We are currently implementing the proposed protocol stack in MK 7.3 using the CORDS system provided (which is an extension of x-kernel with the notion of paths). In particular, the proposed QoS-enhanced CBT protocol and the rate-based message scheduling paradigm are being implemented in the routing module and in the traffic control and message scheduling module, respectively. As a preamble to implementation, we have defined, in compliance with the APIs provided in MK 7.3 and CORDS, the interfaces exported by

We are also using the GateD Multicast source codes (distributed by the GateD Consortium, Merit Network, Inc.) to prototype the proposed QoS-driven core-based tree multicast routing protocol both as a stand alone mechanism and as part of the protocol stack in NetBSD and will empirically measure its performance.

GateD is a portable routing protocol development platform that factors out (and separately provides) functionality common to most protocol implementations. As depicted in the above figure, the modular GateD software consists of core service modules, a routing database, and protocol modules (that support multiple routing protocols). The multicast protocols currently supported by GateD include IGMP (version 2), DVMRP (version 3), CBT, and PIM-SM. We take advantage of all the core services provided, and implement, based on the CBT code available, the proposed QoS-driven core based tree protocol as one of the protocol modules. Moreover, we have defined and are currently implementing a rich, well-specified API through which a suite of multicast services with different QoS guarantees (guaranteed bandwidth, bounded delay, bounded inter-destination delay jitter, and/or a combination thereof) can be exported.

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