SDSL是DSL技术与以太网技术相结合的产物，它采用简单的媒体转换器取代了昂贵复杂的DSL和DSLAM，避免了把IP数据包转换为ATM数据元的麻烦。SDSL实现了可在一对普通铜线上，以上下对称的2.3Mbps速率支持有话音伴随达2.4 Km的传输距离，无话音伴随情况下传输距离更可达到2.7 Km。该设备还具有速率限制功能，配合SNMP可以设定从256Kbps到2.3Mbps的用户速率，以适应不同传输距离的需要。SDSL具有开通率高、覆盖面积广、传输速率高、性能稳定的特点。

Symmetric digital subscriber line (SDSL) refers to digital subscriber line (DSL) technologies, that is, technologies for transmission of digital data over the copper wires of the telephone network where the bandwidth in the downstream direction, from the network to the subscriber, is identical to the bandwidth in the upstream direction, from the subscriber to the network. This symmetric bandwidth can be considered to be the opposite of the asymmetric bandwidth offered by asymmetric digital subscriber line (ADSL) technologies, where the upstream bandwidth is lower than the downstream bandwidth. SDSL is generally marketed at business customers, while ADSL is marketed at private as well as business customers.