8.1.3 Link-state database

Type of LSA

(1) Router LSA

* LSA advertised by each router

* Advertisements list all the links and interfaces of a router, indicating their state and outbound cost along each link, and all known OSPF neighbors on that link.

:: Flooding spread within the region from which they originated

* Check: show ip ospf database router xxx.xxx.xxx.xxx

Routing Bit Set on this LSA

The routing bit is not part of the LSA and indicates that the router arriving at this destination is in the routing table.

(2) Network LSA

* Each DR in a multi-access network will generate a network LSA advertisement

* Network LSA lists all routers connected to it, including DR routers themselves.

:: Flooding spread only within the area where the network LSA originated

Show ip ospf database network xxx.xxx.xxx.xxx

since there is no metric field in that network LSA, the cost from the pseudo-node represen in the LSA to any connected rout is always 0

LSA Network Summary LS

Originated by an ABR, an ABR router will send a network summary LSA to an area advertising destination addresses outside that area

show ip ospf database summary xxx.xxx.xxx.xxx

ASBR Summary LSA ASBR Summary LSA

ABR Router Origination

ASBR rollup LSA advertises that the destination is an ASBR route, not a network

show ip ospf databse asbr-summary

Autonomous System External LSA

Originated from ASBR router

LSAs advertising destinations outside the OSPF autonomous system or default routers outside the OSPF autonomous system

External LSA announcements will flood throughout the autonomous system

show ip ospf database external

LSA Group Membership LSA

(7) NSSA External LSA

LSA advertisements originating from ASBR routers in non-stub areas

The NSSA outer LSA advertisement floods only inside the non-pure stub area from which the NSSA outer LSA advertisement originated

show ip ospf database nssa-external

2. Terminal Area Stub