cisco ccna 1 pdf

cisco ccna 1 pdf.Exam Essentials Don't forget that the command show ip ospf neighbor lists all of the router's OSPF neighbors and the OSPF status, router ID, and interfaces to which those neighbors are connected.In this example, interface Ethernet. three neighbors are connected: 172.16.255.11 (DR).172.16.255.10 (BDR) and 172.16.255.9 (another OSPF router, the DROTHER). Note that the status of DR and BDR is fully adjacency, which is expected since the current router and DR/BDR share routing information with each other. The status of DROTHER is bidirectional, which indicates that it is a neighbor but does not share routing information directly with the current router because it is not a DR or BDRo To learn more details about a particular neighbor, specify its router ID in the command show ip ospf neighborOExperience If two OSPF routers are connected to interfaces with different MTUs, they will not become neighbors; to view the MTUs of neighbors, use the command show interfaces or show ip interfaces o Video 19.09 A multimedia demonstration of using the command show ip ospf neighbor on an OSPF router is included in the companion digital resource to this book. ospf neighbor in a multimedia demonstration.Chapter 19 OSPF Routing 51519.47 The command debugipospfadjThe debug command can be used when performing more complex troubleshooting. To view the process by which a router establishes an adjacency with another router, use the command debugipospfadjoRouter# debugipospf adj172.16.255.11 on Ethernet0z state 2WAY OSPF: end of Wait on interface EthernetO OSPF: DR/BDR election on EthernetO OSPF: Elect BDR 172.16.255.10 OSPF: Elect DR 172.16.255.11DR: 172.16.255.11 (Id) BDR: 172.16.255.10 (Id) OSPF: Send DBD to 172.16.255.11 on EthernetO seq OxlODB opt 0x2 flag 0x7 len 32 OSPF: Build router LSA for area 0, router ID 172.16.255.11This example shows the DR and BDR election process and the process of sharing a link with a DR (DBD ). If the two routers are configured with different OSPF authentication types, for example, one uses plaintext passwords and the other uses MD5, the debug command above will display the following.