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In einer eMail vom 12.07.2008 21:02:46 Westeuropäische Normalzeit schreibt
bill@herrin.us:
On Sat,
Jul 12, 2008 at 12:31 PM, <HeinerHummel@aol.com> wrote:
> In
einer eMail vom 12.07.2008 18:16:25 Westeuropäische Normalzeit
schreibt
> bill@herrin.us:
>
>>>
http://bill.herrin.us/network/geoag-h1.gif.
>>
> >Okay,
good. Now, based on the graph you just agreed to and the two FIB
>
>tables you just agreed to, route a packet from node H to node A.
The
> >path I compute is H->G->F->B->A. Do you get that
path as well?
>
> Sure.
There is your error. You violated
the permission constraint: F is not
a permitted node in the transit path
between H and A.
You added, as I asked for, the red arrows which indicate in which direction
forwarding is allowed.
From G to F forwarding is allowed. Also from F to B. So why can't packets
from H to A go along
H-->G-->F-->B-->A ?
I do not see any error.
Heiner
There is
no
trail of green arrows from H to F. There is also no trail of
green
arrows from A to F. Hence F is not permitted for a packet
whose
addresses are H and A.
There is one permitted path from H to
A: H->G->C->B->A. Each node in
that chain has a trail of
green arrows leading to it from either H or
A. This designates
permission.
Would you like to redraw your red arrows? Can you think of
a
configuration of red arrows where you get *both*
H->G->C->B->A *and*
D->C->G->F->E
?
-Bill
--
William D. Herrin ................
herrin@dirtside.com bill@herrin.us
3005 Crane Dr. ......................
Web: <http://bill.herrin.us/>
Falls Church, VA
22042-3004
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