Ajay,

> Hi,
> As per RFC 2328, Point to Point links can be described in 2 ways as Type 3 Links.
> Option 1 - Neighbor's IP Address + Host Mask
> Optiion 2 - Network + Mask (Subnet).

> Consider 2 Routers A ---- B
> A's IP Address - 21.1.1.1 / 24
> B's IP Address - 21.1.1.2 / 24

> If Router B advertises uses Option 1 above, it will advertise a Type 3 Link with Link Id - 21.1.1.1 and Link Data as 255.255.255.255 in its Router LSA..

> When A performs its SPF, it will perform the processing required for Stub networks. In such cases, what route will A add to its routing table.

> Can the SPF detect that 21.1.1.1 is is own Interface IP Address?

Yes, this can be done.

> A has a connected Route 21.1.1.0 / 24. Since 21.1.1.1 / 32 is a more specific route,
> will Router A add this route to its Routing Table with next hop as 21.1.1.2?
> (This is obviosuly a problem).

As soon as A correctly identifies packets destined for itself
(21.1.1.1), which it should do, this is not a problem.

> What should be the behavior in such cases?

Depends on the preferences. One could prefer not even install
OSPF routes to the calculating router's own IP addresses.
What should be kept in mind is ABR functionality, i.e.,
if A is an ABR, that /32 should be announced in a summary-LSA.

Alex.

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