The D-Link DSL-300T is one of the few ADSL modems on the UK market that can present the ISP assigned IP address to a device connected to the modem via Ethernet. The DSL-300T model has replaced the earlier 300G+ model, but otherwise performs an identical job. The other modems with similar functionality are the X-Modem CE and Westell ProLine 6000 range.
It is worth noting that the D-Link DSL-300T is available in various guises around the world, so there will be some guides for it that show it being used as a simple one port NAT router. The firmware that is used in the UK market is purely for an Ethernet modem, and that is how we will review it.
Ethernet modems are ideal for people who want the reliability of an Ethernet connection rather than a USB based interface. Additionally, the Ethernet connectivity means it is easy to add a wireless router at a later date. Compared to using a ADSL modem/router device, the Ethernet modems also avoid the problems of configuring port forwarding and getting applications to work from behind a NAT router. Of course the fact that the modem offers no security means that running a software firewall is very important.
What you get for your money
The modem itself is obviously the central part of the package, but you also get a power supply, quick install guide, CD-ROM containing manual, RJ11 ADSL lead, and RJ45 Ethernet patch cable. The modem itself can run either laying flat or standing up, and runs almost cool to the touch.
The front fascia is very simple with just four LEDs,
Power – illuminated when power is connected
Status – flashes steadily when the unit is connected and online
ADSL Link – illuminates once the ADSL line is connected, and flashes to indicate traffic
Ethernet – shows that an active Ethernet link is present, and flashes when activity occurs.
The back of the modem is plain and simple again, an RJ11 ADSL socket, RJ45 Ethernet socket, recessed reset button and 9V AC 1Amp power socket. A close-up of the modems innards is shown below:
Configuring the modem
The simplest way to use the D-Link DSL-300T is connected directly to a computers Ethernet port, with the network card should be configured to get its IP address automatically via DHCP. The Quick Installation Guide supplied with the modem goes through the basic steps, but we will give a guide through the process.
Once all the leads are connected and the modem switched on, check that the Ethernet LED is illuminated on the modem. If it is, then you should be able to open the web page http://192.168.1.1/ in your web browser. This page is actually part of the webserver that runs inside the modem, and is used to configure the modem – no software applications need to be installed.
The modem when you first connect to it will present a login webpage, the default username/password is admin and admin. Once logged into the routers web interface, there are five tabbed pages. The one that holds the few things that need configuring is the setup tab.
The areas that need configuring in the basic setup are the modem and connection. The modem setup allows you to pick between the various standards of ADSL used. Generally, the simplest thing is to leave the modem in MMode (MultiMode) which will try all the various DSL flavours before picking most suitable. Clicking Apply will store the setting in the modem.
To configure the connection click Connection Setup on the Setup page.This is the part that supplies your ISP with the login information, and in return the ISP will hand the modem your IP address and other details for the modem to use.
The username and password that your ISP supply should go into the respective username and password boxes. Also check that the other settings match those in the screenshot below, though if you are using a connection that is not a BT Wholesale based connection, check that parameters like VPI and VCI are the same on your providers network.
After clicking Apply again, the modem should take the information you have supplied and attempt to connect to the ISP. If successful, when you look at the Connection Status screen under the Status tab, you should see something like below:
If you also check the IP address of your network card after a short while you should find that the IP address assigned has altered to that listed in the IP column of the Connection status screen. If it has not then it is case of forcing your network card to renew its IP address. In Windows XP the simplest method is to right click on the Local Area Connection in the Network Connections window and select the Repair option. Alternatively in other versions of Windows, open an MS-DOS command window and type ipconfig /release and once that completes type ipconfig /renew to force the computer to reacquire the IP address.
Using the D-Link DSL-300T with a router
Configuring the DSL-300T to use with an Ethernet router such as the Linksys WRT-54G is very simple. Simply connect the Ethernet port of the modem to the Internet port of the router, and ensure that the router is configured to get its Internet IP address via DHCP.
Initially when you first connect the modem to the router, it will hand the router an IP address in the range 192.168.1.x. This means you need to ensure your router does not become confused by using the 192.168.1.x range for its LAN interface. If it does you should change the LAN IP range of the router for example to 192.168.0.x.
The actual configuration of the DSL-300T, can take place from a computer connected to the router, simply by opening the web page http://192.168.1.1/ and setting the modem up as shown above. Then once the modem is configured and has authenticated with the ISP the Internet IP address on the router should become the one your ISP has assigned you. Some routers may need you to manually trigger the renewal of the IP address on the Internet interface, either via their web configuration or switching the unit off and on again.