This paper presents the hardware architecture of DynaCORE, a dynamically reconfigurable system-on-chip for network applications. DynaCORE is an application specific coprocessor for offloading computationally intensive tasks from a network processor. The system-onchip architecture is based on an adaptable network-onchip which allows the dynamic replacement of hardware modules as well as the adaptation of the on-chip communication structure. The coprocessor leverages the active partial reconfiguration feature of modern FPGAs in order to adapt to shifting demand patterns. An embedded general-purpose processor core within the coprocessor runs software which manages the configurations of the device. With reference to a prototypical implementation targeting a Xilinx Virtex-II Pro FPGA, this paper focuses on on-chip communication issues. Topics include the integration of PowerPC processor cores into the configurable logic as well as the mode of operation of the network-on-chip.