Internet Engineering Task Force (IETF) M. Liebsch, Ed.
Request for Comments: 6058 NEC
Category: Experimental A. Muhanna
ISSN: 2070-1721 Ericsson
O. Blume
Alcatel-Lucent Bell Labs
March 2011
Internet Engineering Task Force (IETF) M. Liebsch, Ed.
Request for Comments: 6058 NEC
Category: Experimental A. Muhanna
ISSN: 2070-1721 Ericsson
O. Blume
Alcatel-Lucent Bell Labs
March 2011
Transient Binding for Proxy Mobile IPv6
代理移动IPv6的瞬时绑定
Abstract
摘要
This document specifies a mechanism that enhances Proxy Mobile IPv6 protocol signaling to support the creation of a transient binding cache entry that is used to optimize the performance of dual radio handover, as well as single radio handover. This mechanism is applicable to the mobile node's inter-MAG (Mobility Access Gateway) handover while using a single interface or different interfaces. The handover problem space using the Proxy Mobile IPv6 base protocol is analyzed and the use of transient binding cache entries at the local mobility anchor is described. The specified extension to the Proxy Mobile IPv6 protocol ensures optimized forwarding of downlink as well as uplink packets between mobile nodes and the network infrastructure and avoids superfluous packet forwarding delay or even packet loss.
本文档指定了一种增强代理移动IPv6协议信令的机制，以支持创建瞬态绑定缓存项，该缓存项用于优化双无线电切换和单无线电切换的性能。该机制适用于移动节点在使用单个接口或不同接口的情况下进行的MAG（移动接入网关）间切换。分析了使用代理移动IPv6基本协议的切换问题空间，并描述了在本地移动锚点使用瞬时绑定缓存项。代理移动IPv6协议的指定扩展可确保在移动节点和网络基础设施之间优化下行链路和上行链路数据包的转发，并避免多余的数据包转发延迟甚至数据包丢失。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation.
本文件不是互联网标准跟踪规范；它是为检查、实验实施和评估而发布的。
This document defines an Experimental Protocol for the Internet community. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.
本文档为互联网社区定义了一个实验协议。本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 5741第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6058.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc6058.
Copyright Notice
版权公告
Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2011 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction ....................................................4
2. Conventions and Terminology .....................................5
2.1. Conventions Used in This Document ..........................5
2.2. Terminology and Functional Components ......................5
3. Analysis of the Problem Space ...................................6
3.1. Handover Using a Single Interface ..........................6
3.2. Handover between Interfaces ................................6
3.2.1. Issues with Downlink Traffic ........................7
3.2.2. Issues with Uplink Traffic ..........................9
3.3. Need for a Common Solution ................................10
4. Use of Transient Binding Cache Entries .........................11
4.1. General Approach ..........................................11
4.2. Impact on Binding Management ..............................13
4.3. Role of the LMA and nMAG in Transient State Control .......14
4.3.1. Control at the nMAG ................................14
4.3.2. Control at the LMA .................................15
4.4. LMA Forwarding State Diagram ..............................15
4.5. MAG Operation .............................................18
4.6. LMA Operation .............................................19
4.6.1. Initiation of a Transient BCE ......................19
4.6.2. Activation of a Transient BCE ......................20
4.7. MN Operation ..............................................22
4.8. Status Values .............................................22
4.9. Protocol Stability ........................................22
5. Message Format .................................................24
5.1. Transient Binding Option ..................................24
6. IANA Considerations ............................................25
7. Security Considerations ........................................25
8. Protocol Configuration Variables ...............................26
9. Contributors ...................................................26
10. Acknowledgments ...............................................26
11. References ....................................................26
11.1. Normative References .....................................26
11.2. Informative References ...................................26
Appendix A. Example Use Cases for Transient BCE ..................28
A.1. Use Case for Single Radio Handover ........................28
A.2. Use Case for Dual Radio Handover ..........................30
Appendix B. Applicability and Use of Static Configuration at
the LMA ..............................................33
B.1. Early Uplink Traffic from the nMAG ........................33
B.2. Late Uplink Traffic from the pMAG .........................33
B.3. Late Switching of Downlink Traffic to nMAG ................34
1. Introduction ....................................................4
2. Conventions and Terminology .....................................5
2.1. Conventions Used in This Document ..........................5
2.2. Terminology and Functional Components ......................5
3. Analysis of the Problem Space ...................................6
3.1. Handover Using a Single Interface ..........................6
3.2. Handover between Interfaces ................................6
3.2.1. Issues with Downlink Traffic ........................7
3.2.2. Issues with Uplink Traffic ..........................9
3.3. Need for a Common Solution ................................10
4. Use of Transient Binding Cache Entries .........................11
4.1. General Approach ..........................................11
4.2. Impact on Binding Management ..............................13
4.3. Role of the LMA and nMAG in Transient State Control .......14
4.3.1. Control at the nMAG ................................14
4.3.2. Control at the LMA .................................15
4.4. LMA Forwarding State Diagram ..............................15
4.5. MAG Operation .............................................18
4.6. LMA Operation .............................................19
4.6.1. Initiation of a Transient BCE ......................19
4.6.2. Activation of a Transient BCE ......................20
4.7. MN Operation ..............................................22
4.8. Status Values .............................................22
4.9. Protocol Stability ........................................22
5. Message Format .................................................24
5.1. Transient Binding Option ..................................24
6. IANA Considerations ............................................25
7. Security Considerations ........................................25
8. Protocol Configuration Variables ...............................26
9. Contributors ...................................................26
10. Acknowledgments ...............................................26
11. References ....................................................26
11.1. Normative References .....................................26
11.2. Informative References ...................................26
Appendix A. Example Use Cases for Transient BCE ..................28
A.1. Use Case for Single Radio Handover ........................28
A.2. Use Case for Dual Radio Handover ..........................30
Appendix B. Applicability and Use of Static Configuration at
the LMA ..............................................33
B.1. Early Uplink Traffic from the nMAG ........................33
B.2. Late Uplink Traffic from the pMAG .........................33
B.3. Late Switching of Downlink Traffic to nMAG ................34
The IETF specified Proxy Mobile IPv6 (PMIPv6) [RFC5213] as a protocol for network-based localized mobility management, which takes basic operation for registration, tunnel management, and deregistration into account. In order to eliminate the risk of lost packets, this document specifies an extension to PMIPv6 that utilizes a new mobility option in the Proxy Binding Update (PBU) and the Proxy Binding Acknowledgement (PBA) between the new Mobility Access Gateway (nMAG) and the Local Mobility Anchor (LMA).
IETF将代理移动IPv6（PMIPv6）[RFC5213]指定为基于网络的本地化移动性管理协议，该协议考虑了注册、隧道管理和注销的基本操作。为了消除丢失数据包的风险，本文档指定了对PMIPv6的扩展，该扩展利用了新移动接入网关（nMAG）和本地移动锚（LMA）之间的代理绑定更新（PBU）和代理绑定确认（PBA）中的新移动选项。
According to the PMIPv6 base specification, an LMA updates a mobile node's (MN's) Binding Cache Entry (BCE) and switches the forwarding tunnel after receiving a Proxy Binding Update (PBU) message from the mobile node's new MAG (nMAG). At the same time, the LMA disables the forwarding entry towards the mobile node's previous MAG (pMAG). In case of an inter-technology handover, the mobile node's handover target interface must be configured according to the Router Advertisement being sent by the nMAG. Address configuration as well as possible access-technology-specific radio bearer setup may delay the complete set up of the mobile node's new interface before it is ready to receive or send data packets. In case the LMA performs operation according to [RFC5213] and forwards packets to the mobile node's new interface after the reception of the PBU from the nMAG, some packets may get lost or experience major packet delay. The transient BCE extension, as specified in this document, increases handover performance (optimized packet loss and forwarding delay) experienced by MNs, which have multiple network interfaces implemented while handing over from one interface to the other. The transient BCE extension also increases handover performance for single radio MNs, which build on available radio layer forwarding mechanisms, hence re-use existing active handover techniques.
根据PMIPv6基本规范，LMA在从移动节点的新MAG（nMAG）接收到代理绑定更新（PBU）消息之后更新移动节点（MN）的绑定缓存条目（BCE）并切换转发隧道。同时，LMA禁用朝向移动节点的前一MAG（pMAG）的转发条目。在技术间切换的情况下，必须根据nMAG发送的路由器广告配置移动节点的切换目标接口。地址配置以及可能的接入技术特定的无线电承载设置可以在移动节点准备好接收或发送数据分组之前延迟移动节点的新接口的完整设置。在LMA根据[RFC5213]执行操作并且在从nMAG接收到PBU之后将分组转发到移动节点的新接口的情况下，一些分组可能丢失或经历重大分组延迟。本文件中规定的瞬态BCE扩展提高了MNs所经历的切换性能（优化的数据包丢失和转发延迟），MNs在从一个接口切换到另一个接口时实现了多个网络接口。瞬时BCE扩展还提高了基于可用无线层转发机制的单无线电MN的切换性能，因此重用了现有的主动切换技术。
Some implementation-specific solutions, such as static configuration on the LMA to accept uplink packets from the old MAG in addition to accepting packets from the new MAG for a short duration during the handover and buffering at the new MAG, can help to address some of the issues identified in this document. Please see Appendix B for more details. A dynamic solution by means of the proposed protocol operation helps to optimize the performance for a variety of handover situations and different radio characteristics.
一些特定于实现的解决方案，例如LMA上的静态配置，除了在切换期间短时间接受来自新MAG的分组和在新MAG处缓冲之外，还接受来自旧MAG的上行链路分组，可以帮助解决本文档中确定的一些问题。更多详情请参见附录B。通过所提出的协议操作的动态解决方案有助于优化各种切换情况和不同无线电特性的性能。
Additionally, this document specifies an advanced binding cache management mechanism at the LMA according to well-defined transient BCE states. This mechanism ensures that forwarding states at LMAs are inline with the different handover scenarios. During a transient state, a mobile node's BCE refers to two proxy Care-of-Address (Proxy-CoA) entries, one from the mobile node's pMAG, another from
此外，本文档根据定义良好的瞬时BCE状态，在LMA上指定了一种高级绑定缓存管理机制。该机制确保LMA处的转发状态与不同的切换场景保持一致。在瞬态期间，移动节点的BCE引用两个代理转交地址（proxy CoA）条目，一个来自移动节点的pMAG，另一个来自移动节点的pMAG
its nMAG. MAGs can establish settings of a transient binding on the LMA by means of signaling. An LMA can establish or change the settings of a transient binding according to events, such as a timeout, a change of the radio technology due to a handover, or a completed set up of a radio bearer or configuration of an MN's IP address. Such an event may also be triggered by other protocols, e.g., Authentication, Authorization, and Accounting (AAA) messages. This document specifies advanced binding cache control by means of a Transient Binding option, which can be used with PMIPv6 signaling to support transient BCEs. Furthermore, this document specifies forwarding characteristics according to the current state of a binding to switch the forwarding tunnel at the LMA from the pMAG to the nMAG during inter-MAG handover according to the handover conditions. As a result of transient binding support, handover performance can considerably be improved to smooth an MN's handover without introducing major complexity into the system.
它是nMAG。MAG可以通过信令在LMA上建立瞬态绑定的设置。LMA可以根据诸如超时、由于切换导致的无线电技术的改变、或无线电承载的完成设置或MN的IP地址的配置等事件来建立或改变瞬时绑定的设置。此类事件也可由其他协议触发，例如认证、授权和记帐（AAA）消息。本文档通过瞬态绑定选项指定高级绑定缓存控制，该选项可与PMIPv6信令一起使用，以支持瞬态BCE。此外，本文档根据绑定的当前状态指定转发特性，以根据切换条件在MAG间切换期间将LMA处的转发隧道从pMAG切换到nMAG。由于瞬态绑定支持，切换性能可以显著提高，以平滑MN的切换，而不会给系统带来很大的复杂性。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中所述进行解释。
o IF - Interface. Any network interface, which offers a mobile node wireless or wired access to the network infrastructure. In case a mobile node has multiple interfaces implemented, they are numbered (IF1, IF2, etc.).
o 如果-接口。任何网络接口，提供移动节点对网络基础设施的无线或有线访问。如果移动节点实现了多个接口，则对它们进行编号（IF1、IF2等）。
o Transient Binding Cache Entry. A temporary state of the mobile node Binding Cache Entry that defines the forwarding characteristics of the mobile node forwarding tunnels to the nMAG and pMAG. This transient BCE state is created when the Transient Binding option is included in the PBU and PBA as specified in this document. The LMA forwards the mobile node traffic according to current transient BCE characteristics as specified in this document. The transient BCE state is transparent to the pMAG.
o 临时绑定缓存项。移动节点绑定缓存项的临时状态，定义移动节点转发隧道到nMAG和pMAG的转发特性。当本文档中指定的PBU和PBA中包含瞬态绑定选项时，会创建此瞬态BCE状态。LMA根据本文档中规定的当前瞬态BCE特性转发移动节点流量。瞬态BCE状态对pMAG是透明的。
o Active Binding Cache Entry. A valid mobile node Binding Cache Entry according to [RFC5213], which is not in transient state.
o 活动绑定缓存项。根据[RFC5213]的有效移动节点绑定缓存项，该项不处于瞬态。
This section summarizes the analysis of the handover problem space for inter-technology handover as well as intra-technology handover when using the PMIPv6 protocol as in [RFC5213].
本节总结了使用[RFC5213]中的PMIPv6协议时，技术间切换和技术内切换的切换问题空间分析。
In some active handover scenarios, it is necessary to prepare the nMAG as the handover target prior to the completion of the link-layer handover procedures. Packets sent by the LMA to the nMAG before the completion of the link-layer handover procedure will be lost unless they are buffered.
在某些活动切换场景中，在完成链路层切换过程之前，有必要准备nMAG作为切换目标。在链路层切换过程完成之前，LMA发送到nMAG的数据包将丢失，除非对其进行缓冲。
In some systems, the nMAG will be the recipient of uplink traffic prior to the completion of the procedure that would result in the PBU/PBA handshake. These packets cannot be forwarded to the LMA.
