The Huawei MT882 ADSL Modem that you might have received with your BSNL Broadband connection can be used to connect 2 computers to the internet simultaneously since it is a router. It has a USB interface and an Ethernet interface both of which can be simultaneously used but with a few setting changes.
First of all one PC must use the usb interface and another must use the ethernet interface via a network adapter. That connection being made some settings need to be changed in the modem. For this enter the web based control panel of your modem and go to WAN Settings
Over there select PPP as WAN Type. This converts your modem to a router or an "independant" device which connects to the internet and your computers use it as a gateway. Now this is the router mode or the multiuser mode.
Then type in your username and password in the PPP section.
Use DNS : enabled and Max Idle time : always on
and Apply. After the modem restarts the link light will be orange and not yellow.
In the individual PC's configure the network settings of the corresponding network interfaces which use the modem.
In the TCP/IP settings set the primary gateway as 192.168.1.1 and IP address as 192.168.1.x x can be 1-255 . Subnet should be 255.255.255.0 and DNS servers should be put in
better use the openDNS dns servers which are :
In order to connect more that 2 computers to the modem it will be useful to use a switch like the D-Link 5-port or 8-port switch. All PC's and the modem(router) should be connected to the switch. The PC's should be configured with ips 192.168.1.2 or 1.3 , 1.4 , 1.5 and so on (the modem being 192.168.1.1). And the PC's need to have the same internet setting as mentioned above.
The MT882 modem also has a dhcp option which can be tried as well.