EoC termination equipment is not available yet in all central offices. More is caused by simple distance limitations. What can be done to make Carrier Ethernet available to all the businesses that want it?
MegaPath, a major competitive carrier, has an answer. It’s called EoDS1 or Ethernet over DS1. Now, just what is EoDS1 and how does it differ from EoC?Both EoC and EoDS1 are copper wireline services. Both are provisioned over ordinary twisted pair telco wiring. This is the same copper bundle that brings in multi-line telephone service. Both use multiple bonded pairs to increase bandwidth. However, one has distance limitations and the other doesn’t. Why is that?
It has to do with the technology that sends the digital signals down the line. Ethernet over Copper is seen as a big improvement over T1 lines because bandwidth options go far beyond the 1.5 Mbps that T1 offers. Typical entry level for EoC is 3 Mbps. Many companies are opting for 10 Mbps now. High bandwidth users can get 20, 30, 45, 60 and even 100 Mbps using the copper plant that is already installed to their business. Prior to Ethernet over Copper, companies that needed higher bandwidths had to bring in fiber or do without.
Ethernet over Copper has changed all that for many businesses, especially those in dense metropolitan areas where central offices are plentiful and nearby. The technical issue is that high speed digital signals degrade rapidly with distance. You can only send data so fast on a twisted pair of small diameter copper wires buried in the ground. EoC gets around this to some extent by using multiple pairs to divvy up the datastream so that each pair can run at a slower speed. When added together at the far end, you can get a lot of bandwidth out of 4 or 8 pairs. Even so, the closer you are to the central office that terminates the wiring from your location, the more bandwidth options will be available.
So why does EoDS1 not suffer from these same limitations? Remember the venerable T1 line running along at 1.5 Mbps? DS1 or Digital Signal level 1 is the definition of the way the data is formatted on a T1 line. Sometimes the terms DS1 and T1 are used interchangeably.
You know that T1 lines and their DS1 signals can be connected miles from the central office. In fact, there aren’t very many locations even out in the boonies that don’t qualify for T1 line service. Until recently, it was the preferred backhaul connectivity for cell phone towers. It’s not just the lower line speed that makes this possible. T1 was developed by the telephone companies to interconnect their own switching centers. These can be long distances apart, so a signal regenerator was designed to boost the T1 signal every 6,000 feet or so. Multiple regenerators can be used on one line, greatly extending the transmission distance.
Here’s something else you should know about T1 lines. They can be pair-bonded, just like EoC, to increase the delivered bandwidth. Bond two T1 lines together and you get a 3 Mbps service. Bond 8 T1 lines to get 12 Mbps, pretty much the maximum speed available using multiple T1 lines.
As you might suspect, EoDS1 is nothing more than Ethernet over T1 lines. In many cases, you can order bonded T1 or EoDS1 and get the same bandwidth result. So why not just stick with T1?
The reason is Ethernet services. Your local area networks run the Ethernet protocol. You can interconnect LANs at multiple locations with T1 lines by going through protocol conversions to and from Ethernet. If you keep everything in the Ethernet protocol, the transmission process is more efficient and you have the option to link your LANs at the layer 2 level. This means that ordinary Ethernet switches can be used to route traffic on what is essentially one large Ethernet network.
Are you considering new Carrier Ethernet service or wish to expand your multi-location links to include places where EoC isn’t available yet? If so, take a closer look at the cost and benefit of Ethernet over DS1 bandwidth service.
