爱卫生 发表于 2012-5-19 20:48
9.2.3.2 GGSN-Initiated PDP Context Modification Procedure The GGSN-Initiated PDP Context Modificatio ...
Modification procedures modify parameters that were negotiated during an activation procedure for one or several PDP contexts. An MS, a GGSN, an SGSN, or an RNC can request a modification procedure. The Modification procedures may possibly be triggered by the HLR as explained in subclause "Insert Subscriber Data Procedure" or by an RNC in a RAB Release or an RNC-initiated RAB Modification procedure. An MS and SGSN can also decide about modification procedures after an RNC-initiated Iu release.
修改流程可以用于对一个或多个通过激活的PDP上下文中，通过激活流程所协商出的参数进行修改。修改流程也可以通过HLR来触发（插入用户签约数据流程章节）或由RAB释放流程或RNC发起的RAB修改流程中的RNC网元来触发。MS和SGSN可以决定在RNC发起的Iu释放流程后怎样去执行修改流程。
The following parameters can be modified:
- QoS Negotiated;
- Radio Priority;
- Packet Flow Id;
- PDP Address (in case of the GGSN-initiated modification procedure);
- TFT (in case of MS- or GGSN-initiated modification procedure);
- BCM (in case of GGSN-initiated modification procedure); and
- Usage of Direct Tunnel.
以下参数可以修改：
- 协商的Qos；
- 无线优先级
- PFI
- PDP地址
- TFT
- BCM
- 是否使用直接隧道
The SGSN can request the modification of parameters by sending a Modify PDP Context Request message to the MS.
A GGSN can request the modification of parameters by sending an Update PDP Context Request message to the SGSN.
An MS can request the modification of parameters by sending a Modify PDP Context Request message to the SGSN.
An RNC can request an Iu release by sending an Iu Release Request message to the SGSN. After Iu release the MS and SGSN shall modify the PDP contexts according to the rules defined in clause "RNC-Initiated PDP Context Modification Procedure".
An RNC can request the release of a radio access bearer. After RAB release the MS and the SGSN shall locally modify the corresponding PDP context according to rules defined in the clause "RAB Release-Initiated Local PDP Context Modification Procedure".
SGSN通过发送Modify PDP Context Request消息给MS来发起对PDP上下文参数的修改。GGSN则是通过发送Update PDP Context Request消息给SGSN来对参数进行修改。MS可以发送Modify PDP Context Request消息给SGSN来对参数进行修改。RNC可以发送Iu Release Request消息给SGSN来请求释放Iu资源。Iu释放之后，MS和SGSN可以根据章节"RNC发起的PDP上下文修改流程"中的说明来请求更新PDP上下文参数。RNC可以请求释放掉一个RAB，在RAB释放后，MS和SGSN应本地修改相应的PDP上下文参数，这个规则在章节“RAB release-Initiated Local PDP Context Modication Procedure"中说明。
A trace may be activated while a PDP context is active. To enable trace activation in a GGSN, the SGSN shall send an Update PDP Context Request message to the GGSN. If PDP context modification is performed only to activate a trace, the SGSN shall not send a Modify PDP Context Request message to the MS.
The GGSN shall send an Update PDP Context Request modification to the SGSN when modifying the APN restriction. If the PDP context modification is performed only to change the value of the APN restriction, the SGSN shall not send a Modify PDP Context Request message to the MS.
If the GGSN has stored information that the current SGSN supports the reporting of CGI/SAI/RAI changes, to enable or disable CGI/SAI/RAI change reporting for an already active PDP context, the GGSN shall send an Update PDP Context Request message to the SGSN. The SGSN shall behave according to clause 15.1.1a.
An RNC may request the modification of some negotiated RAB related QoS parameters by sending a RAB Modify Request.
当PDP上下文是active时可以对其进行追踪。为了激活GGSN侧的追踪，SGSN应发送update pdp context request消息给GGSN。如果PDP上下文修改只是为了来激活这个追踪，则SGSN不应给MS发送modify pdp context request消息。
GGSN在需要修改APN限制时，应发送update pdp context request修改给SGSN，如果这个PDP上下文修改只是为了改变APN限制的值，则SGSN不应给MS发送modify pdp context request消息。
如果GGSN保存了当前SGSN支持报告CGI/SAI/RAI等位置变化相关的信息，如果要enable或disable针对一个已经激活的PDP上下文的CGI/SAI/RAI的变化报告，则GGSN应发送update pdp context request消息给SGSN。SGSN应按照章节15.1.1.a的说明来处理。
9.2.3.1 SGSN-Initiated PDP Context Modification Procedure
The SGSN-Initiated PDP Context Modification procedure is illustrated in Figures 70a and 70b.
