本帖最后由 爱卫生 于 2012-5-20 16:20 编辑
9.2.4.1 MS Initiated PDP Context Deactivation Procedure The PDP Context Deactivation Initiated by MS procedures for A/Gb mode and Iu mode are illustrated in Figure 74 and Figure 75, respectively. Figure 74: MS Initiated PDP Context Deactivation Procedure for A/Gb mode Figure 75: MS Initiated PDP Context Deactivation Procedure for Iu mode 1) The MS sends a Deactivate PDP Context Request (TI, Teardown Ind) message to the SGSN. 2) In A/Gb mode security functions may be executed. These procedures are defined in clause "Security Function". 3) The SGSN sends a Delete PDP Context Request (TEID, NSAPI, Teardown Ind) message to the GGSN. If the MS in the Deactivate PDP Context Request message included Teardown Ind, then the SGSN deactivates all PDP contexts associated with this PDP address by including Teardown Ind in the Delete PDP Context Request message. The GGSN removes the PDP context(s) and returns a Delete PDP Context Response (TEID) message to the SGSN. If the MS was using a dynamic PDP address allocated by the GGSN, and if the context being deactivated is the last PDP context associated with this PDP address, then the GGSN releases this PDP address and makes it available for subsequent activation by other MSs. The Delete PDP Context messages are sent over the backbone network. 4) The SGSN returns a Deactivate PDP Context Accept (TI) message to the MS. 5) In Iu mode, radio access bearer release is done by the RAB Assignment procedure, if a RAB exists for this PDP context. 6) In A/Gb mode, BSS packet flow context procedures may be executed. These procedures are defined in subclause "BSS Context". At GPRS detach, all PDP contexts for the MS are implicitly deactivated. If the SGSN receives a Deactivate PDP Context Request (TI) message for a PDP context that is currently being activated, the SGSN shall stop the PDP Context Activation procedure without responding to the MS, and continue with the PDP Context Deactivation initiated by MS procedure. The SGSN determines the Maximum APN Restriction for the remaining PDP contexts and stores this new value for the Maximum APN Restriction. 1)MS发送Deactivate PDP Context Request (TI, Teardown Ind) 消息给SGSN。 2)在A/Gb模式下,可以执行安全功能。这些流程在章节“安全功能”中定义。 3)SGSN发送Delete PDP Context Request (TEID, NSAPI, Teardown Ind) 消息给GGSN。如果MS在Deactivate PDP Context Request消息中包含了teardown指示,那么SGSN将去激活和这个teardown指示相关联的PDP地址的所有PDP上下文,并且给GGSN发送delete pdp context request消息并且携带Teardown指示。GGSN删除相应的PDP上下文,并且返回一个delete pdp context response(TEID)消息给SGSN。如果MS使用GGSN分配的动态地址,并且被去激活的PDP上下文是属于这个PDP地址的最后一个PDP上下文,那么GGSN将释放这个PDP地址并且可用于分配给其他的MS。delete pdp context消息通过骨干网络传送。 4)SGSN给MS返回Deactivate PDP Context Accept (TI) 消息。 5)在Iu模式,如果PDP上下文已经建立了一个用户面的RAB,那可以通过RAB指派流程来释放这个RAB。 6)在A/Gb模式,BSS PFC流程可以被执行。这些流程在章节“BSS Context”中定义。在GPRS去附着时,MS的所有PDP上下文被隐含的去激活了。如果SGSN收到了一个关于某个正在被激活的PDP上下文的Deactivate PDP Context Request (TI)消息,则SGSN应停止PDP上下文激活流程,并且不会给MS任何响应,然后接着完成PDP上下文去激活流程。SGSN为剩下的PDP上下文来决定最大APN限制并且将这个最新的最大APN限制值保存起来。 |