DSL,DSLAM...

[cisred1983]

Hello

I am Redouane from algeria (MCP,A+,Network+2009 soon) , as i am studying networking some times i meet some issues ,

The question that i want to ask is : in the DSL connection i want to know if the DSLAM device that is found in the telco side to connect DSL subscribers to the internet trough an ISP is realy a Modem or it does just the multiplexing task ???????

If it's a modem then what do we call the CPE device that is at home to connect us to the internet ( DSL Modem or DSL Router) ??????

Note that when implementing DSL technology the telephone wire will be digital.

Thank's for help.

[Ganesh Hariharan]

Hello
I am Redouane from algeria (MCP,A+,Network+2009 soon) , as i am studying networking some times i meet some issues ,
The
question that i want to ask is : in the DSL connection i want to know
if the DSLAM device that is found in the telco side to connect DSL
subscribers to the internet trough an ISP is realy a Modem or it does
just the multiplexing task ??????? 
If it's a modem then what do
we call the CPE device that is at home to connect us to the internet (
DSL Modem or DSL Router) ??????
Note that when implementing DSL technology the telephone wire will be digital.
Thank's for help.

Hi,

As per the defination of DSLAM is a equipment at the telephone company (telco) collects the data from its many modem ports and aggregates their voice and data traffic into one complex composite "signal" via multiplexing.It is a network device, located in the telephone exchanges of the service providers, that connects multiple customer Digital Subscriber Lines (DSLs) to a high-speed Internet backbone line using multiplexing techniques.

DSLAMs are generally flexible and able to support multiple types of DSL in a single central office, and different varieties of protocol and modulation -- both CAP and DMT.

How DSLAM works when traffic comes to DSLAM, Genrally what happen is that it accepts and separates outgoing phone and data signals from the customer. It directs the data signals upstream to the appropriate carrier's network, and the phone signals to the voice switch.
Depending on its device architecture and setup, a DSLAM aggregates the DSL lines over its Asynchronous Transfer Mode (ATM), frame relay, and/or Internet Protocol network (i.e., an IP-DSLAM using PTM-TC [Packet Transfer Mode - Transmission Convergence]) protocol(s) stack.

The aggregated traffic is then directed to a telco's backbone switch, via an access network (AN) also called a Network Service Provider (NSP) at up to 10 Gbit/s data rates on the Internet backbone.

Hope to help !!

Remember to rate the helpful post

Ganesh.H

[cisred1983]

Hello

ganeshh.iyer

Thanks a lot for answering it helps me a lot , but i am sorry to tell you that you didn't answer me !!!

 in the DSL connection i want to know
 if the DSLAM device that is found in the telco side to connect DSL
 subscribers to the internet trough an ISP is realy a Modem or it does
 just the multiplexing task ??????? 
 If it's a modem then what do
 we call the CPE device that is at home to connect us to the internet (
 DSL Modem or DSL Router) ??????
 Note that when implementing DSL technology the telephone wire will be digital

[Giuseppe Larosa]

Hello Redouane,

the DSLAM hosts groups of modems each ATU-R modem has a corrispondent ATU-C on the CO.

ATU-R sends on upstream and received on downstream frequencies, ATU-C transmits on the downstream frequencies and receives on the upstream frequencies.

The DSLAM provides also the multiplexing functions.

Hope to help

Giuseppe

[smitesh kharecha]

DSLAM is multiplexer.

And device at CPE is called both DSL router and DSL modem. People tend to use them interchangebly.

Technically speaking, it is DSL modem.

When you subscribe for ADSL line, your connection is over regulars POTS.

Then at your premises, depending upon your requirement filter or splitters will be used (If you want to use PSTN line also as well as DSL too).

Next from that filtered line, you get one Data and another plain anologue voice phone line.

The Data line, aka DSL line can be directly plugged into your router; if your router supports DSL or it needs to be terminated on DSL Modem and from there it comes into your router, genarlly which will be one of your Ethernet ports.

Regards,

Smitesh

[cisred1983]

Hello and thanks a lot for helps

But the dsl device at the CPE is called DSL ROUTER not DSL MODEM because the data itself comes digital from the PSTN whereas the modem modulate and demodulate the signale.....(What do you think?????) Please give me the correct answer if i am wrong.

thanks,

Redouane Sarra from Algiers

MCP,A+,Network+ Certified.

[smitesh kharecha]

Hi,

As i mentioned earlier. Device at CPE is interchangeably call DSL router and DSL modem. However its works as Modem in most of the cases.

And regarding your query on digitalization. Normal telephone line has got much room to accommodate other frequencies other then voice.

They work on technology DMT (Discrete Multitone).

Please refer:

http://en.wikipedia.org/wiki/Asymmetric_Digital_Subscriber_Line

http://www.geoffknagge.com/uni/elec351/351assign.shtml

Hope that Helps.

Regards,

Smitesh

[Giuseppe Larosa]

Hello Redouane,

usually with DSL router is meant a device with a DSL CPE modem as WAN interface and an ethernet port that can perform routing between the two ports.

With DSL modem is meant usually a device that does not provide routing functions and  that can act as an half way bridge, bridging ethernet frames over DSL (RFC 1483 bridged mode)

Both devices have an ATU-R CPE DSL modem as the WAN interface

Hope to help

Giuseppe