T-Mobile traffic through http://1.2.3.12

Posted by Gerben Jacobs on April 16, 2011 in tech

I'm at a place where there's no internet, so jeI hooked up my T-Mobile G1 (an HTC Dream) to my laptop through the PdaNet app.

When I was browsing a site, I noticed an image that wasn't working. So I opened it up in a new tab, where it seemed to work again, but I then noticed the URL. The http:// part of the original source was dropped and replaced by http://1.2.3.12/bmi/, i.e.: http://1.2.3.9/bmi/www.gerbenjacobs.nl/wp-content/uploads/2011/01/cute-kitten-laughing-64x64.jpg

My first instinct was to ask customer support (god, am I that customer?) followed by Google. I then found this blogpost "T-Mobile rewrites image urls" which is 13 months old, but I never noticed T-Mobile doing this. So they must have recently added this 'service' to T-Mobile Netherlands.

T-Mobile Edge

After more research, it turns out that T-Mobile calls this service 'EDGE' (Enhanced Data Rates for Global Evolution) and what it does is basically a giant loadbalancer and CDN in one.

When you inspect the IP address it shows up as an Australian server, which shocked me initially, but after some tests I didn't notice any speed loss. So it must be using some kind of geo-aware content delivery network.
(The weird thing is that I can't seem to trace the IP in Cmd.exe with the 'tracert' command, so I have no idea which server they appoint to my geolocation)

Advantages

So how is this enhanced, you may ask. Well, just look at the following image (click to enlarge):

Parallel downloads with T-Mobile Edge
Parallel downloads with T-Mobile Edge

It's hard to see, because it's not the entire page load, but all of the images (they were avatars on a forum) were loaded simultaneously. I was using Firefox 4 which can handle up to 5 (or was it 8?) parallel downloads at the same time. Then the 'loadbalancing' (for lack of a better word) comes to play, using the multiple servers 1.2.3.9 to 1.2.3.13 (great IP address by the way!) it loaded them all. So that's 5 x 5 (or 8), which is up to 25 (or 40) resources, or forum avatars, at once.

That's the only advantage I can spot of this so called EDGE service, which came unannounced.

Disadvantages

Then there is the disadvantage, that applies to all proxies in general; single entry point and thus single entry point of failure. So in other words, when their servers get hacked, we have no idea what is being send.

Applying to the single entry point, also means the possibility of tracking. But I doubt that this would be any worse than what Google does, they probably know everything about you already. And maybe the CIA is behind it.. or the New World Order..

However, without going off-topic too much, about 95% of T-Mobile customers wouldn't mind this (and probably wouldn't understand it either), but I do wonder why this hasn't been announced, or why there is so little information about it. I'm not really sure what my opinion on the issue is..
At the moment I'm in favour of it, because I like pages to load quickly, duh!
On the other hand I wish there was more transparency, because this is kind of a big thing.