2.2.1. Credit Control Message

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Original RFC Text

2.2.1.  Credit Control Message

   Credit Control Messages are sent by modems and routers.  Each sender
   is only permitted to have one message outstanding at one time.  That
   is, a sender (either modem or router) MUST NOT send a subsequent
   Credit Control Message until a Credit Control Response Message has
   been received from its peer.

   Credit Control Messages are sent by modems to provide credit window
   increases.  Modems send credit increases when their transmission or
   local queue availability exceeds the credit window value previously
   provided to the router.  Modems will need to balance the load
   generated by sending and processing credit window increases against a
   router having data traffic available to send but no available
   credits.

   Credit Control Messages MAY be sent by routers to request credits and
   provide window status.  Routers will need to balance the load
   generated by sending and processing credit window requests against
   having data traffic available to send but no available credits.

   The Message Type value in the DLEP Message Header is set to 17.

   A Credit Control Message sent by a modem MUST contain one or more
   Credit Window Grant Data Items as defined in Section 2.3.3.  A router
   receiving this message MUST respond with a Credit Control Response
   Message.

   A Credit Control Message sent by a router MUST contain one or more
   Credit Window Request Data Items as defined in Section 2.3.5 and
   SHOULD contain a Credit Window Status Data Item, defined in
   Section 2.3.4, corresponding to each credit window request.  A modem
   receiving this message MUST respond with a Credit Control Response
   Message based on the received message and Data Item and the
   processing defined in Section 2.2.2, which will typically result in
   credit window increments being provided.

   Specific processing associated with each Credit Data Item is provided
   in Section 2.3.