Term of the Moment
IPFS
Definition: SONET
(Synchronous Optical NETwork) A fiber-optic transmission system for high-speed digital traffic. Employed by telephone companies and common carriers, speeds range from 51 Mbps to 200 Gbps.
SONET and SDH
SONET is employed in the U.S. and Canada, whereas SDH (Synchronous Digital Hierarchy) is the SONET counterpart in the rest of the world. Although the terms "SONET/SDH" and "SDH/SONET" are widely used, there are differences in frame size and terminology.
Self Healing
SONET can be built in a self-healing ring architecture that uses two or more transmission paths between nodes. In the event one path fails, traffic can be rerouted (see SONET ring).
TDM Multiplexing
SONET uses time division multiplexing (TDM) to send multiple data streams simultaneously. Its smallest increment of provisioning is VT-1.5, which provides 1.7 Mbps of bandwidth. The next increment, STS-1, jumps to 51.84 Mbps. Any data stream that does not fill that channel goes wasted.
ATM Over SONET
Telcordia's GR-2837 standard maps ATM cells onto SONET, turning a SONET pipe into a cell-switched (packet-switched) transmission carrier that utilizes the full bandwidth of the medium without waste. See 10 Gigabit Ethernet.
Transporting IP
SONET and SDH
SONET is employed in the U.S. and Canada, whereas SDH (Synchronous Digital Hierarchy) is the SONET counterpart in the rest of the world. Although the terms "SONET/SDH" and "SDH/SONET" are widely used, there are differences in frame size and terminology.
Self Healing
SONET can be built in a self-healing ring architecture that uses two or more transmission paths between nodes. In the event one path fails, traffic can be rerouted (see SONET ring).
TDM Multiplexing
SONET uses time division multiplexing (TDM) to send multiple data streams simultaneously. Its smallest increment of provisioning is VT-1.5, which provides 1.7 Mbps of bandwidth. The next increment, STS-1, jumps to 51.84 Mbps. Any data stream that does not fill that channel goes wasted.
ATM Over SONET
Telcordia's GR-2837 standard maps ATM cells onto SONET, turning a SONET pipe into a cell-switched (packet-switched) transmission carrier that utilizes the full bandwidth of the medium without waste. See 10 Gigabit Ethernet.
SONET CIRCUITS Optical Electrical Speed Level Level (Mbps) OC-1 STS-1 ---- 51.84 OC-3 STS-3 STM-1 155.52 OC-9 STS-9 STM-3 466.56 OC-12 STS-12 STM-4 622.08 OC-18 STS-18 STM-6 933.12 OC-24 STS-24 STM-8 1244.16 OC-36 STS-36 STM-13 1866.24 OC-48 STS-48 STM-16 2488.32 OC-192 STS-192 STM-64 9953.28 OC-768 STS-768 STM-256 39813.12 OC-1920 STS-1920 STM-640 99532.80 OC-3840 STS-3840 STM-1280 200000.00 OC = Optical Carrier STS-1 = Basic SONET building block STM-1 = Basic SDH building block
In a WAN or over the Internet, IP traffic is widely carried over SONET lines, either using ATM as a management layer or over SONET directly. In the future, IP is expected to travel directly over DWDM fiber (rightmost diagram).