SGSN发起的PDP上下文修改流程在图例70a和70b中描述：
[attach]1261[/attach]
Figure 70a: SGSN-Initiated PDP Context Modification Procedure, A/Gb mode
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Figure 70b: SGSN-Initiated PDP Context Modification Procedure, Iu mode
1) The SGSN may send an Update PDP Context Request (TEID, NSAPI, QoS Negotiated, Trace Reference, Trace Type, Trigger Id, OMC Identity, serving network identity, CGI/SAI/RAI change support indication, DTI) message to the GGSN. If Direct Tunnel is established the SGSN provides to the GGSN the RNC's Address for User Plane and TEID for downlink data and shall include the DTI to instruct the GGSN to apply Direct Tunnel specific error handling as described in clause 13.8. The QoS Negotiated may be equal to, an upgrade or a downgrade compared to the current QoS of the PDP context. The SGSN shall send the serving network identity to the GGSN. If QoS Negotiated received from the SGSN is incompatible with the PDP context being modified, the GGSN rejects the Update PDP Context Request. The GGSN operator configures the compatible QoS profiles. The SGSN shall include Trace Reference, Trace Type, Trigger Id, and OMC Identity in the message if GGSN trace is activated while the PDP context is active. The SGSN shall copy Trace Reference, Trace Type, and OMC Identity from the trace information received from the HLR or OMC.
1）SGSN可以发送Update PDP Context Request (TEID, NSAPI, QoS Negotiated, Trace Reference, Trace Type, Trigger Id, OMC Identity, serving network identity, CGI/SAI/RAI change support indication, DTI) 给GGSN。如果直接隧道建立了，则SGSN应给GGSN提供RNC侧的用户面地址和TEID，以用于下行方向用户数据的传递，并且应包含一个DTI指示位来指示GGSN应用直接隧道（特定的错误处理说明在13.8章节中提到）。协商的Qos可以是针对PDP上下文当前Qos所做的升级或者降级。SGSN应发送服务网络ID给GGSN。如果从SGSN收到的协商Qos值和要修改的PDP上下文不符，则GGSN将拒绝这个update pdp context request消息。GGSN运营商可以配置兼容的Qps profile。如果GGSN的trace激活了，则SGSN应在消息中包含Trace Reference, Trace Type, Trigger Id, and OMC Identity。SGSN应从HLR或OMC收到的trace信息中拷贝Trace Reference, Trace Type, Trigger Id, and OMC Identity值。
2) The GGSN may restrict QoS Negotiated given its capabilities and the current load or increase the QoS Negotiated based on any external input (e.g. policy control). The GGSN stores QoS Negotiated and returns an Update PDP Context Response (TEID, QoS Negotiated, Prohibit Payload Compression, APN Restriction, Cause, CGI/SAI/RAI change report required) message. The Prohibit Payload Compression indicates that the SGSN should negotiate no data compression for this PDP context. The SGSN shall re-verify and may restrict the QoS Negotiated received from the GGSN against the subscribed QoS profile and additionally restrict the QoS negotiated based on its capabilities and current load. The SGSN shall use this updated QoS Negotiated for the subsequent steps.
3) In A/Gb mode, BSS packet flow context procedures may be executed. These procedures are defined in clause "BSS Context".
4) In Iu mode, radio access bearer modification may be performed by the RAB Assignment procedure.
2）GGSN可以根据自己的支持能力和当前的负荷来限制协商的Qos或者根据一些外部的输入（例如PCRF)来提升协商的Qos。GGSN存储这个协商的Qos并返回Update PDP Context Response (TEID, QoS Negotiated, Prohibit Payload Compression, APN Restriction, Cause, CGI/SAI/RAI change report required)消息。Prohibit Payload Compression指示SGSN应该对这个PDP上下文不要做数据压缩。SGSN应重新验证用户的Qos，通过从GGSN收到的协商Qos值、用户签约的Qos profile以及自身当前的支持能力和负荷情况来决定最终的Qos。SGSN将使用这个最终协商好的Qos用于后续的步骤。
3）在A/Gb模式，BSS PFC流程可以执行。可以参考章节“BSS Context“。
4）在Iu模式，RAB更新可以通过RAB Assignment流程来执行。
5) In case the QoS profile, used as input to step 4 for Iu mode and step 3 for A/Gb mode, have been downgraded during those steps, the SGSN may inform the GGSN about the downgraded QoS profile by sending an Update PDP Context Request to the affected GGSN. The GGSN shall not attempt to renegotiate the QoS profile. The No QoS negotiation indication is set in Update PDP Context Request to indicate to the GGSN that the SGSN does not upgrade the previously negotiated QoS profile and that the GGSN shall accept the provided QoS profile without negotiation. The GGSN confirms the new QoS profile by sending an Update PDP Context Response to the SGSN. If the SGSN established Direct Tunnel in step 4 it shall send Update PDP Context Request and include the RNC's Address for User Plane, TEID for downlink data, No QoS negotiation indication and the DTI. DTI is used to instruct the GGSN to apply Direct Tunnel specific error handling as described in clause 13.8.
6) The SGSN selects Radio Priority and Packet Flow Id based on QoS Negotiated, and may send a Modify PDP Context Request (TI, QoS Negotiated, Radio Priority, Packet Flow Id) message to the MS. If the MS indicated in the MS Network Capability it does not support BSS packet flow procedures, then the SGSN shall not include the Packet Flow Id. In A/Gb mode, the QoS Negotiated shall take into account the Aggregate BSS QoS Profile, if any, returned from the BSS.
