Testing - StreamBoost
Highly skeptical of the results I'd get with StreamBoost, I hooked up the DGL-5500 and first tested Team Fortress 2 on its own. As before, I saw game latency around 50ms. I then fired up all the HD video streams. Once they were going, I set uTorrent loose again. After about a minute, I went to Team Fortress 2 to check latency and found it idling at 60 ms, nearly what it was without any other traffic. Netflix still looked degraded, but all the other HD videos were playing smoothly. I stopped Netflix and pulled up an HD Vimeo video on the TV, which played smoothly and without hesitation. I did the same with a Vudu HDX movie and it played flawlessly.
I looked at the Network graph within the DGL-5500 interface and it looked like bandwidth was being allocated very uniformly; uTorrent's download screen also confirmed this. The nice thing about the graph below, is it shows instantaneous bandwidth used by each device.
My Network screen showing realtime bandwidth of all devices
Additionally, digging down into a device shows the application(s) in use. No more wondering why your network is slow and who (or what) could be downloading something.
Priorities screen showing realtime app usage for a device
I was curious why StreamBoost couldn't keep Netflix from degrading, especially since all the other video streams were flawless. So I followed up with D-Link/Qualcomm. The gist of the explanation is that Netflix' current design reduces stream resolution (and bandwidth consumption) when it senses that not enough bandwidth is available to maintain its current resolution level. Netflix apparently downshifts its bandwidth before StreamBoost can allocate more bandwidth to it to prevent Netflix' downshift.
The net result, however, is that Netflix makes StreamBoost look like it isn't doing its job. I'm surprised that Qualcomm hasn't found a way to fix this, given Netflix' popularity. Netflix introduced its automatic bandwidth shifting feature well over a year ago and Qualcomm has had at least a year to fix this.
To confirm Qualcomm's explanation, I looked at StreamBoost's Activity Tracker screen, which you can see below. This screen shows content delivered as "Optimal", "Good" or "Best Effort". Since everything is showing "Optimal", this confirms that StreamBoost was giving Netflix the (reduced) bandwidth it needed (or thinks it needed).
StreamBoost Activity Tracker showing all Optimal
Qualcomm clarification: The observed behavior is actually the intended behavior. If a network is oversubscribed with a certain type of application (video in this case), StreamBoost will sometimes give an adaptive bit rate application a slightly reduced amount of bandwidth. For example, StreamBoost may take Netflix down from 1080p to 720p quality to save a bit of bandwidth and ensure a higher number of good video experiences throughout the home. In other words, StreamBoost is programmed to give adaptive rate video slightly lower resolution vs. making other (non-adaptive) videos freeze.
Netflix changed a bit while the testing for this review was being performed and StreamBoost profiles were updated to adjust for this. The Netflix change resulted in StreamBoost protecting more bandwidth for Netflix even when the network is oversubscribed with video. If the tests were run again, Netflix would back off much less (to 720p quality).
In addition to the Network and device-specific pages, StreamBoost also provides bandwidth usage graphs and charts. I found these screens interesting, but not comprehensive and somewhat different than described. The drop-down selection seemed to indicate it would show information for the last month, however it was different nearly every time I looked and seemed more to reflect past hour usage. Sometimes I also had to refresh the page to get the statistics to appear, just as Tim did in the DGL-5500 review. You can see a screenshot of the usage statistics below.
StreamBoost Usage by Time historical chart
I was a little disappointed with the lack of information in the DGL-5500 manual regarding StreamBoost, seeing as it will probably be the major reason people would buy this router. Specifically, the My Network section of the admin interface has a Priorities page. Devices seem to get populated in Priorities in the order that they are seen on the network. The text on the page says priorities can be changed to give one device priority over another when they have applications of the same classification. I would have liked to know more about how those priorities were initially set and exactly how one device is given priority over another.
Some of the StreamBoost material mentions shaping or prioritizing by application. I assumed this to be different than device priorities, but could find no information in the manual. The reason for looking for this was my degraded Netflix stream. I had put that device at the top of the priority list, but was still seeing a pixelated screen, while the HD Vimeo streams were playing perfectly. With prioritizing by application, I could perhaps give Netflix the highest priority (or perhaps guaranteed bandwidth so it wouldn't dynamically downscale). But I didn't see anywhere that I could do that.
My testing showed StreamBoost lived up to its claims. The table below summarizes the testing in an easy to read format. All tests were run concurrently, with the exception of those labeled "TV2", which were multiple tests on the same device and run separately.
|Edimax BR-6475nd - iQoS disabled||Edimax BR-6475nd - iQoS enabled||DGL-5550 w/ StreamBoost|
|Team Fortress 2 (latency)||300ms||120ms||60ms|
|Pandora via Squeezebox receiver||Flawless||Flawless||Flawless|
|uTorrent (unthrottled)||5 files >1GB||5 files >1GB||5 files >1GB|
|Vimeo HD on iPad via Vimeo app||Flawless||Flawless||Flawless|
|Vimeo HD on Dell laptop via browser||Buffering||Buffering||Flawless|
|Vimeo HD on HP laptop via browser||Buffering||Buffering||Flawless|
|Hulu SD on TV1 via DLNA/PlayOn||Flawless||Flawless||Stutter on start, then Flawless|
|HD on TV2 via Samsung Netflix app (1920x1080)||Downscaled||Downscaled||Downscaled|
|HD on TV2 via Samsung Vimeo app (1920x1080)||Would not start||Would not start||Flawless|
|HDX on TV2 via Samsung Vudu app (1920x1080)||Would not start||Would not start||Flawless|
Table 1: StreamBoost test results
StreamBoost is not just hype, it truly does deliver on the performance it promises. If you have rocking bandwidth, you will see the most benefit if someone in the household does a lot of Torrent downloads or gaming. But even without gaming or Torrent traffic, the realtime traffic reports are very useful. They get down to the individual device level for bandwidth use and even show the application(s) in use.
Even the best bandwidth can slow at certain times of the day. Coupled with a family member leaving a YouTube stream running, it could be enough to make your streaming experience less than satisfactory. The My Networks page would help diagnose that issue quickly. That feature alone is very useful. Other router manufacturers should take note.
The opt-in update service will undoubtedly be troubling to some. But if you want the most from StreamBoost, you'll need to put aside your fears and check the opt-in box. It's unlikely that Qualcomm will be tracking your video tastes. The NSA already does that anyway.
Finally, I'd like to see more complete and detailed information in the DGL-5500 manual regarding StreamBoost. All that is in the manual now is basically the same text already available on the admin interface pages. That isn't enough, given StreamBoost's complexity and its importance in its host router feature set. The historical usage page also needs work; it definitely does not show all traffic for the month.
Bottom line, StreamBoost works well. It's too bad that it hasn't appeared in better performing routers yet.