Fiber optic carrier services have been structured on the SONET or Synchronous Optical Network standards developed by Telcordia, formerly Bellcore or Bell Communications Research. SONET specifies a series of carrier levels from OC1 at 51.8 Mbps through OC-3072 at 159 Gbps. The signal structure was designed to easily multiplex and demultiplex standard telecom digital signal levels such as DS-1 at 1.5 Mbps, which is also carried on T1 lines, and DS-3 at 45 Mbps, which is also carried on T3 lines. DS3 service today is more typically delivered via fiber optic cables.
Typical SONET services commonly seen in metro area networks and coast to coast networks are OC3 at 155 Mbps, OC12 at 622 Mbps, OC48 at 2.5 Gbps and OC192 at 10 Gbps.
SONET has a telephone company heritage. Each of these optical carrier services can be multiplexed from individual DS0 phone channels at 64 Kbps each. For instance, an OC-192 can carry over 100,000 simultaneous telephone calls. But they can also carry huge amounts of digital data. A conversion process is needed, as SONET is based on TDM or rigid time slots. Network data is packetized, most often in the TCP/IP protocols. Transporting Fast Ethernet on an OC3 running at 155 Mbps or Gigabit Ethernet on an OC-48 carrier running at 2.5 Gbps is not too much of a feat. Interfacing with OC192 is a bit trickier.
The reason for this is that OC-192 carrier service has a line rate of 9.953 Gbps and a payload bandwidth of 9.622 Gbps. That's close to 10 GigE but not quite. As such, two standards have emerged: 10GB E LAN PHY for local area networks and 10GB E WAN PHY for 10 Gbps Ethernet over SONET. These are defined in IEEE 802.3ae.
The effect of this standardization is that 10 GigE networks can be extended beyond the campus into the metro area and nationwide or even worldwide using existing telecom based fiber optic networks. Small and medium businesses probably don't need this type of WAN bandwidth yet, but Internet Service providers do. Other bandwidth hungry applications are medical imaging, large CAD/CAM designs, real-time simulations, digital video production and delivery, and data center backup and recovery.
Do you have a serious business demand for high bandwidth wide area networking? Let our team of connectivity experts help you get the best prices on WAN services from fractional T1 lines through carrier Ethernet. Put in a quick request or call the toll free number available at GigaPackets.com.
