Add to the config or make sure you have it already:
service timestamps debug datetime msec
service timestamps log datetime msec
service sequence-numbers
!
logging buffered 5000000 -> 5Mb buffer log (Check to see if there is enough space)
logging rate-limit 10000
logging queue-limit 100000
no logging console -> Disable logging to console
no logging monitor -> Disable logging to terminal session
### Now enable the required debugs
### Before simulating a test, clear the buffer log:
clear logging
### Now, create a new log file (using SecureCRT, Putty, or similar)
### After you get a failed call (or have done the required test), stop the debugging:
show debugs
undebug all
### And collect the debug logs in the following format:
term len 0
sh ver
sh run
sh log