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Re: DSL over Frame Relay [7:76443] posted 09/30/2003
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At 10:45 AM +0000 9/30/03, nrf wrote:
>""Steven Meier""  wrote in message
>news:200309300327.h8U3RjUg031079@xxxxxxxxxxxxxxxxx
>>  I must be thick......or having a blonde day...but DSL over frame relay is
>>  impossible as they are 2 different hardware transport platforms.
>>
>>  DSL is ATM and uses completely different hardware than a frame relay
>circuit
>>  which uses PVC's etc whether permanent or semi permanaent.
>>
>>  The packet structure is different as well.
>>
>>  or am I completely blonde.
>
>I don't want to comment on your hair-color, but you can indeed have DSL over
>frame-relay.  It's rare, but some DSLAM vendors support it.  While DSL is
>usually backhauled through ATM, this is not necessarily so - any backhaul
>mechanism can be used in theory.  It all depends on what the vendor supports
>and how the service-provider wants to build the network.

Well, I confess to being confused by this thread, even though I'm 
more hair-challenged. I have no difficulty understanding the use of 
DSL as a first-mile access technology to FR, as ISDN, dial and even 
X.25 have been used for years.

But DSL, to the best of my knowledge, is a physical layer 
specification, full of modulations, medium requirements, etc., that 
feeds bit streams into a DSLAM, which may pass along bit streams on 
ATM, or, if the DSLAM contains layer 2 or 3 functionality, pass 
frames or packets. ADSL, SDSL, ISDL, VHSDL, etc., don't specify 
frames, to the best of my knowledge.

We speak glibly of Ethernet-over-whatever, but we really are speaking 
there of 802.3 frames, not Manchester-encoded baseband signals or 
optical or broadband equivalents, or the OC-192 PHY for 10 GE. 
DSL-over-whatever sounds like the equivalent of Manchester over 
frame, essentially an analog-to-digital process.

Have people been using sloppy terminology or am I missing something 
fundamental?




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