This is what you look at after a router has crashed owing to a hardware or more often a software error. It can only be of help if you know what the hell it is that you're looking at. The stack trace is a list of active subroutine calls in the current process and includes the PC (program counter) address where the problem originated as well as PCs in superior routines. The symbol table associated with the router's image (IOS version) can translate the PC values in the stack into routine names and offsets, which can then be used to locate lines of source code. The solution is usually the installation of a newer IOS and/or more memory. NOTE: For release 11.3(1) through 11.3(2), the stack trace fails to report the correct version of code as of the last reboot if the Flash doesn't match the current running version of code.