I have a very specific problem on an unnumbered point to point link for
an IPsec tunnel. This link is associated to another IP interfaces
address on the device to borrow an IP (source) address for the packets.
The link itself (as being unnumbered has no IP subnet assigned).
Which option of the following in "12.4.1.1. Describing point-to-point
interfaces" would apply for the stub area advertisement?
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 would read that option 2 would not apply as the link is unnumbered
therefore no subnet has been assigned to that link (even though an
associated address is set).
For my specific PtP case the neighbor address is known as the tunnel
endpoint is manually configured (though not in any local network)
therefore I can use this for the Stub entry.
Is that reading correct?
What if we are talking about a virtual link?
Although a virtual link acts like an
unnumbered point-to-point link, it does have an associated IP
interface address. This address is used as the IP source in
OSPF protocol packets it sends along the virtual link, and is
set dynamically during the routing table build process.
Is has no known neighbor router IP as it knows only the neighbor routers
router-ID (not IP) and it has no subnet assigned to the virtual link
(though an associated IP). How should the stub advertisement look like -
which of the options apply?
Regards
Juergen Arlt
-------------------------------------------------
Juergen Arlt
Nortel GmbH
Senior Network Solutions Engineer
Global Network Technical Support
Mittlerer Pfad 26
70499 Stuttgart
Germany
Tel: +49 (711) 1394361
ESN: 595 4361
Fax: +49 (711) 1394330
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