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Many of my clients have been offered DSL from the friendly phone companies to access the Internet for their
businesses. Cable modems are reasonable alternatives for home offices. Or are
they? What the broadband companies don’t tell is how they can arbitrarily limit the bandwidth the customer actually gets with this service. This is just the tip of the iceberg of how the phone companies may be hoodwinking all customers by selling DSL like mad but not guaranteeing the performance--as they were required to do with the old tariffed services, like ISDN, T-1, and fractional T-1.
There are three problems with using home type
broadband for your business to access the Internet.
Regarding DSL:
DSL is based on a way that the phone companies can piggy back data on your regular phone line while the traditional data services like ISDN and T-1 dedicate the wires on which they are provided to data only signals only. The piggy-back method (using a radio-like signal added to your phone line) is very tricky to get to work right. That’s why even though there are so many solicitations to provide service, due dates are often broken based on equipment unavailability or the offer withdrawn due to ridiculously short distance limitations. Even when the customer does get service, there are lots of complaints from users--who never seem to get the performance they expected. The phone companies love DSL, however, because their costs for providing DSL (where they can!) are very cheap compared to the traditional data services since they use existing phone lines. But they always seem to be pushing DSL more vigorously to residential customers. There’s a reason.
DSL has been heavily promoted to home users as an alternative to costly business grade data services and especially as an alternative to cable (TV) modems based data service. The phone companies claim correctly that DSL avoids the sharing of the connection with other local users. What they don’t say is that internal connections at the phone company are different for DSL compared to the other data services since sharing of an phone company internal network may have as much or more of an
effect on your throughput as with cable modems. On the next page is a diagram that shows how this is. (Follow a connection from you to your ISP’s Point of Presence, right to left). Notice that your connection doesn't go from the telephone company to your ISP directly. Instead it goes through the DSL connection (Network Access) to the local telephone Central Office (CO) and then through the Regional Broadband Network to get to the direct connection to your ISP (via its POP). The Regional Broadband Network is an internal private network that the phone companies set up to handle whatever traffic they want. In most cases it includes their DSL customers. The phone companies do not promise any performance on this network even if they try to provide the promised data rates on the DSL (Access Network). In other words, you may get 256 kilobits per second from your premises to the telephone central office (CO), and your ISP may be capable of receiving 256 Kbps from its POP, but the "Regional Broadband Network" may be loaded to the point that at some times of the day—or even all the time—nobody gets more than 128 Kbps or 64 Kbps or even less.
Again, there are NO requirements on the "Regional Broadband Network". It's a bottleneck that can be controlled by the phone company. The phone companies don't like traditional ISDN, T-1, etc., because those services have come with a promise of a guarantied data rate from your premises to the other end—here your ISP’s Point of Presence (POP). If you pay for 128 Kbps, you can test that rate any time you want. If you don't get the speed promised, you get a refund and can complain to the public utility commission. A matter of fact, the phone companies have historically actually measured and documented both the data rate and the bit error rates on traditional data links such as fractional T-1. With DSL, however, the phone companies often respond to customer complaints about reduced throughput (as measured by the customers) by reminding them of all the many possible causes of bandwidth limitations such as ISP internal or communications problems from their POP, Internet backbone problems, and especially possible customer local area network or router limitations. All these are possible, of course, but this blame the victim finger pointing relates to problems that can be diagnosed and fixed by the customer while the internal phone company’s Regional Broadband Network limitations and overload are under the phone companies’ control and those effects on your throughput is not disclosed. See the law
suit against SBC below.
So with DSL as with cable modems where the cable TV companies add your data to local users and only promise a maximum data rate when your neighbors are not busy, DSL adds your data to other users on their private network and may not EVER provide the promised data rate to you. Resident customers may put up with low data rates at predicable times of the day with cable modem service, but business customers don’t have that luxury with DSL. Indeed, they may have purchased the DSL service expecting that they were getting "fractional T-1" performance as considerably lower prices with DSL. At best, DSL customers are getting only what they pay for or probably a lot less all the time.
The third problem with DSL and Cable
Modems and also not often disclosed by the phone company providers, is that most people are only offered and buy "aDSL" where the "a" is for "asymmetrical". That means that your upload speed is not anything like your download speed. You can get pictures, for example, quickly from your server, but you may be limited to only 32 Kbps for uploading pictures to your server! Again, this may be acceptable for a residential user but is not appropriate for business customers who may have considerable upload needs to the servers at their ISP.
Be aware that there are actually at least six flavors of
DSL and various data rates with cable. Some are even based on the old Bell fashioned digital signal formats of ISDN and T-1 (via the old pure-data line method), and some are really ISDN or T-1 like service actually provided on a digital signal added to your voice phone line via the piggy-back method. (You can usually tell if you are being offered this version of "DSL" if the phone company mentions a ridiculously short distance limitation to their central office.) These new services offered to the public market may be much more subject to "cheating" by the phone companies than the old business services since these new ISDN and T-1 services may also employ their internal networks so that total data rate end to end is limited as well. You may be offered "high speed" data via DSL or what sounds like ISDN or T-1 service, but the phone companies provide look alike service via DSL methods and use their internal "Regional Broadband Network." Bottom line: you need to know how the service is provided and what guaranties the phone companies will provide. That's where consultants can help—at least we try to make sense out of all this. Oh well, so it goes. My friends and I at Bell Labs years ago would never have believed what’s going on now regarding the lack of performance standards.
