OSPF: N1 and N2 routes

waru

Hi,

N1 and N2 routes are obviously external routes from a NSSA. However do they show up as N1 and N2 in the routing table of a router in the NSSA or do they just show up as O ?

Cheers
Waru

dtlokee

Yes the N1 and N2 type routes will show inide the NSSA area (every router in the area) but they will be converted to regualr E1 and E2 when the ABR sends those routes into other areas.

networker050184

The ASBR performs the type 7 to type 5 LSA translation so to routers outside of the area the routes only show as a type 5 LSA which is marked as O E1/2. They are still type 7 LSAs inside the NSSA and are represented by O N1/2.

EDIT: Looks like dtlokee beat me to the punch!

waru

cheers, so would I be right in saying that only the following ospf routes would not be seen in a NSSA: E1 and E2?

networker050184

No type 5 LSAs are allowed into the stub area, so no external routes.

If you look at the LSA types it will become clear.

OSPF NSSA

Mrock4

networker050184 wrote:

The ASBR performs the type 7 to type 5 LSA translation so to routers outside of the area the routes only show as a type 5 LSA which is marked as O E1/2. They are still type 7 LSAs inside the NSSA and are represented by O N1/2.

Correction...The ASBR does not translate from type 7 to type 5. The ASBR passes the Type 7 into the NSSA, then which is translated by the NSSA ABR to a Type 5. I know what you meant, just wanted to clarify.

networker050184

Unless of course the ABR and ASBR are the same router

Mrock4

networker050184 wrote:

Unless of course the ABR and ASBR are the same router

Now you're stretching...all in good fun.

networker050184

Yes I meant ABR thanks for the clarification.