EoDS1 Extends Ethernet over Copper Distance

Demand for Ethernet over Copper has outstripped its availability. Some of this is because
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.

Ethernet Bandwidth For Rural Areas

It is commonly assumed that there is no such thing as Ethernet WAN service beyond the city limits. That’s not really true, as you do have Ethernet connectivity options even in rural areas. Let’s see how that’s done.

Ethernet over Copper (EoC) is becoming the bandwidth service of choice for small and medium businesses. It offers the ease of Ethernet interfacing, ability to transport Ethernet services like E-Line, E-LAN and VPLS, relatively high bandwidths of 3 to 50 Mbps and even 100+ Mbps in select areas, all with provisioning over multiple twisted pair telco wiring that is already installed. Best of all, pricing is more than competitive. Where available, you’ll pay a lot less for EoC vs traditional telecom services like T1 or DS3 on an Mbps basis.

"Where available" is the catch. Ethernet over Copper technology has strict distance limitations. The modulation scheme that is used can transport high bandwidth levels, but signal levels fade rapidly as you get farther and farther away from the telco Central Office (CO). Within a mile or so you can get all sorts of bandwidth options using 2 to 8 twisted pair. As you start moving out to 2 or 3 miles away, signal levels degrade to the point where they are unusable even at low bandwidths.

That pretty much rules out EoC for most rural locations. Beyond the city limits, population densities are low and wire runs are long for telecom services. Fiber may be running right next to the gravel road you are standing on. The hitch is that there is no drop-off. The fiber just keeps on going to the next metropolitan area.

Now, there are exceptions. If you have a rural business location that luckily happens to be within a few thousand feet of the incumbent telephone company’s office, you may qualify for Ethernet over Copper services. What’s needed is for the telco or a competitive service provider to have EoC terminal equipment installed in that CO. You are less likely to find EoC equipment in smaller offices because of the limited number of businesses connected to that facility.

Don’t despair. As I said earlier, you may still have options. There is another way to transport Ethernet over copper lines with virtually unlimited reach. This is called Ethernet over DS1 or EoDS1. If DS1 sounds familiar, it’s because DS1 is the Digital Signal protocol used for T1 lines. DS1 is part of the half-century old T-Carrier specifications that define the technology for T1 and T3 lines. DS1 was originally developed to transport telephone conversations in groups of 24 channels or time slots within a time division multiplexed bit stream. Later, a concept called clear channel T1 was implemented to combine all those channels into one larger channel. That boosted bandwidth per channel from 64 Kbps up to 1.5 Mbps and made it practical to transport data using DS1.

DS1 defines the signal. T1 is the particular physical line consisting of 2 twisted pair copper telco wires with particular voltage and signal shape characteristics. Normally, DS1 and T1 go together. However, It is possible technically to transport Ethernet using DS1. What that means is that Ethernet can be sent over T1 lines. Since T1 was designed to use signal regenerators to boost sagging signal levels every mile or so, T1 service can go out into the boonies for miles, sometimes even 20 miles or more.

Ethernet over DS1 gives you the option to get Ethernet service where only T1 is available. You aren’t limited to the T1 line bandwidth of 1.5 Mbps. T1 lines can be bonded to increase bandwidth, which works for EoDS1 too. Add more lines and you get more bandwidth. It’s the number of lines bonded times 1.5 Mbps.

What about cost? EoDS1 doesn’t offer the same cost advantages as EoC because the price of T1 lines doesn’t go down if you bond more of them together. You have to pay for each line. EoDS1 also isn’t available from all carriers or in all locations.

What’s the best bandwidth solution for your company? It depends a lot on where you are located and what services you require. There’s an easy way to compare options. Simply get competitive quotes for Ethernet and other telecom services from multiple service providers, each tailored to your particular requirements.

Ethernet over TDM

You’ve heard of Ethernet over Copper and Ethernet over Fiber, but have you heard of Ethernet over TDM? Here’s why it’s good to be familiar with this technology and what it can do for you.