One last thing on this. There are suddenly a whole bunch of NEW companies appearing on the scene that will be offering (and some already are) "high speed" data via radio or satellites. Some of these promise 128 Kbps to 1.5 Mbps service--both ways—up-link and down-link! However, some of these providers do not exclude the use of their own ""Regional Broadband Network" to get you to your ISP. Some even make you use their own ISP to get their service (as do most cable modem providers). Also, many of these new providers may not really yet exist or their stability is iffy in terms of FCC licensing or business plan. These new services will be the topic of a future White Paper. But, I've been finding some "Competitive Local Exchange Carriers" (CLECs) for my clients who actually provide "real" fractional T-1 and guarantee the data rate, however, and may be good players in the long run.
My advice to you—and to my clients where I've been asked to research the details of what's offered and actually available in their area—is to decide what data rate you really need and only buy a service that actually guarantees this rate like traditional 128 Kbps ISDN or fractional T-1 provided as true digital end to end service. Some CLECs are appearing that will sell you fractional T-1 when the traditional phone company (called ILECs, for Incumbent Local Exchange Carriers) will not. Of course, the CLECs may also try to sell various schemes where they don't guarantee the data rate. Do you really want to track down all these technical details yourself?
It's the wild west all over.
Hope you enjoy this note and it's helpful.
Let us know what you think of this paper or
for help with your telecommunications decisions. Contact us at info@mborsuk.com
or give us a phone call for more information.
Michael H. Borsuk
Owner and Principal Consultant
M BORSUK & ASSOCIATES
Boulder, Colorado, USA
A full report on this topic is available from
the author for a nominal fee. Also available is a report in which we address the
broad issue of how to ask the broadband
supplying
for what you really want.
Also available is a new
report on Gigabit Ethernet over multi-mode fiber.
Contact us at
info@mborsuk.com
or give us a phone call for more information or assistance with your
communications systems. Contracted proprietary studies and on-site focused
educational programs are our specialties.
Contracted proprietary studies and on-site focused
educational programs are our specialties.
M BORSUK & ASSOCIATES has
been providing technical assistance and education services for today's voice and
data telecommunications systems since 1989. We design and analyze existing and
planned electronic and optical transmission systems, generate and analyze
proposals, manage projects, and help to educate our clients regarding data and
voice communication systems design and acquisitions. All associates are former
telecommunications industry managers, adjunct faculty members in graduate
telecommunications programs, and hold graduate electrical engineering degrees.
This story appeared on Network World Fusion at
http://www.nwfusion.com/ahive/2000/105104_08-21-2000.html
SBC Communications sued over DSL speeds
Class action suit claims telco's is not 'always on.'
By DAVID ROHDE
Network World, 08/21/00
HOUSTON - Mega-telco SBC Communications last week was hit with a class-action lawsuit claiming it's "defrauding" DSL subscribers by limiting promised downstream speeds of at least 384K bit/sec to an actual rate of 128K bit/sec.
The lawsuit, filed by a computer technical support company in Houston and several of its customers, also claims that SBC's DSL service is not "always on" as advertised, but rather times out like an ordinary dial-up connection.
In a statement, SBC said it has to review the suit before responding in detail but noted that "there are many factors that can have an impact on the actual rate at which data is transferred online," including server speeds, protocol overhead factors and public Internet congestion.
But the plaintiffs point to e-mail and newsgroup downloads, where they allege they've noticed the 128K bit/ sec cap. SBC's statement acknowledged that speeds for accessing newsgroup data are maximized at 128K bit/sec "in order to provide a more reliable service for all our customers using the newsgroups," though the plaintiffs claim that hadn't been disclosed.
By contrast, SBC said access to e-mail "and other Internet applications" are not affected by the 128K bit/sec cap. But the plaintiffs claim the network timeout - which allegedly occurs when users stop downloading Internet pages or using e-mail - is a deliberate capacity-saving maneuver by SBC rather than a random fault in the carrier network.
Many DSL proponents have claimed that this kind of potential user competition for bandwidth is only a problem with cable modems sharing a path back to aggregation devices. But that's a myth, says Philip Richards, vice president for Insight Research Corp. in Livingston, N.J. Many initial DSL service providers have indeed had to throttle back port speeds on their DSL access multiplexers
(DSLAM) in order to avoid having their DSL networks seize up entirely.
"There is [bandwidth] concentration in the DSLAM, and in many instances, it's significant concentration, even more so than with cable," Richards says. "The rapid growth of demand doesn't give the engineers time to understand how the users are using it. They're still learning what kind of capacity they need."
Richards says he wouldn't be surprised if other DSL carriers are suffering the same learning curve, adding that could even be SBC's defense of the suit. But the plaintiffs point to SBC's Project Pronto, a $6 billion initiative to install asymmetric DSL remote terminals near 80% of SBC's population. The suit claims Pronto publicity has caused hundreds of thousands of customers to sign up for DSL service that SBC is not ready to provision, forcing it to throttle back its network. SBC countered that "SBC is meeting our obligations to our customers."
