title: InfiniBand explained
body: <p>Can anybody explain what is InfiniBand? What is the key differences in comparison with Ethernet, how these differences allow for it to be faster than Ethernet?</p>
  
  <p>In the official <a href="https://www.mellanox.com/pdf/whitepapers/IB_Intro_WP_190.pdf" rel="noreferrer">description</a> from mellanox it is written that</p>
  
  <blockquote>
    <p>Introduce InfiniBand, a <strong>switch-based serial</strong> I/O interconnect architecture operating at...</p>
  </blockquote>
  
  <p>What does it mean that Infiniband is a <strong>switch-based</strong> interconnect? I found this <a href="http://etherealmind.com/what-is-the-definition-of-switch-fabric/" rel="noreferrer">description</a>, but it does not explain what happens if several inputs want to write to a single output, how is the collision resolved?</p>
  
  <p>It is also said that Infiniband has end-to-end flow control. Does it mean that there is no (need) for any other (in-between) flow control? Why?</p>