Followup British Telecom outage reason

Wayne E. Bouchard web at
Sat Nov 24 20:08:37 UTC 2001

They probably did. The vendor probably did also. Of course, they can't
always simulate real network conditions. Nor can your own labs. Heck,
even a small deployment on 2 or 3 routers (out of, say, 200) can't
catch everything. It is a simple fact that some bugs don't show up
until its too late.

And cascade failures occure more often than you might think (and not
necessarily from software.) Remember the AT&T frame outage? Procedural
error. How about the netcom outage of a few years ago? Someone
misplaced a '.*' if I remember correctly. Human error of the simplest
kind. I've had a data center go offline because someone slipped and
turned off one side of a large breaker box.

These things happen.

The challenge is to eliminate the ones you CAN control. And, IMO, the
industry is generally doing a good job of that.

I chalk this whole thing up to bad karma for BT.


On Sat, Nov 24, 2001 at 11:05:20AM +0000, Neil J. McRae wrote:
> > 
> > 
> > BT is telling ISPs the reason for the multi-hour outage was
> > a software bug in the interface cards used in BT's core network.
> > BT installed a new version of the software.  When that didn't fix
> > the problem, they fell back to a previous version of the software.
> > 
> > BT didn't identify the vendor, but BT is identified as a "Cisco Powered
> > Network(tm)."  Non-BT folks believe the problem was with GSR interface
> > cards.  I can't independently confirm it.
> > 
> I'd be surprised if it was the GSR, and in anycase that doesn't
> absolve anyone. If it was a software issue- why wasn't the software
> properly tested? Why was such a critical upgrade rolled out across
> the entire network at the same time? It doesn't add up.
> Neil.

Wayne Bouchard
web at
Network Engineer

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