If any UK-based Internet users noticed that the Web was running a bit slow last Thursday, I apologize. Probably I was partly to blame. I managed to send an extremely large zip file on a four hundred mile round trip just to move it three quarters of an inch. I'm expecting a large invoice from my ISP to arrive any day now.
How did I manage it I hear you ask? And, more likely, why? Well, in my continuing search to be eco-friendly I run a single server that hosts several Hyper-V virtual machines, one of which is my external Web server and another that is my main file store. As I export copies of the VMs regularly, I don't have any other specific mechanism for backing up individual files from the Web server. And, for security reasons, the Web server VM has only a single network connection going to the ADSL router and out onto the Web.
So when I decided to back up just the Web sites, the only option other than reconfiguring the network was to zip them up, drop the zip file temporarily into the Web root folder, and then download it through a browser on the internal network. As the internal network also connects to the same ADSL router though the gateway and firewall server (another VM), the download runs at 100 MBits/sec and doesn't ever have to leave my server cabinet.
Except I forgot about the ramifications of my recent venture into a more resilient connection with the outside world, which involves a cable Internet line and a load-balancing router on the gateway server. The cable line is ten times faster than the ADSL line, so (as you'd expect) the LB router decided to route my request for the zip file out through the cable connection.
Therefore the zip file ended up travelling out from my ADSL router, over the wet string that is the phone line to my local exchange, via kilostream to the BT data centre in Birmingham, across some high speed optical fiber to TeleHouse in London, out west to the NTL data centre in Bristol, through several fiber cables and distribution routers back to the old Nynex Cable centre in Derby, out to the green box at the end of our street, via coax under my front lawn to the cable modem in my server cabinet, and back onto the other hard disk inside the same server as it came from.
I have to admit that I noticed the download seemed to be taking a long time when I came back an hour later at it was still only at 85%. Next time, I promise I'll unplug the cable modem before I start... but isn't amazing what you can do with modern networking technology?