Acee Lindem <[email protected]> wrote on 14/08/2009 16:23:15:
>
> On Aug 14, 2009, at 3:14 AM, Joakim Tjernlund wrote:
>
> > Acee Lindem <[email protected]> wrote on 14/08/2009 00:13:48:
> >>
> >>>
> >>>> Is there something in the OSPF spec which prevents it from operate
> >>>> on multiple numbered PtoP interfaces with the same local IP
> >>>> address?
> >>>>
> >>>> I have that working, but there are arguments that this is
> >>>> allowed by
> >>>> OSPF, i.e, ethier use unnumbered links or unique local IP
> >>>> addresses.
> >>>>
> >>>>  Jocke
> >>>
> >>> Got some comments on this but nothing conclusive, I really want
> >>> to know. Acee, what do you think?
> >>
> >> Since there is only a type 1 (router link) in the Router-LSA for each
> >> unnumbered link, it makes no difference how many use the same IP
> >> address.
> >
> > Right, but how about multiple NUMBERED PtoP interfaces with the
> > same local IP address?
>
> I'd argue that if your configuration supports this, all but one of
> the interfaces is unnumbered.

hmm, please clarify. I do mean treating each and every PtP
as a numbered PtP link. Is there something that prohibits
this in the spec? Of course not all routers will
be able to handle this but in that case it would be a
limitation in the impl.

Is it allowed to have numbered on one side of the link
and unnumbered on the other side?

>
>
> > Then there will be multiple identical
> > type 3 too.
>
> Even though it is non-standard, I don't see any problems. I believe
> Dave alluded to the fact that some OSPF implementations may have ABR
> SPF optimizations which can have problems when the same address is
> advertised in multiple addresses - I know fixed some problems here in
> one implementation.

Yeah, when one only uses the router LSAs to identify the interface
you are in trouble.

>
> Acee
>
> >
> >  Jocke
> >
>
>

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