Internet outages blamed on routing limitation

Rob Powell/Telecom Ramblings
14 Aug 2014

Every now and then, some obscure limitation in some corner of the hardware or software that makes up the internet manages to take the whole thing down.

The story is always the same: someone long ago thought that the number X was much more than there could possibly ever be a need to use, and boy were they wrong.

Yesterday, that number was active 512,000 BGP routes and the culprit was Ternary Content-Addressable Memory on older routers which could handle that many and not one more. So when we passed that mark and BGP started sending around updates with more than that, bad things started to happen across the internet.

You’d think a mere 512K would seem like a very small number these days to limit anything to when it comes to scaling the internet. But many of us still remember carrying around 5.25 inch floppy disks that would hold an amazingly large (for the time) 360K bytes. Anyhow, they were lots better than the cassette tapes.

So much of the internet staggered and stuttered for part of yesterday as the magic number was reached. Network operators from small to large scrambled to compensate and implement workarounds that have long been out there yet not universally implemented. Not everyone was affected, and Telecom Ramblings seems to have been spared the worst of it.

This article was authored by Rob Powell and was originally posted on

Rob Powell is founder & editor of Telecom Ramblings, which was set up in 2008. The website is dedicated to discussing trends and developments in the telecom industry.

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