DSL Grows Up

Rich Tehrani : Communications and Technology Blog - Tehrani.com
Rich Tehrani
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DSL Grows Up

Somehow, don't ask me why, I am hooked on learning about 802.3ah, an IEEE standard for deploying broadband over copper. I have written about 802.3ah before but I never really had an in-depth understanding of it until recently. By the way, 802.3ah is also referred to as Ethernet in the First Mile or EFM (yes, we desperately needed another protocol, standard and especially another acronym in telecom!)

There are a few reasons why this standard makes sense for service providers to roll out. First of all Ethernet in my opinion is the future of broadband. T1, E1, T3, DSL, etc will fade quickly as Ethernet becomes the standard broadband technology we will all use. 802.3 supports Ethernet.

Furthermore, fiber is in short supply. If you were a financial TV watcher in post-buble months, all they talked about was the excess of fiber. When you have financial people acting like experts in areas like optical, you confuse the public. We have tremendous amounts of fiber in the ground, just not going to office buildings where it is needed. If you have fiber in your office, you are in the lucky 10-20% minority. Our office is in Norwalk, CT and the only fiber we'll see at TMC is on bagel/donut/muffin day (every Friday in case you want to visit - the bran muffins go quickly btw)

But I digress and need to come back to my point which is this 802.3ah stuff is great. It allows service providers to deliver metro Ethernet services at a fraction of the cost of DSL and ATM technology.

802.3ah comes in two flavors, the longer range 2BASE-TL can reach distances of 20,000 feet and greater while the shorter range 10PASS-TS is meant for high-speed broadband deployment and FTTC deployment.

In contrast to 10PASS-TS, 2BASE-TL is designed for delivering symmetrical services from a central office to a business with a maximum delivery rate per pair of 5.7 Mbps and the ability to bond up to 32 pairs into an Ethernet port. Although I haven't seen seen a single app with this sort of bandwidth requirement, this allows a theoretical 182 Mbps! Nice. If I could get that at TMC and pay a few thousand a month, we have a deal. Any takers?

What is it?

In telecom, everything new is old again or the other way around which is why EFM technology leverages existing DSL layers. The good news here is that the technology is new but able to use current DSL chips, etc meaning costs aren’t as high as a radically new technology. One last point is that EFM is more immune from signal interference from voice T1s and other "disturbers," meaning the line will be effectively cleaner than DSL and more suitable for business.


EFM technology doesn't need UNE-P like a traditional T1 and as such will work with UNE-L or dry copper. This is great in a world being cleansed on UNE-P.

Hatteras Networks is a company I met with recently and they were nice enough to show me a demo of their EFM products in action. They have a series of boxes from point to point to point to multipoint allowing a service provider to dabble before he or she commits to the larger solution. Their products are the HN400 and HN4000 series Metro Ethernet Copper Access Switches. Business is good for them right now. They have found a good niche. One area of growth for example is service providers supplying broadband to WiFi hotspots and more recently WiMAX towers. EFM technology is not really too well known and I am not sure why. It seems like a great solution for companies with fiber taste and a copper zip code.

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