Recommendation ITU-T G.7703 describes the reference architecture and requirements for the automatically switched optical network (ASON) as applicable to connection-oriented circuit or packet transport networks. This reference architecture is described in terms of the key functional components and the interactions between them. Amendment 2 aligns with Recommendation ITU-T G.7701, which specifies common control aspects for both ASON and software defined networking (SDN) architecture. This amendment refers to Recommendation ITU-T G.7701 common clauses.