5）一旦在步骤4（用于Iu模式）和步骤3（用于A/Gb模式）的Qos profile被降级了，SGSN应通知GGSN这个降级的Qos profile，通过发送update pdp context request给受到影响的GGSN进行通知。GGSN不应尝试重新去协商Qos profile。"无Qos协商"指示应在update pdp context request消息中进行设置，GGSN收到后将接受SGSN新提供的Qos profile而不会重新进行协商。GGSN发送update pdp context response给SGSN进行确认。如果SGSN在步骤4中决定建立直接隧道，SGSN将在update pdp context request消息并且包含RNC侧的用户面地址和TEID，以用于下行方向用户数据的传递，还将包含"无Qos协商指示"以及DTI。
6）SGSN根据协商的Qos来选择无线优先级和PFI，并且发送Modify PDP Context Request (TI, QoS Negotiated, Radio Priority, Packet Flow Id) 消息给MS。如果MS在之前通过MS Network Capability告知网络侧自己不支持BSS Packet flow流程，那SGSN则不应包含PFI。在A/Gb模式，协商的Qos要被考虑进聚合的BSS Qos profile（如果有的话，从BSS返回）。
7) The MS should accept the PDP context modification requested by the network if it is capable of supporting the modified QoS Negotiated. For a successful modification the MS acknowledges by returning a Modify PDP Context Accept message. If the MS is incapable of accepting the new QoS Negotiated, the MS should initiate application level signalling to lower the QoS requirements for the concerned application(s). If this is not possible then the MS shall instead de-activate the PDP context with the PDP Context Deactivation Initiated by the MS procedure.
NOTE: In order to facilitate operator control of the QoS an MS should accept a new QoS being assigned by the network even if the QoS is different from the one that the MS uses by default for a particular service type. One reason why the MS may not accept the modified QoS is if it has insufficient internal resources available to support the new QoS.
If an APN Restriction is received from the GGSN for this PDP Context, then the SGSN shall store this value for the PDP Context, replacing any previously stored value for this PDP context. The SGSN shall determine a (new) value for the Maximum APN Restriction using any stored APN Restriction and the received APN Restriction.
7）如果MS能够支持修改后协商的Qos，则MS应接受网络侧下发的PDP context修改请求。做为一个成功的修改流程，MS需要返回Modify PDP Context Accept消息进行确认。如果MS不能够接受新的协商的Qos，MS应发起应用层级别的信令（例如HTTP、RTSP等）来请求针对特定的应用来降低对Qos的需求。如果无法从应用层来完成Qos的需求变更，MS可以发起一个PDP上下文去激活流程将PDP上下文去激活。
注释：为了加强运营商对Qos的控制，MS应接受这个新的Qos即使这个Qos与MS上针对特定业务类别所需求的缺省Qos不同。有一个原因，关于为什么不可以接受修改的Qos，可能是因为MS没有足够的内部资源来支持这个新的Qos。
如果从GGSN收到了关于这个PDP上下文的APN限制，那么SGSN应为这个PDP上下文保存这个APN限制值，并且替换掉之前存储的关于这个PDP上下文的老值（old APN限制值）。SGSN应根据存储的APN限制和接收到的APN限制来决定一个新的最大APN限制值。
9.2.3.2 GGSN-Initiated PDP Context Modification Procedure
The GGSN-Initiated PDP Context Modification procedure is illustrated in Figures 71a and 71b.
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Figure 71a: GGSN-Initiated PDP Context Modification Procedure, A/Gb mode
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Figure 71b: GGSN-Initiated PDP Context Modification Procedure, Iu mode
1) The GGSN sends an Update PDP Context Request (TEID, NSAPI, PDP Address, QoS Requested, Prohibit Payload Compression, APN Restriction, CGI/SAI/RAI change report required, TFT, Protocol Configuration Options, BCM) message to the SGSN. QoS Requested indicates the desired QoS profile. The QoS Requested may be equal to, an upgrade or a downgrade compared to the current QoS of the PDP context. PDP Address is optional. The Prohibit Payload Compression indicates that the SGSN should negotiate no data compression for this PDP context. The TFT is optional and included in order to add, modify or delete the TFT related to the PDP Context. Protocol Configuration Options may contain the BCM as well as optional PDP parameters that the GGSN may transfer to the MS. BCM shall also be sent as a separate IE to the SGSN. BCM indicates the Bearer Control Mode applicable to all PDP Contexts within the activated PDP Address/APN pair. The GGSN shall only indicate Bearer Control Modes allowed according to the NRSN and NRSU previously indicated by the SGSN and MS respectively. The SGSN may restrict a desired QoS profile given its capabilities, the current load, the current QoS profile, and the subscribed QoS profile. The BCM is used by the SGSN to handle unexpected session management signalling.
