[c-nsp] general question on VRFs and FIBs...

[Gert Doering]

Hi,

On Mon, Sep 26, 2011 at 01:18:05PM -0700, Derick Winkworth wrote:
> I'm trying to find an archived discussion or presentation discussing
> why exactly the industry generally settled on having a separate
> FIB table for each VRF vs having one FIB table with a column that
> identifies the VRF instance?  I'm not finding it, but I'm guessing
> its because of performance issues?    

Lookup would fail for overlapping address space if you lookup 
"address first, VRF second".

How do you find the right entry if you have

  10.0.0.0/8 vrf red
  10.0.0.0/16 vrf green
  10.0.1.0/24 vrf blue

and try to look up 10.0.0.1 in vrf red?  You'll find the /24 entry, which
is tagged "vrf blue".

Alternatively, you'd need to explode the /8 entry for vrf red if *another*
VRF adds a more specific for that /8.

gert
-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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