在某些系统中，nMAG将在导致PBU/PBA握手的过程完成之前成为上行链路业务的接收者。这些数据包不能转发到LMA。
During an intra-technology handover, some of the MN's uplink traffic may still be in transit through the pMAG. Currently, and as per the PMIPv6 base protocol [RFC5213], the LMA forwards the MN's uplink traffic received from a tunnel only as long as the source IP address of the MN's uplink traffic matches the IP address of the mobile node's registered Proxy-CoA in the associated BCE. As a result, packets received at the LMA from the MN's pMAG after the LMA has already switched the tunnel to point to the nMAG will be dropped.
在技术内切换期间，MN的一些上行链路业务可能仍在通过pMAG传输。目前，根据PMIPv6基本协议[RFC5213]，只要MN的上行链路业务的源IP地址与相关BCE中移动节点的注册代理CoA的IP地址匹配，LMA就转发从隧道接收的MN的上行链路业务。结果，在LMA已经将隧道切换到指向nMAG之后，在LMA处从MN的pMAG接收的分组将被丢弃。
In client-based mobility protocols, the handover sequence is fully controlled by the MN, and the MN updates its binding and associated routing information at its mobility anchor after IP connectivity has been established on the new link. On the contrary, PMIPv6 aims to relieve the MN from the IP mobility signaling, while the mobile node still controls link configuration during a handover. This introduces a problem during an MN's handover between interfaces. According to the PMIPv6 base protocol [RFC5213], the Access Authentication and the Proxy Binding Update (PBU) are triggered in the access network by the radio attach procedure, transparently for the MN. In addition, a delay for the MN's new interface's address configuration is not considered in the handover procedure. As a consequence, the immediate update of the MN's BCE after the PBU from the MN's nMAG has been received at the LMA impacts the performance of the MN's downlink traffic as well as its uplink traffic. Performance aspects of downlink as well as uplink traffic during a handover between interfaces are analyzed in the subsequent subsections.
在基于客户端的移动性协议中，切换序列完全由MN控制，并且在新链路上建立IP连接之后，MN在其移动性锚点处更新其绑定和相关路由信息。相反，PMIPv6旨在将MN从IP移动性信令中释放，而移动节点在切换期间仍然控制链路配置。这在接口之间的MN切换期间引入了一个问题。根据PMIPv6基本协议[RFC5213]，接入认证和代理绑定更新（PBU）通过无线连接过程在接入网络中被触发，对于MN是透明的。此外，在切换过程中不考虑MN的新接口的地址配置的延迟。因此，在LMA处接收到来自MN的nMAG的PBU之后，MN的BCE的立即更新影响了MN的下行链路业务及其上行链路业务的性能。在随后的小节中分析了接口之间切换期间下行链路和上行链路业务的性能方面。
Delay of availability of an MN's network interface can be caused by certain protocol operations that the MN needs to perform to configure its new interface, and these operations can take time. In order to complete the address auto-configuration on its new interface, the MN needs to send a Router Solicitation and awaits a Router Advertisement. Upon receiving a Router Advertisement from the new MAG, the MN can complete its address configuration and may perform Duplicate Address Detection (DAD) [RFC4862] on the new interface. Only then the MN's new interface is ready to receive packets.
MN网络接口的可用性延迟可能是由MN配置其新接口所需执行的某些协议操作造成的，这些操作可能需要时间。为了在其新接口上完成地址自动配置，MN需要发送路由器请求并等待路由器公告。当从新的MAG接收到路由器广告时，MN可以完成其地址配置，并且可以在新接口上执行重复地址检测（DAD）[RFC4862]。只有这样，MN的新接口才准备好接收数据包。
Address configuration can take more than a second to complete. If the LMA has already switched the mobile node tunnel to point to the nMAG and started forwarding data packets for the MN to the nMAG during this time, these data packets may get delayed or lost because the MN's new interface is not yet ready to receive data. However, delaying the PBU, which is sent from the new MAG to the LMA after the MN's new interface has attached to the network, is not possible, as the new MAG retrieves configuration data for the MN from the LMA in the PBA, such as the MN's Home Network Prefixes (HNPs) and the link-local address to be used at the MAG.
地址配置可能需要一秒钟以上的时间才能完成。如果LMA已经切换移动节点隧道以指向nMAG，并且在此期间开始将MN的数据分组转发给nMAG，则这些数据分组可能会延迟或丢失，因为MN的新接口尚未准备好接收数据。然而，在MN的新接口连接到网络之后，延迟从新MAG发送到LMA的PBU是不可能的，因为新MAG从PBA中的LMA检索MN的配置数据，例如MN的家庭网络前缀（hnp）和要在MAG处使用的链路本地地址。
The aforementioned problem is illustrated in Figure 1, which assumes that the HNP(s) will be assigned under control of the LMA. Hence, the HNP option in the PBU, which is sent by the new MAG to the LMA, is set to ALL_ZERO. An MN has attached to the network with interface (IF) IF1 and receives data on this interface. When the MN's new interface IF2 comes up and is detected by the new MAG, the new MAG sends a PBU and receives a PBA from the LMA. If the LMA decides to forward data packets for the MN via the new MAG, the new MAG has to buffer these packets until address configuration of the MN's new interface has completed and the MN's new interface is ready to receive packets. While setting up IF2, the MN may not reply to address resolution signaling [RFC4861], as sent by the new MAG [A]. If the MAG's buffer overflows or the MN cannot reply to address resolution signaling for too long, data packets for the MN are dropped and the MN can experience severe packet losses during an inter-access handover [B] until IF2 is ready to receive and send data [C].
上述问题如图1所示，该图假设HNP将在LMA的控制下分配。因此，PBU中由新MAG发送到LMA的HNP选项被设置为全零。MN已通过接口（IF）IF1连接到网络，并在此接口上接收数据。当MN的新接口IF2出现并被新MAG检测到时，新MAG发送PBU并从LMA接收PBA。如果LMA决定经由新MAG转发用于MN的数据分组，则新MAG必须缓冲这些分组，直到MN的新接口的地址配置完成并且MN的新接口准备好接收分组为止。在设置IF2时，MN可能不会回复新MAG[A]发送的地址解析信令[RFC4861]。如果MAG的缓冲区溢出或MN无法回复地址解析信令的时间过长，则MN的数据分组会被丢弃，并且MN在接入间切换[B]期间会经历严重的分组丢失，直到IF2准备好接收和发送数据[C]。
+------+ +----+ +----+ +---+
| MN | |pMAG| |nMAG| |LMA|
+------+ +----+ +----+ +---+
IF2 IF1 | | |
| | | | |
| |- - - - - - - - - Attach | |
| | |---------------PBU--------------->|
| | |<--------------PBA----------------|
| |--------RtSol------->| | |
| |<-------RtAdv--------| | |
| Addr. | | |
| Conf. | | |
| |<--------------------|==================data============|--
| | | | |
|- - - - - - - - - - - - - - - - - Attach |
| | | |----------PBU-------->|
| | | |<---------PBA---------|
| | | |<-====data============|--
[A]?|<-----------NSol---------------------|<-====data============|--
| | | [B] ?|<-====data============|--
| | | ?|<-====data============|--
|-----------RtSol-------------------->|<-====data============|--
|<----------RtAdv---------------------| : |
Addr. | | | : |
Conf. | | | : |
|<-----------NSol---------------------| : |
|------------NAdv------------------->[C] |
!|<------------------------------------|======data============|--
| | | | |
| | | | |
+------+ +----+ +----+ +---+
| MN | |pMAG| |nMAG| |LMA|
+------+ +----+ +----+ +---+
IF2 IF1 | | |
| | | | |
| |- - - - - - - - - Attach | |
| | |---------------PBU--------------->|
| | |<--------------PBA----------------|
| |--------RtSol------->| | |
| |<-------RtAdv--------| | |
| Addr. | | |
| Conf. | | |
| |<--------------------|==================data============|--
| | | | |
|- - - - - - - - - - - - - - - - - Attach |
| | | |----------PBU-------->|
| | | |<---------PBA---------|
| | | |<-====data============|--
[A]?|<-----------NSol---------------------|<-====data============|--
| | | [B] ?|<-====data============|--
| | | ?|<-====data============|--
|-----------RtSol-------------------->|<-====data============|--
|<----------RtAdv---------------------| : |
Addr. | | | : |
Conf. | | | : |
|<-----------NSol---------------------| : |
|------------NAdv------------------->[C] |
!|<------------------------------------|======data============|--
| | | | |
| | | | |
Figure 1: Issue with dual radio handover
图1：双无线电切换问题
Another risk for a delay in forwarding data packets from a new MAG to the MN's IF2 can be some latency in setting up a particular access technology's radio bearer or access-specific security associations after the new MAG received the MN's HNP(s) from the LMA via the PBA signaling message.
从新MAG向MN的IF2转发数据分组中的延迟的另一个风险可以是在新MAG经由PBA信令消息从LMA接收到MN的HNP之后设置特定接入技术的无线电承载或接入特定安全关联的一些延迟。
In case an access network needs the MN's IP address or HNP to set up a radio bearer between an MN's IF2 and the network infrastructure, the access network might have to wait until the nMAG has received the associated information from the LMA in the Proxy Binding Acknowledgment. Delay in forwarding packets from the nMAG to the MN's IF2 depends now on the latency in setting up the radio bearer.
如果接入网络需要MN的IP地址或HNP在MN的IF2和网络基础设施之间建立无线电承载，则接入网络可能必须等待，直到nMAG在代理绑定确认中从LMA接收到相关信息。从nMAG向MN的IF2转发数据包的延迟现在取决于设置无线电承载的延迟。
A similar problem can occur in the case in which the setup of a required security association between the MN's IF2 and the network takes time and such a setup can be performed only after the MN's IP address or HNP is available on the nMAG.
在MN的IF2和网络之间的所需安全关联的设置需要时间并且这种设置只能在nMAG上的MN的IP地址或HNP可用之后才能执行的情况下，可能会发生类似的问题。
Both scenarios, as depicted above, can be found in [TS23.402], where the protocol sequence during a handover between different accesses considers a PMIPv6 handshake between the nMAG and the LMA to retrieve the MN's HNP(s) before access-specific operations can be completed.
如上所述，这两种情况都可以在[TS23.402]中找到，其中不同接入之间切换期间的协议序列考虑nMAG和LMA之间的PMIPv6握手，以在接入特定操作可以完成之前检索MN的HNP。
In the case of an inter-technology handover between two interfaces, the MN may be able to maintain connectivity on IF1 while it is completing address configuration on IF2. Such a handover mechanism is called "make-before-break" and can avoid uplink packet loss in client-based Mobile IP. However, in a PMIPv6 domain, the attachment of the MN on IF2 will cause the nMAG to send a PBU to the LMA, which will cause the LMA to update the BCE for this mobility session of the MN. According to Section 5.3.5 of the PMIPv6 base specification [RFC5213], the LMA may drop all subsequent packets being forwarded by the MN's pMAG due to the updated BCE, which refers now to the nMAG as a "Proxy-CoA".
在两个接口之间的技术间切换的情况下，MN可以在完成IF2上的地址配置的同时保持IF1上的连接。这种切换机制被称为“先通后断”，可以避免基于客户端的移动IP中的上行链路分组丢失。然而，在PMIPv6域中，在IF2上连接MN将导致nMAG向LMA发送PBU，这将导致LMA为MN的该移动性会话更新BCE。根据PMIPv6基本规范[RFC5213]的第5.3.5节，由于更新的BCE，LMA可以丢弃由MN的pMAG转发的所有后续分组，该BCE现在将nMAG称为“代理CoA”。
A further issue for uplink packets arises from differences in the time of travel between the nMAG and LMA in comparison with the time of travel between the pMAG and LMA. Even if the MN stops sending packets on IF1 before the PBU is sent (i.e., before it attaches IF2 to nMAG), uplink packets from pMAG may arrive at the LMA after the LMA has received the PBU from nMAG. Such a situation can, in particular, occur when the MN's previous link has a high delay (e.g., a Global System for Mobile Communications (GSM) link) and is slow compared to the handover target link. This characteristic is illustrated in Figure 2.
上行链路分组的另一个问题源于nMAG和LMA之间的旅行时间与pMAG和LMA之间的旅行时间相比的差异。即使MN在发送PBU之前（即，在它将IF2连接到nMAG之前）停止在IF1上发送分组，来自pMAG的上行链路分组也可以在LMA从nMAG接收到PBU之后到达LMA。当MN的前一链路具有高延迟（例如，全球移动通信系统（GSM）链路）并且与切换目标链路相比较慢时，尤其可以发生这种情况。该特性如图2所示。
+------+ +----+ +---+
| MN | |nMAG| |LMA|
+------+ +----+ +---+
IF2 IF1 | |
| |\ | |BCE exists
| | \ | | for pMAG
|- -|- - - - \- - - - Attach |
| | s\ |---------PBU----------->|BCE update
| | l\ |<--------PBA------------| for nMAG
| | o\ |
| | | w\ |
| | | l\ |
| | | i\ |
| | | n \ |packet dropped
| | | k --->| as BCE has only
| | | | entry for nMAG
| | | |
| | | |
+------+ +----+ +---+
| MN | |nMAG| |LMA|
+------+ +----+ +---+
IF2 IF1 | |
| |\ | |BCE exists
| | \ | | for pMAG
|- -|- - - - \- - - - Attach |
| | s\ |---------PBU----------->|BCE update
| | l\ |<--------PBA------------| for nMAG
| | o\ |
| | | w\ |
| | | l\ |
| | | i\ |
| | | n \ |packet dropped
| | | k --->| as BCE has only
| | | | entry for nMAG
| | | |
| | | |
Figure 2: Uplink traffic issue with slow links
图2：慢速链路的上行链路流量问题
To reduce the risk of packet loss, some settings on an MN could be chosen appropriately to speed up the process of network interface configuration. Also, tuning some network parameters, such as increasing the buffer capacity on MAG components, could improve the handover performance. However, some network characteristics, such as access link delay or bearer setup latency, cannot be easily fine tuned to suit a particular handover scenario. Thus, a common solution that dynamically controls and enhances this handover complexity using a simple extension to the PMIPv6 base protocol is preferred.
为了降低数据包丢失的风险，可以适当地选择MN上的一些设置，以加快网络接口配置的过程。此外，调整一些网络参数，例如增加MAG组件上的缓冲区容量，可以提高切换性能。然而，一些网络特性，例如接入链路延迟或承载设置延迟，不能容易地微调以适应特定的切换场景。因此，优选使用对PMIPv6基本协议的简单扩展来动态控制和增强这种切换复杂性的公共解决方案。
This document specifies transient BCEs as an extension to the PMIPv6 protocol. Set up and configuration of a transient BCE can be performed by means of extended PMIPv6 signaling messages between the MAG and the LMA component using a new Transient Binding mobility option. The transient BCE mechanism supports three clearly distinguished sequences of transient states to suit various handover scenarios and to improve handover performance for both inter- and intra-technology handover. As a result of using transient BCEs, excessive packet buffering at the nMAG during the MN's handover process is not necessary and packet losses and major jitter can be avoided.
