Credit Flow Control for PPPoE
To support the credit-based flow control extensions described in RFC4938, PPPoE peers can grant each other forwarding credits. The grantee is allowed to forward traffic to the peer only when it has a sufficient number of credits to do so. When credit-based forwarding is used on both sides of the session, the radio client can throttle traffic by limiting the number of credits it grants to the router.
The interfaces statement includes the radio-router attribute, which contains the parameters used for rate-based scheduling and OSPF link cost calculations. It also includes the credit attribute to indicate that credit-based packet scheduling is supported on the PPPoE interfaces that reference this underlying interface. Interfaces that set the encapsulation attribute support the PPPoE Active Discovery Grant (PADG) and PPPoE Active Discovery Credit (PADC) messages in the same way that the radio-router attribute provides active support for the PPPoE Active Discovery Quality (PADQ) message.
The credit interval parameter controls how frequently the router generates credit announcement messages. For PPPoE this corresponds to the interval between PADG credit announcements for each session.