1）GGSN发送Update PDP Context Request (TEID, NSAPI, PDP Address, QoS Requested, Prohibit Payload Compression, APN Restriction, CGI/SAI/RAI change report required, TFT, Protocol Configuration Options, BCM) 消息给SGSN。请求的Qos指示了期望的Qos profile。请求的Qos对PDP上下文的当前Qos进行升级或者降级。PDP地址是可选的。Prohibit Payload Compression指示SGSN不应对这个PDP上下文进行数据压缩。TFT是可选的，如果包含了就是用于添加、修改或删除这个PDP上下文的TFT。PCO可以包含BCM以及GGSN可能需要传送给MS的可选的PDP参数。BCM应作为一个单独的IE发给SGSN。BCM指示了应用到当前激活的PDP地址/APN对的所有PDP上下文的承载控制模式。GGSN应根据NRSN和NRSU来指示BCM。SGSN可以根据自身能力和当前负荷、当前的Qos profile、签约的Qos profile来限制期望的Qos profile。BCM被SGSN用于处理不期望的会话管理信令事件。
2) In A/Gb mode, BSS packet flow context procedures may be executed. These procedures are defined in clause "BSS Context".
3) In Iu mode, radio access bearer modification may be performed by the RAB Assignment procedure.
4) The SGSN selects Radio Priority and Packet Flow Id based on QoS Negotiated, and sends a Modify PDP Context Request (TI, PDP Address, QoS Negotiated, Radio Priority, Packet Flow Id, TFT, PCO) message to the MS. PDP Address is optional. If the MS indicated in the MS Network Capability it does not support BSS packet flow procedures, then the SGSN shall not include the Packet Flow Id. In A/Gb mode, the QoS Negotiated shall be included if modified and take into account the Aggregate BSS QoS Profile, if any, returned from the BSS. The TFT is included only if it was received from the GGSN in the Update PDP Context Request message. Protocol Configuration Options contains the BCM as well as optional PDP parameters that the GGSN may transfer to the MS. Protocol Configuration Options is sent transparently through the SGSN. BCM indicates the Bearer Control Mode applicable to all PDP Contexts within the activated PDP Address/APN pair.
2）在A/Gb模式，BSS PFC流程可以执行。可以参考章节“BSS Context“。
3）在Iu模式，RAB更新可以通过RAB Assignment流程来执行。
4）SGSN根据协商的Qos来选择无线优先级和PFI，并且发送Modify PDP Context Request (TI, PDP Address, QoS Negotiated, Radio Priority, Packet Flow Id, TFT, PCO) 消息给MS。PDP地址是可选的。如果MS在之前通过MS Network Capability告知网络侧自己不支持BSS Packet flow流程，那SGSN则不应包含PFI。在A/Gb模式，协商的Qos要被考虑进聚合的BSS Qos profile（如果有的话，从BSS返回）。只有从GGSN的update pdp context request消息中收到了TFT，SGSN给MS发的时候才会包含。PCO包含了BCM以及GGSN需要发送给MS的可选参数。BCM指示了应用到当前激活的PDP地址/APN对的所有PDP上下文的承载控制模式。
5) The MS should accept the PDP context modification requested by the network if it is capable of supporting any modified QoS Negotiated as well as any modified TFT. For a successful modification the MS acknowledges by returning a Modify PDP Context Accept message. If the MS is incapable of accepting a new QoS Negotiated or TFT it shall instead de-activate the PDP context with the PDP Context Deactivation Initiated by MS procedure.
NOTE: In order to facilitate operator control of the QoS an MS should accept a new QoS being assigned by the network even if the QoS is different from the one that the MS uses by default for a particular service type. One reason why the MS may not accept the modified QoS is if it has insufficient internal resources available to support the new QoS. If the BCM parameter is not included in the Modify PDP Context Request message then the MS shall set the Bearer Control Mode to 'MS_only' for the PDP Address/APN pair (see clause 9.2).
6) Upon receipt of the Modify PDP Context Accept message, or upon completion of the RAB modification procedure, the SGSN returns an Update PDP Context Response (TEID, QoS Negotiated) message to the GGSN. If the SGSN receives a Deactivate PDP Context Request message, it shall instead follow the PDP Context Deactivation Initiated by MS procedure. If an APN Restriction is received from the GGSN for this PDP Context, then the SGSN shall store this value for the PDP Context, replacing any previously stored value for this PDP context. The SGSN shall determine a (new) value for the Maximum APN Restriction using any stored APN Restriction and the received APN Restriction.
