Appendix A. Example DLEP Credit Flow Control and Traffic Classification Data Item Exchange

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Appendix A.  Example DLEP Credit Flow Control and Traffic Classification
             Data Item Exchange

   Figure 2 illustrates a credit flow control and traffic classification
   exchange between a router and a modem.  The modem will initialize a
   number of queues with Credit Window Initialization Data Items, Credit
   Window Association Data Item(s), and Traffic Classification Data
   Item(s) included in DLEP messages as outlined in this document.  If
   the Data Items are successfully validated, traffic is mapped to the
   corresponding credit window on the router and forwarded when there
   are sufficient credits.  Routers can periodically report the status
   of the credit window.  Modems will send periodic updates with more
   credits as packets are transmitted.  If a router requires more
   credits for a particular window, it may request them.  This document
   defines credit window flow information for FIDs that map to the
   queues.  [RFC9892] defines the Traffic Classification Sub-Data Items,
   such as DSCPs, that map to the FIDs.

   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                                   |
     |                                             |

    Figure 2: Example DLEP Traffic Classification / Credit Flow Exchange