[c-nsp] Redundancy vs. Paranoia

[Reuben Farrelly]

As a field engineer, I have to disagree with (only) one point Hank made.  We 
replace blown power supplies on a fairly regular basis (although the number of 
units replaced is probably quite small compared to the number of chassis' out 
there), but the number of Sup's and PA's replaced due to failure is tiny.  If 
you have a chassis that can handle multiple power supplies, I'd strongly 
suggest filling up every spare space with them.

The larger sites I have seen have had three phase power supplies, and run one 
phase to each PSU.  As each phase has it's own transformer/fuse/wiring setup 
from the supplier, it helps provide some redundancy in case power is partially 
lost.

reuben


On 13/05/2005 4:21 p.m., Hank Nussbacher wrote:
> On Thu, 12 May 2005, John Neiberger wrote:
> 
> My motto is always KISS.  That goes here as well.  I would go for 6500s
> with dual power supplies only for the LAN and 720XVXRs for the WAN in your
> case.  Always best to seperate LAN and WAN function if possible.
> 
> I have been now buying Cisco products for well over 15 years now and for
> the life of me I can't remember the time a power supply went or the
> processing card went.  Therefore, I buy all my routers and switches with
> single processors and usually single power supplies (a dual power supply
> is really only needed if you have the ability to connect each power supply
> to totally seperate power sources/utilities) and have never had failures
> from those aspects.  With the extra budget one should buy more remote
> management boxes like remote power on boxes and remote out of band console
> boxes and anything else that makes life easier.
> 
> On the other hand - PA cards fail often as do VIPs.  I can't say anything
> about Flexwans yet.  Our last major failure was screwy VIPs and PA-FEs.
> 
> As others have pointed out, failures don't come from your LAN.  They come
> from many, many other areas whether they be backhoes or power blackouts.
> 
> And of course there is always the lying carrier.  We were supposed to have
> two totally seperate STM1 international circuits, following different
> paths, yada yada yada.  One day some power failure in Sicily knocked out
> both lines at once.  The carrier was hoping that would never happen.  No
> amount of dual SUPs or dual PSs would have saved our network.  I always go
> for different carriers for each WAN line but this particular tender was
> not for me to decide so we ate it for the day.
> 
> -Hank