5）如果MS能够支持修改后协商的Qos，则MS应接受网络侧下发的PDP context修改请求。做为一个成功的修改流程，MS需要返回Modify PDP Context Accept消息进行确认。MS如果不能接受这个协商的Qos，则可以发起一个PDP上下文去激活流程将PDP上下文去激活。
注释：为了加强运营商对Qos的控制，MS应接受这个新的Qos即使这个Qos与MS上针对特定业务类别所需求的缺省Qos不同。有一个原因，关于为什么不可以接受修改的Qos，可能是因为MS没有足够的内部资源来支持这个新的Qos。
6）一旦接收到Modify PDP Context Accept消息，或者一旦完成RAB修改流程,SGSN应给GGSN返回一个update pdp context response(TEID、Qos Negotiated）消息给GGSN。如果SGSN接收到了一个Deactivate PDP Context Request消息，可以接下来按照要求执行MS发起的PDP上下文去激活的后续步骤。如果从GGSN收到了关于这个PDP上下文的APN限制，那么SGSN应为这个PDP上下文保存这个APN限制值，并且替换掉之前存储的关于这个PDP上下文的老值（old APN限制值）。SGSN应根据存储的APN限制和接收到的APN限制来决定一个新的最大APN限制值。
爱卫生 发表于 2012-5-19 20:48
9.2.3.2 GGSN-Initiated PDP Context Modification Procedure The GGSN-Initiated PDP Context Modificatio ...
9.2.3.3 MS-Initiated PDP Context Modification Procedure
The MS-Initiated PDP Context Modification procedure is illustrated in Figures 72a and 72b.
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Figure 72a: MS-Initiated PDP Context Modification Procedure, A/Gb mode
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Figure 72b: MS-Initiated PDP Context Modification Procedure, Iu mode
1) The MS sends a Modify PDP Context Request (TI, QoS Requested, TFT, Protocol Configuration Options) message to the SGSN. Either QoS Requested or TFT or both may be included. QoS Requested indicates the desired QoS profile, while TFT indicates the TFT that is to be added or modified or deleted from the PDP context. Protocol Configuration Options may be used to transfer optional PDP parameters and/or requests to the GGSN.
2) The SGSN may restrict the desired QoS profile given its capabilities, the current load, and the subscribed QoS profile. The SGSN sends an Update PDP Context Request (TEID, NSAPI, QoS Negotiated, TFT, Protocol Configuration Options, serving network identity, CGI/SAI, CGI/SAI/RAI change support indication, DTI) message to the GGSN. If Direct Tunnel is established the SGSN provides to the GGSN the RNC's Address for User Plane and TEID for downlink data and shall include the DTI to instruct the GGSN to apply Direct Tunnel specific error handling as described in clause 13.8. The SGSN shall send the serving network identity to the GGSN. If QoS Negotiated and/or TFT received from the SGSN is incompatible with the PDP context being modified (e.g., TFT contains inconsistent packet filters), the GGSN rejects the Update PDP Context Request. The GGSN operator configures the compatible QoS profile. Protocol Configuration Options is sent transparently through the SGSN if received in Modify PDP Context Request message.
1）MS发送Modify PDP Context(TI, QoS Requested, TFT, Protocol Configuration Options)消息给SGSN。请求的Qos或TFT或者两者可以同时被包含。请求的Qos指示了期望的Qos profile，TFT如果包含了就是用于添加、修改或删除这个PDP上下文的TFT。PCO可以包含可能需要传送给GGSN的可选的PDP参数。
2）SGSN可以根据自己的支持能力和当前的负荷、用户的签约Qos profile来限制协商的Qos。SGSN发送update pdp context request(TEID, NSAPI, QoS Negotiated, TFT, Protocol Configuration Options, serving network identity, CGI/SAI, CGI/SAI/RAI change support indication, DTI)消息给GGSN。如果直接隧道建立，则SGSN应给GGSN提供RNC侧的用户面地址和TEID，以用于下行方向用户数据的传递，并且应包含一个DTI指示位来指示GGSN应用直接隧道，错误处理的说明参考章节13.8。SGSN应发送服务网络ID给SGSN。如果从SGSN收到的协商Qos值和/或TFT（例如TFT包含了不一致的包过滤器)和要修改的PDP上下文不符，则GGSN将拒绝这个update pdp context request消息。GGSN运营商可以配置兼容的Qps profile。PCO在SGSN从MS发过来的modify pdp context request消息后，透明的传送给GGSN。
3) The GGSN may further restrict QoS Negotiated given its capabilities, operator policies and the current load or increase QoS Negotiated based on any external input (e.g. policy control). The GGSN stores QoS Negotiated, stores, modifies, or deletes TFT of that PDP context as indicated in TFT, and returns an Update PDP Context Response (TEID, QoS Negotiated, Protocol Configuration Options, Prohibit Payload Compression, APN Restriction, CGI/SAI/RAI change report required) message. Protocol Configuration Options may be used to transfer optional PDP parameters to the UE. The Prohibit Payload Compression indicates that the SGSN should negotiate no data compression for this PDP context. The SGSN shall re-verify and may restrict the QoS Negotiated received from the GGSN against the subscribed QoS profile and additionally restrict the QoS negotiated based on its capabilities and current load. The SGSN shall use this updated QoS Negotiated for the subsequent steps.
4) In A/Gb mode, BSS packet flow context procedures may be executed. These procedures are defined in clause "BSS Context".
5) In Iu mode, radio access bearer modification may be performed by the RAB Assignment procedure. In case the radio access bearer does not exist the RAB setup is done by the RAB Assignment procedure.
