Damon,
I have no idea where you are getting your information from, but what
you said makes no sense.
DSL based lines, be it ADSL or SDSL, are based upon a connection
technology in the ATM
family. As a result, the upstream and downstream of the connection can
be controlled seperately.
If someone offers you a 1.5 SDSL connection, it doesn't actually mean
that you have 2x768kbps,
it may actually mean that you have 2x1.5Mbps. However, that speed is
only towards your internet
provider, what you get beyond that point would be bound to your ISP's
SLA and contract.
Now, E1 and T1 lines are based upon a channel based connection, which
means you get a line
with X number of data lines and a single control/signalling line. On T1
it means that you have 23
lines dedicated for Voice/Data (each is 64kbps) and a single signaling
line (64kbps). Now, lets
do a little math (23+1)*64 = 1536kbps = 1.536Mbps, hence the speed for a
single T1 circuit.
Now, if you have a T1 installed, and you are currently using 512kbps of
upload, it means that you
are physically using 8 lines out of the 23 data lines for uploading. You
can then use the rest to what
ever purpose you want, but while those lines are in play, you won't be
upload another 512kbps on
the same lines. The reason for that is that each of these lines operates
on a seperate Time Slot
within the physical layer. Once a Time Slot is taken for a specific data
flow, it can't be used for another
data flow.
This actually means that a T1 will give you a shared 1.5Mbps towards
your ISP, with speed that
vary on the upload and download, according to your usage. While when
using a DSL, your quality
of service for the connection to the ISP is described by the policy of
connection. In many countries
(eg: Israel, Turkey, China, UK), DSL lines are actually ADSL lines,
where the downstream is around
1.5Mbps while the uplink is around 128kbps (just enough to do a little
VoIP). Last time I was in the
UK, about 4 weeks ago, I noticed they are now selling 8Mbps ADSL
connection to your house,
however, the uplink is 512kbps.
I would suggest that you get all the information from your providers
regarding the type of services
rendered on the SDSL line, and make sure that it's the right one for you.
Nir S
Damon Estep wrote:
You are aware that DSL (even SDSL) is half duplex and a T1 is full
duplex, right?
1.5m sdsl can only do 768 sustained duplex, or 1.5 out 0 in, or 0 out
1.5 in. a T1 will do 1.5 in and 1.5 out sustained.
This is due to a separate transmit and receive path on a t1 and a shared
path on sdsl.
The s in sdsl means symmetrical, not duplex, that is that the signaling
rate is the same in either direction, but still half duplex.
For VoIP a t1 is worth double what a 1.5 sdsl is because of the duplex
nature of the traffic, unlike most internet that is download-centric.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Wiley
Siler
Sent: Monday, June 13, 2005 9:43 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: RE: [Asterisk-Users] Should I choose DSL @ 1.5 or a full T1?
Speakeasy SDSL Is 1.5 Megs, is business class (so you get an SLA) and
only costs around $100 per month.
W
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Robert
Goodyear
Sent: Friday, June 10, 2005 7:02 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] Should I choose DSL @ 1.5 or a full T1?
On Jun 10, 2005, at 6:38 PM, Michael Welter wrote:
Barton Fisher wrote:
I'm looking to expand my bandwidth for my Asterisk PBX. Why should I
choose a T1 over DSL for my asterisk server? I found someone
offering T1's for $290 a month + Loops or 3 Meg for $561 a month +
Loops. Is this a good deal?
Thanks
Bart
---------------------------------------------------------------------
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Where are you located? What CLEC gives you a T-1 for $290?
FWIW I provisioned a PRI and a DS-1 for $300 each. Don't know if I'm
getting a break for having a voice and a data circuit broken out from
one fiber drop, but that's what I'm paying here in Orange County. Also,
I had a business cable modem before, which was *allegedly* not shared
for business customers (suspicious) and the throughput was a roller
coaster, as was the latency. The DS-1 cleared all that up.
/rg
Robert Goodyear
Brand Up LLC
http://www.brand-up.com
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