Diggin' technology every day

June 15, 2011

Could not stream Netflix HD for months – solved

Filed under: Random Thought — Tags: , — Nate @ 10:58 am

I have been a Netflix subscriber for a couple years now but really haven’t been using it much I can’t find much on it that I’m interested in watching.

One issue that cropped up several months ago for me was I was no longer able to stream in HD. No matter what various “internet speed tests” reported Netflix always resorted to SD streams. Most recently reported my pipe as having 27Mbps of throughput.

Since I don’t use it that much I didn’t care too much, and just stopped streaming stuff for a while (I stream to my Tivo Series 3). Today I decided to try to dig a little deeper, there wasn’t much help on the Netflix site, and calling them was not too helpful they just suggested I ask my ISP to perform a longer running test to see if the connection was stable and reboot the modem.

Before trying that though (well I did reboot the modem to no avail), I decided to run tcpdump on my firewall and see where Tivo was sending it’s packets, and then use something like mtr to measure latency to that destination.

I noticed within seconds my Tivo was sending packets to a Lime Light node in Miami, not exactly next door to the Seattle area where I am at. Sure enough the Miami node is 16 hops away and right at around 100 milliseconds of latency.

Why was this going there?! Well it has to be related to DNS, as I’m sure at some point I started forwarding all of my DNS packets to my personal virtual server(same one that runs this site) which is run out of Miami. So Limelight must be using BGP Anycast for their DNS which is common among other global DNS providers, but it ended up biting me in the ass.

I originally was routing all of my DNS traffic over to my personal system (across a VPN no less) because I don’t know what kind of crap might go on on my consumer broadband connection with Comcast (at one point I remember some ISPs doing funky things with negative DNS responses for example). Probably nothing but I thought what the hell, why not (the VPN is already in place, and I’m already running local caching name servers as well as a remote caching name server (not the same name server that hosts my domains externally those are different), it’s 1 line in a config file to forward the traffic).

Well now I know why not.. at some point I may invest the time to try to figure out how to send Netfix DNS traffic to a local site and the rest go to my server, but for now I’m not going to spend the time.

Once I disabled forwarding of DNS packets to my remote system, and restarted my name server to flush the cache, Tivo started using a Seattle Limelight node, and the hops dropped to 10, and latency dropped to around 15 milliseconds, HD streaming was now possible once again.

It’s also gotten me wondering how many other services that I use that may of been impacted by routing my DNS traffic 3,000 miles away. Though other than Netflix I have not noticed any ill effects, though the amount of data that traverses my connection is pretty minimal (62GB of data since the beginning of March until June 15th according to Comcast, that includes a pretty big backup I did of my personal server to my local network a few weeks ago).

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