# EDIT:  HELP!!! IS MY T1 A DSL LINE?!?!?!??!

## Psionic Pulse

Can someone please explain to me Telextend?  It's Covad's "T1" technology.  All i keep finding is that Telextend is DSL using T1 circuits.  Covad keeps telling me that the connection is 1.5 Megabytes per second.  Someone correct me if i am wrong, but that comes out to about 12 Megabits per seconds.  Now.. Also.. Please correct me if I am wrong in my thinking (tho i'm about 99.999999% sure of this) that a T1 is 15 Megabits per second, which comes out to about 1.875 Megabits per second.

Is this a blatent rip-off?  Covad calls it "True T1 Service for buisness with high bandwidth demands".. but..  if those numbers are correct, then it's NOT "True" T1.  It's just #@#$! DSL!!!

Any comments?

-PsiLast edited by Psionic Pulse on Thu Jun 26, 2003 8:05 pm; edited 1 time in total

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## devon

 *Quote:*   

> 
> 
> Covad keeps telling me that the connection is 1.5 Megabytes per second
> 
> 

 

Wrong! A T1 circiut is approx 1.5 Mbps (Megabits per second).

A T1 has 24 64Kbps channels. Check out All You Wanted to Know About T1 But Were Afraid to Ask.

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## Psionic Pulse

well ok.. 1.54.. but still that's slower than what we're being sold by covad.. correct?

-psi

edit:  just to ask a few more things..  is anyone confused by the fact that the router connects over PPPoA, and that the install was DONE (from order to circuit-up) was a little less than 2.5 weeks?

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## xrn0id

Http://www.dslreports.com/speedtest

Go there for me, and see what speeds you get and post them onto the board. I have a 2 Mb cable line... thats about 250 KB/ps.

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## devon

Did Covad say 1.5 Megabytes per second or megabits?

There is 8 bits in 1 byte. So 1.5 Mbps is approx 187.5Kbps.

 *Quote:*   

> 
> 
> edit: just to ask a few more things.. is anyone confused by the fact that the router connects over PPPoA, and that the install was DONE (from order to circuit-up) was a little less than 2.5 weeks?
> 
> 

 

Hmm... I would say the underlying circuit is DSL. All the T1s I have ever installed use HDLC or PPP and take 30-60 days to provision.  :Smile: 

Edit: Fixed typoLast edited by devon on Thu Jun 26, 2003 12:42 am; edited 1 time in total

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## Psionic Pulse

they did say 1.5 megabytes per second..

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## jimlynch11

after this thread, i discovered bandwidthplace.com no longer does speed tests...

booooo!

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## Psionic Pulse

Dsl reports say:

Download: 1283kbps

upload: 1294kbps

-psi

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## devon

 *Quote:*   

> 
> 
> they did say 1.5 megabytes per second..
> 
> 

 

I would talk to your sales person and clarify this. Most sales people do confuse terms and we engineers have to correct them.

 *Quote:*   

> 
> 
> Download: 1283kbps
> 
> upload: 1294kbps 
> ...

 

Or 1.283 Mbps.  :Smile:  Looks pretty close to a T1 considering protocol overhead.

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## Psionic Pulse

 *devon wrote:*   

> 
> 
> I would talk to your sales person and clarify this. Most sales people do confuse terms and we engineers have to correct them.

 

Believe me i know.  Yeah.. we're trying to get a copy of the contract (that we've yet to sign oddly enough) so we can see what the exact specifications are..

as far as I can tell, Telextend is like T1 over DSL, or.. DSL over T1 or ... i'm not sure which..

It's a T1 local loop, that is multiplexed with the DSLAM as soon as i leave the building...  which means it's.. Shared bandwidth, cause it's multiplexed in with the other DSL lines in the area...

-psi

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## Psionic Pulse

Just guaranteed 80% of that speed.. which .. makes me feel that it's DSL as well..

-psi

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## Psionic Pulse

well here's what i found.

Covad's Telextend service is also delivered over a T1 Local loop.  In the central office it terminates into one of Covad's existing DSLAMS (DSL access Multiplexers).  Internet access is then acheived through Covad's ATM network (the same network they use to provide DSL service).  So although this is a T1 Local Loop, actual throughput will be subject to the Quality of Service options used to provision the connection across their ATM network.  I could not get details from Covad on what kind of ATM PVC would be used.  If it has a CBR (constant bit rate) with a high value (eg 1.5Mbps, then this service should provide equivalent T1 throughput.  However if they use Unspecified Bit Rate, then i'd be very wary as you'd be competing for shared bandwidth with their existing DSL users."

what do you make of that?