TDM stands for Time Division Multiplexing. It’s the basis of T1 lines and SONET fiber optic carrier services. TDM was the chosen protocol of the Public Switched Telephone Network (PSTN) when the decision was made to transition from analog to digital mid-20th century. It is still important is because it is still around and going strong.

TDM is a way to transmit multiple signals on one digital line or wireless channel. The way TDM works is that a digital transmission is divided up into timeslots. Each timeslot contains the digitized information for one signal. All the timeslots are linked together like railroad cars into a frame that contains all of the digital bits, end to end. This frame is then transmitted from source to destination. Once one frame is sent another immediately follows.

Think of TDM as a round-robin polling process. You take a chunk of information from one source, then a chunk from another source, and so on. When you’ve got something from all sources that you wish to multiplex, then you start over with the first source again. That way you always have fresh data from frame to frame.

What TDM did for the phone companies was to pack 24 separate telephone calls onto one T1 line instead of 24 separate telephone wires. The multiplexing process combines all calls into one bitstream that is sent down the physical copper wires. At the other end, a complementary process called demultiplexing separates the individual calls so they can be used by particular telephones.

Ethernet is not a TDM process. Instead, it bundles bits of data into packages called packets. The packets are sent on their way individually when they are ready. There’s no assembling the packets into a multiplexed “train” so that they can all travel together. Each packet is switched and routed individually.

From the sound of it, you would think that TDM circuits, like T1 lines, and packet switched circuits, like Ethernet over Copper, would be incompatible. It’s true that they are completely different technologies and don’t exist on the same piece of wire at the same time. That would really create a mess and you’d get completely jumbled up data. However, clever engineering can let one protocol carry another. This is where the idea of Ethernet over TDM comes about.

How Ethernet over TDM works is that the underlying transmission protocol is TDM. A typical example is a T1 line. The T1 frames are transmitted at a rate of 1.5 Mbps from source to destination. Ethernet packets are loaded into those T1 frames. In this case all the claptrap associated with dividing the T1 line into 24 separate channels is ignored. The internal channels are combined so that Ethernet packets can use the entire frame. The T1 timing and waveforms are preserved so that T1 interfaces and signal regenerators will work as-is.

Why go to all this trouble to piggyback Ethernet on top of a T1 TDM system? It’s to give you more options. Ethernet over Copper is a distance limited technology that works great within a couple of miles from the central office, but loses signal strength and bandwidth fast as you get farther away. T1 has fewer distance limitations and delivers a steady bandwidth of 1.5 Mbps even out into rural areas. As a newer development, Ethernet over Copper is also less available than T1 lines that have been around for 50 years or more.

So, if you want the advantages of Ethernet that include bandwidth scalability, easy interfacing to your network, and standardized services such as Ethernet Line and Ethernet LAN, but can’t get Ethernet over Copper or Ethernet over Fiber, consider Ethernet over TDM. This is also known as Ethernet over T1 or Ethernet over DS1. Check pricing and availability on all Copper Ethernet Services now.

Gaining Ethernet Internet Access

You’ve no doubt heard by now that access to the Internet for business locations offers cost and bandwidth advantages over traditional telecom connections. So, how do you gain Ethernet Internet access? That’s easy. Just use this handy Ethernet Internet Finder.



You’ll likely find that there are a number of options for Ethernet Internet service, although not all of them are available at every business address. Note that this is a business service only. If you need residential or home office broadband, try “Can I Get DSL?” for DSL, cable, satellite, wireless 4G, and fiber to the home.

Your least expensive option for Ethernet Internet access is probably Ethernet over Copper, where available. That’s generally in metropolitan and suburban areas with dense populations. EoC, as it is called, offers bandwidths typically from 3 to 20 Mbps. You’ll pay about as much for a 3 Mbps Ethernet connection as you’d pay for a 1.5 Mbps T1 line. A very popular service is 10 Mbps Ethernet access, which is the standard Ethernet network speed.

