Thank you this is really clear. Though I have to ask, when under bridged mode. I can still access the modem GUI via 192.168.1.1 provided I statically configured my NIC on computer to be in the 192.168.1.0/24 subnet. Can you explain how is this possible? It doesn't make sense this way. How can I reach the 192.168.1.0/24 subnet when modem is bridged? I cant draw out the topology

You don't say which device's configuration page you reach when you connect to 192.168.1.1 Sorry I am accessing the ISP modem/router/switch combo device

@Zanko see my edit...does that explain it? Please also edit your question to indicate which device you're accessing when you connect to 192.168.1.1.

That's normal because even in bridged mode you need a way to access the modem to configure it.

What IP address is assigned to your router's LAN interface?

Hi in this senario I have no router

It is just modem and computer

the ip on modem interface is 192.168.1.1

modem LAN interface*

i bridged to modem LAN port 1

and I use computer to connect to modem LAN port 4 with NIC configured as 192.168.1.10 and is able to access the modem GUI on 192.168.1.1

Do you have internet access with this configuration?

if I connect my own rotuer to modem Port1 and configured as PPPoE with username and password then I am able to use internet

I understand bridge is turning the modem into "modem-only" device, but how does modem interact with a built-in switch to provide network to its management IP?

OK, so without the router connected, the reason you can still access the modem's configuration page is that because bridged mode doesn't disable that page. Otherwise you wouldn't be able to get back into the modem to turn bridged mode off!

Haha I understand why it is built this way and im glad it did! But I am just wonder HOW it is possible? Is it possible to decompose into network topology diagram?

So this ISP device is decomposed into Modem,Router and Switch right?

what does it look like in bridge mode, there should be a path to 192.168.1.1 that is reachable from switch port right?

Not sure what you mean "decompose"? Are you wanting to see a picture of how it works?

Sorry, I mean just a simple diagram of how we are able to reach 192.168.1.1

internally its just another network right?

ISP modem is just a big box of router,switch and modem all in one

Yes, ISP device comprises all those roles. Hang on I'll draw a diagram, though I'm not sure you'll find anything surprising in it. :-)

Thank you so much! I just want to understand this small detail once and for all :)

I just tested the Bridge port(Port1) and somehow I can still access 192.168.1.1

This is how you have things configured now.

If I understand correctly?

Yes

This diagram represent bridging?

Yes, though not how you should use it.

This is how you would use bridging and have access to the Internet, if you didn't want to use a router.

yea we are on the same page:)

In this setup, you have Internet, but no access to the router's config page

but the interesting this is, all this is possible through the same LAN port on modem

thing is*

Why do you find that odd?

so LAN port on modem is a switch right?

there are 4 LAN ports

so must be a switch

Yes, it is a switch.

that switch have to be connected to something in the modem right?

somehow it has access to to IP 192.168.1.1 and 223.206.123.129

two IPs*

Not odd at all.

A switch is merely a Layer 2 device. It doesn't care about IP addresses.

So internall it looks like this?

Hmm....I think I see where you're going.

Gimme a sec.....

thank you! Sorry for not making things clear

Not your fault...communication is hard especially when learning something unfamiliar

Appreciate your patience!

This is what your modem looks like inside, in bridged mode

Notice that its WAN interface has no IP address. That's key

Incoming traffic from the ISP is handled strictly at layer 2. It's passed directly to the modem's LAN interface.

Actually I need to adjust the graphic a bit now that I think about it...hang on.

there should be more cables? hah ok!

This is more accurate in bridged mode. There is no router.

Ignore the arrows on the connectors...Visio keeps adding them. They should just be lines.

hmm let me see thank you!

now i wonder what it looks like with non bridge mode

in non bridged mode the LAN interface 192.168.1.1 is on router LAN interface?

I'm assuming this is what you were trying to learn by asking your original question? If so, I encourage you to post a new question. Your original question is too different and already has two answers, so editing it wouldn't be a good idea.

Yes! I can post a new question!

that is what i udnerstand conceptually too. I just dont know how it fits together, after all it is in the same modem

so LAN interface can appear on two places ? on config webserver or on router?

or the modem config webserver is the router?

Actually, it's probably not best to refer to the web server as having a LAN interface. It's really a service running on the modem that's reachable via "an IP address". It just happens to be the same IP address the modem uses for its LAN interface when in non-bridged mode.

Try this...

What's the dashed line?

The purple line is "Activated" if bridge is turned on

so it bypass the router straight to switch?

i am not sure haha, do you think it go through router too?

Yes, that would be an accurate way of understanding it. The router component gets "turned off" when you activate bridged mode.

This makes much more sense thank you

although the same IP as server and as interface is kinda odd

Your welcome. Ping me on your original question when you write a new one and I'll see if i can answer it.

ok I will try to make it clear this time!

The IP addresses are always assigned to the physical interfaces

Breaking down the modem's functions in a chart like this makes it hard to picture where those interfaces would actually be.

I will try to capture that part in an answer I post for you

i see one more thing, this is called management IP address

is it the same thing as loopback interface?

no

Ok thanks! Ill post the question soon!

ok. bye!