Question About Routing Table

[kmc7468]

Consider the above topology. R1 knows that the existence of the red ports (i.e. R1 knows that 192.168.0.1 and 192.168.0.2 are vaild IP address.) However, I think R1 doesn't know the existence of the blue ports, but it just knows the existence of Subnet 2, Subnet 3 and Subnet 4 thanks to the LSU packets from R2, R3 and R4.

In this situation, what is the query result for 192.168.0.4, 192.168.0.5, 192.168.0.8 and 192.168.0.16 in the perspective of R1? I think the result for 192.168.0.4 and 192.168.0.5 should be 3 (R1 -> R2) and the result for 192.168.0.8 should be 3 (R1 -> R2) and the result for 192.168.0.16 should be 10 (R1 -> R2 -> R3). Am I right? If I'm wrong, is there any way for R1 to know the existence of the blue ports?

[Pusnow]

Yes there is some ambiguity here.
You implement this in your own way.

However, you can know exact place of "router_id". We will grade your implementation with router_ids only.

[kmc7468]

Then if R4's router id is 192.168.0.8, then should the query result be 11? (R1 -> R2 -> R3 -> R4)

Also, I wonder how routing table is generated in reality. If we use real OSPF, what router table does R1 have?

[Pusnow]

Yes.

For the second question, honestly I don't know. Feel free to consult RFCs.