[c-nsp] Cisco RPS for 3550 switch

[Seth Mattinen]

TCIS List Acct wrote:
> We are looking at options to provide redundancy for the internal A/C power 
> supply in some 3550-48-EMIs.  It seems that the following RPS models will work:
> 
> RPS-300
> RPS-675
> RPS-2300
> 
> We plan to do a 1-1 config (1 RPS for 1 switch), so we are leaning towards the 
> RPS-300 for cost reasons.
> 
> I've reviewed various threads in the archive, and see where others have had 
> problems with the RPS-300's allowing fall-back to the internal A/C power supply 
> after it has taken over on the DC source.  Was this an IOS issue, a hardware 
> issue with the switch and/or RPS, or ?
> 

Hardware. There is no way to get the device (in my case, some 2811's on 
a single RPS-300) to go back to internal power without reloading once 
it's switched over to the RPS. Switching back causes the device to lose 
power. You should not expect any kind of real redundancy, but expect a 
full outage and reload if you ever want to go back to internal AC from 
the RPS.

Personally, I'd just skip the one to one "redundancy" and just use them 
for nothing more than protecting the switch from internal PSU failure, 
at which point you'll have to power it down anyway to replace the PSU. 
This doesn't affect any other devices plugged into the RPS, only the one 
actually drawing power from it.

~Seth