The term ring is especially applicable to SONET, which is generally deployed as two counter-rotating data rings over redundant fiber optic cables. The term SONET stands for Synchronous Optical NETwork. It's a fiber optic transmission system based on TDM or Time Division Multiplexing. Developed by the telephone companies to increase the capacity of their digital trunks beyond the T1 and T3 lines of the T-Carrier system, SONET remains the transport technology of choice for the incumbent telcos. The reason for the redundant rings is to implement an automatic failover mechanism. If one path fails, the other automatically picks up the traffic within 50 mSec.
The built-in protection and synchronized TDM channels make SONET ideal for carrier grade digitized telephone call trunking. But SONET can also transport packetized data including voice, video and data. One use of SONET fiber optic circuits is to transport DS1 signals for T1 lines and DS3 signals for T3 lines over long distances. They can be split off or demultiplexed at the drop off destination. If you have a long haul T1 line, chances are that it is carried at least part of the way on fiber optic channels even though your termination is twisted pair copper.
The SONET family of line rates spans OC-1 at 52 Mbps on up to OC-768 at 40 Gbps. But in practice, only a few optical carrier levels are standard and readily available. These are OC-3 at 155 Mbps, OC-12 at 622 Mbps, OC-48 at 2.5 Gbps, OC -192 at 10 Gbps and OC-768 at 40 Gbps. The higher speed services are typically used as carrier backbones and may not be available to business users.
So who is this new contender Carrier Ethernet? It's LAN Ethernet that is adapted for the WAN or Wide Area Network. Carrier Ethernet, a term meaning telecom carrier quality Ethernet service, is designed for packet switched networks and dispenses with the synchronized fixed size channels of SONET technology. It's interface is a standard Ethernet connector and can be set up for Level 3 routing or Level 2 switching. At the switching level, Carrier Ethernet simply extends your local area network to other facilities across town.
Standard Ethernet WAN services mirror the standard Ethernet LAN speeds of 10 Mbps, 100 Mbps, 1 Gbps and 10 Gbps. But some carriers, such as XO Communications, offer incrementally finer Ethernet bandwidths that include 20, 30, 40, 50, 60, 70, 200, 300, 400, or 500 Mbps.
This throw down is more than just a battle among competing technologies. It's also about cost. Ethernet claims a substantial cost advantage, mostly due to aggressive marketing by competitive carriers. At lower bandwidths, they can often use Ethernet over Copper or EoC transmission techniques to avoid having to build out costly new fiber connections. EoC is generally available within 2 to 3 miles of a carrier POP or Point of Presence, at speeds up to 45 Mbps or DS3 equivalent bandwidth.
So, does that mean that Ethernet is always a better deal than SONET? Often, but not always. In some cases, Ethernet service isn't even available, but OC3 services are well established. You should also know that the same competitive cost pressures that have made Ethernet WAN services available at lower costs have also made SONET services much cheaper than they used to be. OC3 is no longer an exotic service suitable for only Internet service providers and the largest corporations. A smaller video production company can easily require OC3 level bandwidth at 155 Mbps or Fast Ethernet at 100 Mbps. OC12 and OC48 are not beyond the reach of larger technology based companies.
So, how do you chose? The best way is to get a list of competitive quotes for the services available at your location and pick the most cost effective solution. Use our GigaPackets.com business bandwidth search tool and free consulting services to make this an easier process. Regardless of which technology reigns supreme, you'll be the true winner.
