Request ID [32 Bit]
- The Request ID field shall consist of a Client ID field [16 bits] and a Session ID field [16 bits].
Request ID 字段应由Client ID字段[16位]和Session ID 字段[16位]组成。 - The Client ID is not used for Service Discovery, The Client ID shall be set statically to 0x0000.
Client ID不用于Service Discovery ，Client ID 应静态设置为0x0000。 - The Session ID is used to detect the reboot or restart of other Service Discovery instances in the vehicle in order to repair the local state of the Service Discovery module.
Session ID用于检测车辆中其他服务发现实例的重新引导或重新启动，以修复服务发现模块的本地状态。 - After initialization of the Service Discovery Module, the Session ID for messages sent by the local ECU shall be 0x0001.
Service Discovery模块初始化后，本地ECU发送的消息的Session ID应为0x0001。 - The Session ID shall be incremented and stored separately for multicast and every single unicast communication partner every time SoAd_IfTransmit() is called.
每次调用SoAd_IfTransmit()时，对于组播和单播通信伙伴，Session ID都会单独增加并单独存储。 - Every time, the Session ID wraps around, the Session ID shall restart with the value 0x0001.
每次Session ID循环， Session ID需要从0x0001重新开始。
Note注意:
- This means that the first SD message sent out to the multicast address has Session ID 0x0001 as well as the first SD message sent out to any unicast communication partner has the Session ID 0x0001 as well.
这意味着发送到多播地址的第一条SD消息具有会话ID 0x0001，并且发送给任何单播通信伙伴的第一条SD消息也具有会话ID 0x0001。 - Wrap around means that the current value of the Session ID is the max value (0xFFFF) and the next increment would mean the counter must start again.
循环意味着会话ID的当前值是最大值（0xFFFF），再增加一次session意味着计数器必须重新启动。