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What is the difference: T1 vs. 1.5Mbps SDSL?

Old 02-26-03, 01:26 PM
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What is the difference: T1 vs. 1.5Mbps SDSL?

I'm currently exploring the above scenario with a price difference of $600.

Thanks you for input.
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Old 02-26-03, 01:58 PM
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a T1 is probably going to be more reliable, better service etc. There is a lot more to setting one up that dsl, and more equipment cost (router, csu/dsu).
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Old 02-26-03, 02:46 PM
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The upload speed.
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Old 02-26-03, 02:51 PM
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SDSL upload and download speed are the same. ADSL is the much more common type where the upload is limited to 128/256 etc.
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Originally posted by BigPete
The upload speed.
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Old 02-26-03, 03:01 PM
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Originally posted by BigPete
The upload speed.
Not true. SDSL provides for equal upload and download speeds as it is synchronous. ADSL (which is what many companies offer for internet access) provides a much higher download than upload speed.

Dave99 pretty much summed it up, in that a T1 by nature of the wiring is more reliable, especially in wetter climates (rainstorms wreak havoc on DSL quality). T1 architecture is a 4 wire (2 pair) connection whereas SDSL relies on a two wire (single pair) design. There are signalling differences as well, in addition to the CSU/DSU electronics. T1's definitely cost more, but have a guaranteed 1.5M stream over long distances. SDSL is a guaranteed 1.5M stream up to a specific distance, determined by the location of the central office (phone switch) and the calibre of the copper. After a certain distance, the throughput will begin to drop to 1.4M, 1.3M etc. Even with repeaters, SDSL is only good to about 12,000 feet. T1's go much further beyond that due to signalling design.

If your work is mission critical (ie: critical to your work/ability to do business), I would pay for the T1. If it is for backup of a primary T1 or for capacity overflow, I would consider the SDSL option.
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Old 02-26-03, 03:07 PM
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Originally posted by Dave99
SDSL upload and download speed are the same. ADSL is the much more common type where the upload is limited to 128/256 etc.
Dave
True. I am being told that the line will be 1.5Mbps Upstream and Downstream. I guess my other question besides the setup and reliability would be the speed. Is 1.5Mbps equivalent to a T1?
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Old 02-26-03, 03:15 PM
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Thanks Thespian68, missed your reply after I posted mine. Your explanation help very much. This is by no mean "mission-critical". Mostly it will be used for email, web access and a weekly file upload.

Thanks to everyone for their input.
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Old 02-26-03, 03:30 PM
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Basically yeah, the speed will be the same, assuming you are close enough to the CO to get the full speed.
Dave
Originally posted by DVD.guy
True. I am being told that the line will be 1.5Mbps Upstream and Downstream. I guess my other question besides the setup and reliability would be the speed. Is 1.5Mbps equivalent to a T1?
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Old 02-26-03, 03:40 PM
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T1 is guarantee speed, xDSL is not.
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Old 02-26-03, 04:17 PM
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Originally posted by Thespian68
Not true. SDSL provides for equal upload and download speeds as it is synchronous. ADSL (which is what many companies offer for internet access) provides a much higher download than upload speed.

Dave99 pretty much summed it up, in that a T1 by nature of the wiring is more reliable, especially in wetter climates (rainstorms wreak havoc on DSL quality). T1 architecture is a 4 wire (2 pair) connection whereas SDSL relies on a two wire (single pair) design. There are signalling differences as well, in addition to the CSU/DSU electronics. T1's definitely cost more, but have a guaranteed 1.5M stream over long distances. SDSL is a guaranteed 1.5M stream up to a specific distance, determined by the location of the central office (phone switch) and the calibre of the copper. After a certain distance, the throughput will begin to drop to 1.4M, 1.3M etc. Even with repeaters, SDSL is only good to about 12,000 feet. T1's go much further beyond that due to signalling design.

