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Reliable or unreliable cloud services?

The question of high-availability cloud services (let’s agree reliable in this context really means highly available) pops up every time I discuss cloud networking requirements with enterprise-focused experts. While it’s obvious the software- and platform services must be highly available (as their users have few mechanisms to increase their availability), Infrastructure-as-a-Service (IaaS) remains a grey area.

However, once you look at the question from the business perspective, it seems Amazon probably made a pretty good choice: offer reasonably-available service at a low price. You’ll find more in-depth arguments in the Cloud infrastructure services: Balancing high availability and cost article I wrote for


  1. For distributed applications that share state there is CAP theorem setting the limits for anyone's dreams :)
  2. ... and I guess we need one for networking as well (or maybe the Fallacies of Distributed Computing cover all cases?)
  3. calculating forwarding tables is distributed computation involving state sharing :) take a look at EIGRP (consistent state sharing) and OSPF (inconsistent) for example. The same "CAP" logic applies to centralized vs distributed control planes comparison :)
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