Not-so-stubby-area (NSSA)

Beginning with software release K.12.xx, this area is available and connects to the backbone area through one or more ABRs. NSSAs are intended for use where an ASBR exists in an area where you want to control the following:
  • Advertising the ASBR's external route paths to the backbone area

  • Advertising the NSSA's summary routes to the backbone area

  • Allowing LSAs from the backbone area to advertise in the NSSA:
    • Summary routes (type-3 LSAs) from other areas

    • External routes (type-5 LSAs) from other areas as a default external route (type-7 LSAs)