[SOLVED] Router in Bridge Mode and IP address

ravin_29

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Mar 24, 2019
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I recently put isp’s ontwifi router (a device which has ont as well as wifi) into bridge mode and connected by own router to isp’s ontrouter and checked the pppoe connection from my own router and it worked.
Isp ontrouter was 192.168.1.1 and my router was 192.168.0.1. But in case my router had been IP 192.168.1.1 would it have caused any issues or it’s normal. I had disabled DHCP on isp’s ontrouter.
I don’t understand much of networking hence the query. I mean in future if I get a new router which is 192.168.1.1, will it cause any issues?
 
Solution
No if they are duplicate all the traffic will just stay on the LAN. Let say instead your router was 192.168.1.1 and the other was 192.168.1.100. If you attempt to send traffic to the 192.168.1.100 your PC will assume it is on the local network and use a ARP command to try to find it and will fail. Only traffic that is outside the subnet is sent to the gateway/router. That is why it is called the gateway IP because it is the IP of the device that provides the path outside the network.

It gets very inconsistent if you can access a private IP behind your public IP. Since private IP are not allowed to be routed on the internet some routers will not pass private ip addresses if there is a public IP assigned to the wan port...
Not sure what you are asking.

Those are all private IP addresses. There are many but you can use 192.168.x. where x can be any number between 0 and 255. It is just very common for most consumer routers to use 192.168.0. You can generally change the LAN subnet to anything you want.

The only restriction would if you were not running the ISP router in bridge mode. In that case the ISP router would assign a IP to the WAN port of your router. You can not have the WAN and LAN subnet the same. But it is trivial to change the LAN subnet to something else if that would happen.
 

ravin_29

Commendable
Mar 24, 2019
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1,535
Ok Thanks. what I meant is the static IP address (private) assigned to isp router (for access over LAN) by default was 192.168.1.1 and the static ip assigned by default to my router was 192.168.0.1. These are written on sticker on back panel of the device.

So basically even if wan port of my router gets public IP I can still access my router by going to 192.168.0.1 from its LAN side.

So the question is would it have been an issue had my router also been 192.168.1.1 by default? In that case 192.168.1.1 (isp router) and my router 192.168.1.1 would connect to each other LAN to WAN. ISP router in bridge mode and a LAN cable from its LAN port goes to WAN port of my router.

Would that cause any IP Conflict or it does not matter because the connection is from isp router's LAn to WAN of my router?
Hope my question is clear. Thanks
 
Last edited:
No if they are duplicate all the traffic will just stay on the LAN. Let say instead your router was 192.168.1.1 and the other was 192.168.1.100. If you attempt to send traffic to the 192.168.1.100 your PC will assume it is on the local network and use a ARP command to try to find it and will fail. Only traffic that is outside the subnet is sent to the gateway/router. That is why it is called the gateway IP because it is the IP of the device that provides the path outside the network.

It gets very inconsistent if you can access a private IP behind your public IP. Since private IP are not allowed to be routed on the internet some routers will not pass private ip addresses if there is a public IP assigned to the wan port.

In your case it is even more questionable because you are using PPPoE which can be though of a as a VPN.
 
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