Is Comcast Throttling Apple TV?

Question

Is Comcast Throttling Apple TV?

I subscribe to Comcast's "Blast" tier, rated at 16Mbps download / 2Mbps upload. Using various speed testing sites, I consistently get well above 6Mbps depending on the time of day (between midnight and 5pm, I test well above 10Mbps -- I test using the various speed testing sites, as well as downloading 100MB files).

However, when I've downloaded HD content from Apple TV, my transfer rate seems to average about 1Mbps. For instance, just now (6:30pm) I downloaded the HD Trailer for Iron Man, a 2 minute 29 second trailer. It took 10 minutes 50 seconds before it started playing. But a test of a download of a 100MB file before and after the download of the Apple TV HD trailer showed a sustained download rate of 1.1MB/s (or about 8.8Mbps).

So what is the problem? I can't imagine network congestion to the Apple servers is this bad. Do they use caching servers, or is it all in the Bay Area? Could it be interference from my TV? I've run speed tests with my laptop placed where the Apple TV is, and noticed no difference, so I don't think interference is the problem.

My suspicion is Comcast is throttling Apple TV traffic to 1Mbps. If this is the case, then it should be made public. In my opinion, such action by a network operator who is also a video distributor is anticompetitive, and given that the FCC is investigating Comcast for blocking Torrents, I'd think they'd like to know.

PoweBook G4 1.33GHz, Mac OS X (10.5.2)

Posted on Apr 9, 2008 3:57 PM

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Answer 1

Apr 9, 2008 4:25 PM in response to Arturo Bandini

Welcome to the  Discussion Forums.

I believe the simple answer would be to phone comcast up and ask them, I suspected this with my ISP and when I contacted them they readily admitted it (since changed ISP and loving it).

As far as I understand things, it is possible to apply filters to your service that could possibly affect downloads of HD movies and not other traffic, so even if your speed tests indicate fast traffic you might well be suffering from specific filtering.

Phone them and ask them.

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Answer 2

Alley_Cat

Level 7

20,560 points

Apr 9, 2008 4:31 PM in response to Winston Churchill

Winston Churchill wrote:

(since changed ISP and loving it).

You changed to 02 I believe (Be backbone LLU?) sounds as though you'd recommend them at this stage?

I only ask as the O2/Be LLU is haappening at my exchange in a few weeks time. My current provider is pretty reliable but no longer cheap. I can only get 1Mbps download at present, and they've advised me against going for the 8Mbps max service tehy also provide as they think i won't even reach 1Mbps on that.

Suspect the LLU won't affect my line quality in any way, but with better contention ratios etc it might be worth looking into.

AC

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Answer 3

Apr 9, 2008 4:57 PM in response to Alley_Cat

AC, the reason I'm loving it is because I'm no longer capped between 18.00 and midnight. There are of course other differences. Yes I'm on o2 and swapped from BT.

My bill has gone from £ 35 to £ 10 (bit of a discount as an o2/iphone user).

Email was a bit of a nightmare, but this was mainly because I kept my BT email account which has a personal domain name pointed at it, I eventually sorted out workarounds to o2's restrictive email policy and all works 100% now. If you ever go down this route I can help you with this issue if it occurs for you.

Contention ratio of 1:1 certainly shines through at peak times.

My basic speed has improved from 6.5 Mbps to 7.1 Mbps, which isn't what was promised but there are reasons for this. My router is at the end of a long extension, my old router coped quite well with this but my new one doesn't, indeed I had no service at all for 8 hours while the new connection stabilised. I'm planning on moving my new router to the main telephone socket and replacing the extension with ethernet cable which I believe should give me speeds of around 14 Mbps (just haven't got round to it yet). o2 will test your line for you while you are on the phone, so a call to them might provide you with some valuable information.

Support isn't as good as BT's, for those less familiar with setting up this type of equipment this might be an issue, I found them hard to work with.

The router they provided is much simpler than the one I was previously using, although to be fair to BT it wasn't one of theirs.

Any more questions, just ask. Email me directly if you wish.

