Solved: Totally NSSA and ASBR

mahesh18 · ‎05-22-2012

Hi all,

Need to confirm few things below

Router R3 is ABR and connected to R1.

R1 is ASBR as it is redistributing EIGRP into the OSPF.

This is what i did

R3

area 11 nssa no-summary -------------This makes it Totally NSSA right?

R1

area 11 nssa.

this is what i saw as soon as i config R3 with

area 11 nssa no-summary and did sh ip ospf

R3 shows ABR and ASBR ????????????????????????

So this means when we make ABR to totally NSSA then it also becomes ASBR as it is redistributing LSA type 5 into OSPF domain????

Thanks

MAhesh

Giuseppe Larosa · ‎05-23-2012

Hello Mahesh,

yes with OSPF NSSA area the ABR between (0, NSSA-area) has the duty to convert LSA type 7 generated by the ASBR internal to NSSA area (R1 in your case) to OSPF LSA type5 and in this it becomes an ASBR.

Conversion is performed if the propagation bit P in the LSA type 7 allows for it. This gives you the capability to generate LSA type 7 that are not translated at area border.

Note that this happens also for NSSA area not only for totally NSSA

Hope to help

Giuseppe

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