D-Link AirPlus XtremeG High Speed 2.4GHz 108Mbps Router

By Joseph Moran

November 14, 2003

D-Link's 11g router has a new look and a lower price and most models can get a free upgrade that supports the fastest Wi-Fi connections we've seen yet.

Model: DI-624
Price: $109
Features
Performance

Pros
: Fast performance, wide compatibility with 802.11g and 802.11

Cons: None

I know what you're thinking--you've read a review of D-Link's router model DI-624 here before. And it's true, products with this model number have been out for quite some time. So why are we looking at it again?

It's very simple. D-Link is providing a free firmware upgrade for the device that supports the new Super G capabilities of its Atheros chipset, effectively making the DI-624 a whole new product. (Note: Rev A of the DI-624 was based on an Intersil chipset, and thus is not compatible with the upgrade. D-Link says that only about 2% of the DI-624s sold fall into this category).

In addition to its new software, the DI-624 (which is also now $109, about $40 cheaper than when we last looked at it) has received an external freshening as well. The chassis has the same basic low-profile rectangular layout, but has been put on a diet and is considerably smaller than the previous version. Also, the latest DI-624 for sale (known as "Rev C") sports only a single dipole antenna, not duals like its predecessor (the antenna is still movable and re-movable).

Like the Netgear WGT-624 router it competes with, the D-Link DI-624 carries over a considerable breadth and depth of LAN/WAN-related features from previous products. The D-Link matches the Netgear in providing capabilities like firewall and content filtering, remote management, logging, and e-mail alerts.

On the WLAN side of the equation, the DI-624 has the full compliment of Super G performance enhancing features, which include fast frames, dynamic packet bursting, and hardware compression in addition to channel-bonding. The DI-624 also provides a dynamic performance setting, which allows the access point to offer a compatible client these Super G features (except for channel bonding) while still being able to communicate with regular 802.11g or even lowly 802.11b clients.

Configuring the wireless side of the DI-624 takes a bit more forethought than usual, owing to the high number of different Super G performance modes available. There are no fewer than four, in fact, plus separate settings for 802.11g only mode and CTS protection, which means you have to configure these options carefully if you want to maximize performance and compatibility.

The four Super G modes are "static turbo", which enables all the Super G features and locks out incompatible clients, "dynamic turbo" which adds accommodation for regular g or b clients, "no turbo" which disables the channel-bonding feature only, and "disabled" which turns off all Super G features, effectively rendering the DI-624 a conventional 802.11g device.

In each of the numerous performance modes, the DI-624 yielded throughput performance in excess of what is customary from a typical 802.11g device. All the performance testing was conducted with a DWL-G650 CardBus client card, similarly updated with new compatible drivers and firmware.

For distance testing, I configured the DI-624 for static mode. At a 10 foot distance the throughput was over twice the 802.11g performance at 47.03 Mbps. This figure was also in excess of the 40.49 Mbps posted by the Netgear WGT-624, owing to the D-Link's implementation of the full Super G feature list. As distance increased, throughput stayed relatively high, starting with 38.84 at 25 feet and 29.83 at 50 feet.

At 75 feet, I saw a strange anomaly, with throughput jumping sharply to 39.75. I saw the same phenomenon with Netgear's WGT-624, though it was significantly less pronounced. I have not encountered anomalously high throughput at this distance point before, but it was repeatable with these products. I can only surmise that it's a peculiar result of some combination of Super G channel-bonding with the environmental characteristics of that particular spot. Throughput remained strong through 100 and 125 feet, at 29.63 and 25.8 Mbps, respectively.

Overall, with the exception of 10 feet and 75 feet, where the D-Link was superior, the throughput performance of the DI-624 and the Netgear WGT-624 were within a stone's throw of each other.

To determine the effectiveness of the compression feature, I configured the Chariot test software to use a text file as the source of the data, as opposed to randomly generated data which is the default. Presumably given the fact that text is compressible to some degree it should have improved performance, and indeed it did, boosting throughput from 47.03 to 51.12 Mbps. While the number is somewhat shy of the 60+ Mbps D-Link is quoting in its own tests, it clearly demonstrates that compression is working.

The idea behind dynamic mode is that Super G clients can utilize most of the performance enhancing features while still allowing g and b clients to connect to the network--albeit with a resultant decrease in performance for said Super G clients. This turned out to be the case with the DI-624. At 10 feet and in dynamic mode, the unit pushed through 36.33 Mbps to the DWL-G650. In this mode, I was able to successfully associate an 802.11b client to the DI-624, which dropped the throughput to the DWL-G650 to 17.19 Mbps-- still well above the 10-14 Mbps an 802.11g device can provide in this scenario.

Adding the aforementioned 11b client to the test resulted in further throughput degradation. Aggregate throughput for the two clients was 11.01 Mbps, with 8.23 for the g device and 2.83 for the b. These figures too, are somewhat better than what can be had in a conventional 802.11g/b mixed scenario.

Rounding out the performance numbers, in "no turbo" mode, which disables channel bonding but leaves the other Super G features intact, the throughput was 23.11 Mbps. Disabling all Super G features resulted in slightly less throughput of 21.93 Mbps. Two Super G clients simultaneously communicating with the DI-624 resulted in 46.20 Mbps of total throughput, almost exactly divided between the two clients (23.38 for one, 23.56 for the other). One of the clients was the Netgear WG511T, indicating that compatibility with non D-Link hardware is possible. Finally, the DI-624's throughput suffered only minimally with WPA (both 802.1x and PSK are supported) turned on, managing 41.83 Mbps.

It's also worth noting that D-Link is the first vendor I've seen to integrate WPA support directly into their client utility, precluding the need for an external supplicant or the Windows XP WPA supplement from Microsoft. However, due to a bug in the utility, I couldn't use WPA through the utility and had to fall back to XP after all. D-Link says a fix is under development.

With a few exceptions, (like SNMP and syslog support) the D-Link DI-624 provides almost any wired or wireless feature you might want in a broadband router in this class. It also offers excellent performance for and compatibility the Netgear can't provide right now (though a forthcoming firmware upgrade should change that.) When you consider that a DI-624 can be had for less than $100 street price, or if you're fortunate enough to already own a DI-624 that's compatible with the upgrade, then getting the speed is pretty much a no-brainer.



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