本文档将瞬态BCE指定为PMIPv6协议的扩展。可以通过使用新的瞬时绑定移动性选项在MAG和LMA组件之间的扩展PMIPv6信令消息来执行瞬时BCE的设置和配置。瞬态BCE机制支持三种明显不同的瞬态序列，以适应各种切换场景，并提高技术间和技术内切换的切换性能。由于使用瞬态BCE，在MN的切换过程中，nMAG处的过度分组缓冲是不必要的，并且可以避免分组丢失和主要抖动。
The use of transient BCE during an MN's handover (HO) enables greater control on the forwarding of uplink (Ul) and downlink (Dl) traffic to harmonize handover performance characteristics with the capabilities of the handover source and target access networks. Updating of an MN's BCE at an LMA is split into different phases before and after the radio setup and IP configuration being associated with the MN's handover from a pMAG to an nMAG.
在MN的切换（HO）期间使用瞬态BCE使得能够更好地控制上行链路（Ul）和下行链路（Dl）业务的转发，以使切换性能特征与切换源和目标接入网络的能力相协调。LMA处MN的BCE的更新在与MN从pMAG切换到nMAG相关联的无线电设置和IP配置前后分为不同的阶段。
The use of a transient BCE during an MN's handover splits into an initiation phase and a phase turning the transient BCE into an active BCE. Figure 3 illustrates the procedure to enter and leave a transient BCE during an MN's handover. As a result of the MN's attachment at the nMAG, the first PBU from the MN's nMAG can turn the MN's BCE at the LMA and the nMAG into transient state by including a Transient Binding option (Section 5.1). The LMA enters the nMAG as a further forwarding entry to the MN's BCE without deleting the existing forwarding entry and marks the BCE state as 'transient'. Alternatively, in case the nMAG does not include a Transient Binding option, the LMA can make the decision to use a transient BCE during an MN's handover and notify the nMAG about this decision by adding a Transient Binding option in the PBA. After receiving the PBA, the nMAG enters the MN's data, such as the assigned HNP(s), into its Binding Update List (BUL) and marks the MN's binding with the LMA as 'transient', which serves as an indication to the nMAG that the transient BCE needs to be turned into an active BCE.
在MN的切换期间使用瞬时BCE分为起始阶段和将瞬时BCE转变为活动BCE的阶段。图3说明了在MN切换期间进入和离开瞬态BCE的过程。由于MN在nMAG处的连接，来自MN的nMAG的第一个PBU可以通过包括瞬态绑定选项将LMA和nMAG处的MN的BCE转换为瞬态（第5.1节）。LMA输入nMAG作为到MN的BCE的进一步转发条目，而不删除现有的转发条目，并将BCE状态标记为“瞬态”。或者，在nMAG不包括瞬时绑定选项的情况下，LMA可以作出在MN的切换期间使用瞬时BCE的决定，并通过在PBA中添加瞬时绑定选项来将该决定通知nMAG。在接收到PBA后，nMAG将MN的数据（如分配的HNP）输入其绑定更新列表（BUL），并将MN与LMA的绑定标记为“瞬态”，这向nMAG指示瞬态BCE需要转变为活动BCE。
During the transient state, the LMA accepts uplink packets from both MAGs, the pMAG and the nMAG, for forwarding. To benefit from the still available downlink path from pMAG to MN, the LMA forwards downlink packets towards the pMAG until the transient BCE is turned into an active BCE. Such a downlink forwarding characteristic is denoted as "late path switch" (L). During a dual radio handover, an MN can receive downlink packets via its previous interface; during a single radio handover, the late path switch supports re-using available forwarding mechanisms in the radio access network. Appendix A describes both use cases.
在瞬态期间，LMA接受来自两个MAG（pMAG和nMAG）的上行链路分组以进行转发。为了受益于从pMAG到MN的仍然可用的下行链路路径，LMA向pMAG转发下行链路分组，直到瞬态BCE变为活动BCE。这种下行链路转发特性被表示为“延迟路径开关”（L）。在双无线电切换期间，MN可以通过其先前接口接收下行链路分组；在单个无线电切换期间，延迟路径交换机支持重新使用无线电接入网络中的可用转发机制。附录A描述了这两个用例。
Decisions about the classification of an MN's BCE as transient during a handover can be made either by the nMAG or the LMA. Detailed mechanisms showing how an nMAG or an LMA finds out to use a transient BCE procedure are out of scope of this document.
关于在切换期间将MN的BCE分类为瞬态的决定可以由nMAG或LMA作出。显示nMAG或LMA如何发现使用瞬态BCE程序的详细机制不在本文件范围内。
A transient BCE can be turned into an active BCE by different means, such as a timeout at the LMA, a PBU from the nMAG, which has no Transient Binding option included, or a deregistration PBU from the pMAG. As soon as the MN's BCE has been initiated to turn into an active BCE, the LMA switches the forwarding path for downlink packets from the pMAG to the nMAG.
瞬态BCE可以通过不同的方式转变为活动BCE，例如LMA处的超时、nMAG的PBU（不包括瞬态绑定选项）或pMAG的注销PBU。一旦MN的BCE被启动以转变为活动BCE，LMA就将下行链路分组的转发路径从pMAG切换到nMAG。
+-----+ +----+ +----+ +-----+
| MN | |pMAG| |nMAG| | LMA |
+-----+ +----+ +----+ +-----+
| | | |[pMAG serves
| | | | MN as
| | | | Proxy-CoA]
| | | |
|<-----------------|===============data tunnel=====|--->data
| | | |
[Handoff | | |
Start] | | |
| | | |
e|-----------------------[MN Attach] |
x| | | |
e| | |---PBU(transient)--->|[Add nMAG to
c| | | | MN's BCE,
u| | |<--PBA(transient)----| enter trans-
t| | | | ient state]
i| | | |
o|<-----Dl+Ul-------|===============data tunnel=====|--->data
n|--------Ul------------------|=====data tunnel=====|--->data
| | | |
[Handoff/ | | |
Configuration | | |
Completed] | [HO Complete] |
| | |--------PBU--------->|[Activate
| | | | MN's BCE,
| | |<-------PBA ---------| update for-
| | | | warding path
| | | | to nMAG]
| | | |
|<---------------------------|=====data tunnel=====|--->data
| | | |
+-----+ +----+ +----+ +-----+
| MN | |pMAG| |nMAG| | LMA |
+-----+ +----+ +----+ +-----+
| | | |[pMAG serves
| | | | MN as
| | | | Proxy-CoA]
| | | |
|<-----------------|===============data tunnel=====|--->data
| | | |
[Handoff | | |
Start] | | |
| | | |
e|-----------------------[MN Attach] |
x| | | |
e| | |---PBU(transient)--->|[Add nMAG to
c| | | | MN's BCE,
u| | |<--PBA(transient)----| enter trans-
t| | | | ient state]
i| | | |
o|<-----Dl+Ul-------|===============data tunnel=====|--->data
n|--------Ul------------------|=====data tunnel=====|--->data
| | | |
[Handoff/ | | |
Configuration | | |
Completed] | [HO Complete] |
| | |--------PBU--------->|[Activate
| | | | MN's BCE,
| | |<-------PBA ---------| update for-
| | | | warding path
| | | | to nMAG]
| | | |
|<---------------------------|=====data tunnel=====|--->data
| | | |
Figure 3: General mechanism and forwarding characteristics during handover with transient BCE
图3：过渡BCE切换期间的一般机制和转发特性
This specification considers an optional state when turning the transient BCE into an active BCE of a transient BCE with a late path switch, which keeps the pMAG for some more time as the forwarding
本规范考虑了当使用延迟路径开关将瞬态BCE转换为瞬态BCE的活动BCE时的可选状态，该开关使pMAG作为转发保持更长时间
entry in the transient BCE, solely to ensure forwarding of delayed uplink packets from the pMAG. This optional activation state has a lifetime associated, and termination does not need any signaling.
进入瞬态BCE，仅用于确保从pMAG转发延迟上行链路数据包。此可选激活状态具有相关的生存期，并且终止不需要任何信令。
Whether or not to enter this optional activation state is decided by the LMA. The LMA may take information about the access technology associated with the MN's pMAG and nMAG from the MN's BCE to decide if using the activation state is beneficial, e.g., since a slow link is associated with the pMAG and uplink packets from the pMAG may arrive delayed at the LMA.
是否进入该可选激活状态由LMA决定。LMA可以从MN的BCE获取关于与MN的pMAG和nMAG相关联的接入技术的信息，以确定使用激活状态是否有益，例如，因为慢链路与pMAG相关联，并且来自pMAG的上行链路分组可能延迟到达LMA。
The Transient Binding option allows configuration of the transient BCE late path switch and signaling of associated settings. Signaling of the Transient Binding option and the LMA's decision whether or not to use an optional activation state defines the sequence through the clearly defined transient BCE states, as illustrated and described in Section 4.4. Section 4.2 describes the required extension to an LMA's binding cache to support transient BCE operation. Section 4.3 provides a concise overview about the possible roles of the nMAG and the LMA to control a transient BCE handover sequence. Details about the Transient Binding option and its use are described in Sections 4.5 and 4.6.
瞬态绑定选项允许配置瞬态BCE延迟路径交换机并发送相关设置的信号。瞬态绑定选项的信令和LMA是否使用可选激活状态的决定通过明确定义的瞬态BCE状态定义序列，如第4.4节所示。第4.2节描述了LMA绑定缓存所需的扩展，以支持瞬时BCE操作。第4.3节简要概述了nMAG和LMA控制瞬时BCE切换序列的可能作用。第4.5节和第4.6节详细介绍了瞬态绑定选项及其使用。
The use of a transient BCE requires temporary maintenance of two forwarding entries in the MN's BCE at the LMA, one referring to the MN's pMAG and the other referring to its nMAG. Forwarding entries are represented according to [RFC5213] and comprise the interface identifier of the associated tunnel interface towards each MAG, as well as the associated access technology information.
使用瞬态BCE需要临时维护LMA处MN的BCE中的两个转发条目，一个引用MN的pMAG，另一个引用其nMAG。转发条目根据[RFC5213]表示，并包括朝向每个MAG的相关隧道接口的接口标识符以及相关接入技术信息。
Each forwarding entry is assigned a forwarding rule to admit and control forwarding of uplink and downlink traffic to and from the associated MAG. Hence, according to this specification, a forwarding entry can have either a rule that allows only forwarding of uplink traffic from the associated MAG, or a rule that allows bidirectional forwarding from and to the associated MAG. At any time, only one of the two forwarding entries can have a bi-directional forwarding rule. The interface identifier and access technology type info can be taken from the PBU received at the LMA and linked to each forwarding entry accordingly.
每个转发条目被分配一个转发规则，以允许和控制上行链路和下行链路业务向关联MAG的转发和从关联MAG的转发。因此，根据本规范，转发条目可以具有仅允许从关联MAG转发上行链路业务的规则，或允许双向转发至相关MAG的规则。在任何时候，两个转发条目中只有一个可以具有双向转发规则。接口标识符和接入技术类型信息可以从LMA处接收的PBU获取，并相应地链接到每个转发条目。
MAGs should maintain the status of an MN's binding and the lifetime associated with a transient BCE at the LMA in their binding update list. This is particularly important if the new MAG needs to explicitly turn a binding into an active BCE after the associated MN's new interface has proven to be ready to handle IP traffic.
MAG应在其绑定更新列表中维护MN绑定的状态以及与LMA处的瞬时BCE相关联的生存期。如果在相关MN的新接口被证明可以处理IP流量后，新MAG需要显式地将绑定转换为活动BCE，则这一点尤为重要。
This section provides an overview about the nMAG's and the LMA's possibility to control a transient BCE. Please refer to the Protocol Operations sections for a detailed protocol description (Sections 4.5 and 4.6).
本节概述了nMAG和LMA控制瞬态BCE的可能性。有关详细的协议说明，请参阅协议操作章节（第4.5节和第4.6节）。
Initiate a late path switch - Since the nMAG needs to have knowledge about the nature of a handover to set the Handoff Indicator (HI) option in the PBU and whether or not the handover implies a change in the used radio interface or technology, the nMAG is a suitable entity to make the decision to delay the downlink path switch in a controlled manner by means of a transient BCE. The nMAG can make the decision to initiate a transient BCE handover for an MN only when it knows that the MN supports a delayed downlink path switch (Section 4.7) according to this specification. It may know this due to a number of factors. For instance, during dual radio handover, most cellular networks have controlled handovers where the network knows that the host is moving from one attachment to another. In this situation, the link-layer mechanism can inform the mobility functions that this is indeed a movement, not a new attachment and that the MN has sufficient control on its interfaces to support a transient BCE handover. Where no support from the link layer exists and no such indication can be provided to the nMAG by the network, the nMAG MUST assume that the host is incapable of this mode of operation and employ standard behavior as specified in [RFC5213]. In other words, the nMAG initiates a regular [RFC5213] handover.
启动延迟路径切换-由于nMAG需要了解切换的性质，以便在PBU中设置切换指示灯（HI）选项，以及切换是否意味着所用无线电接口或技术的改变，nMAG是通过瞬态BCE以受控方式作出延迟下行链路路径切换的决定的合适实体。根据本规范，仅当nMAG知道MN支持延迟的下行链路路径切换（第4.7节）时，nMAG才可以决定为MN发起瞬态BCE切换。由于许多因素，它可能知道这一点。例如，在双无线电切换期间，大多数蜂窝网络具有控制切换，其中网络知道主机正在从一个连接移动到另一个连接。在这种情况下，链路层机制可以通知移动功能这确实是一个移动，而不是一个新的连接，并且MN对其接口具有足够的控制以支持瞬时BCE切换。如果链路层不支持，且网络无法向nMAG提供此类指示，则nMAG必须假设主机无法采用此操作模式，并采用[RFC5213]中规定的标准行为。换言之，nMAG发起常规的[RFC5213]切换。
The nMAG is also a suitable entity to estimate a maximum delay until the new connection can be used, as it knows about its locally connected radio network characteristics. Hence, the nMAG can set the maximum lifetime to delimit the transient BCE softstate at the LMA. The LMA may still override the proposed lifetime and notify the nMAG about the new lifetime in the Transient Binding option included in the PBA.
nMAG也是一个合适的实体，可以估计新连接可用之前的最大延迟，因为它知道其本地连接的无线网络特性。因此，nMAG可以设置最大寿命来限定LMA处的瞬态BCE软状态。LMA仍然可以覆盖提议的生存期，并在PBA中包含的瞬态绑定选项中通知nMAG新的生存期。
Activation of a transient BCE to perform a downlink path switch - During a transient BCE handover, the nMAG may get an indication that the MN's radio link can be used and the MN has completed the setup of the IP address to send and receive data packets via the new link. In this case, the nMAG can initiate turning a transient BCE into an active BCE before the expiration of the associated maximum transient BCE lifetime. To do that, the nMAG sends a PBU message without the Transient Binding option to the LMA. This results in a downlink path switch to the nMAG.
