On Wednesday 09 January 2013 11:55:09 Aleksandar Kuktin wrote:
> I have the same idea in my TODO folder.
> 
> The way I understand it, at a bare minimum, you need (1) a physical
> and link level connection to the first station and (2) a carbon copy of
> whatever mechanism ISPs modem-router uses to route the packets.
> 
> There is a HOWTO which sheds a bit of light on all this:
> http://www.tldp.org/HOWTO/DSL-HOWTO/index.html
> 
> Regarding the physical connection, that is done with DSL. AFAIK, DSL
> lives exclusively in the physical layer and either can not signal, or
> can not signal enough. Therefore, a link layer is put over DSL. The
> most likely candidate for this link layer is ATM. Maybe PPP can also be
> used. Maybe they can even put raw ethernet frames on top of DSL.
> 
> You can gain a bit of information regarding this by loging into the
> modem-router your ISP gives you. Read the manual and try to figure out
> what the device is doing, and then copy that.
> 
> As far as bridging, the idea is simple - take packets from one
> interface and just send them on the other. In the kernels menuconf,
> look under Networking for something called Bridging. Also see
> http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge

thanks for a very informative post, 

This is a fantastic link
http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge

> But, the problems only begin when you get to this point. The ISP
> assumes it owns the firmware in the router and as a consequence of
> that, the "routing" part can be arbitrarily complex. For example, I
> have noticed that my ADSL router appears to be using VLANs. But not
> just any VLANs, sometimes it uses normal once-tagged ethernet frames,
> but some other times it uses double-tagged (QinQ) ethernet frames. It
> appears no more that two tags are ever used. Currently, I have ZERO idea
> which frames get a single tag, and which get two tags, not to mention
> having less than zero ideas on what is the content of those tags.
> Further compicating matters, it appears that yet some other frames have
> an even more bizarre treatment. If I ever want to connect to my ISP, I
> need to carbon copy the mechanism by which the tags are generated. I
> also need to do this while not reverse engeneering the modem-router,

nailed it.  why is a router bundled with  modem?  No WHY is every adsl2 modem 
bundled with a router?

> lest the ISP press a lawsuit against me. Or just cut off my Internet
> pipe, which would be an even bigger problem.



An area  of real interest is whether bridging    can be used to overcome some 
of the asymmetry  that ADSL   has deliberately introduced.  (Assumming one can 
fnd ISPs willing to provide 'symmetric'/bidirectional  packet-routing services 
at low cost -as there are no  justifiable  'economic reasons.   ) Telephony  
still the backbone is intrinsically 'bidirectional but  sDSL has effectively 
been killed off/still-born   as the internet is  being  morphed into a medium 
to  flog movies/information  etc  to consumers.

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