-psi

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## puggy

When talking about data transfer rates bits are always used because it doesn't make sense to talk about bytes as for this purpose the fact that there are 8 bits in a byte is arbitrary. If your going to talk about bytes you might as well talk about a bakers dozen.  :Very Happy: 

Puggy

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## devon

 *Psionic Pulse wrote:*   

> 
> 
> what do you make of that? 
> 
> 

 

Not sure what you are looking for.  Are you looking for more information about UBR and CBR? Check out these link at Cisco.com http://www.cisco.com/warp/public/121/cbr.html and http://www.cisco.com/warp/public/121/ubr.html.

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## Psionic Pulse

No.  I'm more confused about it connecting to the DSLAM.  i thought it went straight to an ATM interface.  i will admit, it's been 3 years since i was a T1 tech, and havent touched one since so...  i could be completley wrong.. if i am, sorry for bein a dumbass.

-psi

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## devon

 *Psionic Pulse wrote:*   

> No. I'm more confused about it connecting to the DSLAM. i thought it went straight to an ATM interface.

 Disclaimer: I have never worked on a DSLAM, so this is all pure conjecture

I would imagine that all the DSL lines terminate into the DSLAM, where it then plugs into the ATM network. From there the DSL lines are assigned VCI/VPIs to traverse the Covad ATM network. 

Regardless, these are valid concerns and things I would ask your sales person about to make sure you understand what you bought and what happens if Joe Blow decides to mirror alt.binaries.vcd.  :Wink: 

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## Psionic Pulse

Well.. ok.. my primary concern is that the link from the DSLAM to the ATM cloud would be congested because of the local DSL traffic running thru the DSLAM to the ATM cloud.

I guess it's just the whole TeleXtend system that allows it to run thru the DSLAM...  But it doesn't seem that bad..  The network is responding appropriatley in each of the separate areas.  So it feels like a T1...

We'll see what happens.. thanks for your help guys.

-psi

P.S.  by reading this thread, you now know more than the Level 2 Techs @ covad. ^_^

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## milkdi

actually, the speed from the DSLAMS to ATM is nothing that you can tell or change.

Even if you have a T9999 from your office/home to the provider, it all depends on the pipe of the provider to the internet, which is actually what matters the most.

That being said, I think their ATM will be good enough for you. 1.5mbps isn't really a big pipe in telco terms.

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## devon

 *milkdi wrote:*   

> actually, the speed from the DSLAMS to ATM is nothing that you can tell or change. 

 Oh trust me... If you bitch enough they can upgrade their interconnects.  :Smile:  I had a friend who moonlighted at the local LEC and there was a note in my "file". Let's just say, they didn't think highly of me and my non-stop phone calls.  :Wink: 

Granted, I was calling on behalf of an ISP and not a residential customer.

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## milkdi

well the point is, all you have is a T1, even at its peak bandwidth it's only 1.5mbps.

A single DSLAMS support maybe at least a few hundred to thousands of DSL lines. So for just weak/normal performance, it will still have way more bandwidth than you T1. Therefore, no worries   :Very Happy: 

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## MacMasta

Question: I was under the impression that a "T1" (or a "T3", etc)  was hardware-independent.

That is, any pipe, whether dsl, cable, (massive-parallel-dialup?) that provides 1.5Mbps is a T1 and any that provides 45Mbps is a T3, and so on.

So, assuming your speed is high enough, you have a T1 over DSL, right?

~Mac~

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## devon

 *Quote:*   

> That is, any pipe, whether dsl, cable, (massive-parallel-dialup?) that provides 1.5Mbps is a T1 and any that provides 45Mbps is a T3, and so on.

 Not quite true. Most pipes that are >1Mpbs have the generic term of being "broadband". But a 1.5Mbps cable/DSL line is not a true T1 as it has different signaling. See the site I posted earlier in the thread. It will explain the T-carrier hierarchy in great detail.  :Smile: 

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## Psionic Pulse

See that's what i'm trying to determine.. It's a T1 that multiplexes with the DSLAM, AND runs over PPPoA...  so i'm not sure that it's a "true T1"  which puts us in an odd spot (being a lan-center).  If we Advertise having a T1, and we have DSL (even if it's sold to us as a T1) then we're falsly advertising.

-psi

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## Athlon_Jedi

T1 and xdsl are two totaly seperate technologies, more than likely what they are doing is connecting you to the co using dsl then the co pipes all its traffic over a t-1 line thus allowing them to legaly claim it is operating at a t-1 bandwidth when in effect it acculy is a higher bandwidth dsl line. xdsl will support speeds up to 8 mbps so basicly all they are doing is routing all the traffic comming in and out of the co through a t-1 instead of the usual dc3 or so. 

its a dirty trick in that all they have really done is set your dsl cap at a higher bandwidth than normaly would be applied. if you ask me its a rip off. but just a legal one.

