The X-modem is a rare hybrid in the UK ADSL hardware market in that it will provide the single IP address issued by the ISP to a computer via an Ethernet or USB interface. This makes the X-Modem the perfect upgrade for people who have a single computer and are looking for something that is perhaps more reliable than a USB modem but will still offer the same level of application support.
The X-Modem in theory should work on any ADSL service that uses PPPoA and provides a single static or dynamic IP address. The one exception at present is AOL, due to the AOL client software. The modem is supplied in its default state to work with a BT Wholesale based service, but can be configured to work with the Karoo service in the Hull area.
The concept used in the X-Modem for delivering the Internet IP address to a computer is not new, various modem/routers exist with PPP Half Bridge and DHCP Spoof modes that accomplish the same. The difference with the X-Modem is that the firmware is set-up to make this bridge mode as reliable and easy to set-up as possible. One major difference is that other devices which feature bridging modes tend not to work well with devices such as wireless routers.
The modem includes the normal range of items. A 12VAC (1.0A) power brick, short quick set-up guide, RJ-45 Cat5 Ethernet patch cable, RJ-11 to RJ-11 lead, USB type A-B lead and the modem itself. The case will look familiar since it is based around the basic Conexant router chipset, but the X-Modem is different in that it has custom firmware loaded onto it by ADSLNation. Missing from the photo is the USB driver CD, which is needed to use the USB port on the modem.
The front of the modem features just two LED's. The ADSL LED flashes when the modem is synchronising with the exchange side hardware, and the LAN LED flashes to indicate traffic on either the Ethernet or USB connections to the modem. In common with most Conexant based devices when the modem is first switched on, a short click can be heard, if ever the modem drops the ADSL connection you will hear the same click as the line drops and reconnects.
The business end of the modem is very simple too. There is the AC-IN socket, the 10/100Mbps Ethernet socket, a recessed reset button, the USB socket, and finally the RJ-11 socket for connecting to the phone line.
The X-Modem is designed to be easy to set-up and is as at home with Microsoft Windows as it is with MacOS X. The configuration is very simple, in fact it is hard to envisage how a web based set-up could be made any easier.
Basic X-Modem set-up
The modem is supplied with a default IP address of 10.0.0.2, and is supplied with its DHCP server enabled. This means that as soon as you connect your computers' Ethernet card to the modem with a cable, a DHCP IP address should be automatically issued. To access the web server in the modem ensure that your browser has no proxy servers configured and is set to use the Ethernet card (this means setting Internet Explorer to 'never dial a connection') and then open the URL http://10.0.0.2. The modem will prompt you for a username and password, the default values are admin and password respectively.
The screenshot above shows what you should see if the modem is working and your computer can see it. The next step if on a BT Wholesale based ADSL line is to click the Account Details button on the left of the screen. This results in the screen below being displayed, on which you need to enter the ADSL account name and password that your ISP has provided you with. The screenshot shows the generic test login, which if it works only allows you to see the webpage http://www.bt.net/digitaldemo, this provides a useful test if your ISP based username does not appear to work. When you click the Save button followed by the Submit button the modem stores the entered username and password and restarts, at which point it will attempt to connect to the service provider.
If your ADSL line is active and your username/password were correct, the modem should automatically connect. If at anytime you are unsure of whether it is connected you can run some internal diagnostics, the output from a working connection is shown below:
That is the end of the basic configuration of the X-Modem, there are no VPI/VCI or other confusing details to change. Though these options are configurable under the Advanced option to allow people not on a BT Wholesale based line to make use of the modem.
If the modem and ADSL line are working your computer should automatically be given the Internet IP address your ISP has assigned you. The screenshot below shows how to verify what the IP address of your computer (to open a DOS command prompt window run command.com under Windows 98/ME or cmd.exe under Windows 2000/XP).
The initial IPCONFIG command shows the IP address the X-Modem has obtained and passed onto the PC. If the PC fails to obtain an IP address, in which case it will likely be showing a 10.0.0.x range IP address, then the command IPCONFIG /RELEASE will release the IP info for the local area network interface, and then IPCONFIG /RENEW will request the X-Modem to issue the IP address again.
The X-Modem while very simple does have some other options you can play around with, the vast majority of people will have no need to though.
The advanced page has eight different options:
The ADSL Line Status screen is useful diagnostic tool and displays the following parameters.
This screen provides useful feedback. 'Showtime' indicates that the modem is online and running as expected. 'G.DMT' describes the modulation type in use, i.e. the flavour of ADSL. 'Startup Attempts' lets you know how many goes it took for the modem connect, this should normally be low, if it is high then you need to check that all your telephone devices are connected to working microfilters. The 'Tx Power' indicates the power level transmitted down the phone line, some lines may have higher or lower Tx powers, since ADSL modems adjust their power output to accommodate different quality lines. 'DSLAM Vendor' in this case shows that the chipset for the DSLAM the modem was connected to was an Alcatel one. The crucial figure for many is the 'Downstream Line attenuation' figure, the X-Modem appears to read within +/- 2dB of an actual BT Woosh attenuation test, indicating the line used for the review will support a 1Mbps or 2Mbps product (this needs a line with less than 45dB of attenuation). The 'SNR Margin' is the signal to noise ratio, and shows how easily the modem is understanding the ADSL signal, if the SNR margin drops to 6dB or lower then most modems will start to perform intermittently.