Of course, local area network bandwidth has increased dramatically since Ethernet was first introduced. Most LANs are now operating at the Fast Ethernet speed of 100 Mbps or Gigabit Ethernet at 1000 Mbps. Would you be surprised to know that Ethernet WAN connections are also available at 100 and 1000 Mbps? That includes dedicated broadband Internet access with Ethernet in the first mile. These services require a fiber optic connection over SONET or native IP network.

Even if your business is located a bit beyond the service footprint for EoC or fiber optic delivery, it may still be possible for you to get Ethernet over DS1. Bonding T1 lines together may give you the Ethernet bandwidth you need at a reasonable price.

Does Ethernet Internet Access offer advantages for your business? Use the Ethernet Internet Finder to run a quick check and see.

Covad and ADTRAN Make Everything Ethernet

The age of Carrier Ethernet is upon us. All the excitement these days is directed at IP core networks and Ethernet access solutions. So, does that mean that legacy TDM services must be abandoned in place? Not at all. With the right equipment, DS1 and DS3 circuits can be repurposed for Ethernet transport. Carrier Covad and equipment maker ADTRAN are doing just that.

Covad is now deploying ADTRAN central office and network termination equipment to expand their Ethernet service area. Covad currently serves 44 states and 235 major markets with a core network that spans the nation. Their specialties have included business DSL, data T1, high bandwidth fixed wireless, bonded T1, and integrated voice and data with SIP, PRI and analog handoff. All of these are designed to serve the small and medium size business market. Ethernet is a natural addition to the Covad portfolio.

What’s special about the ADTRAN Carrier Ethernet solutions? It’s that they can pretty much press any existing line service into transporting Ethernet from the service provider to the end user. A service aggregation unit is installed at the central office to connect with the carrier’s Metro Ethernet and IP Core networks. For Covad, this is the Total Access 5000 MSAP (Multi-Service Access Platform). The aggregation unit brings in GigE or 10 GigE carrier bandwidth connections and apportions it to subscribers.

What makes this system so flexible is that the transport from CO to subscriber can be any of the common circuits already in place. These include DS3 and bonded DS3 bandwidth, T1 and bonded T1 lines, e.SHDSL bonded pairs. DS3 and T1 (DS1) are legacy service that are been used by many businesses for years. Ethernet over TDM or EoTDM allows service provider to keep those circuits in place and use them to provide Metro Ethernet or Carrier Ethernet services over an extensive area.

EoC or Ethernet over Copper has become very popular recently because it offers higher bandwidths and lower prices than traditional digital line services. The e.SHDSL technology can boost speed to 5.7 Mbps per e.SHDSL loop compared to 1.5 Mbps for T1. However, this is a distance limited technology that is typically extends no further than 9 km from the carrier’s point of presence.

An appropriate network termination unit is installed at the customer location. The companion product is the NetVanta 800 Series. These are configured for 2, 4, or 8 bonded e.SHDSL pairs, up to 3 bonded DS3 circuits for a maximum of 134 Mbps, or 2, 4 or 8 four-wire T1/E1 loops. In many cases, bonding multiple copper pair can bring in the bandwidth needed by businesses without the high cost of pulling-in fiber optic cable for a new installation. In many cases, fiber isn’t available nearby and isn’t really an option. Even so, 10 or 12 Mbps and up to 45 Mbps over existing copper wiring offers the requisite bandwidth at very reasonable costs.

Is your business straining at the limit of your current T1 line or dissatisfied with business DSL service? If so, you may find that Ethernet service from Covad and other top carriers is just what you need. Why not find out how much bandwidth you can get for your telecom dollar? It takes just a second to inquire and a knowledgeable consultant will be in contact quickly with prices and install times. Inquire about Carrier Ethernet for your business now.

