Appendix A. DLEP 信用流量控制和流量分类 Data Item 交换示例 (Example DLEP Credit Flow Control and Traffic Classification Data Item Exchange)

图 2 展示了路由器与调制解调器之间的信用流量控制和流量分类交换. 调制解调器会使用 DLEP 消息中包含的 Credit Window Initialization Data Items, Credit Window Association Data Item(s) 和 Traffic Classification Data Item(s), 按照本文档所述初始化若干队列. 如果 Data Items 成功通过验证, 流量会在路由器上映射到对应的信用窗口, 并在有足够信用时转发. 路由器可以周期性地报告信用窗口状态. 调制解调器会在数据包被传输时发送带有更多信用的周期性更新. 如果路由器需要某个特定窗口的更多信用, 它可以请求这些信用. 本文档为映射到队列的 FID 定义信用窗口流信息. [RFC9892] 定义映射到 FID 的 Traffic Classification Sub-Data Items, 例如 DSCP.

   Router                                        Modem

     |<----------------DLEP Messages---------------|
     |   Traffic Classification Data Item(s)       |
     |   Credit Window Association Data Item(s)    |
     |   Credit Window Initialization Data Item(s) |
     |                                             |
     |============================================>|
     |   Traffic                                   |
     |                                             |
     |<----------------DLEP Messages---------------|
     |   Credit Window Grant Data Item(s)          | T
     |============================================>| i
     |   Traffic                                   | m
     |                                             | e
     |----------------DLEP Messages--------------->|
     |   Credit Window Status Data Item(s)         | |
     |                                             | V
     |============================================>|
     |   Traffic                                   |
     |                                             |
     |----------------DLEP Messages--------------->|
     |   Credit Window Request Data Item(s)        |
     |                                             |
     |<------------------------------------------- |
     |   Credit Window Grant Data Item(s)          |
     |                                             |
     |============================================>|
     |   Traffic                                   |
     |                                             |

图 2: DLEP Traffic Classification / Credit Flow 交换示例