[j-nsp] Juniper M20 AC power supplies

[Alex Hsia]

Just wanted to pass on a tidbit of information that I just learned about 
our Juniper M20 router.  If power is temporarily interrupted to the M20 
power supply it will stay in a fault condition and not provide power to 
the router until power is removed for more than 60 seconds.

We discovered this situation when we had a power bump and found out that 
a battery in our UPS had failed (despite passing it's last maintenance 
test) which temporarily interrupted power to our M20.  Both power 
supplies went into a fault state and remained in that condition until 
someone came in and physically cycled power on the router.

I've replicated the situation by pulling the cord for a short while to 
our M20 and have gotten the power supply to stay in a fault state.

According to Juniper, this is "normal" behavior as outlined by the JTAC 
response listed below:

 > Hi Alex,
 >
 > After confirming with our escalation.
 >
 > Unless the actual power outage lasts 60 seconds or longer the power
 > supply will not transition from failure to recover.  This is
 > documented
 > here :
 >
 > 
http://www.juniper.net/techpubs/hardware/m20/m20-hwguide/replace-remove-ac-power-supply.html#replace-remove-ac-power-supply

Alex Hsia ==============================================================
NOAA/OAR                                            Phone: (303)497-6351
Mailstop R/OM62                                    Mobile: (303)356-6545
325 Broadway                                  e-mail: Alex.Hsia at noaa.gov
Boulder, CO  80305                               http://boulder.noaa.gov
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