The DS1 DS3 Relationship

If you are involved with business telecommunications networking or need to be, you have probably heard the terms DS1 and DS3 bandied about. But what do these terms really mean and where did they come from?

The DS in DS1 and DS3 stands for Digital Signal level. It is a designation that is used to specify the capacity of a digital line in the T-carrier system. You know the most popular T-carrier service as T1. Another popular service is T3. In simple terms, DS1 goes along with T1 and DS3 goes along with T3.

Now, let’s see what’s behind these DS levels and T-carriers. The history of this system goes back to the 1950’s, when Bell Labs recognized the advantage of changing from an all-analog telephone system to digital connections between telephone company offices. Digital transmission carries many conversations on few wires and eliminates the noise and cross-talk that were commonly heard on long distance calls at that time.

The most basic service is one two-way telephone conversation. That was made the most basic element of the T-carrier system and given the designation DS0 or Digital Signal level zero. A DS0 signal is the digital representation of a single voice call. It has a bandwidth of 64 Kbps formed by sampling the audio conversation at a rate of 8 Kbps with 8 bits of data. Those numbers are critical, because they represent the minimum bandwidth needed to give the same audio quality as an equivalent analog phone line.

If a DS0 is one phone call and consumes 64 Kbps of bandwidth, then what is a DS1? DS1 is a collection of 24 DS0 “channels” packed together in a bundle. That’s 24 separate telephone conversations. The bandwidth for this bundle is 1.536 Mbps. When you add 8 Kbps for synchronization, the total bandwidth is 1.544 Mbps. It’s commonly referred to as 1.5 Mbps. A T1 line is a DS1 digital signal package carried on a very specific physical network consisting of 2 pair of twisted pair telco wires with a defined voltage and waveform characteristic.

That’s what DS1 means. Now, how about DS3? If you bundle 28 DS1 signals, the equivalent of 672 DS0 voice channels, you get a DS3. The bandwidth of this signal is 44.736 Mbps, often referred to as 45 Mbps. A T3 line carries a DS3 signal on coaxial cable, although T3 service may also be sent by microwave.

Now, here’s where things get interesting. You can generate the DS digital signal protocol but not necessarily use a T1 line or T3 line for transport. In a process called multiplexing, multiple DS1 and DS3 signals can be combined and transported over fiber optic cable. The SONET fiber optic services were designed to directly accommodate this. The lowest bandwidth SONET service generally available is OC3, which carries 3 multiplexed DS3 signals with a total bandwidth of 155.52 Mbps. When the signals get to where they are needed, they are separated or demultiplexed to get back the 3 DS3 signals, which might be constructed of 28 DS1 signals each.

When used to transport data packets instead of telephone calls, the individual channels are generally invisible to the end user, although they exist within the T-carrier and SONET systems. DS1 and T1 can be said to have a bandwidth 1.5 Mbps. DS3 and T3 can be said to have a bandwidth of 45 Mbps. It is these numbers that you can use to compare pricing with competing telecom services , such as Metro Ethernet.

T1 Telephony Has Many Flavors

T1 telephony was originally invented to transfer hundreds and thousands of phone calls between telephone company central offices. It’s grown far beyond that initial vision to become the digital phone line of choice for thousands upon thousands of businesses. You may already have or be thinking about installing a T1 phone trunk for your business. But are you aware that you have many options to consider?

T1 is a digital line standard that can be used for voice, data, video or all of these. In its original form, it transports 24 separate phone calls on individual channels called DS0. The combination of these is the T1 line or DS1. Each of the DS0 channels is responsible for transmitting digitized voice, plus call control and signaling.

Today’s T1 voice circuit of choice is called a T1 PRI or ISDN PRI. It’s is still organized as 24 channels on a single digital phone trunk, but one of the channels is used exclusively for call control and signaling, leaving the other 23 channels as the equivalent of 23 separate phone lines. The signaling channel is also used to support data services such as Caller ID.

