Why does PPPoE work on a DSL line?

Hi,

My understanding of the difference between PPPoA and PPPoE is that the former uses ATM and the latter Ethernet.  Therefore if you have a DSL connection through your normal analogue phone line, you use PPPoA.  If you've got a cable connection, you use PPPoE.

For many years this understanding has fed and clothed the kids and kept the wife in shoes.

However, the other day a friend asked if I could help him setup a wireless router at home on his DSL line - he's got an AOL account.  "Yes, no problem" I said.  But couldn't get it to work.

After a call to AOL they told me that I needed to be using PPPoE not PPPoA.  After much protestation on my part that PPPoE wouldn't work, I grudgingly agreed to try it.  And what do you know - it worked.

How can that be?
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devon-ladAsked:
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bhanukir7Commented:
hi there

PPPOA was used earlier where the the data travelling from the tele exchange was going to the ATM circuit server and the authentication also used to happen on that server, and the customer used to connect. This connection speeds are limitation.

Now for enhanced functionality PPPOE is being used by all the DSL service providers. They no longer provide a PPPOA connection type.

Or rather now a days PPPOE is the global standard for DSL.

as you said
PPPOA - Point to point protocol over the ATM
PPPOE - Point to point Protocol over Ethernet

ideally in a PPPOA connection there is a limitation on the bandwidht or speed a customer can be provided it was ok when the DSL speeds were 256 or 512 kbps now a days we talk about 9 MBPS speeds a PPPOA connection dose not provide that flexibility.

thats the reason why u find PPPOE even if its a DSL connection.

regards

bhanu
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devon-ladAuthor Commented:
bhanu - I look after a number of company networks, and their DSL lines all use PPPoA - and most of them have 8Mbps lines.  So how can there be a restriction on PPPoA?

Also, PPPoE implies an ethernet connection - how can an ethernet connection be established on a phone line without some other underlying connection?
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bhanukir7Commented:
hi

i am sure you are aware of how PPPOE works this is the RFC for it.
http://www.faqs.org/rfcs/rfc2516.html

PPPoE is used to allow Internet Service Providers (ISPs) the use of their existing Radius authentication systems from their Dial-Up service on a Broadband / Ethernet based service. Dial-Up is PPP, most broadband connections are Ethernet, hence Point to Point Protocol over Ethernet. It also allows for ISPs to resell the same line multiple times. IE: Rated services, Broadband specific content (movies, etc.), metered services, etc.

above all a dsl modem unlike the conventional modem the telephone line goes into the modem and a ethernet cable connects the modem and the computer.

PPPoA has negatives over PPPOE

• Only a single session per CPE can be established. In PPPoE we offer the ability to log in to multiple services or create multiple sessions all at the same time over the same line
• CPE setup and access, in general PPPoA must be configured on the CPE itself, PPPoA software is not available on platforms. Either the CPE must support PPPoE or an ATM network interface must be installed in the PC. ATM network interface cards are expensive and both can be difficult for an end user to configure. Once an end user has the ability to configure the CPE it opens up the problem for incorrect configurations making trouble shooting by the provider very difficult resulting in increased support costs
What if the CPE was pre configured by the provider? This leads to increased fulfillment costs. The provider would then have to configure each CPE separately to enter the customer’s userid and password and loses the ability to batch process the CPE

regards
bhanu

please refer to these articles for further clarification
 PPPOE
http://www.carricksolutions.com/pppoe.htm

PPPoA v/s PPPoE
http://www.carricksolutions.com/pppoe/pppoevspppoa.php

 
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devon-ladAuthor Commented:
Ah, right...think I've got it now.

Thanks
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