OSPF protocol troubleshooting 3

OSPF protocol troubleshooting 3 24. Why is the LSDB in the same region the same in OSPF and how is the route table derived? There are five types of OSFP groups: the first is the primary HELLO data packet, the two sides establish a neighbor relationship, and the second is the description data packet of the database. During this period, the master and slave devices are selected and route information is exchanged, therefore, the LSDB in the same region is the same, in order to select an optimal non-ring path. At the same time, it also carries a lot of LSA header information, when a router does not have this LSA in its own routing information library, it sends a link status request. The route table is calculated based on the SPF algorithm. 25. What is the role of virtual links in OSPF? It is mainly used to fix discontinuous regional connections. This is mainly a design problem, so the design area is actually a bad design. 26. What are link IDs and advertised router IDs? What are their differences with router IDs? In OSPF, DR and BDR are only attributes of an interface or port, rather than a router. The link ID is used to identify the link. In router LSA, the link ID is the router ID. A Router ID is the router ID that advertises the route. They are the same as the router ID in a special LSA. 27. Can the MTU at both ends establish a neighbor if it does not match? If a neighbor can be established, what kind of status will the neighbor be in? The establishment of OSPF neighbors does not involve MTU information, but the establishment of OSPF neighbors may be affected. It may cause the neighbor to stop in the EXSTART/EXCHANGE status. 28. How does OSPF ensure reliable data transmission? OSPF uses a reliable mechanism such as inspection, serial number, and aging time to ensure reliable data transmission. Link status confirmation is also one of them. 29. If a port is closed, Will OSPF notify the route information on this port? If an interface is not started, will the OSPF process start? No. OSPF does not advertise the route entry information on the disabled port. If no interface is started, OSPF cannot be started. 30. Will OSPF advertise an interface address when it is configured with a layer-2 address? Under what circumstances? This depends on what the situation is. If the L2 address and the primary address do not belong to the same region, OSPF will not advertise the L2 address, if the L2 address and the primary address are in the same region, OSPF will advertise the route entry information. 31. If an ABR is not connected to Zone 0, will this generate four types of LSA? No. An ABR must be connected to Region 0. It is not connected to Region 0 and cannot generate four types of LSA.