请教关于PDP上下文去激活的问题？

hycl5410

楼主恐怕搞混了一个概念，RAB release甚至Iu release不是一定会触发PDP释放。那是某些定时器超时，释放RRC资源的一个过程。跟MM,SM都没有关系的。所谓的“保留机制”严格说压根就不应该叫机制，而是必须这么做。而PDP去激活是跟SM直接联系的。貌似楼主接触RNC比较多，对核心网不太熟，建议好好看看23.060里的3G状态变迁图。

hycl5410

回复 jianglibing 的帖子
9.2.5.2
Re-establishment of RABs

The procedure for re-establishment of RABs allows the SGSN to re-establish RABs for active PDP contexts that don't have an associated RAB.

The MS initiates the re-establishment of RABs by using the Service Request (Service Type = Data) message. This is described in the sub-clause "MS Initiated Service Request Procedure". SGSN shall not establish RABs for PDP contexts with maximum bit rate for uplink and downlink of 0 kbit/s. For these PDP contexts, the MS shall perform a MS-initiated PDP Context Modification or Deactivation procedure.

When RABs for an MS that has no RRC connection needs to be re-established, the CN must first page the MS. The clause "Network Initiated Service Request Procedure" describes this.

6.12.1
MS Initiated Service Request Procedure

4)
If the network is in PMM-CONNECTED state and the Service Type indicates Data, the SGSN shall respond with a Service Accept message towards the MS, in case the service request can be accepted. In case Service Type indicates Data, the SGSN sends a Radio Access Bearer Assignment Request (NSAPIRAB ID(s), TEID(s), QoS Profile(s), SGSN IP Address(es)) message to re-establish radio access bearer for every activated PDP context, except the ones having maximum bit rates for uplink and downlink of 0 kbit/s.

这个写的都比较清楚。3G里Iu-PS接口可以release而不用delete pdp，这是一个很基本的认知吧。。。想想RAB建立过程，U平面是SGSN和RNC的GTP-U地址和TEID。为了节约空口资源，当某些idle定时器超时，就可以release RRC和Iu-PS,Iu-PS release了必然会release所有的RAB。但是这完全没必要影响到用户的PDP啊，SGSN与GGSN之间的C和U通道都是好的。当有上行数据，MS可以发service request，有下行就SGSN先paging再MS发service request。
9.2.5
Preservation Procedures

By sending a RAB Release Request or Iu Release Request message to the SGSN, an Iu mode RAN initiates the release of one or more RABs. The preservation procedure allows the active PDP contexts associated with the released RABs to be preservedin the CN, and the RABs can then be re-established at a later stage, see clause 9.2.5.2 and clause 9.2.3.5.

An Iu mode RAN uses the Iu Release Request to request release of all RABs of an MS, and the RAB Release Request in other cases.

这段说的难道不是这个事？

为了能够更好的理解这个问题，可以参照23.401的EMM,ESM,ECM状态变迁图。23.060的PMM状态变迁图也有涉及，请看PMM-idle与PMM-connected变化，SM是active或inactive的。

hycl5410

哪个规范会写delete pdp之后还有Preservation Procedures么？这里一直都在说RAB，没有看到deactivate pdp或者delete pdp字眼哦。