draft-ietf-ospf-abr-alt-04.txt

[Manohar Naidu Ellanti <[e-mail]>]

Is it possible that a router which is attached to multiple areas but not
attached to area 0, can still be an ABR?

For isntance, if a R1 has area 1,2 and 3 . Can it advertise summary-lsa for
area 1 into 2 and 3 ? and similarly summary-lsa for 2 into 1 &3 etc.

Both Cisco and IBM definition cited in the draft don't qualify a router as
ABR unless it is attached to backbone. But isn't that restrictive if one
knows that there is no real area 0 for some applications? Even if one were
to have area 0, in the above example  R1 might have an additional interface
that is not connected to anything but configured with area id 0.0.0.0. The
router may not have any adjacency over the backbone as there is no other
router.

-Ellanti