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Friday, June 29, 2007

Using two network connection, modem and LAN together

When our LAN connection has no good internet access or limited internet but we need to work such as accessing office servers, probably we have our own internet connection as additional connection. In my case, this internet connection uses modem (GPRS from 3G handphone).

To configure both connection together, we should also consider to modify network routing table in laptop or computer. To configure this we need to

  • test LAN connection without modem
    • make sure our modem is not dialed up / connected, only our LAN cable
    • to test, run menu Start | Run | cmd ENTER | ipconfig /all ENTER
    • notice gateway IP address and ping out to this address e.g “ping″, the connection is OK if there is reply
    • note: in Unix/Linux the command would be ifconfig
  • test modem connection without LAN
    • make sure our LAN cable is not connected
    • use your own procedure to connect the modem to service provider
    • after connected, use same procedure for LAN to test the connection
  • test modem and LAN
    • connect LAN cable to computer, and dial up to internet provider with the modem
    • run menu Start | Run | cmd ENTER | ipconfig /all ENTER
    • run “route print”
    • run “route delete″
    • run “route add mask″ to create routing for our LAN to gateway of our office LAN
    • run “route add mask″ to create network routing for our internet connection to gateway of internet provider
    • we can copy and paste the above commands with probably there will be change in internet gateway everytime we connect / dial-up again using the modem


BengGaBoy said...


I have read your article with great interest. However, I'm still not very sure on the instructions.

1. Connect up both the LAN and 3G modem [Clear]

2. route delete [clear]

3. route add mask to create routing for LAN.

what is ? IP address of the LAN ?

What is ? Default or standard setting ?

What is ? IP address of the gateway ?

sapikota said...

nice post..its very helpful..

keep posting^^

Agung said...

It works! Thanks :)
I think we can set the destination route for LAN only (, because when modem is plugged in, Windows will automatically set its routing to

- means any destinations in local network (10.x.x.x)
- subnet mask
- yes, gateway's IP address

Ahmed Fouad said...

Working like charm :)