激活瞬态BCE以执行下行链路路径切换-在瞬态BCE切换期间，nMAG可能会得到指示，表明可以使用MN的无线链路，并且MN已完成IP地址的设置，以通过新链路发送和接收数据包。在这种情况下，nMAG可以在相关的最大瞬态BCE寿命到期之前启动将瞬态BCE转换为活动BCE。为此，nMAG向LMA发送一条不带瞬态绑定选项的PBU消息。这将导致到nMAG的下行链路路径切换。
Initiate a late path switch - If the LMA has received a PBU without a Transient Binding option included, the LMA can take a decision to use a transient BCE to optimize the handover performance. The LMA indicates its selected settings for the late path switch (L) and the associated maximum lifetime in the Transient Binding option, which is included in the PBA and sent to the nMAG.
启动延迟路径切换-如果LMA已接收到未包括瞬态绑定选项的PBU，则LMA可以决定使用瞬态BCE来优化切换性能。LMA在瞬态绑定选项中指示其为延迟路径开关（L）选择的设置和相关的最大生存期，该选项包括在PBA中并发送给nMAG。
Decision to use an optional activation state - The LMA is a suitable entity to decide about the use of an optional activation state, as the LMA has the knowledge about the MN's previous and new access technology. Hence, the LMA can make this decision to use an activation state to temporarily keep alive the forwarding of uplink packets from both MAGs, the pMAG, and the nMAG, even though the downlink path has been switched to the nMAG already. One reason to enter such an activation state may be a slow link between the pMAG and the LMA as described in Section 3.2.2.
决定使用可选激活状态-LMA是决定使用可选激活状态的合适实体，因为LMA了解MN以前和新的接入技术。因此，即使下行链路路径已经切换到nMAG，LMA也可以做出使用激活状态来临时保持来自mag、pMAG和nMAG两者的上行链路分组的转发活动的决定。进入这种激活状态的一个原因可能是pMAG和LMA之间的慢速链接，如第3.2.2节所述。
The current specification of transient BCEs covers three clearly defined transient BCE states at the LMA, which can be used during an MN's handover. Each state implies a dedicated characteristic regarding forwarding entries, in which forwarding rules for uplink traffic are maintained separately from downlink traffic. This section explains how the forwarding state sequentially changes during the optimized handoff. To suit different handover scenarios, different sequences through the forwarding states can be entered. Figure 4 depicts the possible cases, their sequence of forwarding states, and the triggers for the transitions. Two example use cases are described in detail in Appendix A to illustrate which sequence through the forwarding states suits a particular handover.
瞬态BCE的当前规范涵盖LMA处三种明确定义的瞬态BCE状态，可在MN切换期间使用。每个状态意味着关于转发条目的专用特性，其中上行链路业务的转发规则与下行链路业务分开维护。本节说明了在优化切换期间转发状态是如何顺序变化的。为了适应不同的切换场景，可以通过转发状态输入不同的序列。图4描述了可能的情况、它们的转发状态序列以及转换的触发器。附录A中详细描述了两个示例用例，以说明通过转发状态的哪个序列适合特定的切换。
According to this specification, each BCE has a state associated, which can be either 'Active' or any of the specified transient states 'Transient-L', 'Transient-LA', or 'Transient-A'. In the case that a BCE is in 'Active' state, the information in a BCE and associated forwarding conforms to [RFC5213].
根据本规范，每个BCE都有一个相关的状态，该状态可以是“激活”状态，也可以是任何指定的瞬态状态“瞬态L”、“瞬态LA”或“瞬态a”。在BCE处于“活动”状态的情况下，BCE中的信息和相关转发符合[RFC5213]。
Any of the transient states imply that the transient BCE has two forwarding entries, which are denoted as pMAG and nMAG in the forwarding state diagram. The diagram includes information about the forwarding rule along with each forwarding entry. This rule indicates whether a forwarding entry is meant to perform forwarding only for Uplink (Ul) traffic or to perform bi-directional forwarding for Uplink (Ul) and Downlink (Dl) traffic.
任何瞬态都意味着瞬态BCE有两个转发条目，它们在转发状态图中表示为pMAG和nMAG。该图包括有关转发规则的信息以及每个转发条目。此规则指示转发条目是仅针对上行链路（Ul）业务执行转发，还是针对上行链路（Ul）和下行链路（Dl）业务执行双向转发。
State transitions can be triggered as a result of processing a received PBU or by a local timeout event on the LMA. In the forwarding state chart below, the presence of a Transient Binding option in a PBU is indicated by 'Topt' as an argument to a PBU or PBA, respectively. As a further argument to a PBU message, the source of the message is indicated, which can be either the MN's nMAG or pMAG. A PBA is always sent by the LMA and addressed to the originator of the associated PBU.
处理接收到的PBU或LMA上的本地超时事件可触发状态转换。在下面的转发状态图中，PBU中存在的临时绑定选项分别用“Topt”表示为PBU或PBA的参数。作为PBU消息的另一个参数，指示消息的源，它可以是MN的nMAG或pMAG。PBA始终由LMA发送，并发送至相关PBU的发起人。
A handover with transient BCE is either triggered when the nMAG sends a PBU with a Transient Binding option or when the LMA decides to answer a normal PBU with a PBA after including a Transient Binding option. Figure 4 illustrates the possible transitions between an active BCE and a transient BCE from the LMA's point of view. It also shows the direct transition between two active BCE states during an MN's handover according to [RFC5213], bypassing any transient states.
当nMAG发送具有瞬时绑定选项的PBU时，或者当LMA在包括瞬时绑定选项后决定使用PBA应答正常PBU时，触发具有瞬时BCE的切换。图4从LMA的角度说明了活动BCE和瞬态BCE之间的可能转换。根据[RFC5213]，它还显示了MN切换期间两个活动BCE状态之间的直接转换，绕过了任何瞬态状态。
The diagram refers to two timeout events. TIMEOUT_1 is set according to the Lifetime value in a Transient Binding option (see Section 5 for the format of the Transient Binding option), whereas TIMEOUT_2 is set to ACTIVATIONDELAY (see Section 8 for the default value).
该图涉及两个超时事件。TIMEOUT_1根据瞬态绑定选项中的生存期值设置（参见第5节了解瞬态绑定选项的格式），而TIMEOUT_2设置为ACTIVATIONDELAY（参见第8节了解默认值）。
The first sequence of a transient BCE handover is followed when the LMA decides not to use the optional activation state and is going through Transient-L state, in which the LMA continues forwarding downlink packets to the pMAG, whereas uplink packets are accepted and forwarded from both, the pMAG and the nMAG. On reception of a PBU without a Transient Binding option from the nMAG, a TIMEOUT_1 event, or the reception of a deregistration PBU from the pMAG, the forwarding entry of the pMAG is removed from the MN's BCE, and the BCE state changes to active.
当LMA决定不使用可选激活状态并且正在经历瞬态L状态时，跟随瞬态BCE切换的第一序列，在该瞬态L状态中，LMA继续将下行链路分组转发给pMAG，而上行链路分组从pMAG和nMAG两者接受并转发。在从nMAG接收到没有瞬态绑定选项的PBU、超时事件或从pMAG接收到注销PBU时，从MN的BCE中删除pMAG的转发条目，BCE状态变为活动。
If the LMA decides to use the activation state, the second sequence is used. In this case, the BCE state turns into Transient-LA. Forwarding characteristics in the Transient-LA state are the same as for the Transient-L state, but the Transient-LA state follows a Transient-A state when the LMA receives a PBU from the nMAG without a Transient Binding option included or a TIMEOUT_1 event occurs. In the Transient-A state, the LMA performs a downlink forwarding path switch from the pMAG to the nMAG, whereas uplink packets are still accepted and forwarded from both, the pMAG and the nMAG. The Transient-A state is terminated by a TIMEOUT_2 event, the forwarding entry of the pMAG is removed from the MN's BCE, and the BCE state turns to active. If the LMA receives a deregistration PBU from the pMAG while the associated MN's BCE is in Transient-LA state, the uplink forwarding rule of the pMAG is no longer valid and the transition through Transient-A state is skipped. In such a case, the BCE turns into active state immediately.
如果LMA决定使用激活状态，则使用第二序列。在这种情况下，BCE状态变为瞬态LA。瞬态LA状态中的转发特性与瞬态L状态相同，但当LMA从nMAG接收到PBU而不包括瞬态绑定选项或发生超时事件时，瞬态LA状态遵循瞬态a状态。在瞬态A状态中，LMA执行从pMAG到nMAG的下行链路转发路径切换，而上行链路分组仍然从pMAG和nMAG两者接受和转发。瞬态A状态由超时_2事件终止，pMAG的转发条目从MN的BCE中删除，BCE状态变为激活状态。如果LMA在关联MN的BCE处于瞬态LA状态时从pMAG接收到注销PBU，则pMAG的上行链路转发规则不再有效，并且跳过通过瞬态a状态的转换。在这种情况下，BCE立即变为活动状态。
+----------------+ Before
PBU(nMAG) & PBA(LMA) | Active | Handover
+-----------------------| | --------
| | pMAG [Dl,Ul] | .
| *----------------* .
| | .
| | V
| PBU(nMAG, Topt) | PBU(nMAG) & PBA(LMA, Topt) .
| | .
| | .
| V Handover
| __________ Procedure
| / LMA \ .
| _________ / selects \ _________ .
| No| \ activation / |Yes .
| | \_state_?__/ | .
| | | V
| V V .
| +--------------+ +--------------+ .
| | Transient-L | | Transient-LA | .
| | | | | .
| | pMAG [Dl,Ul] | +-------| pMAG [Dl,Ul] | .
| | nMAG [Ul] | | | nMAG [Ul] | .
| +--------------+ | +--------------+ .
| | | |
| | PBU(pMAG, | PBU(nMAG) | TIMEOUT_1
| | lifetime=0)| | .
| | | V .
| | | +--------------+ .
| | | | Transient-A | .
| PBU(nMAG) | TIMEOUT_1 | | | .
| | | | nMAG [Dl,Ul] | .
| |PBU(pMAG, | | pMAG [Ul] | .
| | lifetime=0) | +--------------+ .
| | | |
| | | PBU(pMAG, | TIMEOUT_2
| | | lifetime=0)| .
| | | | V
| | | | -------
| | | | Handover
| | | V Complete
| | | +--------------+
| | +------->| Active |
| +-------------------------->| |
+----------------------------------------->| nMAG [Dl,Ul] |
+--------------+
+----------------+ Before
PBU(nMAG) & PBA(LMA) | Active | Handover
+-----------------------| | --------
| | pMAG [Dl,Ul] | .
| *----------------* .
| | .
| | V
| PBU(nMAG, Topt) | PBU(nMAG) & PBA(LMA, Topt) .
| | .
| | .
| V Handover
| __________ Procedure
| / LMA \ .
| _________ / selects \ _________ .
| No| \ activation / |Yes .
| | \_state_?__/ | .
| | | V
| V V .
| +--------------+ +--------------+ .
| | Transient-L | | Transient-LA | .
| | | | | .
| | pMAG [Dl,Ul] | +-------| pMAG [Dl,Ul] | .
| | nMAG [Ul] | | | nMAG [Ul] | .
| +--------------+ | +--------------+ .
| | | |
| | PBU(pMAG, | PBU(nMAG) | TIMEOUT_1
| | lifetime=0)| | .
| | | V .
| | | +--------------+ .
| | | | Transient-A | .
| PBU(nMAG) | TIMEOUT_1 | | | .
| | | | nMAG [Dl,Ul] | .
| |PBU(pMAG, | | pMAG [Ul] | .
| | lifetime=0) | +--------------+ .
| | | |
| | | PBU(pMAG, | TIMEOUT_2
| | | lifetime=0)| .
| | | | V
| | | | -------
| | | | Handover
| | | V Complete
| | | +--------------+
| | +------->| Active |
| +-------------------------->| |
+----------------------------------------->| nMAG [Dl,Ul] |
+--------------+
Figure 4: Possible transient forwarding states during a handover
图4：切换期间可能的瞬态转发状态
In case of a handover, the MN's nMAG may decide to control the MN's handover at the LMA to perform a late path switch according to the transient BCE procedure. In such a case, the nMAG includes the Transient Binding option in the PBU and sets the L-flag to 1 to indicate a late path switch. Furthermore, the nMAG MUST set the Lifetime field of the Transient Binding option to a value larger than 0 to propose a maximum lifetime of the transient BCE and to delimit the delay of switching the downlink path to the nMAG. The chosen lifetime value for the Transient Binding option SHOULD be smaller than the chosen lifetime value for the PBU registration. Other fields and options of the PBU are used according to [RFC5213].
在切换的情况下，MN的nMAG可以决定在LMA处控制MN的切换，以根据瞬态BCE过程执行延迟路径切换。在这种情况下，nMAG在PBU中包括瞬态绑定选项，并将L标志设置为1以指示延迟路径切换。此外，nMAG必须将瞬态绑定选项的生存期字段设置为大于0的值，以提出瞬态BCE的最大生存期，并限定将下行链路路径切换到nMAG的延迟。为瞬态绑定选项选择的生存期值应小于为PBU注册选择的生存期值。根据[RFC5213]使用PBU的其他字段和选项。
In case the nMAG does not include a Transient Binding option but the LMA decides to perform a handover according to the transient BCE procedure, the nMAG may receive a Transient Binding option along with the PBA from the LMA as a result of the PBU it sent to the LMA.
