The Incredible Shrinking Megabit

It’s the network installer’s chronic nightmare: you go out to the new subscriber’s premises, get a clean test at full speed from the signal test mast, perform the actual nuts and bolts installation, aim and configure the subscriber’s radio… and instead of seeing the full two or three megabits you saw during the survey test, you’re seeing a half or three-quarters of a megabit. Or, you see full speed during the final acceptance test, and while you’re putting away your equipment, the subscriber comes out to report that his network performance has just tanked.

Being an engineer, your mind immediately goes to the straightforward, technical, effort-intensive reasons for such a failure: infant mortality in the radio unit? Intermittent neighborhood contention on the frequency that wasn’t there during the test? Problems developing in your tower?

I’ve lived this nightmare several times, and it’s never pleasant. Yet often, the real reason turns out to be pretty innocuous, and a little attention spent on remembering the more common possibilities first would have saved me a lot of needless anxiety.

The Group Cannonball: While I’m packing the trailer to depart, the father of a family of homeschoolers reports his bandwidth has suddenly disappeared. The radio’s own meters say it’s operating at full capacity. They also inform me that each of the kids has disappeared into his or her own bedroom with their respective iThings and are all hammering on their new toy at full speed, with only a smidgen left over for Dad. Problem solved.

The Microsuck: This is similar to the Group Cannonball, only automated. Something about the appearance of a new and faster network tends to prompt the Windows OS, its various anti-virus packages, and its utilities such as Adobe Flash (there’s always a security update you haven’t loaded for Adobe Flash) to decide that now would be the perfect time to download huge system updates, virus definition files, security patches, and so on—all at once. Now, the Mac OS does this too… with the difference that it usually notifies you when it’s doing it. Windows seems to prefer downloading all this stuff silently in the background, not letting you know what’s going on until it’s a fait accompli. All your subscriber sees is that his network response has just gone to pot for no apparent reason. This syndrome is especially puzzling when it’s being caused by an unattended PC in another room, one the installer doesn’t even know exists. The prescription for this one is simply patience: when all the little robo-processes have finally eaten their fill, they’ll let you have your network back.

The Low-Flow Appliance: One subscriber’s complaint of low bandwidth turned out to be due to a box he had added to handle his network-based telephone system (voice over IP, or VOIP). The unit was not only constantly using a small but significant fraction of his bandwidth, even when no phones were in use, but was also throttling bandwidth to his computers, all of which had to pass through the VOIP interface because of the way it was designed. A simple test showed that the network was operating to the full specified bandwidth, when measured directly at the network ingress cable. The subscriber replaced his VOIP box with a more flexible unit that eliminated this overhead.

The good news is that since the spring of this year, Grand Avenue Broadband has transitioned from the market-commodity customer premise units used in the past (Engenius, Tranzeo, Deliberant) and standardized on a new line of extremely flexible, extremely capable customer premise radio/routers made by MikroTik and configured by ourselves for best performance on our own network. These rooftop units have vastly superior metering and diagnostic capabilities, as well as beefier radio sections. Being able to see exactly where the traffic is going, and run accurate end-to-end speed measurements directly between any subscriber and our internet portal interface in Morristown allows us to analyze and correct your bandwidth issues more quickly and more completely than ever before.


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