From: Scott Morris (swm@emanon.com)
Date: Thu May 12 2005 - 16:58:39 GMT-3
Actually, it boils down more to the oversubscription model used by service
providers. People who have T-1's (synchronous and/or point-to-point
interfaces) get really pissy when the bandwidth they paid for isn't
available at random intervals.
ADSL catered more to the way that traffic patterns exist at a consumer level
and allowed service providers to work within the statistical probability of
usage/bursty traffic. And the expectation was delivered to customers as
that of an "availble, but not always usable" bandwidth. T-1 never worked
that way.
All traffic COULD still be muxed. Just depends on your engineering! (and
your market expectations!)
Scott
-----Original Message-----
From: Anthony Pace [mailto:anthonypace@fastmail.fm]
Sent: Thursday, May 12, 2005 3:46 PM
To: swm@emanon.com; 'Hogo, Trust'; 'Group Study'
Subject: RE: T1 delievered on 2 wires or 4???
Scott,
again, very good info in your post! I know that HDSL was born out of the
desire to deliever the equivolent of a T1 on 1 pair, and that then the other
tecnologies sparang up simutaneous to the TELCO laws changing (thus DSL
emerged as an alternative to serial point-to-point in that it could be
delievered by a CLEC renting 1 single loop from the ILEC)
I know that T1's are ferquently MUXED onto ATM and then transparently
delievered as to the CPE gear on either end as serail T1, but if it's going
to a last mile of something other than a T1 (ESF with all the signalling
bits and CRC and all the stuff backward compatible to 1962) why not just
sell and deliever the new and improved DSL (whatever
flavor) right into the CPE device (router in my case).
Is it just the idea of a T1= good and DSL=bad for marketing purposes? Or is
it just to be able to hand the customer what they want (T1) and then finding
the best technical approach (separate form the terminology being used to
sell it)
does that question make sense? probobly not.
Anthony Pace
On Thu, 12 May 2005 15:25:54 -0400, "Scott Morris" <swm@emanon.com>
said:
> Hehehe... Telco Voodoo Magic. :)
>
> It's just a way to transport bits. The design concepts behind ADSL
> (shared medium with varying xfer rates) are significantly different at
> the telco-side of things than designing for HDSL or VDSL. So the
> assumptions people have about DSL in general don't always apply.
>
> For the telcos, it's all about conserving wire pairs. Physical
> infrastructure is a pain in the butt to fix, upgrade and change out.
> So any reuse is great!
>
> Where can you learn more about it? Hmmmmm... Good question.
> www.protocols.com perhaps, or Newton's Telecom Dictionary. It's just
> part of my vast collection of useless knowledge from working in the
> field so long!
>
> HTH,
>
> Scott
>
> -----Original Message-----
> From: Anthony Pace [mailto:anthonypace@fastmail.fm]
> Sent: Thursday, May 12, 2005 3:11 PM
> To: swm@emanon.com; 'Hogo, Trust'; 'Group Study'
> Subject: RE: T1 delievered on 2 wires or 4???
>
> Scott,
>
> This is very good information. Where can I learn more about it?
>
> ok. So people have come to believe T1=good DSL=flakey and opted for
> the old tried and true 4 wires delieverd by the ILEC, with many
> repeaters along the path; rather than gamble on DLS delievered by the
> CLECS. BUT now the smartjack accepts the 4 wires comming from my
> router interface and converts it to DSL so that it can be transmitted
> on 2 wires - and then does the same conversion at the other end of the
> circuit (keeping the entire process transparent to me)
>
> Anthony Pace
>
>
>
>
> On Wed, 11 May 2005 18:30:40 -0400, "Scott Morris" <swm@emanon.com>
> said:
> > A T-1 is 2-pair or 4 wires.
> >
> > However, many of the smartjacks are now HDSL capable (or VDSL
> > depending on proximity to CO) and that is delivered over a single
> > pair or two wires.
> >
> > The smartjack is doing magical conversion between the two. ;)
> >
> > HTH,
> >
> > Scott
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> > Of Hogo, Trust
> > Sent: Wednesday, May 11, 2005 6:05 PM
> > To: Anthony Pace; Group Study
> > Subject: RE: T1 delievered on 2 wires or 4???
> >
> > Hope this might help.
> >
> > http://www.cisco.com/warp/public/788/products/vwicmf_t1.html
> > http://www.cisco.com/warp/public/63/wic-1dsu-t1.html
> >
> > ------
> > HQ
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> > Of Anthony Pace
> > Sent: Wednesday, May 11, 2005 4:50 PM
> > To: Group Study
> > Subject: T1 delievered on 2 wires or 4???
> >
> > I recently terminated a T1 and ISDN PRI in a remote location and was
> > able to see that the TELCO had terminated the T1 using a single pair
> > and the PRI using a single pair from the 25 pair bundle coming into
> > the Data Center's smart jacks.
> >
> > I was always under the impression that from the CSU/DSU (in my case
> > it was built into the router) to the smartjack and subsequently the
> > NI card in the MPO was 4 wires. 1 pair TX and 1 pair RX.
> >
> > Maybe between the CSU/DSU and the NI card it's 2 wires and then 4
> > for the distance to the CO? ??? I am confused because I always
> > believed that DSL was born out of the efforts of finding a single
> > pair alternative to
> > T1 technology.
> >
> > Should PRI and DS1 be 1 pair or 2?
> >
> > Anthony Pace CCIE 10349
> >
> > --
> > Anthony Pace
> > anthonypace@fastmail.fm
> >
> > ____________________________________________________________________
> > __ _ Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
> > ____________________________________________________________________
> > __ _ Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
> --
> Anthony Pace
> anthonypace@fastmail.fm
>
-- Anthony Pace anthonypace@fastmail.fm
This archive was generated by hypermail 2.1.4 : Fri Jun 03 2005 - 10:11:57 GMT-3