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LSAs Types

Hi ,

Could any help me on different types of LSAs in OSPF. I would like to know whats the content of these LSAs Type 1 , Type 2 , Type 3 , Type 4 , Type 5 and Type7.



Community Member

Re: LSAs Types

Type 1 is a router LSA. They are produced by every router and are flooded only within the area in which they originated.

Type 2 is a network LSA. They are produced by the DR and represents a pseudonode (virtual).

It lists all attached routers and is only flooded within originating area.

Type 3 is a Network summary LSA. They are produced by an ABR. They are sent into a single area to advertise destinations outside it.

Type 4 is an ASBR Summary LSA. They are produced by an ABR. They are the same as a type 3 but advertise the destination to an ASBR not a network. This will be a host address as it is a route to a router.

Type 5 is an AS External LSA . Produced by an ASBR and advertise external destinations (outside the OSPF AS) or a default route. They are flooded within the AS.

Type 7 is a NSSA External LSA. Originated by an ASBR within a not so stubby area. It is like a type 5 but instead of it being flooded within the AS it is only flooded within the NSSA where it came from.

I hope this is of help

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