Friday, October 5, 2007

Frame Relay Over DSL – Hybrid T1

Another Possible Service Option, but Not Quite Worth It

Frame relay over DSL (FRoDSL), also known as Hybrid T1, Covad TeleXtend, Rhythms T1, TDSL, TransEdge T1 (New Edge Networks) and more, is a cost-effective means of obtaining the reliability of T1’s. There is a satisfaction with frame relay, ATM, MPLS-based VPNs and Internet-based IPSec VPNs. WorldCom lists frame relay as its number two source of revenue after long-distance voice, so there is still money to be made through this older technology. A way to extend the life of an existing frame relay infrastructure is to use DSL services to access it. FRoDSL service is considered a great option for companies who currently use frame relay services, but would like to explore lower cost network options.

FRoDSL access use DSL technology to access a service provider’s existing frame relay infrastructure. What happens is that the provider will run a T1 line local loop then plug it into a Digital Subscriber Line Access Multiplexer (DSLAM), a mechanism at a phone company's central location that links many customer DSL connections to a single high-speed ATM line. From there, the line runs over Covad’s ATM network and its frame relay Internet.

This leads to price advantages because of the way the service is delivered. FRoDSL can be extended over greater distances, but at a fraction of T1 speeds. Because of this, FRoDSL will not need the use of repeaters in to relay data, meaning fewer lines are in use.

The service could possibly cost even less because the guaranteed response time is longer, but this doesn't necessarily mean that FRoDSL is any less reliable in terms of the mean-time-between-failure (MTBF). However, since fast response cost money, the guaranteed mean-time-to-repair (MTTR) may be somewhat longer than with a traditional service.

The problem comes when some service providers advertising FRoDSL as “T1 service”. Ultimately, the service is a T1 line that goes through DSL equipment. There is no way you can get speeds comparable to T1 by running the connection through DSL equipment. Frame relay networks also don’t come with a CIR. CIRs, if you recall, guarantees you your level of service with a T1 service. Since you’re essentially getting a DSL connection, they can only guarantee 384k of bandwidth, tops.

The only real T1 line is the line going into the phone company (eg Verizon) central office. Basically, FRoDSL delivers DSL service using a physical T1 line instead of a phone line. Unknowing customers see the T1 infrastructure being installed and figure they’re getting T1. Therefore, paying top dollar for T1, but only getting DSL. Following me guys?

Seriously, FRoDSL is strictly for those who are too far for DSL and can’t afford real T1. Customers should know what it is they’re paying for. A real Clear Channel T1 costs $100-200 more a month for 3X times the speed, which isn’t much more in terms of business costs. If you need reliability and performance, a FRoDSL connection can hurt your business, and should be avoided.

It is not a wise-choice for those who want to get what they pay for. Surfers expecting real T1 performance will be sorely mistaken. Imagine a company stock trading firm that heavily relies on their Internet service. If they were to use FRoDSL without a guarantee of reliability, they can lose an unspeakable amount of money when the system slows down or cuts off. Not only that, they’re stuck in a multi-year contract with the unreliable product.

The only benefit with a T1 line instead of a phone line is that, if the physical line breaks, Verizon (as an example) will fix it within four hours. A regular phone line can take days. Your DSL can be down for days if your phone line is on the fritz.

The main reason FRoDSL is offered is because traditional DSL only goes 20,000 feet. T1 can go on forever so you can get your DSL at longer distances through the T1 line. If service providers advertised that they can deliver DSL service anywhere, that’d be great, but they don’t. They try to market FRoDSL as a real T1 service though a T1 line. The line does not mean the service. The legitimate way of advertising this service is “DSL over T1” or something to that effect.

Another name it’s known by in the industry is TeleXtend (TDSL). TeleXtend is the name of the FRoDSL product Covad offers “comparable” to T1 service. TeleXtend is a T1 loop into the Central Office (CO) where it hits Covad's DSLAM. From that point on it rides the ATM backbone like SDSL or ADSL, then to the internet via frame relay.

The service provider XO sells real T1s for $499. Covad offers their product for $399. You’ll be paying around $400 for 35% CIR, but $500 would offer 100%. Why not just shell out the extra cash.

New Edge, another ISP, sells both real T1 and TeleXtend. They call their FRoDSL “TeleXtend Burstable T1”, or just Burstable T1. New Edge states that their “burstable T1 Internet access service offers high-speed T1 Internet access in tier 2 and 3 markets at 50% below traditional T1 prices. New Edge's burstable T1 service is available in speeds ranging from 384k, to 768K, to 1.1 mbps, to 1.5 mbps with 35% guaranteed CIR and burstable up to 100%.” Though a bit wordy and possibly misleading, they’re at least telling you the truth. Also, just to point out, the guaranteed 35% CIR is about the speed of a normal DSL line.

When purchasing a T1 service, make sure you ask the competing companies whether or not they’re selling Covad’s TeleXtend T1/FRoDSL. Find out if they’re offering you a Clear Channel T1 or Frame over DSL. T1 connections are capable of delivering 1.5Mbps, and while DSL connections are also capable of delivering this speed, they’re not nearly as reliable. Depending on the size of your business and its needs, consider getting an actual T1 connection. A full service T1 will support up to 50 workstations.

A list of Wholesale FRoDSL aka TDSL providers and their resellers:

FRoDSL Wholesaler:

Resold by:

Covad TeleXtend T1

Covad, Megapath, Speakeasy, DSL.Net, Bway

New Edge Networks T1

Transedge, Speakeasy, Earthlink

MCI-Rhythms NetConnections T1

MCI, Verizon, Intermedia, Telocity (DirecTV DSL)