>On Tue, 8 Jan 2013 12:15:41 +0000 >"lux-integ" <[email protected]> wrote: > > On Tuesday 08 January 2013 09:17:51 Simon Geard wrote: > > Every DSL device I've seen in years - including the free ones ISPs > > hand out to new customers - has just been a router with an ethernet > > port. The device itself takes care of the DSL part - you just need > > to plug in your PC, and do whatever you'd normally do for an > > ethernet device. > > > thats just it I dont want the routing mulki, I can do this meself > and for multiple subnets. There is a pci adsl2 modem (ikanos > chipset ??? (I think ) by sangoma (and others ) I think and support > for it is in the kernel, but it is quite expensive. > > How does bridging work and can one put router(s) behind an > ethernet bridge? > > by the way thanks for all the responses
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 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, lest the ISP press a lawsuit against me. Or just cut off my Internet pipe, which would be an even bigger problem. -- You don't need an AI for a robot uprising. Humans will do just fine. --Skynet -- http://linuxfromscratch.org/mailman/listinfo/blfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
