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If I want to advertise an OSPF default into an NSSA, why does the area haveneed explicit configuration to be eitheradvertise a default route:

  • A Totally Stubby NSSA (advertise a Type 3 summary LSA default route via the no-summary keyword on the abrABR)
  • The ABR must be an/ ASBR (advertise a Type 7 LSA default route - default-information-originate keyword on the ABR)

This is in contrast with the a stub area where the ABR advertises the Type 3 summary LSA default route without extra config.

If I want to advertise an OSPF default into an NSSA, why does the area have to be either:

  • A Totally Stubby NSSA (advertise a Type 3 summary LSA default route via the no-summary keyword on the abr)
  • The ABR must be an ASBR (advertise a Type 7 LSA default route - default-information-originate keyword on the ABR)

This is in contrast with the a stub area where the ABR advertises the Type 3 summary LSA default route without extra config.

If I want to advertise an OSPF default into an NSSA, why does the area need explicit configuration to advertise a default route:

  • A Totally Stubby NSSA (advertise a Type 3 summary LSA default route via the no-summary keyword on the ABR)
  • The ABR / ASBR (advertise a Type 7 LSA default route - default-information-originate keyword on the ABR)

This is in contrast with the a stub area where the ABR advertises the Type 3 summary LSA default route without extra config.

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What is the reason that for a routerIf I want to advertise aan OSPF default route to a nssa areainto an NSSA, why does the area has to be totally nssa (type 3 lsa def route - 'no-summary keyword' on the abr) or the abr hashave to be an asbr (type 7 lsa def route - 'default-information-originate keyword' on the abr)either:

  • A Totally Stubby NSSA (advertise a Type 3 summary LSA default route via the no-summary keyword on the abr)
  • The ABR must be an ASBR (advertise a Type 7 LSA default route - default-information-originate keyword on the ABR)

This is in contrast with the a stub area where the abrABR advertises the defType 3 summary LSA default route without extra config.

Thanks, Silviu

What is the reason that for a router to advertise a default route to a nssa area, the area has to be totally nssa (type 3 lsa def route - 'no-summary keyword' on the abr) or the abr has to be an asbr (type 7 lsa def route - 'default-information-originate keyword' on the abr)

This is in contrast with the a stub area where the abr advertises the def route without extra config.

Thanks, Silviu

If I want to advertise an OSPF default into an NSSA, why does the area have to be either:

  • A Totally Stubby NSSA (advertise a Type 3 summary LSA default route via the no-summary keyword on the abr)
  • The ABR must be an ASBR (advertise a Type 7 LSA default route - default-information-originate keyword on the ABR)

This is in contrast with the a stub area where the ABR advertises the Type 3 summary LSA default route without extra config.

1
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stub vs nssa ospf

What is the reason that for a router to advertise a default route to a nssa area, the area has to be totally nssa (type 3 lsa def route - 'no-summary keyword' on the abr) or the abr has to be an asbr (type 7 lsa def route - 'default-information-originate keyword' on the abr)

This is in contrast with the a stub area where the abr advertises the def route without extra config.

Thanks, Silviu