Physical layer protocol, delivering high speed data networking over single pair copper phone lines, where the upstream and downstream data transmission rates are the same. Base transmission distance is 24,000 feet (about 5 miles), extendable to over 30,000 feet with repeaters, and beyond with fiber optic.
SDSL) DSL connection that provides equivalent upstream and downstream transmission rates over one copper wire pair for business services up to approximately 2 Mbps. Useful for business applications: the equal speeds make this good for LAN (local area network) access, distributed applications, video-conferencing, and for sites hosting their own Websites.