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question about redistribution type 5 into nssa


hi ,

assume i have the topology below :


now rip was redistributed into area0

the clear point is

now it will appear as type 5 , , and will not pass area 10 cause it is nssa


now the unclear point

now  on asbr 2,

if i createf a route mapth and matched with it the external routers of ospf 1  and redistributed it into ospf process 2

will it be redistributed ?

my question is , does the asbr2 will convert the type 5 to 7 when it redistributed, or will reject it cause its type is 5


3 Replies 3


Hi Ahmed,

Area 0 will send only LSA 3 ( default route only) in any NSSA.

And regarding your query on LSA 5 to LSA 7 translation, it is always 7 to 5 and never 5 to 7.




Sukanya ,

thanks for ur reply ,

i know that type 5 will never enter nssa ,

but if i make a redistribution of a routes which was type 5 , will it enter the nss as type 7 ?

or only the ospf routes that type 1 2 3 4  and other routing protocols such eigrp , rip  can be redistributed into nssa ?

anyway , i testes it on gns3 and it seems , type 5 cant be redistributed into nssa ,

hint i know that type 5 cant pass nssa , but my question was about redistributiong this type 5 and see if it will pass nssa


Giuseppe Larosa
Hall of Fame Master Hall of Fame Master
Hall of Fame Master

Hello Ahmed,

an OSPF NSSA area is intended to be used for those cases where:

A)-a stub area behaviour is desired with ABR nodes of the NSSA blocking all LSA type 5 and type 4 from entering the NSSA area.   LSA type 3 can be blocked if the area is a totally NSSA (no summary option in ABR area configuration)

B) - within the NSSA area there is a need to inject routes in the OSPF domain and they are injected as LSA type 7

ABR can translate LSA type 7 to LSA type 5 at area border depending on the propagation bit P in the LSA type 7.

The opposite conversion of backbone learned LSA type 5 to type  7 to be injected in the NSSA area does not happen because it is still a stub area in this direction.

So your test confirms the theory as expected.

Hope to help


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