OSPF Scnario:1: Routing convergence between 3 Routers


We have got some scenario based questions

Here is the Scenrio 1:


Description : Router R1 connected to R2 , Router R2 connected to R3.
There is no connectivity between R1 to R3.
OSPF is running on three Routers

Requirement : R1 Network should be availble at R3 but not in R2.How to prevent Putting Routing information of r1 into R2's Routing table in OSPF?

Scenario :2  R1 - R2 ,

Router R1 connected R2.

Router R1 packet MTU is 1400 and R2 packet MTU is 1500 .. Will neighbor adjacency forms ? Is any convergene issue
happens? what wil happen if MTU of packets in OSPF is not proper?

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RAMU CHAuthor Commented:
Will you plz give insight of Scenario :1


Regarding scenario 1: I have difficulty understanding the requirement - If you want to send traffic from R3 to R1, you have to traverse R2, therefore R2 must know of R1's network, or it will not forward the packets.  There is no way past this using simple OSPF, as OSPF is a hop-by-hop routing protocol (i.e. every router makes its own forwarding decisions, independent of the routing decisions made by other routers).

If you want to use R2 to forward traffic between R1 and R3, and not allow hosts connecting to R2 to be able to reach R1, you can do a simple access list to prevent this.  Or remove the R1 network from OSPF, and build a tunnel between R1 and R3. Or perhaps build a VPN.  Without more details regarding the constraints of the scenario, we will not be able to provice much more assistance.

I hope this helps.

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Ram, is this for a class? There is an EE rule which prohibits us from helping you with class work. This concern is why I was circumspect about the 2nd scenario.

Otto, your statement isn't quite correct. There is a way to do exactly what he's asking for with OSPF. I can give you a clue to point you in the right direction, even if it is for a class: Look into distribute lists. They use access lists but in a completely different way.
RAMU CHAuthor Commented:
Thanks for your time
RAMU CHAuthor Commented:
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