An asynchronous high-speed fiber-optic local area network is described that supports ordinary data packet traffic simultaneously with synchronous TI voice traffic over a common FDDI (fiber-optic distributed data interface) token ring channel. A voice interface module was developed that parses, buffers, and resynchronizes the voice data to the packet network. The technique is general, however, and can be applied to any deterministic class of networks, including multitier backbones. A conventional single-token access protocol was used at the lowest layer, with fixed packet sizes for voice and variable for data. In addition, the higher-layer packet data protocols are allowed to operate independently of those for the voice, thereby permitting great flexibility in reconfiguring the network. Voice call setup and switching functions were performed external to the network with PABX equipment.>