cisco ccna 2 9.2.3.6

cisco ccna 2 9.2.3.6.Overview of OSPFKeeping in mind that OSPF is an open standard protocol, it or EIGRP should be used in larger Layer 3 networks: it supports hierarchical routing (two layers - backbone area and other areas) and uses overhead as a metric. :How OSPF worksBe able to determine the ID of an OSPF router based on the active interface and the configured loopback interface. understand how OSPF routers establish adjacencies and know which of their configurations must be the same remember the difference between bidirectional and full adjacency states. know how LSAs are propagated and the multicast address used to transmit LSAs. Know the differences between DR, BDR, and DROTHER and in what environments DR and BDR are used: broadcast and multiple access segments. Be familiar with how DRs and BDRs are elected and be able to determine which routers will play DR and BDR roles based on the output of the show command and network schematics.Familiarize yourself with basic OSPF configuration of Cisco routers: simulation questions may require you to create basic OSPF configurations on multiple (possibly 3.5) routers as well as troubleshoot OSPF. The process ID is only locally meaningful and takes a value in the range 65535O Use a different process number for each OSPF instance (autonomous system) to which the routing device is connected. Don't forget that in the command network. use a wildcard mask to add the interface to the area. understand why loopback interfaces are typically configured on OSPF routers. Become familiar with the OSPF routing metric and the load balancing methods used by this routing protocol.OSPF TroubleshootingThe CCNA exam may require you to troubleshoot OSPF configurations. Be sure to familiarize yourself with the various OSPF-related show and debug commands. Be able to identify OSPF routes in the routing table and their overhead. Understand the output of the show and debug commands and be able to identify problems that result in failure to establish adjacencies: inconsistent timers, incorrect authentication configuration, and not belonging to the same subnet o19.5 Authentication SynopsisOSPF is an open standards-based IP routing protocol that uses overhead as a metric. It uses Dijkstra's algorithm (SPF) to provide a loop-free routing topology, uses incremental updates, and supports route summarization. OSPF uses a hierarchical design containing two layers: the backbone (area 0) and the area connected to the backbone. The disadvantage of OSPF is that it requires more memory and CPU cycles and is more difficult to configure and troubleshoot than distance vectoring protocols.Each OSPF router has a router ID, which is the largest loopback interface IP address or the largest active interface IP address. The LSA is used to establish an adjacency, which is sent as a multicast with a 10-second sending interval. In the LAN segment, the DR (router with the largest router ID) and BDR are elected to propagate the routing information o OSPF routers use 224.0.0.6 to send the information to the DR/BDR o OSPF is connection-oriented and must use ACK to acknowledge the routing information when it is received. DR uses multicast address 224.0.0.5 to share information with neighbors.