Throughput vs. Path Loss - Competitive Comparison
Now comes the face-off that you've been waiting for, the only dual-band, dual-radio draft 11n routers available: the 855 vs. Linksys' WRT600N. (I didn't include the Buffalo Nfiniti Dual-band router, since Buffalo is still out of the WLAN market until it comes to some sort of agreement with CSIRO.)
Once again, we have the 3T3R Linksys WPC600N client providing some advantage over the 2T2R Netgear WNDA3100 client used with the 855. For both downlink (Figure 18) and uplink (Figure 19), the WPC600N provides significantly more throughput under high signal levels.
Figure 18: Competitive dual-band comparison - 2.4GHz, 20 MHz, downlink
The WRT600N / WPC600N combo also stays connected longer running downlink, but not running uplink (Figure 19).
Figure 19: Competitive dual-band comparison - 2.4GHz, 20 MHz, uplink
The 40 MHz mode provides more throughput boost to the 855 than to the WRT600N, so the throughput gap grows smaller running downlink. The 40 MHz mode uplink comparison shows just about equal performance between the two products.
Figure 20: Competitive dual-band comparison - 5 GHz, 20 MHz, downlink
In the 5 GHz band, the 600N once again turns in higher speeds with strong signal levels, both down (Figure 20) and uplink (Figure 21).
Figure 21: Competitive dual-band comparison - 5 GHz, 20 MHz, uplink
The 5 GHz, 40 MHz mode once again provides more throughput boost to the 855 than to the WRT600N, so the throughput gap grows smaller running downlink. The 5 GHz, 40 MHz mode uplink comparison, however shows a faster falloff in throughput for the 855.
Use the Wireless Charts to generate other comparisons or dig deeper into these.
The main thing that the DIR-855 has going for it is a solid, fast routing section that is based on Ubicom's impressive IP5170 SoC. That, coupled with a gigabit switch that supports up to 9K jumbo frames and even a gigabit WAN port for those who think that matters.
The wireless, however, is another matter. It's no so much that the two Atheros-based radios aren't good performers, than it is the lack of a client that can hold up its end of the deal. It's bad enough that it took so long for D-Link to come out with its DWA-160 dual-band client. But its current driver makes the 855 (and probably other routers) run at 802.11b speeds at 2.4 GHz and the 2T2R radio is a mismatch with the 855's 3T3R radios, preventing it from reaching competitive top speeds.
The bottom line is that there isn't anything in the 855 that makes it worth the $100 premium over Linksys' WRT600N, which seems to be the simultaneous dual-band draft 11n choice right now. Unless D-Link wants to sit on a pile of inventory, they need to match or beat Linksys' price and get the product on the shelves! As I write this, the word is "end of June", but we'll just have to see what happens.