A scalable QoS routing architecture for real-time CSCW applications

Computer supported cooperative work (CSCW) has the potential of providing the environment needed for groups of diverse users to cooperate in real-time to achieve their common goals. This potential has been under-utilized due to the lack of cooperation between CSCW systems and the underlying network services to accommodate the dynamic behavior and varying quality-of-service (QoS) requirements of CSCW groups and the applications they use. To satisfy such requirements, QoS multicast routing should be employed. Unfortunately, current multicast services are inadequate for the traffic generated in CSCW environments. The authors present a CSCW-specific routing architecture that supports QoS requirements and is both scalable and robust. Scalability is needed to accommodate a large number of multicast groups and highly dynamic group membership and behavior, while robustness provides reliability and stable performance for each group during adaptation and in presence of the other existing groups. In the architecture, a router QoS manager, on behalf of a multicast routing manager, negotiates with host and CSCW-specific QoS managers for efficient resource utilization and guaranteed QoS delivery. The multicast routing manager switches between routing trees and algorithms as warranted by the changes in the characteristics and requirements of the CSCW systems running at the hosts. They present a class-based and a partial view-based method to scalability. They also present a centralized and a distributed method to establishing a group's QoS multicast path while providing robustness.