RouterBoard + Radius + volume-based prepaid model

Hi,
I would like to implement a WiFi service following the following requirements:

  • Prepaid, volume-based quota (Tx+Rx)
  • Both HTTP P(CH)AP and pppoe to be used
  • New Subscribers to get a restricted connectivity, allowing to access a Portal for them to purchase a voucher on-line
  • AAA using Radius, quota left provided by Radius at authorisation step
  • Radius accounting to be used to record subscriber activity (quota management)
  • Router/AC to enforce the associated quota limit
  • Subscriber connectivity to switch to a restricted one, to the voucher portal for buying additional bandwidth, when quota is reached
  • Router/AC to possibly reissue a Radius auth to check if additional quota is available when quota is reached
  • Radius backend to issue a CoA to Router/AC to reenact normal connectivity upon purchase of additional bandwidth

I have almost everything but:

  • The Radius attribute managing allocated volume Tx+Rx (I don’t see how to aggregate Mikrotik-Xmit(Rcv)-Limit for that matter) for the Authorisation phase (or for CoA)
  • How the RouterBoard is managing a volume-based quota connection when quota is breached: session closed? restricted connectivity possible (specially in case of pppoe)?

Best regards
Pierre