro.html.
12 Author's Address
12提交人地址
Christian Huitema Microsoft Corporation One Microsoft Way Redmond, WA 98052-6399
Christian Huitema微软公司华盛顿州雷德蒙微软大道一号，邮编：98052-6399
EMail: huitema@microsoft.com
EMail: huitema@microsoft.com
13 Full Copyright Statement
13完整版权声明
Copyright (C) The Internet Society (2001). All Rights Reserved.
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This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English.
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The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns.
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Acknowledgement
确认
Funding for the RFC Editor function is currently provided by the Internet Society.
RFC编辑功能的资金目前由互联网协会提供。