06-03-2010 09:22 PM - edited 03-04-2019 08:40 AM
What is the correct Answer
PS4A will redistribute RIP Subnets as Type 7 into NSSA , and then PS4B will flood Type 7 LSAs throughout the backbone
or
PS4A will redistribute RIP Subnets as Type 7 into NSSA , and then PS4B will translate Type 7 LSAs into Type 5 before flooding throughout the backbone
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06-03-2010 11:07 PM
This one is the correct answer :
PS4A will redistribute RIP Subnets as Type 7 into NSSA , and then PS4B will translate Type 7 LSAs into Type 5 before flooding throughout the backbone
When you perform redistribution in NSSA, it shows up as N1 or N2 routes in NSSA area but when the ABR connecting NSSA to Backbone advertises it further it will change the Type 7 external to Type 5 external and shows up as E1 or E2.
HTH
Hitesh Vinzoda
Please rate useful posts.
06-04-2010 12:02 AM
Hello Sohail,
an OSPF NSSA area is an area that cannot receive LSA type 5 from backbone as any other stub area type.
However, special LSA type 7 can be used by an ASBR node internal to the stub area to inject external routes into the OSPF domain.
LSA type 7 cannot go out of the OSPF NSSA area in which they are generated. Depending on a setting on ASBR node PSA, the ABR node between OSPF NSSA area and backbone area will translate the OSPF LSA type 7 in a an OSPF LSA type 5 that can be propagated to the backbone and to all non stub areas (standard areas)
So OSPF NSSA is a design tool that allows the following:
to minimize OSPF database size
to allow to import routes in the area without the need to import all the external routes in OSPF domain
to even allow to import some routes that will be confined to OSPF NSSA area for local use (if P bit is not set by ASBR)
shortly the correct answer is the second one:
PS4A will redistribute RIP Subnets as Type 7 into NSSA , and then PS4B will translate Type 7 LSAs into Type 5 before flooding throughout the backbone
Hope to help
Giuseppe
06-03-2010 11:07 PM
This one is the correct answer :
PS4A will redistribute RIP Subnets as Type 7 into NSSA , and then PS4B will translate Type 7 LSAs into Type 5 before flooding throughout the backbone
When you perform redistribution in NSSA, it shows up as N1 or N2 routes in NSSA area but when the ABR connecting NSSA to Backbone advertises it further it will change the Type 7 external to Type 5 external and shows up as E1 or E2.
HTH
Hitesh Vinzoda
Please rate useful posts.
06-04-2010 12:02 AM
Hello Sohail,
an OSPF NSSA area is an area that cannot receive LSA type 5 from backbone as any other stub area type.
However, special LSA type 7 can be used by an ASBR node internal to the stub area to inject external routes into the OSPF domain.
LSA type 7 cannot go out of the OSPF NSSA area in which they are generated. Depending on a setting on ASBR node PSA, the ABR node between OSPF NSSA area and backbone area will translate the OSPF LSA type 7 in a an OSPF LSA type 5 that can be propagated to the backbone and to all non stub areas (standard areas)
So OSPF NSSA is a design tool that allows the following:
to minimize OSPF database size
to allow to import routes in the area without the need to import all the external routes in OSPF domain
to even allow to import some routes that will be confined to OSPF NSSA area for local use (if P bit is not set by ASBR)
shortly the correct answer is the second one:
PS4A will redistribute RIP Subnets as Type 7 into NSSA , and then PS4B will translate Type 7 LSAs into Type 5 before flooding throughout the backbone
Hope to help
Giuseppe
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