0

So the main router have 1 LAN and 1 WAN. WAN is connected to the modem and receive the IP Address of 123.123.123.123.

The main router IP address is SET TO BE 192.168.1.1. ( I can use this to login to router webpage)

A secondary router come in and was SET TO HAVE IP of 192.168.2.1. Secondary router WAN is connected to the LAN port of main router.

enter image description here

Conceptually, so are the IP addresses of the following interfaces correct?

  • Main Router WAN 123.123.123.123
  • Main Router LAN 192.168.1.1
  • Sec. Router WAN ??????
  • Sec. Router LAN 192.168.2.1

What is assigned to Sec. Router WAN and whose responsibility is it?

Zanko
  • 211
  • 1
  • 4
  • 12
  • A router is a device that connects between 2 different networks. Its internal network (LAN) to the external network (WAN). So on the WAN side of the router - it will have the IP address of the external network. On the LAN side of the router - it will have the IP address of the internal network. So on your 2nd router, the Internal (LAN) is on 192.168.2.x as you said. The external (WAN) would be as what Ramhound said - somewhere on the 192.168.1.x. The 2nd router WAN IP address can the 2nd router responsibility (if you set static IP address), or if 1st router responsibility (if you set DHCP) – Darius May 18 '18 at 03:05
  • Is it a coincidence that the interface IP that was set also act as management IP for that router? From what I read router should have another IP for management(Acessing web page). But somehow they reuse this ip. – Zanko May 18 '18 at 03:18
  • 1
    Possible duplicate: [Expanding wireless coverage: What are the differences between LAN to LAN and LAN to WAN when it comes to connecting two wireless routers?](https://superuser.com/questions/936062/expanding-wireless-coverage-what-are-the-differences-between-lan-to-lan-and-lan?noredirect=1&lq=1) – Ramhound May 18 '18 at 03:46
  • Gotta agree with ramhound here. This absolutely is a duplicate. And there seems to be a whole slew of this same question recently. Not linking to the original question that was already answered, destroys the spirit of this site. – Tim_Stewart May 18 '18 at 12:31

1 Answers1

0

Conceptually, there are three ways to use "routers" (as in "home routers you can buy as physical device"):

1) A simple switch/bridge. This works on OSI level 2. All LAN and WAN ports share the same segment (e.g. 192.168.1.*). The installed firmware often cannot set this up, you may need to install an open-source firmware like OpenWRT.

This is the simplest and best setup if you just want to extend your LAN.

2) A real router that connects different LAN segments (e.g. 192.168.1.* on the WAN port, and 192.168.2.* on the LAN ports). It will forward packets between the different segments. Most home routers can be configured for this.

3) In the default configuration, a home router is configured as (2), and in addition it does NAT (network address translation) between LAN and WAN. This is because your ISP only gives you a single IP address, so the router pretends towards the ISP that there is just a single computer in your LAN, when in fact there are several. It also offers services like DHCP to computers in your LAN.

This configuration is not desirable for a second router, because the first router already does NAT, leading to "double NAT".

So, my recommendation would be to setup the second router for (1) (if possible) or (2), depending on your requirements. After you've decided on that, you assign LAN segment prefixes and internal IP addresses for the routers.

If you just think about "what IP address must I assign in the GUI", you are still missing some fundamentals about networking, and I'd suggest to read some tutorials.

dirkt
  • 16,421
  • 3
  • 31
  • 37
  • Thank you! I have read up on double NAT, In what senario do we absolutely need to have new subnet and willing to sacrifice having double NAT? I am planning to have ip cameras on its own subnet but I can not reason why I want it that way. Any practical benefits? Thanks! – Zanko May 18 '18 at 07:14
  • You generally **don't** want double NAT, because it's wasteful, unnecessary, and can lead to problems when the connections are exhausted. How many different segments you want to have in your network depends on how you want to organize your network, and is entirely up yo you. Note that some protocols using broadcasts will only work between hosts in a single subnet. Routing multicasts between subnets is not trivial. What protocol(s) do your IP cameras use? Which hosts are the supposed to communicate with? – dirkt May 18 '18 at 08:57