Must Read: When Redundancy Actually Helps

Stumbled upon an excellent redundancy-focused blog post (HT: High Scalability). Here are just a few important points:

  • Don’t make things too complex;
  • Don’t add more risk than you take away;
  • You’ve got to fail over in the right direction;
  • You must be able to return to fully-redundant mode.

I’m guessing that people promoting stretched VLANs, vSphere and/or NSX clusters running across multiple sites, weird combination of EVPN and OTV, and a dozen similar shenanigans never considered any one of these points.


  1. No, some people never considered stable and scalable application architecture like you were preaching for years. That's the root cause why we're experiencing this huge mess in networks today.
  2. His article on Why Must Systems Be Operated? is related and also interesting.
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