Since the X-Modem presents a full unprotected connection to your computer, it is strongly advisable to run a software firewall. The integrated firewall in Windows XP provides a simple level of security by dropping unsolicited incoming connections, which has the same effect as a basic ADSL NAT router. If you want a higher level of security then you need to install a software firewall such as Kerio WinRoute or ZoneAlarm that lets you control ports in both the incoming and outgoing directions.
One oddity of the X-Modem is that TCP port 80 of the modem is visible to the outside world, although people who access it will be given a permission denied message. This causes problems for people who want to run a web server on their computer on the standard TCP Port 80, since people from the Internet will only see the closed port 80 of the X-Modem. To overcome this problem the simple solution is to move the X-Modem web server from port 80 to another port. We should add that this blocked port 80, does not affect normal web browsing, as any port 80 requests that originated from the LAN side of the X-Modem still work.
The screenshot below shows the default settings for the X-Modem web administration section. Changing the HTTP server port from 80 to 8080 as shown in the second screenshot overcomes the port 80 block, allowing TCP Port 80 traffic through again. To access the web console after this change type http://10.0.0.2:8080.
The X-Modem generally is targeted at people wanting to use a single computer with ADSL, but it will also work with some Cable/DSL routers (i.e. routers with no ADSL modem in them). With the non-availability of an 802.11g ADSL modem/router (July 2003) this becomes a useful option for those seeking a high speed wireless network. Additionally there is a large range of cable/DSL routers with support for extra features like VPN termination.
Alas things are never simple, and while the DHCP presentation of the IP address by the X-Modem works with most computers, the short lease time can result in some routers not working reliably, since they drop the connection rather than invisibily renewing with the same IP address. Generally this is down to the way that the WAN port on the cable/DSL router handles DHCP, some manufacturers may fix this via firmware upgrades. This means that you need to be careful in selecting a router to work in conjunction with the X-Modem. The list of routers that are known to work is Apple Airport Extreme, Buffalo WBR-11, Buffalo WBR-54 and the Linksys WRT54G (with latest firmware).
Setup of X-Modem with Wireless router, e.g. Buffalo WBR-54
Unfortunately there is a corresponding list of devices that are known not to work, these are the Netgear FVM318, Apple Airport Snow, Belkin F5D7230, Linksys BEFSR41/81 and Origo WBR-2200 Wireless Broadband router. One problem that can occur when using an X-Modem with a router is a clash of IP ranges, the X-Modem uses the 10.0.0.x range, which is compatible with most routers, but if the router you are attempting to use has a LAN side IP address in the range 10.0.0.1 to 10.0.0.254 then you will need to change the IP range used on the LAN side of the router.
The X-Modem performs well, coping with various outages from both the ADSL line and ISP induced glitches. The lack of firewalling or NAT to complicate things ensures that applications such as MSN Messenger and Netmeeting run with no problems. For gamers the modem performs smack in the middle of the crowd ping wise.
|Modem||Average Ping Time (ms)|
|EA 900 USB||21|
|Thomson 510 v4||13|
|BT Voyager 2000||16|
|BT Home Network 1200||
Based upon 100 pings to first hop using bt_test@startup_domain username
One possible concern for gamers is whether the short lease time will cause problems. Long sessions of Counter Strike were playable without any problems, and large downloads of more than 100MB would procede with no interruptions.
The only time we found the occasional problem was when swapping kit around or switching it on, occasionally the Internet IP address would not be issued to the computer. In these cases simply renewing the IP address or using the Windows XP Repair LAN connection option would get the Internet IP address issued to the PC.
The X-Modem is a great simple to use device, and is ideal for the single computer user who wants to use Ethernet to connect their computer to the ADSL line. The ability to work with cable/DSL routers at a later date is useful, although it is a shame router manufacturers are not more proactive in getting their routers to work with the X-Modem and the similar DLink 300G+. One nice aspect for people used to dealing with anonymous dealers is that ADSLNation has a local rate 0845 number that can be used to get support for the X-Modem.
The modems web interface perhaps shows the way forward, in other words keeping the initial configuration as simple as possible. It is harder to think of something that would be simpler without using software that runs on the computer to actually ensure all the computers settings are correct also, but then this creates extra problems for people with non Microsoft operating systems. Configuration can become more complex if you add a router to the X-Modem, but the trick to that is to get the X-Modem running with a single computer and then replace the computer with the router.
To conclude, while many of the ADSL modem/routers on the market have similar bridging type modes, at this time the X-Modem is much more stable. In the next year as the option of PPPoE arrives on the UK market we may see a change, but while the UK is firmly PPPoA based, the X-Modem is a very useful device.
£59.57 – X-Modem
Prices listed above are excluding postage and VAT.
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The contents of this review should not be relied upon in making a purchasing decision - You should always discuss your requirements with your service provider and hardware supplier.