Open Source BGP Route Optimization?

Michael Hallgren m.hallgren at
Sat May 29 11:26:17 UTC 2004

> Per Gregers Bilse <bilse at> wrote:
> > On May 28, 10:37am, "Sam Stickland" <sam_ml at> wrote:
> >> Are there any BGP extensions that would cause a BGP 
> speaker to foward 
> >> all of it's paths, not just it best? I believe quagga had 
> made some 
> >> recent attempts
> >
> > It has been discussed and been on wish lists, but:
> >
> >> in this direction. IIRC the problem isn't to do with the route 
> >> annoucements, it's the route withdrawals. I believe BGP only 
> >> specifies the prefix being withdrawn and not the path, so if it's 
> >> advertised multiple paths to a prefix it's impossible to 
> know which 
> >> has been withdrawn.
> >
> > That is 100% correct, yes.  Selective withdrawal is not supported.
> >
> > Another issue is that there isn't much point, as far as regular BGP 
> > and routing considerations go.  Whichever is the best path for a 
> > border router is the best path; telling other routers about 
> paths it 
> > will not use serves no (or at best very little) point in 
> this context.
> Well something came up recently on a transit router. It takes multiple
> Tier-1 feeds, but management wanted to sell a just MFN to a 
> customer. It's possible to policy route all of their traffic 
> to the MFN interface and only advertise their prefixes to 
> MFN, but not possible to only feed them the MFN routes 
> without starting to use VRFs etc.
> Of course this is a great perversion of resources ;)

Indeed. Makes me somehow wonder how come that customer did not think 
of buying transit directly from MFN? KISS, that is. Or am I missing


> Sam

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