在nMAG不包括瞬时绑定选项但LMA决定根据瞬时BCE过程执行切换的情况下，nMAG可以作为其发送给LMA的PBU的结果从LMA接收瞬时绑定选项以及PBA。
In case the nMAG receives a PBA with a Transient Binding option having the L-flag set to 1, it SHOULD link the information about the transient BCE sequence and the associated transient BCE lifetime with the MN's entry in the BUL. Since the L-flag of the Transient Binding option is set to 1 to indicate a late path switch, the nMAG MAY turn an MN's transient BCE into an active BCE before the expiration of the transient BCE lifetime (TIMEOUT_1), e.g., when the MN's nMAG detects or gets informed that address configuration and radio bearer setup has been completed. To initiate turning a transient BCE into an active BCE, the nMAG sends a PBU to the LMA without including the Transient Binding option. All fields of the PBU are set according to the procedure for the binding lifetime extension described in Section 5.3.3 of [RFC5213]. In case the lifetime of a transient BCE expires or the LMA approves turning a transient BCE into an active BCE as a result of a PBU sent by the nMAG, the nMAG MUST delete all information associated with the transient BCE from the MN's BUL entry.
如果nMAG接收到一个PBA，其瞬时绑定选项的L标志设置为1，则它应将有关瞬时BCE序列和相关瞬时BCE寿命的信息与BUL中MN的条目相链接。由于瞬态绑定选项的L标志被设置为1以指示延迟路径切换，因此nMAG可以在瞬态BCE生存期（TIMEOUT_1）到期之前（例如，当MN的nMAG检测到或被通知地址配置和无线电承载设置已经完成时）将MN的瞬态BCE转变为活动BCE。为了启动将瞬态BCE转换为活动BCE，nMAG向LMA发送PBU，而不包括瞬态绑定选项。PBU的所有字段均根据[RFC5213]第5.3.3节所述的绑定寿命延长程序进行设置。如果瞬态BCE的寿命到期，或者LMA批准将瞬态BCE转换为活动BCE，则nMAG必须从MN的BUL条目中删除与瞬态BCE相关的所有信息。
In case the nMAG includes a Transient Binding option into the PBU, only one instance of the Transient Binding option per PBU is allowed.
如果nMAG在PBU中包含一个临时绑定选项，则每个PBU只允许一个临时绑定选项实例。
A MAG, which serves the MN current Proxy-CoA while the LMA already has an active or transient binding for the MN pointing to this MAG, SHALL NOT include a Transient Binding option in any subsequent PBU to create or update a transient BCE for the MN's current registration with this MAG.
当LMA已经具有指向该MAG的MN的活动或瞬态绑定时，为MN当前代理CoA服务的MAG不应在任何后续PBU中包括瞬态绑定选项，以创建或更新MN当前与该MAG注册的瞬态BCE。
In case the LMA receives a handover PBU from an MN's nMAG that does not include a Transient Binding option and the associated MN's BCE is active and not in transient state, the LMA MAY take the decision to use a transient BCE and inform the nMAG about the transient BCE characteristics by including a Transient Binding option in the PBA. In such a case, the LMA should know about the nMAG's capability to support the Transient Binding option. The configuration of the MN's transient BCE is performed according to the description in this section and the selected transient state. Otherwise, the LMA processes the PBU according to the PMIPv6 protocol [RFC5213] and performs a normal update of the MN's BCE.
如果LMA从MN的nMAG接收到不包括瞬时绑定选项的切换PBU，并且相关联的MN的BCE是活动的且不处于瞬时状态，则LMA可以作出使用瞬时BCE的决定，并通过在PBA中包括瞬时绑定选项来通知nMAG关于瞬时BCE特性。在这种情况下，LMA应该知道nMAG支持瞬态绑定选项的能力。MN瞬态BCE的配置根据本节中的描述和所选瞬态执行。否则，LMA根据PMIPv6协议[RFC5213]处理PBU，并执行MN的BCE的正常更新。
In case the PBU from the nMAG has a Transient Binding option included, the LMA must enter the sequence of transient BCE states according to its decision whether or not to use an optional activation state. In case the LMA decides not to use an activation state, it configures the MN's transient BCE and the forwarding rules according to Transient-L state. As a result, the LMA performs a late path switch and forwards downlink packets for the MN towards the MN's pMAG, whereas uplink packets being forwarded from both Proxy-CoAs, the MN's pMAG, as well as from its nMAG, will be routed by the LMA.
如果来自nMAG的PBU包含瞬态绑定选项，则LMA必须根据其是否使用可选激活状态的决定输入瞬态BCE状态序列。在LMA决定不使用激活状态的情况下，它根据transient-L状态配置MN的瞬时BCE和转发规则。结果，LMA执行延迟路径切换并将MN的下行链路分组转发到MN的pMAG，而从两个代理coa、MN的pMAG以及其nMAG转发的上行链路分组将由LMA路由。
In case the PBU from the nMAG has a Transient Binding option included and the LMA decides to use an optional activation state, the LMA configures the MN's transient BCE and the forwarding rules according to Transient-LA state. As a result, the LMA performs a late path switch and forwards downlink packets for the MN towards the MN's pMAG, whereas uplink packets being forwarded from both Proxy-CoAs, the MN's pMAG, as well as from its nMAG, will be routed by the LMA. In addition, the LMA marks the transient BCE to enter a temporary activation phase in Transient-A state after the LMA received an indication to turn a transient BCE into an active BCE.
如果来自nMAG的PBU包括瞬时绑定选项并且LMA决定使用可选激活状态，则LMA根据瞬时LA状态配置MN的瞬时BCE和转发规则。结果，LMA执行延迟路径切换并将MN的下行链路分组转发到MN的pMAG，而从两个代理coa、MN的pMAG以及其nMAG转发的上行链路分组将由LMA路由。此外，在LMA接收到将瞬态BCE转变为活动BCE的指示后，LMA将瞬态BCE标记为在瞬态a状态下进入临时激活阶段。
The LMA sets the lifetime of the transient BCE according to the lifetime indicated by the nMAG in the Transient Binding option's lifetime field or may decide to reduce the lifetime according to its policy. If the lifetime value in the Transient Binding option exceeds the lifetime value associated with the PBU message, the LMA MUST reduce the lifetime of the transient BCE to a value smaller than the registration lifetime value in the PBU message. In the case of a successful transient BCE registration, the LMA sends a PBA with a Transient Binding option back to the nMAG. The L-flag of the
LMA根据nMAG在瞬态绑定选项的生存期字段中指示的生存期设置瞬态BCE的生存期，或者可以根据其策略决定缩短生存期。如果瞬态绑定选项中的生存期值超过与PBU消息相关联的生存期值，则LMA必须将瞬态BCE的生存期减少到小于PBU消息中的注册生存期值的值。在瞬时BCE注册成功的情况下，LMA将带有瞬时绑定选项的PBA发送回nMAG。英国国旗
Transient Binding option MUST be set to 1 in this version of the specification. The lifetime field is set to the value finally chosen by the LMA.
在此版本的规范中，瞬态绑定选项必须设置为1。寿命字段设置为LMA最终选择的值。
In any case where the LMA finds the L-flag of the received Transient Binding option set to 1, but the lifetime field of the Transient Binding option is set to 0, the LMA MUST ignore the Transient Binding option and process the PBU according to [RFC5213]. After the PBU has been processed successfully, the LMA sends back a PBA with the status field set to PBU_ACCEPTED_TB_IGNORED_SETTINGSMISMATCH.
在LMA发现已接收瞬态绑定选项的L标志设置为1，但瞬态绑定选项的生存期字段设置为0的任何情况下，LMA必须忽略瞬态绑定选项，并根据[RFC5213]处理PBU。成功处理PBU后，LMA发回PBA，状态字段设置为PBU_ACCEPTED_TB_IGNORED_SettingsMatch。
In case the LMA receives a Transient Binding option with the L-flag set to 0, this version of the specification mandates the LMA to ignore the Transient Binding option and process the PBU according to [RFC5213]. After the PBU has been processed successfully, the LMA sends back a PBA with the status field set to PBU_ACCEPTED_TB_IGNORED_SETTINGSMISMATCH.
如果LMA接收到L标志设置为0的瞬态绑定选项，则此版本的规范要求LMA忽略瞬态绑定选项，并根据[RFC5213]处理PBU。成功处理PBU后，LMA发回PBA，状态字段设置为PBU_ACCEPTED_TB_IGNORED_SettingsMatch。
In case the LMA receives a PBU with a Transient Binding option included from a MAG that serves already as Proxy-CoA to the associated MN in an active or transient BCE, the LMA MUST ignore the Transient Binding option and process the PBU according to [RFC5213]. After the PBU has been processed successfully, the LMA sends back a PBA with the status field set to PBU_ACCEPTED_TB_IGNORED_SETTINGSMISMATCH. In case the MN's BCE was in transient state before receiving such PBU from the MAG, the LMA SHALL interpret this PBU as indication to turn a transient BCE into an active BCE and proceed with leaving the Transient-L or Transient-LA state, respectively.
如果LMA接收到一个PBU，该PBU包含一个瞬时绑定选项，该选项来自一个MAG，该MAG已经作为活动或瞬时BCE中相关MN的代理CoA，LMA必须忽略该瞬时绑定选项，并根据[RFC5213]处理该PBU。成功处理PBU后，LMA发回PBA，状态字段设置为PBU_ACCEPTED_TB_IGNORED_SettingsMatch。如果MN的BCE在从MAG接收此类PBU之前处于瞬态，LMA应将该PBU解释为将瞬态BCE转变为活动BCE的指示，并分别继续离开瞬态L或瞬态LA状态。
In any case where the LMA includes a Transient Binding option in the PBA, only one instance of the Transient Binding option per PBA is allowed.
在LMA在PBA中包括瞬时绑定选项的任何情况下，每个PBA仅允许一个瞬时绑定选项实例。
When the LMA receives a PBU from the MN's nMAG that has no Transient Binding option included but the MN's BCE is in a transient state or the LMA receives a local event trigger due to expiration of the MN's transient BCE, the LMA should check whether the forwarding rules for the associated MN are set to route the MN's downlink traffic to the MN's pMAG. If the forwarding entry for downlink packets refers to the MN's pMAG, the LMA must update the forwarding information to forward downlink packets towards the MN's nMAG. After the forwarding path has been switched, the LMA must update the MN's BCE accordingly.
当LMA从MN的nMAG接收到一个PBU，该PBU不包括瞬时绑定选项，但MN的BCE处于瞬时状态，或者LMA由于MN的瞬时BCE过期而接收到一个本地事件触发器，LMA应检查关联MN的转发规则是否设置为将MN的下行链路业务路由到MN的pMAG。如果下行链路分组的转发条目指的是MN的pMAG，则LMA必须更新转发信息以向MN的nMAG转发下行链路分组。在转发路径被切换之后，LMA必须相应地更新MN的BCE。
If the transient BCE indicates that the LMA must consider an activation state Transient-A after leaving a transient BCE has been initiated, the LMA must keep both forwarding entries for the pMAG and the nMAG for uplink packets and perform forwarding of packets it receives from both Proxy-CoAs. If no activation phase is indicated, the LMA sets the state of the MN's BCE to active and deletes any forwarding entry referring to the MN's pMAG. The LMA must delete any scheduled timeout event for the MN that is associated with a transient BCE.
如果瞬态BCE指示LMA必须考虑在离开瞬态BCE之后激活状态A，则LMA必须保持用于PMAG和NMAG的上行链路分组的转发条目，并且执行从两个代理COAS接收的分组的转发。如果未指示激活阶段，则LMA将MN的BCE的状态设置为active，并删除引用MN的pMAG的任何转发条目。LMA必须删除与瞬态BCE相关联的MN的任何计划超时事件。
When the LMA receives a deregistration PBU from the MN's pMAG, which has the registration lifetime set to 0 and the MN's BCE is in transient state, the LMA must update the forwarding rules for the MN and switch the downlink traffic path from the pMAG to the nMAG. Furthermore, the LMA sets the state of the MN's BCE to active and removes any forwarding entry towards the pMAG from the MN's BCE, irrespective of whether or not the transient BCE was configured to enter an activation state of Transient-A.
当LMA从MN的pMAG接收到注销PBU（其注册寿命设置为0且MN的BCE处于瞬态）时，LMA必须更新MN的转发规则，并将下行链路业务路径从pMAG切换到nMAG。此外，LMA将MN的BCE的状态设置为active，并从MN的BCE中移除朝向pMAG的任何转发条目，而不管瞬态BCE是否被配置为进入瞬态A的激活状态。
When the LMA receives a local event trigger due to the expiration of a timer that has been set to ACTIVATIONDELAY and scheduled to terminate the activation state of an MN's transient BCE, the LMA sets the state of the MN's BCE to active and removes any forwarding entry towards the pMAG from the MN's BCE.
当LMA由于设置为ACTIVATIONDELAY并计划终止MN的瞬时BCE的激活状态的计时器的到期而接收到本地事件触发器时，LMA将MN的BCE的状态设置为active，并从MN的BCE移除任何朝向pMAG的转发条目。
When the LMA receives a PBU for binding lifetime extension from the MN's pMAG while the MN's BCE is in transient state, the LMA must approve the lifetime extension to pMAG according to [RFC5213] and proceed with the transient BCE handover towards nMAG according to this specification.
当MN的BCE处于瞬态时，LMA从MN的pMAG接收到用于绑定寿命延长的PBU时，LMA必须根据[RFC5213]批准对pMAG的寿命延长，并根据本规范继续向nMAG进行瞬态BCE移交。
When the LMA receives a PBU from pMAG or a (n+1)MAG, which indicates a handover, e.g., according to the indications specified in [RFC5213], while the MN's BCE is in any of the specified transient states, the LMA MUST terminate the transient state and perform a handover to pMAG or (n+1)MAG, respectively, according to [RFC5213]. After the PBU has been processed successfully, the LMA sends back a PBA to the MAG that sent the PBU. If the PBU included a Transient Binding option, the LMA must ignore the Transient Binding option and set the status code of the PBA to PBU_ACCEPTED_TB_IGNORED_SETTINGSMISMATCH.
