Abstract This paper presents a comparative evaluation of the Scalable ReservationBased QoS (SRBQ) and the RSVP Reservation Aggregation (RSVPRAgg) architectures, both designed to provide QoS levels similar to RSVP/IntServ without the scalability concerns that prevent its usage in high-speed core networks. The comparative analysis, based on simulation results, shows that SRBQ provides the same QoS guarantees of RSVPRAgg, with significantly increased network resource utilisation and a small penalty in signalling processing overhead. This stems from the fact that although based on end-to-end reservations, SRBQ makes use of techniques and algorithms that reduce the computational complexity of signalling processing, increasing its scalability.