应该怎么理解Bearer Control Mode (BCM)

scrapersky

MS_only和MS/NW是怎么回事？能用实际应用的场景解释一下吗？

爱卫生

回复 scrapersky 的帖子

  规范TS23060的9.2.0部分有说明。摘过来如下：
“During the PDP Context Activation Procedure the bearer control mode, applicable to all PDP Contexts within the activated PDP Address/APN pair, is negotiated. The Bearer Control Mode (BCM) is one of 'MS_only' or 'MS/NW':
- When 'MS_only' the MS shall request any additional PDP contexts for the PDP Address/APN pair through the Secondary PDP Context Activation Procedure. Session Management procedures described in 9.2 apply with the following restrictions:
- The P GW or GGSN shall not initiate any Network Requested Secondary PDP Context Activation;
- The P GW or GGSN shall not modify or delete the TFT.
- When 'MS/NW' both the MS and the P GW or GGSN may request additional PDP contexts for the PDP Address/APN pair. The MS shall use the Secondary PDP Context Activation Procedure.The P GW or GGSN shall use the Network Requested Secondary PDP Context Activation Procedure. The MS shall, when modifying the QoS of a PDP context, include a TFT with at least packet filter identifiers to indicate which packet filters in the TFT that is associated with the QoS change.   
   在PDP上下文激活流程期间的承载控制模式，适用于所有带有激活的PDP地址/APN对的PDP上下文，是采用的协商机制。承载控制模式可以是'MS_only"或者'MS/NW':
1 当'MS_only'时，MS应通过二次PDP上下文激活流程来为PDP地址/APN对来请求额外的PDP上下文。在9.2中描述的会话管理流程有以下的限制：
- PGW或GGSN不应发起网络侧请求的二次PDP上下文激活。
- PGW或GGSN不应修改或删除TFT。
2 当'MS/NW'时，MS和PGW或GGSN可以为PDP地址/APN对来请求额外的PDP上下文。MS应使用二次PDP激活流程。PGW或GGSN应使用网络侧请求的二次PDP上下文激活流程.MS应，在修改PDP上下文的QOS时，包含一个至少带有一个包过滤ID的TFT来指示在这个TFT中是哪个包过滤需要涉及到QOS的变更。”
   已在规范版块翻译。目前在现网中由于不支持网络侧发起的PDP激活流程，所以一般BCM都没有使用，都是MS发起的PDP二次激活。

scrapersky

因为始终没见过BCM的应用的地方，所以提出这个问题。
看到版主的回复，还是觉得很受启发。多谢！