当LMA从pMAG或（n+1）MAG接收到PBU时，该PBU指示切换，例如，根据[RFC5213]中规定的指示，而MN的BCE处于任何规定的瞬态状态，LMA必须终止瞬态，并根据[RFC5213]分别向pMAG或（n+1）MAG执行切换。成功处理PBU后，LMA将PBA发送回发送PBU的MAG。如果PBU包含瞬态绑定选项，则LMA必须忽略瞬态绑定选项，并将PBA的状态代码设置为PBU_ACCEPTED_TB_IGNORED_SettingsMatch。
For a single radio handover, this specification does not require any additional functionality on the mobile node, when compared to [RFC5213].
对于单个无线电切换，与[RFC5213]相比，本规范不需要移动节点上的任何附加功能。
During dual radio handover, the MN benefits most from the transient BCE extension to PMIPv6 when it is able to keep communication on the previous interface while it is setting up its handover target interface with the configuration context that has been received as a result of the new interface's attachment to the nMAG. Various techniques enable support for such an operation, e.g., the use of a virtual interface on top of physical radio interfaces [NETEXT] or implementation-specific extensions to the MN's protocol stack. Details about how to enable such make-before-break support on the MN are out of scope of this document.
在双无线电切换期间，MN从PMIPv6的瞬态BCE扩展中获益最大，因为它能够在前一个接口上保持通信，同时使用新接口连接到nMAG时接收到的配置上下文设置其切换目标接口。各种技术支持这种操作，例如，在物理无线电接口[NETEXT]上使用虚拟接口或对MN的协议栈进行特定于实现的扩展。关于如何在MN上启用这种先制造后破坏支持的详细信息超出了本文档的范围。
This section specifies the following PBA status value (6) for transient binding cache entry support. This status value is smaller than 128 and has been added to the set of status values specified in [RFC5213].
本节为瞬态绑定缓存项支持指定以下PBA状态值（6）。该状态值小于128，并已添加到[RFC5213]中指定的状态值集合中。
PBU_ACCEPTED_TB_IGNORED_SETTINGSMISMATCH: 6
PBU_已接受\u TB_已忽略\u设置匹配：6
The LMA has processed and accepted the PBU, but the attached Transient Binding option has been ignored.
LMA已处理并接受PBU，但已忽略附加的瞬态绑定选项。
The specification and use of transient BCEs ensures that correct PMIPv6 operation according to [RFC5213] will not be broken in any case. Such cases include loss of signaling information and incompatibility between an nMAG and an LMA in case one or the other side does not support the transient BCE option. The following list summarizes such cases and describes how the PMIPv6 protocol operation resolves incompatibility or loss of a signaling message.
瞬态BCE的规范和使用确保在任何情况下都不会破坏符合[RFC5213]的正确PMIPv6操作。这种情况包括在一方或另一方不支持瞬态BCE选项的情况下，nMAG和LMA之间的信令信息丢失和不兼容。下表总结了此类情况，并描述了PMIPv6协议操作如何解决信令消息的不兼容或丢失。
LMA does not support transient BCEs: In case the nMAG sends a PBU with a Transient Binding option included to an LMA but the LMA does not support transient BCEs, the LMA ignores the unknown option [RFC3775] and processes the PBU according to [RFC5213]. Since the nMAG receives a PBA that has no Transient Binding option included, it does not set any transient binding information in the MN's BUL entry and operates according to [RFC5213].
LMA不支持瞬时BCE：如果nMAG发送包含瞬时绑定选项的PBU到LMA，但LMA不支持瞬时BCE，LMA将忽略未知选项[RFC3775]，并根据[RFC5213]处理PBU。由于nMAG接收到的PBA不包含瞬时绑定选项，因此它不会在MN的BUL条目中设置任何瞬时绑定信息，并根据[RFC5213]进行操作。
nMAG does not support transient BCEs: In case the LMA makes the decision to perform a handover according to any of the specified transient BCE sequences and includes a Transient Binding option in the PBA, the receiving nMAG ignores the unknown option [RFC3775] and processes the PBA according to [RFC5213]. As the LMA does not get any further indication or feedback about the incompatibility at the nMAG, the LMA enters the selected transient state, which will be terminated at the latest time after (TIMEOUT_1 + ACTIVATIONDELAY) seconds. During this period, the nMAG performs according to the PMIPv6 specification [RFC5213], whereas the LMA will accept all uplink packets for the MN, from the pMAG, as well as from the nMAG according to the transient BCE specification. It is transparent to the nMAG if the LMA forwards downlink packets to the pMAG during the transient BCE phase; thus, no protocol conflict occurs due to the different states on the nMAG and the LMA.
nMAG不支持瞬时BCE：如果LMA决定根据任何指定的瞬时BCE序列执行切换，并在PBA中包含瞬时绑定选项，则接收nMAG忽略未知选项[RFC3775]，并根据[RFC5213]处理PBA。由于LMA没有收到关于nMAG不兼容的任何进一步指示或反馈，LMA进入所选瞬态，该瞬态将在（超时1+激活显示）秒后的最晚时间终止。在此期间，nMAG根据PMIPv6规范[RFC5213]执行，而LMA将根据瞬态BCE规范接受来自pMAG以及来自nMAG的MN的所有上行链路分组。如果LMA在瞬态BCE阶段将下行链路分组转发给pMAG，则对nMAG是透明的；因此，由于nMAG和LMA上的状态不同，不会发生协议冲突。
Loss of Transient Binding option: As the Transient Binding option is included in the PBU and PBA, recovery from signaling packet loss is according to the PMIPv6 protocol operation and associated re-transmission mechanisms [RFC5213].
丢失瞬态绑定选项：由于瞬态绑定选项包含在PBU和PBA中，因此根据PMIPv6协议操作和相关的重新传输机制来恢复信令包丢失[RFC5213]。
Missing PBU to turn a transient BCE into an active BCE: According to this specification, a lifetime for TIMEOUT_1 is signaled in the Transient Binding option, and turning a transient BCE into an active BCE is initiated at the latest time after the timer TIMEOUT_1 has elapsed. In case PBU signaling is lost or the nMAG fails to initiate turning a transient BCE into an active BCE, the transient state of the MN's BCE will be terminated after expiration of the set lifetime, i.e., stable operation of the PMIPv6 protocol [RFC5213] has reliably recovered.
缺少PBU以将瞬态BCE转换为活动BCE：根据本规范，在瞬态绑定选项中发出超时生存期_1的信号，并在计时器超时_1过去后的最晚时间启动将瞬态BCE转换为活动BCE。如果PBU信令丢失或nMAG未能启动将瞬态BCE转换为活动BCE，则MN的BCE的瞬态将在设定的寿命到期后终止，即，PMIPv6协议[RFC5213]的稳定运行已可靠恢复。
Lost connection with pMAG during late path switch: In case an MN loses connectivity to its pMAG during a transient BCE phase with late path switch and the nMAG fails to initiate turning a transient BCE into an active BCE to perform the path switch to the nMAG, in a worst-case scenario, downlink packets are lost until the chosen TIMEOUT_1 expires. After TIMEOUT_1 seconds, the protocol operation has been recovered successfully. However, this case is very unlikely for two reasons: If the connectivity to the pMAG is lost, the pMAG will send a deregistration PBU for the MN to the LMA, which results in turning the transient BCE into an active BCE and in a path switch. Furthermore, the nMAG will initiate turning the transient BCE into an active BCE as soon as the setup of the data link between the MN and the nMAG has been completed (Section 4.4). Note that this case, in particular, affects downlink packets, whereas uplink packets can be sent
在延迟路径切换期间与pMAG的连接中断：如果MN在延迟路径切换的瞬态BCE阶段与其pMAG失去连接，并且nMAG无法启动将瞬态BCE转换为活动BCE以执行到nMAG的路径切换，则在最坏情况下，下行链路数据包将丢失，直到所选的超时_1过期。超时1秒后，协议操作已成功恢复。然而，这种情况不太可能发生，原因有两个：如果与pMAG的连接丢失，pMAG将向LMA发送MN的注销PBU，这将导致瞬态BCE变为活动BCE和路径开关。此外，一旦MN和nMAG之间的数据链路设置完成，nMAG将启动将瞬态BCE转换为活动BCE（第4.4节）。注意，这种情况尤其影响下行链路分组，而上行链路分组可以被发送
through the new connection after a broken link to the pMAG has been detected.
检测到pMAG的断开链接后，通过新连接。
Binding lifetime extension from pMAG while MN's BCE is transient: As the binding lifetime of the pMAG and the nMAG is not correlated, pMAG may send a PBU for binding lifetime extension to the MN's LMA while the MN's BCE is in transient state. In such a case, the LMA will approve the binding lifetime extension to pMAG according to [RFC5213] and proceed with the transient BCE handover towards nMAG according to this specification.
当MN的BCE处于瞬态时，pMAG的绑定生存期延长：由于pMAG和nMAG的绑定生存期不相关，当MN的BCE处于瞬态时，pMAG可能会向MN的LMA发送PBU以延长绑定生存期。在这种情况下，LMA将根据[RFC5213]批准对pMAG的绑定寿命延长，并根据本规范继续向nMAG进行短暂BCE移交。
The specification of the transient BCE extension maintains stable operation of PMIPv6 in case the MN performs very frequent handover, e.g., movement while the MN's handover between the pMAG and the nMAG is still in progress. Such corner cases are summarized in the following list.
瞬态BCE扩展的规范在MN执行非常频繁的切换（例如移动）的情况下保持PMIPv6的稳定运行，而MN在pMAG和nMAG之间的切换仍在进行中。下面的列表中总结了此类角落案例。
Handover to (n+1)MAG during transient BCE: In case the MN's BCE is transient due to a handover from the pMAG to nMAG and during the transient BCE, the MN performs a further handover to a MAG that is different from pMAG and nMAG, say to (n+1)MAG, the LMA terminates the transient BCE and performs a handover to (n+1)MAG according to [RFC5213].
在瞬态BCE期间向（n+1）MAG的切换：如果MN的BCE由于从pMAG向nMAG的切换而是瞬态的，并且在瞬态BCE期间，MN执行向不同于pMAG和nMAG的MAG的进一步切换，例如向（n+1）MAG的切换，则LMA终止瞬态BCE并根据[RFC5213]执行向（n+1）MAG的切换。
Handover back to pMAG during transient BCE (ping pong): In case the MN's BCE is transient due to a handover from the pMAG to nMAG and the MN moves back from nMAG to pMAG during the transient BCE, the LMA terminates the transient BCE and performs a handover to pMAG according to [RFC5213].
在瞬态BCE（乒乓）期间切换回pMAG：如果MN的BCE由于从pMAG切换到nMAG而变为瞬态，并且MN在瞬态BCE期间从nMAG移回pMAG，则LMA终止瞬态BCE，并根据[RFC5213]执行到pMAG的切换。
This section describes the format of the Transient Binding option, which can be included in a Proxy Binding Update message and a Proxy Binding Acknowledge message. The use of this Mobility Header option is optional.
本节介绍临时绑定选项的格式，该选项可以包含在代理绑定更新消息和代理绑定确认消息中。此移动标头选项的使用是可选的。
The Transient Binding option can be included in a PBU message, which is sent by an MN's nMAG as a result of a handover. In such a case, the nMAG controls the transient BCE on the LMA. Alternatively, the LMA may attach the Transient Binding option in a PBA for two reasons. Either it replies to a received PBU with an attached Transient Binding option to approve or correct the transient BCE lifetime, or it notifies the nMAG about its decision to enter a transient BCE without having received a Transient Binding option from the nMAG in the associated PBU beforehand.
临时绑定选项可以包含在PBU消息中，该消息由MN的nMAG作为切换的结果发送。在这种情况下，nMAG控制LMA上的瞬态BCE。或者，出于两个原因，LMA可以在PBA中附加瞬时绑定选项。它使用附加的瞬态绑定选项回复接收到的PBU，以批准或更正瞬态BCE生存期，或者通知nMAG其决定进入瞬态BCE，而事先未从关联PBU中的nMAG收到瞬态绑定选项。
The Transient Binding option has no alignment requirement. Its format is as follows:
瞬态绑定选项没有对齐要求。其格式如下：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |L| Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |L| Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: Identifies the Transient Binding option (43).
类型：标识瞬态绑定选项（43）。
Length: 8-bit unsigned integer indicating the length of the option in octets, excluding the Type and the Length fields. This field MUST be set to 2.
长度：8位无符号整数，以八位字节表示选项的长度，不包括类型和长度字段。此字段必须设置为2。
L-Flag: Indicates that the LMA applies late path switch according to the transient BCE state. If the L-flag is set to 1, the LMA continues to forward downlink packets towards the pMAG. Different setting of the L-Flag may be for future use.
L标志：表示LMA根据瞬态BCE状态应用延迟路径切换。如果L标志设置为1，则LMA继续向pMAG转发下行链路分组。L标志的不同设置可供将来使用。
Lifetime: Maximum lifetime of a Transient-L state in multiple of 100 ms.
寿命：瞬态-L状态的最大寿命（100 ms的倍数）。
This specification adds a new Mobility Header option, the Transient Binding option. The Transient Binding option is described in Section 5.1. The Type value (43) for this option has been registered in the Mobility Options registry, the numbering space allocated for the other mobility options, as defined in [RFC3775].
该规范添加了一个新的移动头选项，即瞬态绑定选项。第5.1节描述了瞬态绑定选项。此选项的类型值（43）已在移动性选项注册表中注册，即为其他移动性选项分配的编号空间，如[RFC3775]中所定义。
This specification also adds one status code value to the Proxy Binding Acknowledge message, the PBU_ACCEPTED_TB_IGNORED_SETTINGSMISMATCH status code (6). The PBU_ACCEPTED_TB_IGNORED_SETTINGSMISMATCH status code is described in Section 4.8. Its value has been assigned from the Status Codes sub-registry as defined in [RFC3775] and has a value smaller than 128.
该规范还向代理绑定确认消息添加了一个状态代码值，即PBU_已接受_TB_已忽略_设置匹配状态代码（6）。第4.8节中描述了PBU_接受_TB_忽略_设置匹配状态代码。其值已从[RFC3775]中定义的状态代码子注册表分配，且其值小于128。
Signaling between MAGs and LMAs as well as information carried by PBU and PBA messages is protected and authenticated according to the mechanisms described in [RFC5213]. No new security considerations are introduced in addition to those in [RFC5213]. Thus, the security considerations described throughout [RFC5213] apply here as well.
