学习5G知识，势必要去阅读相关的技术标准，而纯英文的标准协议对于初学者来说是个门槛。
个人在学习5G标准3GPP TS 29244-g30过程中，也发现google的机器翻译实在晦涩难懂，所以个人在借助百度翻译（中国人更懂中文）的同时，人工对每句话进行了校对。
在自己学习的同时，也将翻译内容分享给给广大网友。由于个人能力有限，翻译不到位的地方还请各位网友们指正。
6.4 Reliable Delivery of PFCP Messages 可靠传递PFCP消息
Reliable delivery of PFCP messages is accomplished by retransmission of these messages as specified in this clause.
PFCP消息的可靠传递是通过重新传输本条款中规定的这些消息来完成的。
A PFCP entity shall maintain, for each triplet of local IP address, local UDP port and remote peer's IP address, a sending queue with Request messages to be sent to that peer. Each message shall be sent with a Sequence Number and be held until a corresponding Response is received or until the PFCP entity ceases retransmission of that message. The Sequence Number shall be unique for each outstanding Request message sourced from the same IP/UDP endpoint. A PFCP entity may have several outstanding Requests waiting for replies.
PFCP实体应为本地IP地址、本地UDP端口和远程对等体的IP地址的每个三元组维护一个发送队列，其中包含要发送给该对等体的Request消息。每条消息应以Sequence Number发送，并在收到相应Response或PFCP实体停止重新传输该消息之前保持。对于来自同一IP/UDP端点的每个未完成Request消息，Sequence Number应是唯一的。一个PFCP实体可能有几个未完成的Request等待答复。
When sending a Request message, the sending PFCP entity shall start a timer T1. The sending entity shall consider that the Request message has been lost if a corresponding Response message has not been received before the T1 timer expires. If so, the sending entity shall retransmit the Request message, if the total number of retry attempts is less than N1 times. The setting of the T1 timer and N1 counter is implementation specific.
当发送Request消息时，发送PFCP实体应启动计时器T1。如果在T1计时器到期之前没有收到相应的Response消息，则发送实体应认为Request消息已经丢失。如果是，如果重试尝试的总数小于N1次，发送实体应重新传输Request消息。T1定时器和N1计数器的设置是特定于实现的。
A retransmitted PFCP message shall have the same message content, including the same PFCP header, UDP ports, source and destination IP addresses as the originally transmitted message.
重新传输的PFCP消息应具有与原始传输消息相同的消息内容，包括相同的PFCP报头、UDP端口、源和目标IP地址。
A Request and its Response message shall have the same Sequence Number value, i.e. the Sequence Number in the PFCP header of the Response message shall be copied from the respective Request message. A Request and its Response messages are matched based on the Sequence Number and the IP address and UDP port.
Request及其Response消息应具有相同的Sequence Number值，即Response消息的PFCP报头中的Sequence Number应从相应的Request消息中复制。Request及其Response消息根据Sequence Numbr、IP地址和UDP端口进行匹配。
Not counting retransmissions, a Request message shall be answered with a single Response message. Duplicated Response messages shall be discarded by the receiver. A received Response message not matching an outstanding Request message waiting for a reply should be discarded.
在不计算重传的情况下，Request报文应以单个Response报文进行应答。接收方应丢弃重复的Response消息。接收到的Response消息与等待答复的未完成Request消息不匹配，应丢弃该消息。
The PFCP entity should inform the upper layer when detecting an unsuccessful transfer of a Request message to enable the controlling upper entity to take any appropriate measure.
PFCP实体应在检测到Request消息的不成功传输时通知上层，以使控制上层实体能够采取任何适当的措施。