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## kashani

 *Psionic Pulse wrote:*   

> See that's what i'm trying to determine.. It's a T1 that multiplexes with the DSLAM, AND runs over PPPoA...  so i'm not sure that it's a "true T1"  which puts us in an odd spot (being a lan-center).  If we Advertise having a T1, and we have DSL (even if it's sold to us as a T1) then we're falsly advertising.
> 
> -psi

 

In these post boom days some technology has been deemed "unfancy" and marketing people like to think that refering to it by other names makes it sexier.

You have SDSL aka symetric DSL which supports 1.5mb/s up and 1.5mb/s down. We know this because your line requires ATM and a DSLAM, two fairly expensive technologies that are not required for terminating a T1 and routing IP traffic over it.

DSL lines are cheaper than T1 local loops hence the price difference between an actual T1 and the quick install time.

The speed you can attain to the Internet at large is dependant on a few factors.

1. Congestion on the local network, aka from the local POP to the core.

2. Your ISP peering or transit agreements

3. The congestion at the far end.

These factors are the same no matter what technology you are using for the last mile. Obviosuly the first two are the only factors you have some influence on... mostly by changing your provider or harassing them. 

Again in the post boom Internet internal congestion is fairly rare. A DS-3 could be installed today for the price of a 1997 ds-1 in many cases, especially in metro areas. Peering and transit agreements are more a mixed bag, but again pulling circuits and paying for bandwidth at the ISP level is a fraction of the cost it used to be. Also ATM allows some QoS stuff where T1-really-DSL connections could be set to take preference over joe bob's home DSL. You might want to ask about that.

The real question is, "Are you happy with your connection and speed for the price you pay regardless of what people decided to call it this week?"

Whether you call it a T1 or DSL in your marketing speak is up to you, but the differneces between them in this case is negligible from a speed perspective. Personally I'd think any perspective customer should be more concerned about what your 2nd connection to the Internet is.

kashani, who worked for the first company to offer DSL connections to the consumer

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## Dr_Stein

I've had 2 T1 circuits installed - one of them they called an HDSL2 circuit, and only required 1 pair. 

The other one at the new location is through Speakeasy/Covad, and SBC special services came out and took up 2 pair. Another HDSL circuit? The install time was less than 2.5 weeks.

So, if it's a funky kind of xDSL technology being sold as a T1 (I get full T1 speeds all over)... can I use my Kentrox DataSMART 688 CSU/DSU and a Cisco 2501? Or is there something with the line that would prevent me from doing so? 

I much prefer Cisco stuff to the Netopia thing that I got..  :Wink: 

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## kashani

Using HDSL circuits for T1 has been industry practice since the 80's. HDSL has 4 wires whereas HDSL2 has only 2 which is why most companies are switching to them. The other reason is that HDSL lines can run 12000ft before they need a repeater where traditional T1 lines needed one at 6000ft. 

Wheter HDSL or HDSL2 is used to provide the line, you're still getting a T1 if that's what you ordered. HDSL2 makes a ton of economic sense within 12000ft of the CO which is why you will usually see local loop charges jump through the roof at distances over that.

I googled the following up which has some good information about HDSL

http://www.arcelect.com/HDSL3698.htm

I imagine the Cisco should work, though a 2501 comes dangerously close to choking on a full t1 if you're doing anything interesting in your ACL's.

kashani

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## Psionic Pulse

ok then... so is there a difference between HDSL (which appears to be what we have with the 4 wires) and the TeleXtened?  if yes.. what is it? 

I"m just worried about legal issues.. i.e. Using out T1 as an advertising point, but not having a T1....

-psi

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## kashani

I'm confused about the PPPoA you mentioned several posts back. I assumed that anything requiring ATM was more than likely xDSL. Further reading on Covad's site indicates that this is a real T1 since it supports normal T1 equipment which wouldn't be the case if ATM were involved at the customer end.

http://www.covad.com/business/telextend/index.shtml?t=details

If you got through most of the links I posted earlier you should understand that a T1 is framing on the line... like say Gigabit Ether and the actual physical plant is beside the point. HDSL and HDSL2 is just a way of delivering the line to your premise just like copper or fiber would be for GigE. Or going back to the OSI model HDSL is layer 1, T1 framing is layer 2, and IP is layer 3.

In any case it sounds like the guys at Covad did more to confuse the issue for you than clear it up. Something that doesn't seem to have changed since the last time I dealt with them.   :Rolling Eyes: 

kashani

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## Dr_Stein

Hrm.. if you have any advice on getting that Kentrox CSU/DSU to work, let me know.  :Wink:  I haven't had much luck with it so far.  :Smile: 

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