Expand your local area network
Sunday, July 04th, 2010 | Author: Bruce

A typical home or small business router usually has only 4 Local Area Network (LAN) ports.  You may find yourself in a situation where you have used all of your router’s LAN ports.  In that case, you may add additional ports to the network by adding a device called a SWITCH, or you may make use of a spare router.  Switches are available with multiple ports – 4, 5, 8, 16 and 24 are common sizes.  Note that they do not provide routing capability, they extend the local ports only, and leave the routing function to the router.  They also do not provide DHCP functionality (Domain Host Control Protocol) which assigns IP addresses to devices automatically.  Lastly, if there is a WiFi network involved, a switcfh does not provide WiFi – again, that functionality is left to the combination router/WiFi access point.

Ethernet wiring makes use of Cat-5  ‘(or Cat-5e or Cat-6) unshielded twisted pair wiring.  One pair of wires is used for sending, another pair is used for receiving.  If you connect a router to a switch, provision must be made such that the sending pair from one device is connected to the receiving pair on the other.   There are three ways to accomplish this:

  • Use a “Cross-Over” cable.  The wires are switched within the cable.
  • Make use of an “UPLINK” port if available on one of the devices.  The wiring within the port (jack) performs the switch.   On some devices there is a push-button which converts the adjacent port from a standard port to an UPLINK port.  On others two adjacent ports are marked such that one is wired as an uplink port, in which case the other port in the pair may not be used.
  • For any device made since about 2004 or so, the port automatically senses that it must operate in an uplink mode, you don’t need to do anything.  If you have the specifications this will be noted as “autosensing”.

If you happen to have a spare router (for example, you may have retired a non-WiFi router and now are using a WiFi router) you may use the older router as a switch.  To do so, you must do the following:

  • Connect your computer to the new router and get your network operational.
  • Determine the pool of IP addresses being used by the router’s DHCP service.  A typical pool might be to  The 3rd number (“octet”) in the address varies from manufacturer to manufacturer, but is typically 0 or 1.  See “How to Determine Router’s WAN Address” below.
  • Connect a computer to the old router’s LAN port and boot.  Use your web browser to connect to the control panel of the old router.
  • DISABLE the DHCP server in the old router.
  • Set the old router’s IP address to a number that is NOT in the new router’s DHCP pool, and is NOT the same as the new router.  For the above example, you might set the old router to

Note: This typically will require a ‘boot’ or ‘reset’ of the router.  You connection from the browser to the router will be lost since it has changed address.  Type the new address into the browser address bar after the old router has reset and you will regain the control panel.

  • Connect the old router to the new router using LAN ports on each router.  Do NOT use the WAN (Wide Area Network) port on the old router.  Put a piece of tape over it.

Connect a switch or second router to your LAN

While the diagram implies that the two devices are near each other, they need not be.  For example the second router, used as a switch, might be in another room or even another floor.   If it is inconvenient to run a CAT-5 cable through the walls, you may also use a pair of PowerLine adapters.  Use a Cat-5 cable to connect a LAN port on the router to the first  PowerLine adapter, and a second Cat-5 cable to connect the second PowerLine adapter to the second router/switch.

It is up to you as to whether you make use of any WiFi capability in the old router.  If you do, you must use a different channel number.

Computers, servers, printers, print servers etc. may be connected to any of the open LAN ports on either device and will be able to ’see’ any other device.

How to Determine Router’s Address

It is assumed that you have basic network connectivity – a working Local Area Network.
Open a DOS command window -

  • Windows 7 -  type CMD.EXE into the ‘Search’ field immediately above the Windows button lower left corner.
  • Windows Vista, XP – click START / RUN / type CMD.EXE then click OK
  • Windows 98, Me – click START / RUN / type COMMAND.EXE then click OK

In the resultant DOS command window, type
IPCONFIG /ALL    then press ENTER key
(Note space before the /ALL)
You will get a screen full of information about your IP configuration.  Find the line labelled “Default Gateway” – that is your router’s IP address.
While you are at it – make note of the IP ADDRESS – this is the address of the computer you used.  If it is, say 100, 101, etc., that indicates that you are using DHCP and that the pool probably starts at 100.

How to get to the Control Panel of the Router
Open your web browser and enter HTTP:// followed by the IP address of the router (identified as the default gateway in the above steps.)   You should get a LOGON prompt from the router.
The router manufacturers vary as to what to use for a logon and password.  I’ve seen various combinations, such as

If you have a problem, crank up Google and do a search using the router’s model number and the words logon and password and you should be able to find the default.  As a last resort, follow the procedure for resetting the device to factory settings.  This usually involves pushing a straightened paper-clip through a small hole in the case.

Category: Networking