pulse-time x statement; When do you use it and When not to use it?

richard_ciccarella · ‎03-25-2008

My current network I have two connections with two CSU/DSU connected to external encryption devices connected to a serial interface port on a 3825 series cisco router. The distant end is connected the same way.

My first connection I have pulse-time 5 set on the interface and the interface is up up. My second connection is the same setup however when I set pulse-time 5 on the interface, the interface will flap between up down and down down even when I am in loopback. When I take pulse-time 5 off, the interface will stay up down. I tired switching the serial interface cards and the problem still occurs.

Can anyone explain why my first connection is good with pulse-time 5 and my second connection is not when they are the same configurations?

paolo bevilacqua · ‎03-25-2008

Hi, the pulse time was historically needed because encryption devices needed a longer time of low DTR to resync. Your devices may or may not need that after all.

The fact that one of your circuits doesn't come up no matter what, suggest a problem with either the encryption devices, or the circuit that links them, and not necessarily a problem with the router.

richard_ciccarella · ‎03-29-2008

Thank you for all the information. It was very helpful and informative. Indeed it was not a problem with my router and in fact was a strapping issue with my external encryption device. After strapping my encryption device to get DTR resync from the router, I had no further issues with my circuit.