3）GGSN可以根据自己的支持能力和当前的负荷来限制协商的Qos或者根据一些外部的输入（例如PCRF)来提升协商的Qos。GGSN存储这个协商的Qos，存储、修改或删除TFT中指示的PDP上下文对应的TFT，并返回Update PDP Context Response (TEID, QoS Negotiated, Prohibit Payload Compression, APN Restriction, Cause, CGI/SAI/RAI change report required)消息。Prohibit Payload Compression指示SGSN应该对这个PDP上下文不要做数据压缩。SGSN应重新验证用户的Qos，通过从GGSN收到的协商Qos值、用户签约的Qos profile以及自身当前的支持能力和负荷情况来决定最终的Qos。SGSN将使用这个最终协商好的Qos用于后续的步骤。
4）在A/Gb模式，BSS PFC流程可以执行。可以参考章节“BSS Context“。
5）在Iu模式，RAB更新可以通过RAB Assignment流程来执行。
6) In case the QoS profile, used as input to step 5 for Iu mode and step 4 for A/Gb mode, have been downgraded during those steps, the SGSN may inform the GGSN about the downgraded QoS profile by sending an Update PDP Context Request to the affected GGSN. The GGSN shall not attempt to renegotiate the QoS profile. The No QoS negotiation indication is set in Update PDP Context Request to indicate to the GGSN that the SGSN does not upgrade the previously negotiated QoS profile and that the GGSN shall accept the provided QoS profile without negotiation. The GGSN confirms the new QoS profile by sending an Update PDP Context Response to the SGSN. If the SGSN established Direct Tunnel in step 5 it shall send Update PDP Context Request and include the RNC's Address for User Plane, TEID for downlink data, No QoS negotiation indication and the DTI. DTI is used to instruct the GGSN to apply Direct Tunnel specific error handling as described in clause 13.8.
7) The SGSN selects Radio Priority and Packet Flow Id based on QoS Negotiated, and returns a Modify PDP Context Accept (TI, QoS Negotiated, Radio Priority, Packet Flow Id, Protocol Configuration Options) message to the MS. If the MS indicated in the MS Network Capability it does not support BSS packet flow procedures, then the SGSN shall not include the Packet Flow Id. In A/Gb mode, the QoS Negotiated shall take into account the Aggregate BSS QoS Profile, if any, returned from the BSS. Protocol Configuration Options is sent transparently through the SGSN if received in Modify PDP Context Response message. If the MS is incapable of accepting the new QoS Negotiated, the MS should initiate application level signalling to lower the QoS requirements for the concerned application(s). If this is not possible then the MS shall instead de-activate the PDP context with the PDP Context Deactivation Initiated by the MS procedure.
6）一旦在步骤5（用于Iu模式）和步骤4（用于A/Gb模式）的Qos profile被降级了，SGSN应通知GGSN这个降级的Qos profile，通过发送update pdp context request给受到影响的GGSN进行通知。GGSN不应尝试重新去协商Qos profile。"无Qos协商"指示应在update pdp context request消息中进行设置，GGSN收到后将接受SGSN新提供的Qos profile而不会重新进行协商。GGSN发送update pdp context response给SGSN进行确认。如果SGSN在步骤5中决定建立直接隧道，SGSN将在update pdp context request消息并且包含RNC侧的用户面地址和TEID，以用于下行方向用户数据的传递，还将包含"无Qos协商指示"以及DTI。
7）SGSN根据协商的Qos来选择无线优先级和PFI，并且发送Modify PDP Context Request (TI, QoS Negotiated, Radio Priority, Packet Flow Id，PCO) 消息给MS。如果MS在之前通过MS Network Capability告知网络侧自己不支持BSS Packet flow流程，那SGSN则不应包含PFI。在A/Gb模式，协商的Qos要被考虑进聚合的BSS Qos profile（如果有的话，从BSS返回）。PCO通过SGSN发送的modify pdp context response消息透传。如果MS没有能力接受新的协商的Qos，MS应发起应用层的信令（例如HTTP和RSTP）来请求针对特定应用降低对Qos的需求。如果不成功的话，MS应发起PDP去激活流程。
NOTE 1: If the SGSN does not accept QoS Requested, then steps 2 and 3 of this procedure are skipped, and the existing QoS Negotiated is returned to the MS in step 4.
NOTE 2: In this release of the standards no procedure is defined that uses the Protocol Configuration Options in the PDP context modification procedure. If an APN Restriction is received from the GGSN for this PDP Context, then the SGSN shall store this value for the PDP Context, replacing any previously stored value for this PDP context. The SGSN shall determine a (new) value for the Maximum APN Restriction using any stored APN Restriction and the received APN Restriction.
