Steven M. Bellovin
smb at cs.columbia.edu
Sun Nov 5 20:28:44 UTC 2006
On Sun, 05 Nov 2006 07:16:07 -0800, Stephen Satchell <list at satchell.net>
> David Lesher wrote:
> > Speaking on Deep Background, the Press Secretary whispered:
> >> On Nov 5, 2006, at 1:51 AM, Randy Bush wrote:
> >>>>>> "Could you be any less descriptive of the problem you are seeing?"
> >>>>> the internet is broken. anyone know why?
> >>>> Did you ping it?
> >>> is that what broke it?
> >> I'm sure it just needs to be rebooted.
> > Is this the day we disconnect everything and blow all the dirt out?
> You only *think* you are joking. I still remember the Day of the Great
> Restart when everyone on the ARPAnet had to shut down the IMPs and TIPs,
> and reload the control software. Why? There were literally thousands
> of rogue packets flying around the net, eating up bandwidth (and in
> those days, we are talking 56 kbps links!) and boy were those
> tubie-thingies plugged up!
> Shortly after that cusp event, per-packet TTL field was added to the NTP
> protocol, which is why TCP/IP has the TTL field in the IP packet.
I assume you mean NCP rather than NTP.
Anyway, I don't think that would have helped if you're talking about the
same incident I'm thinking of. There were application-level
retransmissions of (corrupted) packets, complete with building new bad
packets from bad data structures, all over the net
The problem is documented in RFC 789 It and "The Bug Heard 'Round the
World" are two of my favorite "how complex systems fail" papers; all
system designers should read, memorize, and undertand both.
> The network had added to it a self-cleaning function. Think of it as
> one long continuous sneeze.
--Steven M. Bellovin, http://www.cs.columbia.edu/~smb
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