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OSPF Design NSSA

I had this question after viewing OSPF Design NSSA.

In the above scenario how can i insert the 20.20.20.0/22 network into the existing NSSA Area.
Can i have the same area for this network or should i use different area for this new network.

Is it recommended to use static route or use OSPF only.
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SrikantRajeev
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SrikantRajeev
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1 Solution
 
PredragNetwork EngineerCommented:
I am not sure what are you asking.

If you want to advertise 20.20.20.0/22 (typically external route according to IP address range) into nssa area default route should do it's job if there is no more specific route or lower AD - default route will be used. The point of having stub and nssa is not to advertise LSA type 5 (for nssa and type 4 LSA) into area stub area. If you want LSA messages type 4 or 5 to be advertised into stub area  you need to convert nssa area to proper area (stub or normal).
If you want add that IP address range in nssa, just configure it on router and advertise it to OSPF, other areas will receive route through OSPF process.

But again... I am not sure what you are trying to achieve.
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SrikantRajeevAuthor Commented:
Thanks
I just wanted to add the IP range 20.20.20.0/22 into the NSSA.
At present the NSSA Area has the network 10.10.10.0/22 & it is summarized at the ABR device represented in the diagram.
So from your explanation, i need to just advertise the IP Segment 20.20.20.0/22 in the router#1 & router#2 represented in my diagram.

Let me know if my understanding is right.
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PredragNetwork EngineerCommented:
Then just add network the same way you added 10.10.10.0/22 previously.
(Assign it to interface (physical or SVI) and advertise it in OSPF by network command.)
Is it NSSA or not, it does not make any difference. Treat it like any other network that should be propagated in OSPF.
:)
Networks from stub and nssa areas are always propagated to normal areas (but may not be the other way around, that's why default route is advertised into stub area ("ultimate summarization" :) to replace any more specific route)).

Summary route only "hides" more specific networks than 10.10.10.0/22, however if there is a network outside IP range that was summarized, network outside summarized IP range will still be advertised (if it is not filtered).
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SrikantRajeevAuthor Commented:
Thanks
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PredragNetwork EngineerCommented:
You're welcome.
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