Mechanical Verification of a Generic Incremental ABR Conformance Algorithm
Résumé
The Available Bit Rate protocol (ABR) for ATM networks is well-adapted to data traffic by providing minimum rate guarantees and low cell loss to the ABR source end system.The protocol relies on a contract between the operator who ensures a minimum rate and the source who must respect a rate that is dynamically allocated to him, according to the resources available in the networks. An ABR conformance algorithm for controlling the source rates through an interface has been defined by ATM Forum. A more efficient version of this algorithm has been designed \cite{rk97}. We present in this work the first complete mechanical verification of the equivalence between these two algorithms. The proof is rather involved and has been supported by the PVS theorem-prover. It has required many lemmas, case analysis and induction reasoning for the manipulation of non bounded scheduling lists. Some ABR conformance protocols have been automatically verified in previous works.However these protocols are approximations of the one we consider here.