How does a bridged modem work?

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shadow23_69

shadow23_69

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I'm just curious when you put a modem in bridge mode, how does it tell if it is on ADSL or VDSL line?

Since ADSL is different to VDSL how can the modem determine what settings it needs to function on VDSL?
 
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Tom Tancredi
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t53186

t53186

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I think you are asking two distinctly different questions. When two modems are placed in bridge mode it actually disables one of the router's dhcp server. ADSL and VDSL are different technologies and some modem have the capability to distinguish between both and handle the incoming signal appropriately.
 
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boosted1g

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Bridged mode simply means that it bridges the input WAN to the LAN port and strips away all router functionality of providing NAT, DHCP and other functions.

The modem still does everything a modem would do, but once it converts it to etherent packets it then outputs all data straight out the LAN port with no restrictions.
 
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Tom Tancredi

Tom Tancredi

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It doesn't. Bridge mode is basically turning of the 'brains' in the modem and turning it into a dumb 'pass through' device (you should try Google instead of posting to the forum first to speed up getting a answer).

As it is a 'bridge' or passthrough device, it doesn't know or care what sort of 'connection' it has, all it does is 'passes' the data back and forth and relies on each end (your service provider / your network) to resolve anything else.

Commonly if some high end technology is in place either at your POE (point of entry), in the local node (the box that all the homes in the neighborhood are tied to), or the CLEC (the building your Provider connects to all the houses in that 'region' or 'area' together) can make the use of a smart modem redundant (aka gets in the way) and thus they set the modem to just be a 'bridge' as they manage the network at the POE/Node/CLEC instead of you doing anything in the modem/router (setup the firewall, adding VPN, DMZ, etc.).

That previously proved to be too costly (hardware and endpoint hardware) and too restrictive, but most of all too obtrusive (literally did SPY on what you were accessing). So to reduce liability, costs, and most of all the support staff (anytime you wanted to do something you had to call the ISP for service), they went with the current model. Just endpoint connection, then it is up to you to either RENT a modem/ router THEY preconfigured and just 'walked away' OR you provided your own and you supported it on your own.
 
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shadow23_69

shadow23_69

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I did actually Googled it. But it doesn't explain how it works. I know that a bridge modem just passes on the info to the router. But having a ADSL/VDSL modem it doesn't explain how the modem knows which settings to have like G Vectoring and G INP needs to be enabled otherwise here in Australia if those settings are disabled, your port will get locked and you will have no internet. http://forums.whirlpool.net.au/archive/2558213

 
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shadow23_69

shadow23_69

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@t53186 and @boosted1g

I'm not talking about 2 modems nor am I asking how a modem in bridge mode works.

The question was how does a modem know what settings it needs when a modem is capable of ADSL and VDSL? Like I mentioned before in VDSL the G. Vectoring and G. INP needs to be enabled. When I put a modem in bridge mode how does it decide what settings to have. I have researched it or Googled it. And there's no definitive answer. And that's why I'm here.
 
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Tom Tancredi

Tom Tancredi

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Think of it this way, on a home phone do you need a special modem switch and settings to make a home phone 'work' or do you just PLUG INTO the telephone jack and it connects when they 'activate' the line? THEY (the Telco) has all the equipment at their facility to make the 'telephone' connect to the world, all they do is lay WIRE to just get to the handset.

When you enable BRIDGE it DEACTIVATES the whole thing, your turning your Modem/Router into a telephone handset, DUMB, NO Tech involved just 'plugged in. Your Telco has to handle the ADSL / VDSL on the TELCO equipment NOT on the Modem/Router, just like your phone, it handles the whole Telephone connection.

Does that make it more clear?
 
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shadow23_69

shadow23_69

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@Tom,

Kind of does. But the telco actually doesn't work that way. With our NBN (National Broadband Network) it will lock your port if your modem has the wrong settings. You can get the supplied modem from your service provider and all you'll need to do is plug it in since it's preconfigured.

But last year when I got my NBN FTTN I had a modem that is VDSL capable. Since the current firmware at the time didn't have the right settings and I plugged the phone line in, it locked my port which stopped me from getting internet access.

And now with the latest firmware on the ASUS DSL-AC68R the firmware has the right settings and even if you use the setup wizard it will detect whether you are on ADSL or VDSL. You can even set it up manually and when you look at the DSL profile on the VDSL, you will see the settings that the G. Vectoring and G. INP are enabled by default.

However I recently acquired a modem TG799vac that has a custom firmware from Telstra {a major telco in Australia). And since it has the custom firmware there's no way of knowing what settings it has. I have read many posts from other TG799vac owners of using it in bridge mode and using it with a different telco.

So it made me ask the question of how it at all works. And a poster who I PM'd said that the modem will detect the type of line I'm on as he himself is using the same modem and all he did was put it in Bridge mode and plug in the phone line and didn't have to change any settings.

Thanks for trying to answer my questions. I appreciate the time you have given me.
 
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Tom Tancredi

Tom Tancredi

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Right I got all that a while ago from your link. And I keep repeatedly saying, ALL that you just are saying is with the device in NORMAL MODE aka NOT BRIDGED.




And that is what I am saying is different, not just it called a 'different telco' NAME but the telco is NOT doing it the way NBN does it. The different telco, as I keep repeatedly saying, has the 'ADSL / VDSL' part of your 'modem' IN the equipment set up AT the different telco's Building (the one down the road or in the center of town). So all there needs to be (like your telephone handset) is just a pair of 'wires' going from "different telco' building down the street to your home, NO ADSL / VDSL setup needed, just 'pass' the data (aka Bridge mode) through.



And that is exactly what I just said. The ADSL / VDSL is TURNED OFF in Bridge mode, as the "poster" service provider (NOT NBN) has the 'modem ADSL / VDSL' hardware in the poster's local CLEC building already and is just running the wires to the poster's home so he just "put it in Bridge mode (turning off all settings options) and plug in the phone line (doesn't need special modem for this right? like I said before) and didn't have to change any settings."
 
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shadow23_69

shadow23_69

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Thanks Tom.
 
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