Introduction

Home networking products comprise a large part of the networking market nowadays - and it has surely come a long way. Just 10 years ago, home networking was a fringe area, only for the enthusiasts and geeks with nothing else to do. Nowadays, it's somewhat of an essential area, with Dad having his PC, Mom having hers, and the kids having their own systems. With all these systems, comes the need to share resources such as the omnipresent Internet connection, a printer, scanner, or even storage capacity, and networks are the ideal way to do this, being able to do much more than just allow computers to communicate with one another.

Furthermore, proliferation of home networking products has created more than just widespread adoption of networks, as it has also spawned the newest generation of communication through wireless networks. Ten years ago I couldn't have imagined seeing wireless networking products lining the shelves of every major retailer - but yet here we are. Wireless networks have become ideal for most home users wanting to implement a network, as they eliminate the need for unsightly and cumbersome cables. Let's face it, unless a home has been built with CAT-5 cabling and the jacks throughout, setting up a wired network throughout your house can be difficult, as it will entail either one of two things - doing some reconstruction, or running ugly cables along the walls or in conduits. This has caused most people to just choose one room as the "computer room", and thereby confine all the system and networking cables to one messy area.

Wireless networks promise to eliminate all of that clutter, but let's face it - wireless networking cannot compete with wired networks in terms of raw speed and easy of security. I've reviewed some wireless network products in the past, namely, 802.11b and 802.11a products, and each had their shortcomings. 802.11b, even with the proprietary technologies many vendors included that doubled the theoretical speed from 11Mbps to 22Mbps, was still too slow for large file transfers and lots of network traffic in the form of streaming media to multiple clients. 802.11a, at 54Mbps, was quite a bit faster (though still not nearly as fast as 100Base-TX), but suffered from a ideal-speed operating area that was quite small, and just didn't create enough momentum for people to adopt it; after all, it was incompatible with 802.11b, the leading wireless specification at the time most 802.11a products were reaching the market. 802.11a is pretty much a no-show nowadays, with most vendors having to tie 802.11a capability into products that also support different standards.

Enter 802.11g. Promising speeds of 54Mbps, the same as 802.11a, but maintaining backwards compatibility with 802.11b by operating in the same frequency range of 2.4GHz, this specification promised to bring coherency and speed to wireless networks. This specification also offered many other benefits over 802.11b, so much so, in fact, that many vendors early last year began releasing 802.11g products based on draft specifications - that is, they began to release 802.11g-based products before the 802.11g specification was even finalized! This did create a little of confusion, but most, if not all vendors released driver and firmware updates for their products when 802.11g was finalized around June 2003.

D-Link was one of these "early adopters", and since then they have released revisions to their original 802.11g hardware, so that products bearing model numbers currently, may be slightly different from the products sold last year with the same model number. I assume this was to refine the feature set to reflect the final 802.11g spec., and to add additional features and capability that wasn't possible with just a firmware update. One of the notable features added was a Turbo mode, similar to Turbo modes features on previous products and products from other vendors. These Turbo modes use more than one wireless channel to increase the theoretical bandwidth from 54Mbps to 108Mbps - on paper, this looks very good; I mean, it's faster than 100Base-TX! However, we all know that this probably isn't the case. Today, I'll be looking at four of D-Link's products from this category: The DI-624 Router, the DWL-G810 Wireless Bridge, the DWL-G520 PCI Adapter and the DWL-G650 Cardbus Adapter. All of these products support a Turbo mode - how fast are they compared to other wireless networks, and how does the speed compare to a wired network?

Specifications

Speaking in general terms, all of the products except for the DWL-G810 Bridge support WPA (which uses 802.1x) for increased security over the faulty WEP. WPA is inherently more secure than WEP and with the use of 802.1x, which requires a RADIUS server, authentication can be better controlled. If you're serious about security, this is one step to securing your wireless network. Some tidbits on WPA can be found here and here.

Also supported on these devices is WPA-PSK or Wi-Fi Protected Access Pre-Shared Key. This is a limited form of WPA that does not require a RADIUS server to be setup, which can be a daunting task unsuitable for some users with limited resources. WPA-SPK eliminates the need for RADIUS server or 802.1x authentication and instead relies on a passphrase that must be entered into the AP (in this case, the DI-624) and any wireless device communicating with the AP. It still has advantages over WEP in that WPA uses Temporal Key Integrity Protocol (TKIP) encryption, which uses dynamic keys versus WEP's usage of static keys. An interesting short read on this can be found here.

I have listed the product pages for each item below, as I do not want to copy the list of specs just for copying's sake.

• DI-624
• DWL-G810
• DWL-G520 PCI Adapter
• DWL-G650 Cardbus Adapter

If you intend to use security on your network, you will need to make sure that all devices support the same security you're using; if the DWL-G810 is part of your network that means the best you can support is WEP. (The DWL-G810 currently doesn't support WPA in its shipping firmware but a beta firmware upgrade does add this functionality.)

Additionally, all the products, except for the DWL-G810 again, use Atheros' Super G chip to provide 802.11g compatibility and the additional speeds in the Turbo modes. This chip is used in other products, and their FAQ provides ample information. Of particular interest was the partial increase in speed, even if only the AP is Super G enabled.

Lastly, it is worthy to note that both adapters can function in Ad-hoc mode, that is, without an AP, but this method of wireless networking is a bit outdated and not really viable; the 802.11g spec doesn't require ad-hoc speeds to be anything over 11Mbps, so the adapters will only work at 11Mbps in ad-hoc mode. Ad-hoc mode is also not ideal for larger networks or ones being used to share an Internet connection, so I won't really discuss it.

All of these products support Super G, a set of technologies aimed and increasing wireless network speeds. These features are enabled by the Atheros chip used in the D-Link products and this chip has also been used in some products from other companies. The D-Link products can operate in one of four different modes, which I'll outline briefly.

Base mode without Super G

This mode doesn't offer any Super G capabilities and is identical to just straight 802.11g.

Super G without Turbo

This mode is still 802.11g compatible, but makes use of Fast Frames and Packet Bursting to increase speeds. It doesn't use any proprietary protocols so these benefits are available to every connected 802.11g client, even if only the AP (or the Router with an AP) supports Super G.

Super G with Dynamic Turbo

This method makes use of channel bonding to use two 802.11g channels for transmission, producing the theoretical maximum speed of 108Mbps. However, both the client and AP need to support these features; if they do not, then the network will "downshift" out of Turbo mode to the previous mode, hence the "Dynamic" specification.

Super G with Static Turbo

This method is like the Dynamic Turbo mode above, but doesn't downshift to accommodate non-supporting products; hence, this mode only works when all the products are D-Link and support the Super G modes. It provides the best theoretical performance, and is claimed to produce up to 60-70Mbps of useable bandwidth.

Since I don't want to turn this into a technical white paper sort of thing, here are some links about these technologies, straight from D-Link and Atheros, the manufacturers. Most interesting is the claim that the Super G mode can produce up to a 20% increase in performance over standard speeds when only the AP is Super G enabled.

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