Re: Good UPS for network equip?

From: DaveC (me_at_privacy.net)
Date: 07/23/04 

Date: Thu, 22 Jul 2004 19:21:33 -0700

Environment: small 4-person medical office. These are not huge
bandwidth-using people.

Equipment: 1 PC, 3 Macs connected via 10-baseT to Netgear RP614v2 router.
Router firmware is current release.

Symptoms:
1. Every 2 weeks, or so, suddenly no one connected to the router can access
the 'net. No one was attempting to use the internet at the time of the
failure, they just found that their computer couldn't print to the network
printer. I can ping the "immediate" router (that their computer is plugged
into), but not the one beyond (that the printer and DSL router are plugged
into).

Replaced the router, as it seemed defective.

Then, on one weekend, an office worker was present when the "lights
flickered", and network symptom occurred. I started thinking about power
problems, and office workers confirmed that the lights would flicker several
times a week.

Restarting the router fixes the symptom, every time it occurs.

> Plug-in UPSes, such as the recommended Tripplite, connect
> computer directly to AC mains when not in battery backup
> mode. Where is the protection? Furthermore, these UPSes
> typically output some of their dirtiest electricity when in
> battery backup mode. If a network was suffering from line
> noise, then power the computer from a UPS in battery backup
> mode. The network would crash immediately. If not, then AC
> mains noise is not a reason for network failure.
>
> One example of a UPS under light load is demonstrated. When
> in battery backup, the 120 VAC output is two 200 volt square
> waves with a 270 volt spike between those square waves.
> Dirtiest electricity is from that UPS in battery backup mode.
> But not problematic to any properly constructed computer. If
> that noise caused computer problems, then the computer
> hardware was defective when purchased or assembled.

Understood.

> Find the problem rather than trying to cure a symptom. IOW
> first identify the reason for a problem before speculating -
> before 'fixing' everything.
>
> Another 'suspect' is existing cables. Also execute those
> diagnostics with computers connected together by a known good
> cable, no router, and not using existing building cables.
> Even an ethernet cable plug or mismatched cable pairs can be
> reason for intermittent - which is why the loope (magnifying
> lens) is important for visual inspection of each RJ-45
> connector. Identify reason for problem before fixing
> problem. Provided are tools to accomplish that. A UPS to fix
> the problem means the computer has defective hardware. Don't
> cure defective computer hardware with a UPS.

I see no evidence that a cable has locked up the router. Have you experienced
this?

Thanks, 

-- 
Please, no "Go Google this" replies. I wouldn't 
ask a question here if I hadn't done that already. 
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

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