Large uploads on Uverse kill download bandwidth.
So it turns out if you’re uploading something on a Uverse connection, they kill your download bandwidth.
I had been poking around in iTunes, looking at the section of the store that shows what other members of your Apple Family have “purchased” (in quotes, because even “free” apps and music show up as “purchases”). The Wife had purchased several albums (or at least songs) that I would not have purchased myself, but wouldn’t mind having a copy, since we’d already paid for it. I clicked to download them (mostly songs from our high school days), then went to watch some YouTube videos. Normally we have enough bandwidth to handle this just fine, but the video kept stuttering (play for two seconds, pause for four seconds to download the next two seconds worth of video, play for two, pause for four for the next two seconds of playback download). I switched back to iTunes and saw that what should have taken about 3 seconds per song was predicting six MINUTES or more.
The Cisco ASA showed a lot of OUTGOING bandwidth being used, and very little incoming. Well that was odd. I wasn’t uploading anything that I knew of.
Speediest showed my download speed to be 5Mbps and upload of about 77Kbps. WELL below normal.
So, drop to terminal, do a tcpdump and low and behold lots of packets going out to Apple IP addresses (I’m sure I could have found this out from ASDM, but I don’t know the interface well enough yet and I do know tcpdump.)
Turns out when I stuck the SD card from my camera into the iMac and told Photos to download 10GB worth of video I shot today, it dutifully did so, then began uploading that to iCloud. There doesn’t seem to be a setting to permit uploading photos, but not video. With a 12Mbps down / 1.5Mbps up Uverse connection, 10+GB is going to take a WHILE to upload (especially since it was only uploading at about 500Kbps).
It would seem Uverse will only let you use either upload or download at any given time, but not both. If they’re going to screw you like that, they could at least give you a reach around and let you do it at the same SPEED in either direction.
(Of course it’s possible the throttling of download speed is due to the TCP/HTTPS “ACK”s coming back from Apple signaling receipt of the upload packets and readiness for the next upload packet, but those shouldn’t take much bandwidth at all. Barely more than the TCP/IP header and a few bits of payload, I would think.)
Edit: As soon as I stopped (really, paused for one day) the “Photos” upload, my download bandwidth came roaring back: 15Mbps down (from a connection that is technically only supposed to be 12Mbps…) / 1.5Mbps up on speedtest.net and my iTunes downloads were completing in seconds.