Seven types of LSA in OSPF (link status announcement)

Seven types of LSA (link status announcement) in OSPF are also necessary to define multiple types of LSA announcements because the OSPF protocol defines multiple router types. For example, a DR router must advertise a multi-channel access link and all routers connected to this link, while other types of routers
You do not need to advertise this type of information. Seven types of LSA for OSPF: www.2cto.com 1. Router LSA is generated by all routers in the region and can only broadcast flood in the region. These basic LSA announcements list all the links and interfaces of the vro and indicate their statuses and directions along each link.
The cost of outbound traffic. 2. The Network LSA is generated by the DR or BDR router in the region. The packets include the link information of the router connected by DR and BDR. The Network LSA only carries out flooding in the area where the network LSA is generated. Www.2cto.com 3. The Network summary LSA (Network summary LSA) is generated by the ABR and can notify the routers in the region to route information outside the region. This LSA can also be used to advertise the default routes outside a region but still in an OSPF autonomous system.
If an ABR router receives multiple network summary LSAs from other ABR routers in the backbone area
The router selects the LSA with the lowest cost in these LSA announcements, and notifies the LSA of the lowest cost to the non-backbone areas connected to it. 4. ASBR summary LSA (ASBR summary LSA) is also generated by the ABR, but it is a host route pointing to the ASBR router address. 5. The external LSA (Autonomous system external LSA) of the Autonomous system is generated by ASBR, which tells the router of the same Autonomous Region to the path of the external Autonomous Region.
The external LSA of the autonomous system is the only LSA announcement that is not associated with a specific region and will conduct flooding throughout the autonomous system. 6. Group membership LSA * currently does not support OSPF (MOSPF Protocol). 7. NSSA External LSA (NSSA External LSA) www.2cto.com is generated by ASBR, almost the same as the LSA 5 announcement, but The NSSA external LSA announcement is only issued by The NSSA external LSA announcement
Flood occurs in non-pure peripheral areas. In The NSSA region, when one vro is ASBR, the LSA 5 packet must be generated, but The NSSA cannot contain the LSA 5 packet,
All asbrs generate LSA 7 packets and send them to vrouters in the region. * There is only one exception. One type 3 is used on each ABR router to advertise the default route. Flood allowed in each region
LSA type area type 1 & 2 3 & 4 5 7 backbone areas allowed allow not allow non-backbone (non-peripheral) allow allow not allow * only one exception, one type 3 is used on each ABR router to advertise the default route. 1. Peripheral Area: (Stub Area) The AS external notice (LSA 5) is not allowed to carry out flood attacks within it. Network usage Summary of the ABR router at the border of the Peripheral Area
LSA (LSA 3) notifies this region of the default route, and this default route is not advertised to the outside of this region. Router (config-route) area 1 stub // set Area 1 to the ending area
2. Full peripheral region: (Totally stub) use the default route to reach the destination address outside the OSPF autonomous system, and use the default route to reach all external addresses in this region
The target address. The ABR router in the completely ending area not only blocks LSA 5, but also all summary LSA-in addition to notifying the default route
The Type 3. www.2cto.com Router (config-route) # area 1 stub no-summary // set Area 1 to the completely ending area.
Type 3 is replaced by the default route, and NO-summary is used to simplify type 3 and 4 with the default route. 3. Non-pure ending area (Not-so-stubby-area) allow external routes to be advertised to the OSPF autonomous system while retaining the peripheral region features of the other parts of the autonomous system. ASBR will
Launch type 7 LSA to advertise those external networks. These NAAS external LSA will be flooding throughout the NAAS region and blocked on the ABR.
The ABR will convert type 7 to type 5 and advertise it to other regions.