> -----Original Message-----
> From: Dave Katz [mailto:dk...@juniper.net]
> Sent: den 6 januari 2009 19:47
> To: Joakim Tjernlund
> Cc: 'Acee Lindem'; ospf@ietf.org
> Subject: Re: [OSPF] Unnumbered PtoP router LSA question.
>
> The idea of Option 1 is to provide connectivity to the remote router
> itself. The remote router has an address, and it is known to the
> local router as soon as the first Hello is received. So by definition
> it is always possible to do (since the remote router's address must be
> known in order to have an adjacency in the first place.)
>
> One could claim that it would make more sense for a router to announce
> its *own* address in a link, and in fact some implementations do so
> gratuitously for safety's sake. Or a loopback interface (with an
> independent address) is included in the OSPF configuration to achieve
> the same thing. But without either Option 1 or one of the hacks, it
> may not be possible to address the router itself for management
> purposes.
True, but that is addressed in footnote 2:
[2]It is possible for all of a router's interfaces to be unnumbered
point-to-point links. In this case, an IP address must be assigned
to the router. This address will then be advertised in the router's
router-LSA as a host route.
An related question: what to do with an interface that is UP but not RUNNING?
I would think that such an interface should be treated as a LoopBack interface
and so a host route should be announced. That would help to always have an
address
to reach the router for management purposes.
>
> So I would not suggest to omit the second link; the inaccuracy is in
> the example instead.
>
> --Dave
>
>
>
> On Jan 6, 2009, at 11:31 AM, Joakim Tjernlund wrote:
>
> > Hi Acee
> >
> > Thanks for your quick answer. I have seen the example but I didn't
> > think
> > an example was authorative. Can I trust this example and/or your
> > statement
> > to be authorative?
> > Can I have your list of RFC 2328 inaccuracies?
> >
> > Jocke
> >
> >> -----Original Message-----
> >> From: Acee Lindem [mailto:a...@redback.com]
> >> Sent: den 6 januari 2009 17:56
> >> To: Joakim Tjernlund
> >> Cc: ospf@ietf.org
> >> Subject: Re: [OSPF] Unnumbered PtoP router LSA question.
> >>
> >> Hi Joakim,
> >> While it certainly isn't described very well, the intent is that the
> >> second router link is omitted for unnumbered links. If you look at
> >> the example for RT3's backbone area router LSA on page 134, you'll
> >> note the omission.
> >>
> >> ; RT3's router-LSA for the backbone
> >>
> >> LS age = 0 ;always true on origination
> >> Options = (E-bit) ;
> >> LS type = 1 ;indicates router-LSA
> >> Link State ID = 192.1.1.3 ;RT3's router ID
> >> Advertising Router = 192.1.1.3 ;RT3's router ID
> >> bit E = 0 ;not an AS boundary router
> >> bit B = 1 ;area border router
> >> #links = 1
> >> Link ID = 18.10.0.6 ;Neighbor's Router ID
> >> Link Data = 0.0.0.3 ;MIB-II ifIndex of P-P link
> >> Type = 1 ;connects to router
> >> # TOS metrics = 0
> >> metric = 8
> >>
> >> I'll keep this in my list of RFC 2328 inaccuracies.
> >>
> >> Thanks,
> >> Acee
> >>
> >>
> >> On Jan 6, 2009, at 11:18 AM, Joakim Tjernlund wrote:
> >>
> >>> In RFC 2328, Chap 12.4.1.1, reads:
> >>> 12.4.1.1. Describing point-to-point interfaces
> >>>
> >>> For point-to-point interfaces, one or more link
> >>> descriptions are added to the router-LSA as follows:
> >>>
> >>> o If the neighboring router is fully adjacent,
> >>> add a
> >>> Type 1 link (point-to-point). The Link ID
> >>> should be
> >>> set to the Router ID of the neighboring router.
> >>> For
> >>> numbered point-to-point networks, the Link Data
> >>> should specify the IP interface address. For
> >>> unnumbered point-to-point networks, the Link Data
> >>> field should specify the interface's MIB-II
> >>> [Ref8]
> >>> ifIndex value. The cost should be set to the
> >>> output
> >>> cost of the point-to-point interface.
> >>>
> >>> o In addition, as long as the state of the
> >>> interface
> >>> is "Point-to-Point" (and regardless of the
> >>> neighboring router state), a Type 3 link (stub
> >>> network) should be added. There are two forms
> >>> that
> >>> this stub link can take:
> >>>
> >>> Option 1
> >>> Assuming that the neighboring router's IP
> >>> address is known, set the Link ID of the
> >>> Type 3
> >>> link to the neighbor's IP address, the Link
> >>> Data
> >>> to the mask 0xffffffff (indicating a host
> >>> route), and the cost to the interface's
> >>> configured output cost.[15]
> >>>
> >>> Option 2
> >>> If a subnet has been assigned to the point-
> >>> to-
> >>> point link, set the Link ID of the Type 3
> >>> link
> >>> to the subnet's IP address, the Link Data
> >>> to the
> >>> subnet's mask, and the cost to the
> >>> interface's
> >>> configured output cost.[16]
> >>>
> >>> I have a hard time figuring out what to do with Option 1 and Option
> >>> 2 for unnumbered
> >>> PtoP interfaces. I don't think either of them applies to an
> >>> unnumbered link so
> >>> I wonder if one should omit both Options?
> >>> However 12.4.1.1 starts with:
> >>> For point-to-point interfaces, one or more link
> >>> descriptions are added to the router-LSA as follows
> >>>
> >>> which could be read as there must always be one or more items and
> >>> as the first
> >>> item needs to have a fully adjacent router you could end up with
> >>> zero items in the LSA for
> >>> a PtoP interface.
> >>> So what should one do?
> >>>
> >>> Jocke
> >>>
> >>>
> >>> _______________________________________________
> >>> OSPF mailing list
> >>> OSPF@ietf.org
> >>> https://www.ietf.org/mailman/listinfo/ospf
> >>
> >
> >
> > _______________________________________________
> > OSPF mailing list
> > OSPF@ietf.org
> > https://www.ietf.org/mailman/listinfo/ospf
> >
>
>
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