注释1：如果SGSN不能接受请求的Qos，那么步骤2和3将被跳过，现有的协商的Qos将在第4步返回给MS。
注释2：本版本的规范中，没有定义PDP上下文修改流程中的PCO。如果从GGSN收到了关于这个PDP上下文的APN限制，那么SGSN应为这个PDP上下文保存这个APN限制值，并且替换掉之前存储的关于这个PDP上下文的老值（old APN限制值）。SGSN应根据存储的APN限制和接收到的APN限制来决定一个新的最大APN限制值。
9.2.3.4 RNC/BSS-Initiated PDP Context Modification Procedure
The RNC can request the release of the Iu connection (see clause "Iu Release Procedure"). The BSS may terminate the downlink data transfer to a MS by the Suspend procedure (which is triggered by the MS) or by the Radio Status procedure with cause "Radio contact lost with MS" or "Radio link quality insufficient to continue communication" both defined in TS 48.018 [78]. After Iu Release in Iu mode, or after termination of the downlink data transfer in A/Gb mode, the PDP contexts are modified as follows:
- In the SGSN, for a PDP context using background or interactive traffic class, the PDP context is preserved with no modifications.
- In the SGSN, for a PDP context using streaming or conversational traffic class, the PDP context is preserved, but the maximum bit rate is downgraded to 0 kbit/s (for both uplink and downlink). The SGSN sends an Update PDP Context Request (TEID, QoS Negotiated) message to the GGSN to set the maximum bit rate to 0 kbit/s in the GGSN. The value of 0 kbit/s for the maximum bit rate indicates to the GGSN to stop sending packets to the SGSN for this PDP context. For the Iu mode the value of 0 kbit/s for the maximum bit rate for both uplink and downlink indicates to the SGSN that a RAB shall not be re-established for this PDP Context in subsequent Service Request Procedure. For the A/Gb mode the value of 0 kbit/s for the maximum bit rate for both uplink and downlink indicates that the SGSN shall not send any downlink data for this PDP Context.
RNC可以请求释放Iu连接（参考章节“Iu释放流程"）。BSS可以通过Suspend流程（通过MS触发）或者带有原因"丢失与MS的无线联系或无线链路质量不能满足后续通信"（在TS48.018中定义）的无线状态流程来终止到MS下行数据的传输。在Iu模式下释放Iu连接后，或者在A/Gb模式下终止了对下行数据的传输后，PDP上下文可以参照以下进行修改：
- 在SGSN中，对于背景或交互式的流量类别的PDP上下文，PDP上下文可以保留并不做修改。
- 在SGSN中，对于使用流媒体或会话类业务类别的PDP上下文，PDP上下文可以保留，但是MBR将被降级到0 kbit/s（包括上行和下行）。SGSN发送update pdp context request(TEID、Qos negotiated）消息给GGSN来通知GGSN设置MBR为0 kbit/s。MBR为0将指示GGSN，停止向SGSN转发该PDP上下文的数据包。对于Iu模式，如果上下行的MBR都为0，则表明SGSN，这个RAB不应通过后续的业务请求流程进行重建。对于A/Gb模式，如果上下行的MBR都为0，则表明SGSN不应为这个PDP上下文发送任何下行数据。
In Iu mode the following procedures shall be performed in the MS when radio coverage is lost:
- For a PDP context using background or interactive traffic class, the PDP context is preserved even if RRC reestablishment procedures have failed.
- For a PDP context using streaming or conversational traffic class, the PDP context is preserved, but the maximum bit rate is downgraded to 0 kbit/s (for both uplink and downlink) when the RRC re-establishment procedure has failed. After coverage is regained on the GERAN or the UTRAN and if the MS did not deactivate the PDP Context locally the MS should start MS-initiated PDP Context Modification procedure or the PDP Context Deactivation procedure. The MS shall use the PDP Context Modification procedure to re-activate the PDP context and re-establish the RAB .
在Iu模式下，当MS丢失了无线覆盖后，下述流程将被执行：
-对于背景或交互式的流量类别的PDP上下文，PDP上下文可以被保留（即使RRC重建流程失败）
-对于使用流媒体或会话类业务类别的PDP上下文，PDP上下文可以被保留，但当RRC重建流程失败后，MBR将被降级为0 kbit/s（包括上行和下行）。在MS重新获得GERAN或UTRAN的覆盖后，如果MS没有在本地将PDP上下文去激活，则MS应发起PDP上下文修改流程或PDP上下文去激活流程。MS应使用PDP上下文修改流程来重新激活PDP上下文以及重建RAB。
In A/Gb mode the following procedures shall be performed in the MS when radio coverage is lost, when the radio link quality is insufficient or when the MS suspends GPRS:
- For a PDP context using background or interactive traffic class, the PDP context is preserved.
- For a PDP context using streaming or conversational traffic class, the PDP context is preserved, but the maximum bit rate is downgraded to 0 kbit/s (for both uplink and downlink). After coverage or radio link quality is regained on the GERAN or the UTRAN or when GPRS services shall resume and if the MS did not deactivate the PDP Context locally the MS should start MS initiated PDP Context Modification procedure or the PDP Context Deactivation procedure. The MS shall use the PDP Context Modification procedure to re-activate the PDP context.