MAG和LMA之间的信令以及PBU和PBA消息携带的信息根据[RFC5213]中描述的机制进行保护和认证。除[RFC5213]中的安全注意事项外，未引入新的安全注意事项。因此，[RFC5213]中描述的安全注意事项也适用于此处。
In case the MAGs or LMAs make use of a further protocol interface to an external component, such as for support of transient BCE control, the associated protocol must be protected and information must be authenticated.
如果MAG或LMA使用与外部组件的进一步协议接口，例如用于支持瞬态BCE控制，则必须保护相关协议，并且必须对信息进行身份验证。
LMA values:
LMA值：
o 'ACTIVATIONDELAY': This value is set by default to 2000 ms and can be administratively adjusted.
o “ACTIVATIONDELAY”：此值默认设置为2000毫秒，可以进行管理调整。
Many thanks to Jun Awano, Suresh Krishnan, Long Le, Kent Leung, Basavaraj Patil, and Rolf Sigle for contributing to this document.
非常感谢Jun Awano、Suresh Krishnan、Long Le、Kent Leung、Basavaraj Patil和Rolf Sigle对本文件的贡献。
The authors would like to thank Telemaco Melia, Vijay Devarapalli, Rajeev Koodli, Ryuji Wakikawa, and Pierrick Seite for their valuable comments to improve this specification.
作者要感谢Telemaco Melia、Vijay Devarapalli、Rajeev Koodli、Ryuji Wakikawa和Pierrick Seite对改进本规范提出的宝贵意见。
[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。
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004.
[RFC3775]Johnson，D.，Perkins，C.，和J.Arkko，“IPv6中的移动支持”，RFC 37752004年6月。
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5213]Gundavelli，S.，Leung，K.，Devarapalli，V.，Chowdhury，K.，和B.Patil，“代理移动IPv6”，RFC 5213，2008年8月。
[NETEXT] Melia, T., Ed. and S. Gundavelli, Ed., "Logical Interface Support for multi-mode IP Hosts", Work in Progress, October 2010.
[NETEXT]Melia，T.，Ed.和S.Gundavelli，Ed.，“多模式IP主机的逻辑接口支持”，正在进行的工作，2010年10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。
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007.
[RFC4862]Thomson，S.，Narten，T.，和T.Jinmei，“IPv6无状态地址自动配置”，RFC 48622007年9月。
[TS23.401] "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access", <http://www.3gpp.org>.
[TS23.401]“通用分组无线业务（GPRS）增强，用于演进通用地面无线接入网（E-UTRAN）接入”<http://www.3gpp.org>.
[TS23.402] "Architecture enhancements for non-3GPP accesses (Release 9)", <http://www.3gpp.org>.
[TS23.402]“非3GPP接入的架构增强（第9版）”<http://www.3gpp.org>.
In some systems, such as the 3GPP Evolved Packet Core, PMIPv6 is supported for providing network-based mobility between the Serving Gateway (i.e., MAG) and the Packet Data Network Gateway (i.e., LMA) and handover mechanisms are implemented in the access network to optimize handover for single radio mobile nodes [TS23.401].
在一些系统中，例如3GPP演进分组核心，支持PMIPv6以在服务网关（即MAG）和分组数据网络网关（即LMA）之间提供基于网络的移动性，并且在接入网络中实现切换机制以优化单个无线移动节点的切换[TS23.401]。
In such a system, a well structured inter-MAG handover procedure has been developed and effectively used. In order to switch the data tunnel path between the LMA and the pMAG in a systematic way that reduces packet loss and delay, this inter-MAG handover sets up the uplink data path from the mobile node through the nMAG and to the LMA first. As soon as the uplink data path is set up, the mobile node is able to forward uplink data packets through the nMAG to the LMA.
在这样一个系统中，已经开发并有效地使用了结构良好的MAG间切换程序。为了以减少分组丢失和延迟的系统方式在LMA和pMAG之间切换数据隧道路径，该MAG间切换首先建立从移动节点经由nMAG到LMA的上行链路数据路径。一旦建立了上行链路数据路径，移动节点就能够通过nMAG将上行链路数据分组转发到LMA。
Since the downlink data path between the LMA and the nMAG is not set up at the same time as the uplink data path, the LMA must continue to forward downlink data packets to the pMAG. Additionally, this system utilizes a layer 2 forwarding mechanism from the previous Access Network (pAN) to the new Access Network (nAN), which enables the delivery of the downlink data packets to the mobile node location while being attached to the nMAG.
由于LMA和nMAG之间的下行链路数据路径不是与上行链路数据路径同时建立的，因此LMA必须继续向pMAG转发下行链路数据分组。此外，该系统利用从先前接入网络（pAN）到新接入网络（nAN）的第2层转发机制，这使得能够在连接到nMAG的同时将下行链路数据分组传送到移动节点位置。
In order for the LMA to be able to forward the mobile node uplink data packets to the Internet, the transient BCE mechanism is used at the nMAG to send a PBU with the Transient Binding option to allow the LMA to create a transient BCE for the mobile node with uplink forwarding capabilities while maintaining uplink and downlink forwarding capabilities for the Proxy-CoA that is hosted at the pMAG.
为了使LMA能够将移动节点上行链路数据分组转发到因特网，在nMAG处使用瞬时BCE机制来发送具有瞬时绑定选项的PBU，以允许LMA为具有上行链路转发能力的移动节点创建瞬时BCE，同时保持在pMAG处托管的代理CoA的上行链路和下行链路转发能力。
During the lifetime of the transient BCE, the LMA continues to accept uplink traffic from both previous and new MAG while forwarding downlink traffic to the pMAG only. While the MN is able to receive downlink traffic via the pMAG, the mechanism used in the pMAG's access network to forward downlink traffic to the current location of the mobile node in the nMAG's access network during an intra-technology handover is out of scope of this description.
在瞬态BCE的生存期内，LMA继续接受来自先前和新MAG的上行链路业务，同时仅将下行链路业务转发给pMAG。虽然MN能够经由pMAG接收下行链路业务，但是在技术内切换期间，pMAG的接入网络中用于将下行链路业务转发到nMAG的接入网络中的移动节点的当前位置的机制不在本描述的范围内。
When the nMAG receives an indication that the inter-MAG handover process has completed, the nMAG sends another PBU without including a Transient Binding option to update the mobile node's transient BCE to a regular PMIPv6 BCE with bi-directional capabilities. This mechanism is used by the LMA as an indication to switch the tunnel to point to the nMAG, which results in a smoother handover for the MN.
当nMAG接收到MAG间切换过程已经完成的指示时，nMAG发送另一个PBU，而不包括瞬时绑定选项，以将移动节点的瞬时BCE更新为具有双向能力的常规PMIPv6 BCE。LMA使用该机制作为切换隧道以指向nMAG的指示，这导致MN的平滑切换。
An example of using a transient BCE for intra-technology handover is illustrated in Figure 5. When the nMAG receives the indication that the MN is moving from the pMAG's access network to the nMAG's area, the nMAG sends a PBU on behalf of the MN to the MN's LMA. In this PBU, the nMAG includes the MN-ID, the HNP, and the interface ID as per PMIPv6 base protocol [RFC5213].
图5说明了使用瞬态BCE进行技术内切换的示例。当nMAG接收到MN正从pMAG的接入网络移动到nMAG的区域的指示时，nMAG代表MN向MN的LMA发送PBU。在该PBU中，nMAG包括符合PMIPv6基本协议[RFC5213]的MN-ID、HNP和接口ID。
Furthermore, the nMAG indicates an intra-technology handover by means of the HI option and includes the Transient Binding option to indicate to the LMA that this registration should result in a transient BCE with a late downlink path switch. The nMAG sets the value of the transient BCE lifetime to a value that is dependent on the deployment and operator specific [D].
此外，nMAG通过HI选项指示技术内切换，并包括瞬时绑定选项，以向LMA指示该注册应导致具有后期下行链路路径开关的瞬时BCE。nMAG将瞬态BCE生存期的值设置为一个取决于部署和特定于操作员的[D]的值。
After the nMAG receives an indication that the MN has completed the handover process and the data path is ready to move the tunnel completely from the pMAG to the nMAG, the nMAG SHOULD send a PBU to allow the LMA to turn the MN's transient BCE into a regular BCE and to switch the data path completely to be delivered through the new Proxy-CoA. In this case, the nMAG sends a PBU with the MN-ID, Interface ID, and HNP and at the same time indicates an intra-technology handover by means of the HI option. In this PBU, the nMAG MUST NOT include the Transient Binding option, as shown in Figure 5 [E].
在nMAG接收到MN已完成切换过程且数据路径已准备好将隧道从pMAG完全移动到nMAG的指示后，nMAG应发送PBU，以允许LMA将MN的瞬态BCE转换为常规BCE，并完全切换数据路径以通过新的代理CoA交付。在这种情况下，nMAG发送具有MN-ID、接口ID和HNP的PBU，同时通过HI选项指示技术内切换。在这个PBU中，nMAG不能包括瞬态绑定选项，如图5[E]所示。
In the event that the nMAG receives downlink traffic destined to the MN from the LMA after sending a PBU with the Transient Binding option included, the nMAG MUST deliver the downlink traffic to the MN. In this case, the nMAG SHOULD send a PBU to ensure that the transient BCE has been turned into an active BCE.
在nMAG在发送包括瞬时绑定选项的PBU之后从LMA接收到目的地为MN的下行链路业务的情况下，nMAG必须将下行链路业务传送到MN。在这种情况下，nMAG应发送一个PBU，以确保瞬态BCE已变为活动BCE。
+-----+ +----+ +----+ +-----+
| MN | |pMAG| |nMAG| | LMA |
+-----+ +----+ +----+ +-----+
| | | bi-directional |
| |<<<<<<<<======================>>>>>>>>|<-->
| | | |
| | | |
[Handoff Event] | | |
| [MN HO Event] | |
| | [HO Event Acquire] |
| | | |
[LL Attach to | | |
nMAG] | |-----PBU(transient)----->|
| | | [D]
| | |<-----PBA(transient)-----|
| | | |
| | bi-directional |
| |<--->|<<<<<<<<======================>>>>>>>>|<-->
| pAN | | |
| |----------->| | |
| | nAN | |
|<------------------| |uplink only |
|------------------>|---->|>>>>>>===========>>>>>>>>|--->
| | | |
| | [HO Complete] |
| | |----------PBU----------->|
| | | [E]
| | |<---------PBA -----------|
| |` | |
| | |<<<<<<<<=========>>>>>>>>|<-->
| | | |
+-----+ +----+ +----+ +-----+
| MN | |pMAG| |nMAG| | LMA |
+-----+ +----+ +----+ +-----+
| | | bi-directional |
| |<<<<<<<<======================>>>>>>>>|<-->
| | | |
| | | |
[Handoff Event] | | |
| [MN HO Event] | |
| | [HO Event Acquire] |
| | | |
[LL Attach to | | |
nMAG] | |-----PBU(transient)----->|
| | | [D]
| | |<-----PBA(transient)-----|
| | | |
| | bi-directional |
| |<--->|<<<<<<<<======================>>>>>>>>|<-->
| pAN | | |
| |----------->| | |
| | nAN | |
|<------------------| |uplink only |
|------------------>|---->|>>>>>>===========>>>>>>>>|--->
| | | |
| | [HO Complete] |
| | |----------PBU----------->|
| | | [E]
| | |<---------PBA -----------|
| |` | |
| | |<<<<<<<<=========>>>>>>>>|<-->
| | | |
Figure 5: Transient BCE support for an intra-technology handover
图5：技术内切换的瞬时BCE支持
During an inter-technology handover, the LMA shall, on the one hand, be able to accept uplink packets of the MN as soon as the MN has finalized address configuration at the new IF2 and may start using the new interface for data traffic, i.e., the PBU for the uplink shall be done before the radio setup procedure is finalized. But, to allow the MN to keep sending its data traffic on IF1 during the handover, uplink packets with the previously existing binding on IF1 shall still be accepted by the LMA until the MN detaches from pMAG with IF1 and the pMAG has deregistered the MN's attachment at the LMA by means of sending a PBU with lifetime 0. This is of particular importance as sending the registration PBU from the nMAG is transparent to the mobile node, i.e., the MN does not know when the
在技术间切换期间，一方面，一旦MN在新IF2处完成地址配置，LMA应能够接受MN的上行链路分组，并且可以开始使用新的数据业务接口，即，上行链路的PBU应在无线电设置程序完成之前完成。但是，为了允许MN在切换期间继续在IF1上发送其数据业务，LMA仍应接受IF1上先前存在的绑定的上行链路分组，直到MN使用IF1从pMAG分离，并且pMAG通过发送生存期为0的PBU在LMA上注销MN的附件。这是特别重要的，因为从nMAG发送注册PBU对移动节点是透明的，即MN不知道注册的时间
PBU has been sent. On the other hand, switching the downlink path from the pMAG to the nMAG shall be performed at the LMA only after completion of the IP configuration at the MN's IF2 and after a complete setup of the access link between the MN and the nMAG. How long this takes depends on some interface-specific settings on the MN as well as on the duration of the target system's radio layer protocols, which is transparent to the LMA but may be known to MAGs.
已发送PBU。另一方面，从pMAG到nMAG的下行链路路径的切换应仅在MN的IF2处的IP配置完成之后以及在MN和nMAG之间的接入链路的完整设置之后在LMA处执行。这需要多长时间取决于MN上的某些接口特定设置以及目标系统无线电层协议的持续时间，该协议对LMA是透明的，但MAG可能知道。
Similar to the use case for single radio handover, a transient BCE can be utilized for MNs with dual radio capability. Such MNs are still able to send and receive data on the previous interface during the address configuration on the new interface. Forwarding between the nMAG and pMAG is not required, but the case in which the LMA immediately starts forwarding downlink data packets to the nMAG has to be avoided. This is enabled by a PBU that has the Transient Binding option included, so that it is not necessary that MN and LMA synchronize the point in time for switching interfaces and turning a transient BCE into an active BCE.
与单无线电切换的用例类似，瞬时BCE可用于具有双无线电能力的MNs。在新接口上的地址配置期间，此类MN仍然能够在先前接口上发送和接收数据。nMAG和pMAG之间不需要转发，但是必须避免LMA立即开始向nMAG转发下行链路数据分组的情况。这由包含瞬态绑定选项的PBU启用，因此MN和LMA无需同步切换接口和将瞬态BCE转换为活动BCE的时间点。
When the handover is finalized, the nMAG sends a second PBU without including the Transient Binding option and the LMA turns the MN's BCE into an active BCE. This PBU may overtake packets-on-the-fly from MN to LMA via pMAG (e.g., if the previous interface was of type GSM or Universal Mobile Telecommunications System (UMTS) with up to 150 milliseconds of uplink delay). The LMA has to drop all these packets from the pMAG due to the characteristics of the MN's active BCE. This can be avoided by entering another transient BCE state (Transient-A) during the activation phase and is characteristic for this use case. Whether or not to enter a Transient-A state is decided by the LMA.
