Daily notes--OSPF Nssa area and discontinuous region Unicom

OSPF basic theory, single-zone configuration OSPF multi-zone configuration, ABR, OSPF route type internal: declared by network mode, Intra-area inter-area external: Declared by means of redistribution ( Redistribute|import-route) #5类LSA可以在 anywhere in the OSPF network; Special Areas: Class 5 Lsa-stub: 4 classes and 5 classes are not allowed; The ABR in this area automatically generates a default route to the zone (inter-area Requires a stub configuration for all routers in the zone; OSPF 1 area stub-totally stub: The 3, 4, and 5 types of LSA are not allowed in the fully stub zone, but there is a special 3 class LSA, which means that the default route only needs to be in the stub area at this time ABR configuration on: OSPF 1 area stub no-summary Normal zone:-lsa Type 1-any OSPF router will be generated, will be generated in each area of the connection, the route is calculated by the 1 class LSA is the INTRA-A REA route; 2-3-only ABR can produce (0[intra-area/inter-area]--> not 0; non-0[intra-area]-->0;) represents routes between regions, and in transit, the LSA is changed: every An ABR, the "Advertise router" will change once. 4-5-only ASBR can be generated, an external route is represented, and the LSA is not changed during transmission; Prefix/mask [Preference/cost] type, via Next-hop, interface------------ -------------------------------------------------------OSPF Special Zone: Nssa:no so stub area, which does not allow the 4, 5-class LSA, but allows external routing to exist; The external route behaves as a 7-class LSA. The Class 7 LSA can only exist in the NSSA region. That is, only 1, 2, 3, 7-Application Scenario-configuration: NSSA is configured on every router in the region. OSPF 1 Area Nssa The ABR in this region also automatically generates a default route to the Nssa region, and isThe 7-Class LSA representation, and the ABR of the zone translates the external route represented by the 7 class LSA into the 5 class LSA, allowing the other OSPF region (normal) to obtain the external routing entry, and in the case of a one-way conversion of 7 to 5, only the ABR with the RID large in the NSSA region can be The final conversion. Compared to NSSA, totally NSSA is also a less detailed route for the 3-class LSA representation, i.e. only 1, 2, 7, or only the default route that is automatically generated by the ABR in the NSSA area, which is a 7 class LSA, which can be used to communicate the NSSA zone to other regional and external routes; configuration Command: Just need all the ABR in the NSSA area to do it. OSPF 1 area nssa no-summary OSPF discontinuous zone solution:-Constructs the ABR so that routes in the non-backbone region exist as internal routes in other regions; #在连接多个非骨干区域的路由器上, establish an OSPF neighbor relationship with zone 0 is by re-linking a "physical link" way; #virtual the OSPF neighbor relationship established by the-link is always part of region 0, and the virtual link is built on the region where the underlying real link is needed to transmit the OSPF message (hello, etc.). Therefore, if the underlying "traversal/transmission area" is unstable, it will cause the upper layer of "virtual link" instability, the backbone of the entire network to affect the stability of the region. Therefore, it is generally not recommended to use this method. If you have to use it, it's just a temporary solution. -Configuration: The following command is configured on the true ABR of the router and transmission area that wants to be the ABR: R1:OSPF 1 areas vlink-peer 4.4.4.4//Here, must be rid of the opposing router R4:OSPF 1 area vlink-peer 1.1.1.1//must not be written to the interface IP premise of the other device, it must be ensured that: the OSPF neighbor relationship in zone 14 is intact; display OSPF Vlink//view OSFP neighbor relationships built on the virtual link locally-build different OSPF processes and let The delivery of the route is rendered in the form of an external route. R4: Create a new OSPF process-OSPF 8 OSPF 8//R4 establishes a neighbor relationship with R7 through OSPF 8. Area network 192.168.47.4 0.0.0.0 quit import-route OSPF 1 OSPF 1//R4 establishes a neighbor relationship with R1 through OSPF 1. Import-route OSPF 8 OSPF LSA analysis:

Daily notes--OSPF Nssa area and discontinuous area Unicom