Cisco boxen hang after 213-and-a-half days If you're the lucky owner of Cisco Firepower or Adaptive Security Appliance devices, check the version number and see if you need to reboot your kit. Switchzilla has discovered an operational (that is, not security) bug that makes the devices hang after continuous operation for around 18,446,400 seconds (213-and-a-half days …
The usual reason for this is a 32 bit counter of milliseconds overflowing, but that happens after 49 days and 17 hours, approximately.
I still remember when someone managed to run Windows for 50 days without a reboot for the first time...
Now, it would seem to me that Cisco have learnt that lesson and use a 64 bit counter. Unfortunately, they also decided to count picoseconds...
$ echo '2^64/18446400/10^12' | bc -l
1.00001865262108333420
There was something similar with one model of Cisco switch around 4 years ago where after a period of uptime something b0rked in the arp cache algorithm and the switches turned into hubs - you knew when it happened as network traffic ground to a halt and all the port LEDs flashed in unison.
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