How CRL supported a smart redesign of a real-life protocol

The speciication language crl, based on process algebra with data, and the CCsar/Ald ebaran tool set are used to support the optimised redesign of Transaction Capabilities Procedures (tcap), which is part of the SS No. 7 protocol stack. To this end, both the original and the optimised tcap are speciied in crl, for each of these a transition system is generated with the crl tool set, after which these are checked on bisimulation equivalence with the CCsar/Ald ebaran tool set. In an iterative process of reening and debugging, speciications and designs of increasing accuracy are developed, nally resulting in a correct optimisation. The optimised redesign beneets indeed from the combined use of crl and CCsar/Ald ebaran, although the application of veriication in design still requires a good deal of insight and human inventivity.