NAPs - Temperature vs Packet loss

Darren Kerr dkerr at
Fri Mar 28 21:09:11 UTC 1997

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> Date: Fri, 28 Mar 1997 20:26:57 +0000
> From: "Alex.Bligh" <amb at>
> Sender: owner-nanog at
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> We've noticed an interesting phenomenon with MAE-East. Packet loss
> corelates nicely to temperature.
> At first I assumed the relationship was Busy Network => Hot routers
> and also Busy Network => Packet Loss. But this is not the case.
> It appears to be Hot Routers => Packet Loss.
> Boone Boulevard MAE-East is currently running very hot. Intake temp
> on our router has been up to 40 degrees today, and output at 70.
> Under these conditions, the router (a 7010) starts dropping a pile
> of packets occassionally. Mostly these seem to be through the AIP
> and a clear int a0/0 fixes it. The time it stays fixed for is
> heavilly corelated with temperature. The higher the temperature,
> the shorter it stays fixed for. Eventually MFS put a fan on the
> router and it seems a lot better now, intake temperature being
> down to 36/37 degrees.

First I've heard of it, but sounds like you've captured a lot of
empirical evidence, so could you send me your data (hopefully
telling me whether these were output drops, input ignores, input
drops, or other errors).  Did you notice any errors logged?
Anyways, send me all your usual "show ver", "show int", "show
contr cbus" info (nanog un-cc'ed, please) and I'll pass it around.


PS - I've noticed that ever since I moved to San Diego, people
around here have been dropping like flies.  Coincidence, or
cause&effect?  ;-)

> 40 degrees is Cisco's default "warning" threshold. One would have
> thought boxes should work OK at 40 degrees. On the other hand one
> might also have thought a 18-22 degree aircon environment was a
> prerequisite of running a decent IXP.
> Is anyone else seeing high temperature and otherwise inexplicable
> packet loss at MAE-East? Or does anyone else have data to corelate?
> Alex Bligh
> Xara Networks

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