当切换完成时，nMAG发送第二个PBU而不包括瞬时绑定选项，LMA将MN的BCE转变为活动BCE。该PBU可通过pMAG（例如，如果先前的接口为GSM或通用移动通信系统（UMTS）类型，上行链路延迟高达150毫秒），在从MN到LMA的飞行中超越数据包。由于MN的活动BCE的特性，LMA必须从pMAG丢弃所有这些数据包。这可以通过在激活阶段进入另一个瞬态BCE状态（瞬态-A）来避免，这是本用例的特征。是否进入瞬态a状态由LMA决定。
The use of a transient BCE for an inter-technology handover is exemplarily illustrated in Figure 6. The MN attaches to the PMIPv6 network with IF1 according to the procedure described in [RFC5213]. The MN starts receiving data packets on IF1. When the MN activates IF2 to prepare an inter-technology handover, the nMAG receives an attach indication and sends the PBU to the LMA to update the MN's point of attachment and to retrieve configuration information for the MN (e.g., HNP). The LMA is able to identify an inter-technology handover by means of processing the HI option coming along with the PBU sent by the nMAG. As in this example, the nMAG includes the Transient Binding option in the PBU to control the transient BCE at the LMA, the LMA updates the MN's BCE according to the transient BCE specification described in this document and marks the state of the BCE as 'transient' [F].
图6举例说明了使用瞬态BCE进行技术间切换。MN根据[RFC5213]中描述的程序，通过IF1连接到PMIPv6网络。MN开始在IF1上接收数据包。当MN激活IF2以准备技术间切换时，nMAG接收到连接指示并将PBU发送到LMA以更新MN的连接点并检索MN的配置信息（例如，HNP）。LMA能够通过处理nMAG发送的PBU随附的HI选项来识别技术间切换。如在该示例中，nMAG在PBU中包括瞬态绑定选项以控制LMA处的瞬态BCE，LMA根据本文档中描述的瞬态BCE规范更新MN的BCE，并将BCE的状态标记为“瞬态”[F]。
As a result of the transient BCE, the LMA keeps using the previous forwarding information towards the pMAG binding as forwarding information until the transient BCE gets turned into active. The LMA acknowledges the PBU by means of sending a PBA to the nMAG. The nMAG now has relevant information available, such as the MN's HNP, to set up a radio bearer and send a Router Advertisement to the MN. While the MN's BCE at the LMA has a transient characteristic, the LMA forwards uplink packets from the MN's pMAG as well as from its nMAG. The nMAG may recognize when the MN's IF2 is able to send and receive data packets and sends a new PBU to the LMA without including the Transient Binding option to initiate turning the MN's transient BCE into an active BCE [G]. As a result of successfully turning the MN's transient BCE into an active BCE, downlink packets will be forwarded towards the MN's IF2 via the nMAG [H].
作为瞬态BCE的结果，LMA将继续使用前一个针对pMAG绑定的转发信息作为转发信息，直到瞬态BCE变为活动状态。LMA通过向nMAG发送PBA来确认PBU。nMAG现在有可用的相关信息，例如MN的HNP，用于设置无线电承载并向MN发送路由器广告。当LMA处的MN的BCE具有瞬态特性时，LMA转发来自MN的pMAG及其nMAG的上行链路分组。nMAG可以识别MN的IF2何时能够发送和接收数据分组，并向LMA发送新的PBU，而不包括瞬态绑定选项以启动将MN的瞬态BCE转变为活动BCE[G]。作为成功地将MN的瞬时BCE转变为活动BCE的结果，下行链路分组将经由nMAG[H]转发到MN的IF2。
+------+ +----+ +----+ +---+
| MN | |pMAG| |nMAG| |LMA|
+------+ +----+ +----+ +---+
IF2 IF1 | | |
| | | | |
| |- - - - - - - - - Attach | |
| | |---------------PBU--------------->|
| | |<--------------PBA----------------|
| |--------RtSol------->| | |
| |<-------RtAdv--------| | |
| Addr. | | |
| Conf. | | |
| |<------------------->|==================data============|<--->
| | | | |
|- - - - - - - - - - - - - - - - - Attach |
| | | |----PBU(transient)--->|
| | | |<---PBA(transient)---[F]
|------RAT Configuration--------------| |
| |<--------------------|==================data============|<---
|-------RtSol-(optional)------------->| |
|<-----------RtAdv--------------------| |
Addr. | | | |
Conf | | | |
|------------NSol-------------------->|---------PBU-------->[G]
| | | |<--------PBA----------|
|<------------------------------------|========data=========[H]<-->
| | | | |
| | | | |
| | | | |
+------+ +----+ +----+ +---+
| MN | |pMAG| |nMAG| |LMA|
+------+ +----+ +----+ +---+
IF2 IF1 | | |
| | | | |
| |- - - - - - - - - Attach | |
| | |---------------PBU--------------->|
| | |<--------------PBA----------------|
| |--------RtSol------->| | |
| |<-------RtAdv--------| | |
| Addr. | | |
| Conf. | | |
| |<------------------->|==================data============|<--->
| | | | |
|- - - - - - - - - - - - - - - - - Attach |
| | | |----PBU(transient)--->|
| | | |<---PBA(transient)---[F]
|------RAT Configuration--------------| |
| |<--------------------|==================data============|<---
|-------RtSol-(optional)------------->| |
|<-----------RtAdv--------------------| |
Addr. | | | |
Conf | | | |
|------------NSol-------------------->|---------PBU-------->[G]
| | | |<--------PBA----------|
|<------------------------------------|========data=========[H]<-->
| | | | |
| | | | |
| | | | |
Figure 6: Late path switch with PMIPv6 transient BCEs
图6：具有PMIPv6瞬态BCE的延迟路径交换机
During the working group discussion of the functionality introduced by this document, it was mentioned that some current Home Agents are already handling some features and functionality introduced in this document via some static configuration. This Appendix captures the analysis that describes which functionality can be handled securely using a static configuration and which can not. In these cases where static configuration can be used, this section documents the possible disadvantages versus using the procedures captured in this document.
在工作组讨论本文档介绍的功能时，提到一些当前的家庭代理已经通过一些静态配置处理本文档中介绍的一些特性和功能。本附录捕获了描述哪些功能可以使用静态配置安全处理，哪些功能不能安全处理的分析。在这些可以使用静态配置的情况下，本节记录了与使用本文档中捕获的过程相比可能存在的缺点。
This use case is related to the handoff scenario when the access network establishes the uplink tunnel to the LMA before the downlink portion is done. Consequently, when the mobile node is attached to the nMAG and in the case of active handoff, the UE will start sending uplink traffic to the LMA through the nMAG.
该用例与当接入网络在下行链路部分完成之前建立到LMA的上行链路隧道时的切换场景相关。因此，当移动节点连接到nMAG并且在主动切换的情况下，UE将开始通过nMAG向LMA发送上行链路业务。
Since the LMA has a proxy BCE for this mobile node that points to the Proxy-CoA that is hosted at the pMAG, the LMA has a routing entry for the MN HNP that points to the pMAG-LMA tunnel. Any uplink packet coming from the nMAG will be dropped by the LMA.
由于LMA具有用于该移动节点的代理BCE，该代理BCE指向托管在pMAG处的代理CoA，因此LMA具有用于MN-HNP的路由条目，该MN-HNP指向pMAG-LMA隧道。来自nMAG的任何上行链路数据包都将被LMA丢弃。
Allowing the LMA to forward the received uplink traffic from the nMAG to the Internet while the MN BCE points to the Proxy-CoA hosted at the pMAG is a violation of all mobility protocols that require a secure signaling exchange between the nMAG and the LMA before forwarding such traffic to the Internet. Otherwise, the LMA will be modifying the mobile node's routing entry based on an unsecured data traffic packet coming from the nMAG.
当MN BCE指向pMAG处托管的代理CoA时，允许LMA将接收到的上行链路业务从nMAG转发到因特网，这违反了所有移动协议，这些协议要求在将此类业务转发到因特网之前在nMAG和LMA之间进行安全信令交换。否则，LMA将基于来自nMAG的不安全数据业务分组修改移动节点的路由条目。
Therefore, this case cannot be addressed by any statically configured information on the LMA. On the contrary, a secure signaling using Transient Binding option as detailed in this document is required to create a transient state for the mobile node BCE at the LMA. This transient state will allow a temporary routing entry of the mobile node to point to the nMAG Proxy-CoA.
因此，这种情况不能通过LMA上的任何静态配置信息来解决。相反，需要使用本文档中详述的瞬时绑定选项的安全信令来在LMA处为移动节点BCE创建瞬时状态。该瞬态将允许移动节点的临时路由条目指向nMAG代理CoA。
This case is a very common case where the mobile node is handing over to another MAG while there is still some uplink traffic in flight coming from the pMAG. In this case, the LMA has the MN BCE points to the mobile node location before the handoff, i.e., pMAG Proxy-CoA. Then the LMA receives a PBU from the nMAG over a secure signaling tunnel, e.g., IPsec tunnel, which indicates some type of handoff as per the value in the handoff indicator mobility option.
这种情况是一种非常常见的情况，其中移动节点正在移交给另一个MAG，而飞行中仍有一些上行链路流量来自pMAG。在这种情况下，LMA使MN-BCE在切换之前指向移动节点位置，即pMAG-Proxy-CoA。然后，LMA通过安全信令隧道（例如IPsec隧道）从nMAG接收PBU，该隧道根据切换指示符移动性选项中的值指示某种类型的切换。
If the PBU received from the nMAG was sent using the secure tunnel and successfully processed by the LMA, the LMA according to [RFC5213] switches the IP-in-IP tunnel to point to the nMAG Proxy-CoA. However, as the LMA is fully aware of the mobile node movement via secure signaling from the nMAG and the content of the PBU, which, in particular, contains the Handoff Indicator mobility option, the LMA can process some intelligence to allow the mobile node's late in-flight uplink traffic coming over the pMAG-LMA tunnel to proceed to the Internet.
如果从nMAG接收到的PBU是使用安全隧道发送并由LMA成功处理的，则LMA根据[RFC5213]将IP隧道中的IP切换到指向nMAG代理CoA。然而，由于LMA完全知道通过来自nMAG的安全信令的移动节点移动和PBU的内容，其尤其包含切换指示符移动选项，LMA可以处理一些智能，以允许通过pMAG LMA隧道的移动节点的飞行中后期上行链路流量进入互联网。
In order to handle all handoff circumstances, the activation mechanism as described in this document is preferable over a statically configured timer, and it would dynamically help in ending the late forwarding from the pMAG based on a protected signaling from the pMAG.
为了处理所有切换情况，本文档中描述的激活机制优于静态配置的计时器，并且它将动态地帮助基于来自pMAG的受保护信令结束来自pMAG的延迟转发。
One main use case of transient bindings is the late switching of downlink traffic routing at the LMA. This allows IP mobility protocol signaling between nMAG and LMA to be performed decoupled from the setup of the new link-layer connectivity, e.g., for performing a handover to an interface with time-consuming link setup procedures or for a make-before-break handover between interfaces.
瞬时绑定的一个主要用例是LMA处下行链路业务路由的延迟切换。这允许nMAG和LMA之间的IP移动性协议信令在与新链路层连接的设置分离的情况下执行，例如，用于执行到具有耗时链路设置过程的接口的切换或用于接口之间的先通后断切换。
LMA behavior according to [RFC5213] does not allow for late path switching. The LMA, according to [RFC5213], can only act upon the Handover Indicator and has no information on the time of completion of link layer setup. Even if an LMA implementation would be configured to delay the path switching by a fixed time, which would violate [RFC5213], this would not lead to smooth handover performance but would even add latency to the handover. Only additional signaling as provided by this document provides the information that late switching is applicable and enables a synchronization of the handover sequence, i.e., the switching is adapted both to the finalization of the link between mobile terminal and nMAG and to the release of the link between mobile terminal and pMAG, whatever comes first. Stable handover performance is achieved using protected PMIPv6 signaling as per [RFC5213].
根据[RFC5213]的LMA行为不允许延迟路径切换。根据[RFC5213]，LMA只能作用于切换指示符，并且没有关于链路层设置完成时间的信息。即使将LMA实现配置为将路径切换延迟固定时间，这将违反[RFC5213]，这也不会导致平滑切换性能，但甚至会增加切换延迟。只有本文件提供的附加信令提供了延迟切换适用的信息，并实现了切换序列的同步，即切换既适用于移动终端和nMAG之间链路的最终确定，也适用于移动终端和pMAG之间链路的释放，先到先得。根据[RFC5213]，使用受保护的PMIPv6信令实现稳定的切换性能。
Authors' Addresses
作者地址
Marco Liebsch (editor) NEC Laboratories Europe NEC Europe Ltd. Kurfuersten-Anlage 36 69115 Heidelberg, Germany
Marco Liebsch（编辑）NEC实验室欧洲NEC欧洲有限公司Kurfuersten Anlage 36 69115德国海德堡
Phone: +49 6221 4342146
EMail: marco.liebsch@neclab.eu
Phone: +49 6221 4342146
EMail: marco.liebsch@neclab.eu
Ahmad Muhanna Ericsson 2201 Lakeside Blvd. Richardson, TX 75082, USA
艾哈迈德·穆哈纳·爱立信湖畔大道2201号。美国德克萨斯州理查森75082
Phone: +1 (972) 583-2769
EMail: ahmad.muhanna@ericsson.com
Phone: +1 (972) 583-2769
EMail: ahmad.muhanna@ericsson.com
Oliver Blume Alcatel-Lucent Deutschland AG Bell Labs Lorenzstr. 10 70435 Stuttgart, Germany
奥利弗·布鲁姆·阿尔卡特朗讯德国贝尔实验室。10 70435德国斯图加特
Phone: +49 711 821-47177
EMail: oliver.blume@alcatel-lucent.com
Phone: +49 711 821-47177
EMail: oliver.blume@alcatel-lucent.com