求解：GTP Recovery IE的实际作用

爱卫生

图没有显示。还是很有用的。

爱立信Alex里的一段原文如下：

“SGSN supports the following categories of GTP signaling traffic:

Path Management messages (signaling and control planes)

-The main purpose of these messages is to supervise a UDP/IP path to ensure that a connectivity failure can be detected in a timely manner. Typically, a path is an IP connection between two processors managed by frequently sending GTP echo or echo response packets between the GTP peers. Detection of path failure in the SGSN triggers an alarm, but no action is taken on affected PDP contexts.

To inform the GGSN about lost connections when a failure results in a large restart or node restart, the restart counter is increased and the new value is sent to the GGSN. The restart counter enables the GGSN to be informed when connections for a group of subscribers have been lost. At large restart and node restart, the restart counter will be increased.”

综上所述，该信息元素可以用于主动通知对方该GTP隧道的用户都已丢失，并且原因是本端发生了重启所导致的，对方收到了以后就可以释放掉该GTP隧道上所有的用户资源了（可能不只一个用户，因为GTP Echo消息并没有携带TEID）。否则的话，SGSN需要发送很多的delete pdp context request消息去释放，但可能根本来不及完成整个delete流程，因为它马上就要重启了。

另外，该参数也用于性能统计的目的。

个人理解供参考。