Wireless Performance - Maximum Throughput
In the Preview, I pooh-poohed NETGEAR's press-release claims of "real-world Transmission Control Protocol (TCP) throughput of up to 350 Mbps combined", since I've never seen any 802.11n product come anywhere near that. Well, it turns out that I was right...and wrong.
After the Preview article, NETGEAR sent me a copy of its test data, which was taken using IxChariot, running IxChariot's High Performance Throughput script (which reduces overhead a bit) and using TCP/IP. Data was taken using Intel 5300, Atheros XB72 / XB92 (PCIe reference design modules) and NETGEAR WNDA3100v2 clients.
Figure 12 shows that NETGEAR switched from Atheros to Broadcom for the new version of its dual-band USB client adapter. So the NETGEAR data reflected performance with three commonly-used 802.11n client chipsets.
Figure 12: NETGEAR WNDA3100v2 board
NETGEAR's data did indeed show throughput of ~200 Mbps for each radio running separately and over 300 Mbps with both radios running simultaneously. The trick was that each radio was running four simultaneous connections. I always run a check with a single up and downlink stream running concurrently. But I've never tried running more than one stream in a single direction.
So, I set up a second notebook using the NETGEAR WNDA3100v2 client connected to the 5 GHz radio and my standard Intel 5300-equipped notebook connected to the 2.4 GHz radio and ran some tests with multiple streams. Both clients were in the same room, within 10 feet of the router and both radios were set to Up to 300 Mbps (40 MHz channel bandwidth) mode.
Figure 13 shows 252 Mbps of total bandwidth running four downstream connections between each radio and client. Running the same setup upstream yielded a slightly better 262 Mbps of aggregate throughput. (Here's the upstream plot.)
Figure 13: WNDR3700 aggregate wireless throughput - downlink
But since I previously had not run this measurement, maybe there were other simultaneous dual-band routers that could also deliver this much aggregate throughput. The only other dual-band, dual-radio router with Gigabit ports that I had on hand was a D-Link DIR-825 [A1] (original version), so I gave it a shot.
The 825 [A1] uses a Ubicom IP5170U processor clocked at 350 MHz and mini-PCI radio modules with Atheros AR9160 BB/MAC and AR9103 3T3R 2.4 GHz radio on one and AR9160 and AR9106 2.4/5 GHz 3T3R radio on the other.
Figure 14 shows that it managed only 187 Mbps total downlink throughput with the same test setup. Uplink was slightly better (upstream plot) at 227 Mbps of aggregate uplink throughput.
Figure 14: D-Link DIR-825 [A1] aggregate wireless throughput - downlink
These results show that I was right that totaling the throughput from single connections on each radio didn't add up to 300 Mbps. But if you have a busy WLAN, the 3700 really can provide around 300 Mbps of real, usable throughput—if all your clients are within 10 feet or so of the router in the same room and with no other WLANs in range.
NETGEAR told me that the 3700 can actually support more than a thousand simultaneously-connected clients using WPA2 / AES encryption and around 350 using WPA / TKIP. So the 3700 looks like it could function very nicely as the centerpiece of a busy small-business WLAN.
And for those of you who have been asking about a test of D-Link's DIR-825 [B1] (I'm looking at you, claykin...), I've asked D-Link to send one. It will be interesting to see if the B1 matches the 3700's performance, since it uses the same Atheros AR7161, AR9220, AR9223 design, but sells for about $100 vs. the 3700's $160.