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Answer 4

Apr 9, 2008 5:08 PM in response to Winston Churchill

Thanks Winston. A Comcast (a U.S. cable company, the largest ISP here) tech flatly denied that they throttled Apple TV. Though this was the first tech I could get on the phone, the kind that tells me to reset my modem, even though I explained in detail that the speed problem was only on Apple TV downloads. The tech eventually blamed Apple TV's servers for the problem.

But I've run the scenario I outlined above at different times of day, and always the same result -- an HD trailer that is about 2 minutes 30 seconds, takes about 11 minutes to start playing. At 4.5Mbps (h.264's data rate) this is a download speed of about 1Mbps.

Very odd. I'd like more anecdotal data before I take this to the next level. Comcast flat out denied they were interfering with Bit Torrent until the AP published evidence they were using TCP RST packets. So I'm not surprised their tier-1 tech denies that they throttle Apple TV.

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Answer 5

Apr 9, 2008 5:21 PM in response to Arturo Bandini

Yes I understand what you are saying, to the ISP filtering and capping are not the same thing, it may well boil down to how you ask the question, but if they are being evasive then who knows where you stand. One thing that did cross my mind is your location, to an outsider this is a hotbed for mac users and maybe it is just overload on the apple servers or overload on the route to the apple servers.

I would have thought though that if some kind of filtering wasn't being used then at 3.00 in the morning you would have seen some sort of improvement. Have you spoken to friends and neighbours to ask what their experiences are.

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Answer 6

k-man55

Level 1

30 points

Apr 9, 2008 5:22 PM in response to Arturo Bandini

Arturo,

I am very near you (Ashburn) and also have Comcast. I just downloaded Iron Man HD Trailer and it took about 45-50 seconds to begin. I have rented several HD movies over the last 2 months and they always start within a minute or two, though I have not rented one in the last week and a half.

So it sounds like the problem may be your network saving any differences in Comcast service between your location and mine.

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Answer 7

Apr 9, 2008 7:13 PM in response to k-man55

OK, I'm marking this particular question as solved (since I've determined it not to be Comcast) and going to start another separate post for my follow-up question.

Based on k-mann55's response, I got my neighbor who has Comcast to open up his network. He subscribes to the 8/1 tier, and his speeds were testing below mine, but about 4-5Mbps. The HD trailer downloads were incredibly fast, on the order of 30 seconds to start.

I then brought my cable modem downstairs and plugged it into the Apple TV via ethernet. Very fast HD trailer downloads, less than 20 seconds. I then plugged the router into the chain, but connected the Apple TV via ethernet (out of the router), and again, great HD trailer speeds. I then unplugged the ethernet cable, and connected to the Apple TV via the router wirelessly (i.e. the same initial set up that caused me the problem, but with the router right next to the Apple TV instead of one floor above). Slow Apple TV download problem returned.

So to sum it up, the problem is in how the router wirelessly communicates with the Apple TV, and it doesn't appear to be caused by interference. My router is a Linksys WRT54G. I've read in other threads here that the "multicast" setting on Apple Extreme routers could cause poor download speeds, but the Linksys has no such setting, just a "transfer speed" setting which I've fooled with to no avail.

Apologies to Comcast for jumping the gun and assuming the worst.

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Answer 8

Alley_Cat

Level 7

20,560 points

Apr 10, 2008 10:20 AM in response to Winston Churchill

Thanks Winston - when they enable the exchange I'll look into it further.

AC

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Answer 9

Chenks

Level 5

7,435 points

Apr 10, 2008 10:38 AM in response to Alley_Cat

Alley_Cat wrote:
Thanks Winston - when they enable the exchange I'll look into it further.

AC

i moved from a heavily throttled plusnet 8mb for £21.99 a month (where i was lucky to get anywhere near 4mb) with peak time limits.

i am now on sky LLU 16mb with no throttling and no peak time limits and i average around 14mb.. and all for £10 a month.

keep your eye on samknows.com and it will tell you when new services are added to your exchange.

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Answer 10

varjak paw

Level 10

182,668 points

Apr 10, 2008 2:34 PM in response to Arturo Bandini

EDIT: deleted; problem identified.

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