Windows LAN Router Management and Subnet Tricks

In this windows security tutorial, you will learn some common (and not so common) LAN router management subnet tips and tricks.

Networking with a Windows computer is very common at home, in a small office and even in most large offices. Networking can be very simple if you plan to create a small network that uses only one subnet.

For example, you can create a small network using only one router with this:

Start by connecting only one computer to the router. Connect a LAN cable from your computer network card to the LAN port of your router, not the WAN port. Open a browser and then type the default IP address assigned to it by your manufacturer. You can refer to the manuals for the number. For Linksys routers, it is 192.168.1.1, so enter this in your browser http://192.168.1.1 then press enter. You can type the username and passwords (refer to the manual for the default username and login).

Simply configure the router with DHCP server enabled and assign a local IP address (say for example 192.168.1.1). Once configured, connect all computers using either a LAN cable or a wireless connection (enable the wireless encryption for better security).

The rest of the computers on the network (such as PC 1, 2 and 3) will be assigned with an IP address automatically by the router. This is because it is DHCP enabled and your computer is configured to be assigned automatically with an IP address by default (which can be set in the Network Connections).

So the IP address to be assigned will still belong to the same subnet such as 192.168.1.100, 192.168.1.101 and 192.168.1.102 respectively. If you have an internet connection, plug the modem input from your ISP to the WAN port of the router. You can ask your ISP for support if you have a connection issue.

In your Windows computer, go to Start and then click “Run” in the Open type CMD. This will launch the DOS command line; you can get the information out of your network by typing ipconfig, for example:

C:>ipconfig

It will give you all the information about your computer on the network. For example: what is your IP address, the subnet mask used, and the IP address of the Default gateway (router). If you have an active internet connection, it will show the DNS server used by your ISP.

{mospagebreak title=Connecting Two Routers with DHCP Enabled}

There are times when you need to connect more than one router. This can be the case in a very large network or if you just need two routers for more flexibility and better wireless signal reception for your Internet. One way of doing this is by connecting two routers – both with DHCP enabled.

In this case, suppose you have two routers A and router B. Router A has its own network and Router B has its own network also.  Router A is the one connected to your ISP for an internet connection. You can connect it as follows:

If you want to enable DHCP for both routers and connect them in the network, you can read this tutorial: http://www.devhardware.com/c/a/Networking-Hardware/How-to-Connect-Two-Routers-on-the-Same-Network/ . You need to follow those instructions step by a step.

Basically what will happen at the end of the configuration is this:

a.) Router A and Router B has its own subnet or small sub-network. It is because if the router IP addresses are as follows:

Router A- 192.168.1.1
Router B- 192.168.2.1

Computers in Router A will have these IP address (example only):

Windows PC1: 192.168.100
Windows PC2: 192.168.101
Windows PC3: 193.168.102

While computers in Router B will these IP addresses (example only):

Windows PC4: 192.168.2.100
Windows PC5: 192.168.2.101
Windows PC6: 192.168.2.102

b.) All of the computers in Router B will get an Internet Connection from Router A.
c.) Computers in Router B can communicate or ping to computers in Routers A including Router A itself.

For example if you are in Windows PC4 and you like to ping Router A, you can get a reply:

C:>ping 192.168.1.1

Pinging 192.168.1.1 with 32 bytes of data:

Reply from 192.168.1.1: bytes=32 time=3ms TTL=63
Reply from 192.168.1.1: bytes=32 time=2ms TTL=63
Reply from 192.168.1.1: bytes=32 time=2ms TTL=63
Reply from 192.168.1.1: bytes=32 time=2ms TTL=63

Ping statistics for 192.168.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% l
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 3ms, Average = 2ms

You can even login to the Router administration panel of Router A if you belong in the Router B sub-network.

d.) But computers in Router A cannot communicate with Router B. So if you are in Windows PC1 (that belongs to Router A) and you would like to ping Windows PC4 or even Router B, you cannot get a reply.

e.) The advantage of this setup is that if you have a laptop or any wireless devices you can easily connect to either network because its DHCP enabled. Your device can automatically be assigned with an IP address after authentication.

f.)  The disadvantage is that you cannot network computers in Router A and Router B. There is no full-duplex communication. So that means that if someone setup a game server on Router A, Router B cannot join the game.

{mospagebreak title=Connect Two Routers with Only One DHCP Server}

This is a solution to the disadvantages of having two DHCP servers on the Windows network. In this type, there is only one subnet, so that means all computers in the network (Windows PC1 to Windows PC6) share the same Class C IP range, for example 192.168.1.xxx. And finally they can communicate with each other in full duplex.

Suppose you have already configured your entire network to run with two DHCP servers by following the instructions in the previous section – how will you be able to convert it to only one DHCP server and one subnet?

This is how to do this:

1.) Disconnect the LAN cable that connects Router A to the WAN port of Router B.

2.) Disconnect other LAN cables that connect to Router B from other computers except one computer. Retain one computer connected to Router B.

3.) In that computer, launch a browser and connect to the router administration panel e.g. http://192.168.2.1 . Enter your router administrator credentials.

4.) You need to do two things to Router B:

a.) Disable DHCP server so that only Router A has DHCP enabled.
b.) Assign a new IP address to Router B so that its IP address will fall within Router A IP address range.

5.) Lets first disable the DHCP server on Router B. Simply select “Disabled” in the DHCP Server selection.

6.) Now assign a new local IP address to Router B. Make sure this is within the Router A IP address range. If Router A IP address starts with 192.168.1.100 and there are 50 maximum DHCP users. Then assign something far like 192.168.1.121 to Router B.
This is how it looks in a LinkSys router:

The subnet mask is unchanged.

7.) Finally click “Save Settings”.
8.) It will take time for the configuration to succeed. Wait until it is done. If it appears to freeze over a 5 minute period, this is what you should do:

a.) Clear the browser cache and its history then close the browser.
b.) Restart your computer.
c.) Launch the browser again and type the new router B address that belongs to Router A subnet: http://192.168.1.121, you should be able to see the Router admin login panel. This is just for confirmation purposes that the IP address has been changed successfully for Router B. You do not need to login.

8.) Now connect the LAN cable from Router A (the one you have disconnected from Router B WAN port earlier) to any of the Router B LAN port.

WARNING: Make sure you do NOT connect Router A LAN cable output to the Router B WAN port.

Test the connection in DOS mode:

1.) Try pinging Router A from any computer in Router B.

C:>ping 192.168.1.1

You should get a reply.

2.) Try pinging any computer on Router A, you should get a reply.
3.) Ping any computer to Router B from Router A, you should now get a reply.
4.) You can then connect other computers to Router B. The Internet should also work fine.
4.) If you have multiplayer games, you can try creating a server and test if all computers in the network can now connect and join the game.

One big advantage of this implementation is that it is easy reversible. If you plan to re-configure your network again to use “double NAT” or two DHCP servers, then it’s very easy. You can simply reverse the process such as re-assigning back a local IP address in Router B back to 192.168.2.1 and enabling again the DHCP server on it. These are the only changes needed and its back again to two DHCP server configurations.

This is a simpler and an easier solution as compared to other technical methods such as port forwarding, static routing, etc. which might be too technical for an average Windows network user. This tutorial is tested to work on Linksys routers.

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