NAP/ISP Saturation WAS: Re: Exchanges that matter...

Tony Li tli at
Sat Dec 21 06:39:02 UTC 1996

   >So what's the $0.02 fix for eliminating the fate-sharing between routing
   >and payload that GGP got wrong?

   Did i say anything about eliminating fate-sharing?

   What i said is that routing updates should not be _routable_.

Excuse me, I misunderstood.  I thought you were trying to solve the DoS
problem and were advocating out-of-band signaling.

   Actually, given the simple fact that a properly implemented
   link keepalive protocol provides adequate discovery of link and
   gateway failures, it is not clear that sending routing updates
   over the same physical medium as data has any intrinsic value.

Agreed.  However, the link keepalive must fate-share with the traffic.  And
that alone is sufficient to allow DoS attacks.

   Similarly, there's no reason why medium cannot be shared between
   network control and user traffic, as long as network control is
   given unconditional priority.

Agreed, this would be the best of all worlds.  Not implemented anywhere as
far as I know.

   (And, no, practially all link keepalive protocol implementations
   are insane; cisco's a notorious example.  No flap dampening, no
   hold-down "blackholing" after a failure (so as not to generate
   route withdrawals for transient link outages), silly priority
   and no sub-second ping intervals, and forget about LQM).

None of these have anything to do with the link keepalive protocol and
everything to do with internal link implementation.  Let's not confuse the


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