For a relatively modern cluster the standard is FDR Infiniband, which gives you 56 Gbit&#x2F;s throughput. The latency for a small (&lt; 32 kbytes) packet is less than 10 microseconds, down towards 1 microsecond for a 8 byte packet.<p>Glenn Lockwood has a nice blogpost with much more detail: <a href="http:&#x2F;&#x2F;glennklockwood.blogspot.com&#x2F;2013&#x2F;05&#x2F;fdr-infiniband-vs-dual-rail-qdr.html" rel="nofollow">http:&#x2F;&#x2F;glennklockwood.blogspot.com&#x2F;2013&#x2F;05&#x2F;fdr-infiniband-vs...</a>