NAPs - Temperature vs Packet loss

Brian Horvitz horvitz at
Sun Mar 30 05:09:54 UTC 1997

I experienced an airflow problem on a 7010 once which just made it shut
down and restart when it got hot.  Are you sure that this is not
happening occesionally?  It would seem to me that a 7xxx router should be
able to survive its shutdown threshold without affecting performance.

	Brian Horvitz
	WebSecure, Inc.

On Fri, 28 Mar 1997, Alex.Bligh wrote:

> 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.
> 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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