T1 PRI is popular with businesses that have their own PBX telephone systems and with telephone intensive operations, such as customer contact centers and call centers. Nearly all PBX equipment supports this line format. If more than 23 outside lines are needed, then additional T1 PRI lines can be installed.

There’s a T1 telephony solution designed especially for smaller companies that can’t fathom needing 23 phone lines. Integrated T1 lets you have up to a dozen outside phone lines and uses the rest of the T1 line capacity for broadband Internet service. If you get what’s called a dynamic T1, it will automatically assign any bandwidth not currently being used for phone calls into the broadband pool. This is a very efficient use of resources and can be less expensive than having a dozen separate phone lines plus an independent broadband service.

VoIP has become a popular form of telephone service. An Internet connected T1 line can provide the bandwidth and reliability to support VoIP phone services for a dozen or more simultaneous calls.

T1 PRI lines will also interface with IP PBX systems, the VoIP equivalent of the PBX telephone system. T1 PRI is known for its high voice quality, reliability and support of telephony features such as Direct Inward Dialing.

There is also a new form of T1 telephony called SIP trunking. SIP is the signaling standard used in VoIP phone systems. A SIP trunk is often implemented on a T1 data line, but it is not connected to the Internet. It is a direct point to point connection between your business location and your service provider. This avoids the vagaries of Internet performance and helps the service provider ensure high voice quality and service reliability.

Are you ready for T1 telephony or interested in comparing lower cost options for the service you already have? If so, then check T1 telephony prices and options now.

DS1 Telephone Service Lowers Business Phone Bills

DS1 is the business telephone line service you've probably never heard of, but one that can potentially save you a small fortune. So if it's so good, why haven't you heard of it yet?

Actually, you have heard of DS1 in its more popular name: T1. That's right. DS1 and T1 refer to the same thing. They are a digital telecommunications line standard that replaces analog phone service. They are also widely popular for point to point data links and dedicated connections to the Internet. But why the two names?

There is a hair of difference between DS1 and T1. DS1 stands for Digital Signal 1. It's the format of the bit pattern that is used in TDM (Time Division Multiplexing) digital trunk lines. T-1 refers to the physical line itself, a 4-wire connection made up of two copper twisted pairs. T-1 or T1 carries the DS-1 or DS1 signal that actually conveys the information. These standards can be written with or without the dashes in-between the letter and the number.

Let's take a closer look at what DS1 can be used for. As a telephone service, DS1 offers 24 independent phone lines in a single digital trunk. Each of those phone lines is carried in a channel, also known as a DS0. The DS0 channel is 8 bits wide sampled at 8 KHz for a data rate of 64 Kbps. That's enough to provide "toll quality" telephone calls for local or long distance service.

Toll quality is the gold standard by which other services, such as VoIP or cellular phone, can be judged. The voice quality of cell phone calls doesn't really come close. VoIP can sound nearly indistinguishable from TDM toll quality if properly engineered. But on many consumer grade Internet connections, VoIP voice quality can easily degrade if the broadband service is highly congested.

The voice quality of DS1 service is locked-in by careful synchronization of the DS1 channels on the line. Unless the line is cut or something in the phone system fails, every call should sound as good as every other call as far as the line is concerned. That's one reason why DS1 (T1) service is so popular for business. You know it will be reliable day after day and is unaffected by anything going on with the Internet.

So how does DS1 save businesses money? Remember that the purpose of the digital trunking standards is to consolidate up to 24 separate analog phone lines on a single digital line. There is an efficiency to this, an economy of scale if you will, that makes T1 lines with DS1 service less expensive once you have more than 8 to 12 outgoing lines installed. At that point you no doubt have a PBX telephone system managing your lines. By plugging a T1 line into an interface card in your PBX instead of a dozen separate analog lines, you can get the same level of telephone service but with a lower monthly phone bill.

Is your business in a position to save considerable money on your telecommunications expenses? Find out how much DS1 telephone service can lower your telephone bill.