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OSPF & LSA propagation

OSPF is running throughout the network & user wants to minimize the LSA progation in and out of area 1, which ospf feature would be best suited for the goal?

Rtr1--- RIP ---Rtr2--AREA_1 ---Rtr4 ----AREA_0----Rtr9---AREA 3---Rtr10---|

Selections are :
A. STUB
B. TOTALLY STUB
C. NSSA
D. TOTALLY NSSA
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totaram
Asked:
totaram
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1 Solution
 
arnoldCommented:
Assignment? What are your thoughts on the possible answer and why?
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SouljaCommented:
Totally Stub. LSAs 3, 4 and 5 are not advertised in totally stub area, only the default summary routes are advertised in this area to reduce the routing table size and processor overhead also.
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rfc1180Commented:
I am going to have to disagree with the answer, the correct answer should be D, Totally NSSA;
You have a router in the network that has one interface utilizing the RIP protocol and another that is utilizing OSPF. Router2 is ultimately an NSSA ASBR that will send a type 7. Type 3, 4, 5, can not propagate inside an area that the ABR has already been labeled as a totally stubby, so you are forced to make the ABR a totally NSSA.

Additionally, plagiarism is frowned upon in this community, if you are going to copy and paste from another site, at least provide the link for the original authors work.

http://www.computerfreetips.com/Cisco_router_tips/Totally-Stub-Area.html

Billy
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SouljaCommented:
Well, how about that! U da man rfc.

http://www.sadikhov.com/forum/index.php?showtopic=183627

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totaramAuthor Commented:
Thanks.. Just a little digression.. What is the key difference between Stub and toally stub network.. To me both advertise a ext route into the stub area via a default summary-route. Any stark difference that sets both apart??
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rfc1180Commented:
THe key is that: "external routes are not propagated inside the stub areas and even inter-area routes (summary routes) are not propagated inside the totally stubby areas"

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094a74.shtml?referring_site=bodynav#stubandtotallystubareas


Billy
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totaramAuthor Commented:
In your above example (from cisco), by external route you mean the routes coming in from RIP Domain...

Somehow, in the example, ext route meant anything that is not connected with backbone area 0.
:
http://www.computerfreetips.com/Cisco_router_tips/Totally-Stub-Area.html

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rfc1180Commented:
For stub area, I meant external routes that were redistributed from other protocols, so, with that said, an area that has a single transit to area 0 will block  type 5/7 LSA types and will receive type 3 and4 LSA’s with a default route (0.0.0.0/0).

A totally stubby area blocks all other types of LSAs 3, 4, 5, and 7, etc. (Types 1 and 2 are contained only in an area and do NOT traverse outside that area) and will receive a default route. Hope this helps.

Billy
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