EIGRP & OSPF Route Manipulation

Hi Experts I have come across this site: http://www.gns3-labs.com/2010/06/26/gns3-lab-exercise-eigrp-ospf-route-manipulation/
as below:

Scenario
 
Company Tapan wants to enable EIGRP AS 1 on R1, R2 and R3. They would like to connectivity between all routers and subnets with the exception of the loopback interface on R1. R3 should NOT be able to communicate with R1’s Loopback interface. Unfortunately Tapan cannot eliminate advertisement of R1’s Loopback interface due to other network dependecies on the other side of R1 (unseen here).
 
Additionally Tapan is planning to segment the networks between R1, R2 and R3 using OSPF. They would like 2 OSPF areas. The OSPF area between R1 and R2 will be the core (Area 0). The area between R2 and R3 will be Area 1.
 
Tapan has determined that they’d like to reach R1’s loopback via OPSF. Tapan would like that R1’s Loopback interface be reachable via OSPF ONLY.
 
Tapan has hired you as the network consultant to configure their required network scenario.
 
When R3 can communicate with R1’s Loopback using the scenario above, your job is done.
 
Because R1 is a bit inflexible, the IP and EIGRP configuration is already in place and CANNOT be changed. Only OSPF can be configured on R1 to R2.


Note:  Correct me if I mis-interpret from the above Scenario and URL, that between R1, R2 & R3 are configured with EIGRP but R1's loopback Address should NOT be added to the EIGRP routing process...Because Im assuming R1 cannot be removed or maybe does not have the capacity to deal with extra processing or something I think....So adding OSPF which separates via Area 0 & 1 is one way of optimizing making more efficient a network in view of R1's Loopback not required in Eigrp ?

Ive never looked at things in this kind of analogy, which is exactly the knowledge Im trying to grasp...............!!!!!!!!!
mikey250Asked:
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rochey2009Connect With a Mentor Commented:
Hi,

I think they mean that you should filter 10.0.0.1 from EIGRP on R3, but allow R3 to see 10.0.0.1 via OSPF.
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ArneLoviusCommented:
have you built this in GNS3 yet ?
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mikey250Author Commented:
Hi, No not yet as did some browsing on that GNS3 link you sent me on a previous thread and after reading a few this is the one I was wondering about....

I've set up 'EIGRP' before and 'OSPF' but it was the explanation of R1's Loopback NOT being part of the EIGRP process due to R1 not upto spec I suppose as an analogy from whoever added this to the site as a learning lab...! So when it mentioned adding 'OSPF' which creates Area 0 & 1, this is what made me think in terms of my comments in my thread to see if Im on the right track....!!that was all..

I understand if R1's loopback was NOT in EIGRP routing process then it would not propagate across the network to also be seen at R3..!
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ArneLoviusCommented:
building it and seeing it in action is what I would suggest
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mikey250Author Commented:
Hi yes I will have to but on configuring OSPF it seems then R3 will obviously see R1's loopback, in which case I understand..!

Its this text as above in main thread that makes me wonder why:

'Company Tapan wants to enable EIGRP AS 1 on R1, R2 and R3. They would like to connectivity between all routers and subnets with the exception of the loopback interface on R1.

This part of the sentence below is what I wanted to make sense of:

R3 should NOT be able to communicate with R1’s Loopback interface.

((UNFORTUNATELY Tapan CANNOT ELIMINATE advertisement of R1’s Loopback interface)) due to other network dependecies on the other side of R1'. - ?
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mikey250Author Commented:
I can only assume as 'Loopback interfaces' provide multiple 'tcp connections', this somehow ties into what the lab is trying to get me to understand..!
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mikey250Author Commented:
Hi rochey,  Yes I can see that as R3 should not see R1's loopback, but it states:

Unfortunately Tapan cannot eliminate advertisement of R1’s Loopback interface due to other network dependecies ...!!

You could be write but as it was a lab Im trying to think about the above specific part of setence and it maybe that yes you are right as just wanted to clear this up ie a learning curve for me...
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Marius GunnerudConnect With a Mentor Senior Systems EngineerCommented:
Just to support Rochey's statement.  If you read further down in the question:

Tapan has determined that they’d like to reach R1’s loopback via OPSF. Tapan would like that R1’s Loopback interface be reachable via OSPF ONLY

This statement indicates that you should be filtering the route from EIGRP but allowing it in OSPF.

Cisco have a habit of wording their questions like this.  First they say one thing and then they change their mind and say they want to do away with the previous requirement and go with another option.
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mikey250Author Commented:
Hi Mag03,  Yes I did realise this but because it used words like 'eliminate and other network dependencies', it made me think there was something else.  Ok that is fair enough thats what I wanted..
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mikey250Author Commented:
My own comment is just to bring clarity to my own main thread question in relation to both Experts due to specifically what I was actually asking..Sound advice..
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