The idea for this post came from someone I was working with recently. Thanks Fan (and Carson, and Shree) :-) In Service Software Upgrade (ISSU) is a method of upgrading software on a switch without interrupting the flow of traffic through the switch. The conditions for successfully completing an ISSU are usually pretty strict and if you don't comply, the hitless upgrade can all of a sudden become impacting. The conditions for ISSU on the Nexus 5000 are pretty well documented (cisco.com link) ...
