I live in New York and have 100/100mb FiOS service (which is usually more like 102/115) so I am always frustrated when I visit my parents in Texas where their U-Verse which is theoretically 24/5mb (Max Turbo, I infer the 5 from the modem as it's almost impossible to find any reference to the actual upload speed on the account information) however actual speeds are rarely that and fluctuate wildly.
Last month I happened to have a few days alone in the home when I finally discovered that internet performance fluctuated based on television usage so I decided to conduct a test. The install has four STBs. I started with each box on a help screen. I ensured nothing was recording (though in retrospect I cannot say with 100% certainty I got that right though i'm not sure it matters in the end as my understanding is 4 HD streams is the maximum so the only thing that might be unaccounted for would be 1 SD stream). I ensured there was no other significant network traffic and conducted a speed test, which showed the expected 24/5 service. Then one by one I tuned each box to a different HD channel and redid the speed test. The tests were all conducted using an ethernet connection.
The results (attached) show that internet speed degrades with more than 1 HD stream by about 5-6mb/s (the expected bitrate for U-Verse HD video). I understand the technological differences between FiOS and U-Verse, with U-Verse using a VDSL connection for last mile connectivity and delivering IP based video so I understand why this might happen in theory. However, looking at the modem section of the gateway shows a "User Rate" of 32200 kbps and a "Max User Rate" of 55394 kbps. My understanding is that the excess between User Rate and Max User Rate is for video. Now I presume these data rates are for the physical layer so if I assume 32200 physical corresponds to 24000 logical then apply the same ratio to the 23194kbps difference between User and Max User I come up with 12468 which means the link should support at least two HD streams before degrading internet speeds.
Or have I got this totally wrong? Is 32mb actually the data rate available for Internet+TV. Throw in a little overhead and the numbers seem to match up but then I don't understand what "Max User Rate."
I don't find a lot of references in this forum to internet speeds slowing due to television usage. On the other hand, maybe this is an unusual install as it is several years old and has four STBs over a single twisted pair (i.e. non-bonded connection). Incidentally, about a year ago I made an online order to a higher internet speed but the cancelled it when I learned they would need to do a new physical install due to the need for the bonded DSL (they home is very complicated and the risk of AT&T screwing something up was too high). Originally, I thought this was a factor in slower speeds because they were testing at half the expected speed (some sort of provisioning issue where it was provisioned for bonded) though now I suspect it is more likely coincidence. I know the VDSL run is very clean with the node a greenfield install only a few hundred feet from the property.
So what's going on here? Is there a missing 6mb/s of bandwidth or no? If so, I guess it could come down to:
a) A problem in my testing
b) This is a normal part of the U-Verse experience
c) There is something wrong with this install
Thoughts? I'm leaning to b or a+b as U-Verse seems overall just a crap service.
Would I be correct to assume that moving to the 45mb tier, which uses a bonded DSL link, would offer significantly more bandwidth for video such that 4 streams would not eat into Internet speeds or is it just more of the same sort of thing?
If it is (c) any hypotheses on the problem?
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