If your work is mission critical (ie: critical to your work/ability to do business), I would pay for the T1. If it is for backup of a primary T1 or for capacity overflow, I would consider the SDSL option.
Good answer.
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Old 02-26-03, 06:12 PM
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Originally posted by Dave99
SDSL upload and download speed are the same. ADSL is the much more common type where the upload is limited to 128/256 etc.
Dave
Just to add that upload depends on your provider (stating the obvious).

My ADSL is 1.5/750.
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Old 02-26-03, 08:32 PM
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Whats the differnce beetween ADSL and SDSL and T1 and T2? Is T1 and T2 cable internet?
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Old 02-26-03, 10:50 PM
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Originally posted by moyam
Whats the differnce beetween ADSL and SDSL?
Found at dslreports.com

Q: What's the difference between ADSL and SDSL?
A: ADSL is a DSL line that is mostly for low use. It has download speeds many times faster than its upload speeds. This is usually for simple tasks such as downloading and viewing webpages.

SDSL has upload speeds almost the same as its download speeds. This makes it optimal for gaming and servers of any type. Because the upload speed is high it is more expensive than ADSL.

For most uses ADSL is the best choice.

Originally posted by moyam
Whats the differnce beetween T1 and T2? Is T1 and T2 cable internet?
The difference between a T1 and T2 (I'll be back-couldn't resist) is the speed. No, they are not cable.
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Old 02-26-03, 10:53 PM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

Hey, I found the answer to my question. Although, you guys already came through for me. Also found at dslreports.com

Q: What is the difference between T1 and 1.5mbit SDSL?
A: A T1 line and an SDSL line uses the same underlying technology - HDSL. The differences between them are not in performance, they are in ease of provisioning and speed of repair.


In the US, lines for T1 data are normally treated as higher importance by telcos, than DSL lines, so time to repair and provisioning can be considerably faster. A T1 fault may be repaired within hours, or a day, whereas a DSL line fault could be a 5 day turn around time.


The other important difference is that T1 lines are more easily repeated to cover longer distances, something that has not yet happened for SDSL lines.

T1 lines are significantly more expensive than DSL lines, a monthly T1 lease, with internet bandwidth, can amount to $1000 or more, compare that with SDSL prices of a few hundred dollars for the same speed.
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Old 05-01-09, 05:10 PM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

I have a 1.5 Mb SDSL here. A while ago my provider (Covad Communications) was promoting a DSL-to-T1 upgrade at a lower-than-usual price. I checked with them about it.

They explained the difference to me, which was pretty much just as the previous post says. They checked the particulars of my service and told me that, thanks to my closeness to the DSLAM and whatever other factors were involved, I would not have any appreciable performance difference between the two. (My transfer speeds have never dropped below the full bandwidth, at least, never in a way that could be ascribed to the service.) Yes, there is better support for a T1, but after jawboning about it, and assessing the quality of support I've had over the years, I didn't see that as much of an issue.

In a way, once they got the picture of my needs vs. my current service, they more or less talked me out of it, and given that they were recommending against my getting a more expensive service from them, there's not much reason to doubt them (and give them a nice pat on the back for not pushing for the sale just for the sake of the sale).

One correction, though: The S in SDSL doesn't mean synchronous; it means symmetric, referring to the equal speeds in the two directions.
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Old 05-01-09, 06:41 PM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

Welcome to the forum and all that, but you joined just to answer a question in a thread that has been dead for more than six years?
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Old 05-01-09, 06:44 PM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

T-lines still exist?
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Old 05-01-09, 07:18 PM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

If this is for business then check out mpls as well
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Old 05-02-09, 08:32 PM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

Originally Posted by Case01 View Post
T-lines still exist?
yes. I think for the dedicated aspect and in theory better/faster support if it goes down
I say in theory because the ones the bank I do tech support uses have circuit issues frequently enough that I truly think they'd be better off with business class cable
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Old 05-05-09, 04:06 AM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

The SLA.
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Old 05-08-09, 11:51 PM
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Re: What is the difference: T1 vs. 1.5Mbps SDSL?

Originally Posted by Case01 View Post
T-lines still exist?


?
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