Redundancy requires routing service from two different directions.
I deal with underground telecommunications services. It is amazing how few companies in my area utilize redundant access. And how few of the communication facilities managers have any clue where their communication services come from.
It is amazing how few companies in my area utilize redundant access.
When the internet was first getting started, here in Minnesota, it began with a line running from Chicago to the University of Minnesota. Redundancy was, of course, one of the design concerns, so another line was run through the Dakotas to Seattle. Then one to Ames, Iowa, then out to Portland, etc.
But they all ran into the University of Minnesota.
As businesses, and particularly the banks and insurance companies, began to rely upon the internet, some of them understood the importance of redundancy, and insisted upon completely independent, redundant cables connecting them to the internet.
But they all ran into the University of Minnesota.
And most importantly, every single one of those independent redundant cables ran through the same PVC conduit running under the 14th Street railroad bridge in Dinkeytown.
And when a couple of homeless people, living under the bridge, lit a fire one January night, trying to keep warm, and managed to set the PVC on fire, every single one of those independent, redundant cables was destroyed.