[zebra 22873] Re: [Fwd: Re: Clarification on OSPF RFC2328]

Robin,
           It looks like with unnumbered interfaces option 1 will be
applied always.
With numbered interfaces the statement for option 2 "If a subnet has
been assigned to the point-to-point link" holds true and the network
number and mask will be used in the stub link.

I haven't used unnumbered interfaces with quagga (I don't think they
are supported) so I cannot inspect manually. Tell me if that has
changed in the newer release.

So you wouldn't configure one end of a link as unnumbered and the
other as numbered - this would result in spf not including that link
for computation.

Therefore you have to force Ra, Rb and Rc to follow either option 1 or
option 2 for the interfaces common to a link, by using unnumbered on
both or assigning a subnet to them.

CC'ing zebra for completeness. (Don't you hate all those discussion
threads that end nowhere without giving an answer? (: )



Rgrds

On 6/1/06, Gobbledegeek <[email protected]> wrote:
> Correction:
>
> >               To continue, If one router uses option 1 and the other
> > option 2, then because there is no matching pair of stub entires with
> > common subnet mask - Rb will have  a /32 and Rc may have  say a /28
> > for example. Both Rb and Rc *must* advertise the common link between
> > them denoted by lbc-lcb,  or else it will not be included in spf
> > computation by any of the routers.
>
> Should read as:
>
>  because they do not have stub entries with common subnet mask - *the
> link will not be included in spf computations*
>
> Apologies.
>
> On 6/1/06, Gobbledegeek <[email protected]> wrote:
> > Hi Robin,
> >               To continue, If one router uses option 1 and the other
> > option 2, then because there is no matching pair of stub entires with
> > common subnet mask - Rb will have  a /32 and Rc may have  say a /28
> > for example. Both Rb and Rc *must* advertise the common link between
> > them denoted by lbc-lcb,  or else it will not be included in spf
> > computation by any of the routers.
> >
> > So the question is when to use option 1. I only remember seeing
> > routers use option 2. I need to run again. Will check tomorrow.
> >
> > Yesterdays comment holds though. I do not understand you comment  that
> > "interface Ibc is not advertised in the LSA of Rb."
> >
> >
> > HTH
> >
> > Rgrds
> >
>
>
> --
> Nonchalantly yours
> GobbledeGeek
> [Everything but Gobbledegook.. !!]
>


-- 
Nonchalantly yours
GobbledeGeek
[Everything but Gobbledegook.. !!]