[c-nsp] OSPF router gets separated from a broadcast domain

[Peter Rathlev]

On Fri, 2008-02-01 at 11:37 +0100, Gabor Ivanszky wrote:
> Christopher E. Brown wrote:
> >
> >> the point is that even if all your devices speak OSPF, they will 
> >> suffer from this issue as well.
> >> d4 speaking OSPF doesn't help Router A not to use it's connected 
> >> interface to try to reach the network, and d4 also(and all the 
> >> possible networks behind d4), still creating the blackhole, as far as 
> >> our tests shows.
> >>
> >>
> >
> > The point is that subnets should be transport or destination, *not 
> > both*.  The partition of a OSPF speaking transport network does not 
> > matter, only the partition of a destination subnet (or a shared 
> > transport+dest subnet).
> >
> >
> That makes sense. But our experience in a real life scenario is that the 
> partitioning of  "OSPF speaking transport network" creates the blackhole 
> as well. I will try to build this in the lab. May the root cause of the 
> blackhole wasn't the network separation, but something else...

If you only use these networks as OSPF transport networks, it's not a
big problem if they're black holed. Since they're not destinations,
neither clients nor servers ever see them in anything but a trace.

Just make sure that you have a bit bucket to collect them, and make sure
to correct the problem asap of course.

Regards,
Peter