在A/Gb模式下，当无线链路不足以满足后续通信或当MS挂起GPRS或MS丢失了无线覆盖后，下述流程应被执行：
- 对于背景或交互式的流量类别的PDP上下文，PDP上下文可以被保留。
- 对于使用流媒体或会话类业务类别的PDP上下文，PDP上下文可以被保留，但MBR将被降级为0 kbit/s（包括上行和下行）。在MS重新获得GERAN或UTRAN的覆盖并且能够得到较好的链路质量或当GPRS业务需要被resume（重新获取），如果MS没有在本地将PDP上下文去激活，则MS应发起PDP上下文修改流程或PDP上下文去激活流程。MS应使用PDP上下文修改流程来重新激活PDP上下文。
9.2.3.5 RAB Release-Initiated Local PDP Context Modification Procedure
The RNC can request a RAB to be released through the RAB Release procedure without releasing the Iu connection. After the RAB(s) release the SGSN shall modify the PDP context as follows:
- In the SGSN, for a PDP context using background or interactive traffic class, the PDP context is preserved with no modifications.
- In the SGSN, for a PDP context using streaming or conversational traffic class, the PDP context is preserved, but the maximum bit rate is downgraded to 0 kbit/s (for both uplink and downlink) when the associated RAB is released. The SGSN sends an Update PDP Context Request (TEID, QoS Negotiated) message to the GGSN to set the maximum bit rate to 0 kbit/s in the GGSN. The value of 0 kbit/s for the maximum bit rate indicates to the GGSN to stop sending packets to the SGSN on this PDP context. The value of 0 kbit/s for the maximum bit rate for both uplink and downlink indicates to the SGSN that a RAB shall not be re-established for this PDP Context in subsequent Service Request Procedure.
The following procedures shall be performed in the MS when the RRC layer indicate to higher layer that a RAB has been released and the RAB release was not initiated due to a PDP Context Deactivation Procedure:
- For a PDP context using background or interactive traffic class, the PDP context is be preserved with no modifications.
- For a PDP context using streaming or conversational traffic class, the PDP context is preserved, but the maximum bit rate is downgraded to 0 kbit/s (for both uplink and downlink).
At this point or at a later stage, the MS may start a PDP Context Deactivation procedure or PDP Context Modification procedure. The MS shall use the PDP context modification procedure to re-activate the PDP context and to re-establish the RAB.
RNC可以在不释放Iu连接的情况下，通过RAB释放流程来释放一个RAB。在RAB释放后，SGSN应按照以下要求修改PDP上下文：
- 在SGSN侧，对于背景或交互式的流量类别的PDP上下文，PDP上下文可以被保留不需要修改。
- 在SGSN侧，对于使用流媒体或会话类业务类别的PDP上下文，PDP上下文可以被保留，但当相关的RAB被释放后，MBR将被降级为0 kbit/s（包括上行和下行）。SGSN发送update pdp context request(TEID、Qos negotiated）消息给GGSN来通知GGSN设置MBR为0 kbit/s。MBR为0将指示GGSN，停止向SGSN转发该PDP上下文的数据包。上下行MBR为0也表示SGSN不应通过后续的业务请求流程完成RAB的重建。
当RRC层指示高层RAB已经被释放并且因为一个PDP上下文去激活流程引起的RAB释放并没有发生，则下述流程将被执行：
- 对于背景或交互式的流量类别的PDP上下文，PDP上下文可以被保留不需要修改。
- 对于使用流媒体或会话类业务类别的PDP上下文，PDP上下文可以被保留，但MBR将被降级为0 kbit/s（包括上行和下行）。
在这一点上或者迟一点的阶段，MS可以发起一个PDP上下文去激活流程或PDP上下文修改流程。MS应使用PDP上下文修改流程来去激活一个PDP上下文并且重建RAB。
9.2.3.6 RAN-initiated RAB Modification Procedure (Iu mode)
The RNC-initiated RAB Modification procedure permits an Iu mode RAN to propose modifications to any negotiable RAB parameter for an MS after RAB establishment, TS 25.413 [56b]. RAB parameters are equivalent to RAB attributes as defined in TS 23.107 [58] for each QoS class. The procedure is depicted in the figure below.
[attach]1267[/attach]
Figure 73: RAN-initiated RAB Modification Procedure
1) The RAN sends a RAB Modify Request (RAB ID, RAB Parameter Values) message to the SGSN.
2) The SGSN may decide to ignore the message or to invoke the PDP Context Modification procedure as described in clause 9.2.3.1, which includes the SGSN RAB Modification procedure.
RNC发起的RAB修改流程允许一个Iu模式的RAN在一个MS的RAB建立之后，来对任意可协商的RAB参数进行重新修改。参考TS25.413。RAB参数和RAB属性是等价的，这在TS23.107中对每个Qos类别的定义中说明。下图为流程：
1）RAN发送一个RAB Modify Request (RAB ID, RAB Parameter Values) 消息给SGSN。
2）SGSN可以决定是忽略这个消息或者调用9.2.3.1章节中定义的PDP上下文修改流程，当然，这也包括了一个SGSN RAB修改流程。
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