Multimedia applications need support for both real-time computation and real-time communications because of their sensitivity to delay and jitter. It therefore requires the operating system to provide soft real-time support in the processor and the network subsystems. In this work, we present a network subsystem which can cooperate with any CPU scheduler to provide network Quality of Service (QoS) to multimedia applications. This system, called VRE-NET, allows applications to reserve bandwidth for the protocol processing capacity of the network subsystem. The bandwidth reservation can be adjusted according to different QoS requirements. We provide a mechanism for users to associate each multimedia application with a rate controller that automatically adjusts the bandwidth reservation. The implementation was done in the Linux 2.6.0 kernel.