ccna job description

ccna job description.(partial output is omitted here )Neighbor Count is 2, Adjacent neighborcount is 2 //R2 is DR, has 2 neighbors, and forms adjacency with all 2 neighbors Adjacent with neighbor3.3.33 (Backup Designated Router) forms adjacency with BDR Adjacent with neighbor4.4.4.4 and DROTHER Suppress hello for 0 neighbor(s) interface does not suppress Hello packets2 ) DR and BDR have their own multicast address 224.0.0.6.3) DR and BDR election is based on independent networks, that is, DR and BDR election is an interface characteristic of a router, not a characteristic of the whole router. For example, one router can be the DR of a certain multi-access network, and it can be the BDR of another multi-access network.4) DR election principle: The primary factor is the time, which is the Wait time under the OSPF routing protocol enabled interface. If the Hello interval is adjusted by the command ip ospf hello-interval, or the Dead time is adjusted by the command ip ospf dead-interval, the Wait time will follow automatically. This is the maximum time to wait for the DR election to proceed, after which the DR election process will begin. Second, if all interfaces in the network join the OSPF process within the Wait time or re-elect, the interface priority is compared (in the range of 0~255 ), and the router with the highest priority is elected as DR. By default, the interface priority of the multi-access network is 1, and the interface priority of the point-to-point network is 0. The command to modify the interface priority is ip ospf priority priorityo If the priority of an interface is configured to 0, then the interface will not participate in the DR election. If the interface priority is the same, finally compare the router ID, the router with the highest router ID is elected as DR.5) DR election is non-preemptive, but DR can be re-elected in the following cases. 1 The router restarts or deletes the OSPF configuration, and then reconfigures the OSPF process. 2 The router participating in the election executes the clear ip ospf process command. 3 The DR fails. 4 Set the priority of the OSPF interface to 0.6) Only when theDR fails, the BDR takes over the task of DR and then elects a new BDR; if the BDR fails, a new BDR will be elected. so the DR election that people often talk about actually elects the BDR first, then elevates the BDR to DR, and then elects a new BDR. so it is impossible to have a network with a BDR and no DR in a network that needs to elect a DR; however It is possible for a network to have a DR and no BDR.0 [Technical point no].Unlike destination-based routing and policy-based routing schemes, multi-topology routing ( Multi-topologyRouting, MTR) dynamically selects routes based on traffic types, and its most important feature is the ability to separate different traffic (e.g., voice traffic) so that they are routed and forwarded independently in different topologies according to the network structure of this topology. Multi-topology routing does not change the original physical topology of the network.