Ping flooding

Per Gregers Bilse bilse at
Fri Jul 12 03:24:15 UTC 1996

On Jul 11, 20:53, Alan Hannan <alan at> wrote:
>   If rtra is down, I do not want rtre to send packets to rtrd to get
>   to rtra, do I?  Wouldn't I prefer them to be stopped ASAP?

This makes no difference.  For most intents and purposes, one-way
traffic doesn't exist.  The only thing going down that line will
be the odd packet intended to open a conversation -- the volume of
this will be minimal compared to normal traffic volumes.  And even
if you had one-way traffic in volume, it wouldn't exceed normal
traffic levels, for which you will already have the capacity.

Whenever you do dynamic routing when it isn't necessary, you -will-
be emitting unnecessary updates, which nobody is interested in.  We
have several ASs behind unstable lines behind us, from which we do
not propagate routing changes; we set origin AS and announce
nailed-up static routes in their AS.  Neat, stable, works -- no flap
and no global propagation delay when the connection comes back up.

> * Another situation is what happens when you renumber networks?

Your router configuration will be changed ... ?  :-)

>   What hapens when you've large number of downstream networks?  Do
>   you really want static routes in rtrf for all networks attached to
>   rtrs a,b,c,d,e?

Where you cut dynamic updates off doesn't really matter.  The key
issue is not to propapgate unnecessary updates.  I mean, is it really
interesting that a tail circuit in Cargolia went down?  Does this
event -have- to be announced to the Net?

A different issue is that there are many networks with broken
configuration.  If these people would "do the right thing", and not
announce their instability to the Net, we'd be rid of, what?, 90% of
all route flap.

------ ___                        --- Per G. Bilse, Mgr Network Operations Ctr
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