OSPF issue

Unanswered Question
Mar 4th, 2007

Hi Expert,


As I know, OSPF stub area is used to reject type 3,4,5 LSA

Type 5 LSA is considered as External route

Type3 LSA is considered is Inter-area route

How about Type 4 LSA ?


According to below connection, can I form virtual link between Router Area3 to Area0 ?

Router Area3 <-> Router Stub area 2 <-> Router Area0 <-> Router Rip

I have this problem too.
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Amit Singh Sun, 03/04/2007 - 09:02

Hi Friend,

Q1: Type $ LSA is also blocked in a stub area.Type 4 LSA is sent by the ABR router to advertise the route to reach the ASBR.

Q2.No, the virtual connection will not work as the transit area for the virtual connection cannot be a stub area.

HTH,Please rate if it does.

-amit singh

Richard Burts Sun, 03/04/2007 - 13:43


Your original post asserts that type 3, 4, and 5 LSAs are not in stub area. But type 3 LSAs are permitted in stub areas. It would be totally stub areas that do not have type 3, or 4, or 5 LSAs.



acbenny Sun, 03/04/2007 - 18:36

For virtual link connection -

Is it mean that transit area can not be

Stub, Totally stub, NSSA, NSSA totally ?

o_dogorshom Mon, 03/05/2007 - 01:52


Stub areas are the areas that have single exit. and for that it doesn't accept type 5 LSAs which are for external routes, and also it doesn't accept type 4 LSAa which contains the information how to reach the ASBR and because you don't need to know about the External routes it is as well not needed to reach the ASBR who will take outside, for that type 4 and 5 LSAs are blocked and only the accepted are type 3 LSAs which are called summary LSA and contains defualt route towards the ABR or a summary of inter-area routes.

the totally stuby area blocks also type 3 LSAs.

and virtual link can't be configured in stub, totally stuby or NSSA areas.


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