Four Cisco routers (R1, R2, R3, and R4) are connected to a single Layer 2 Ethernet switch on the 192.168.1.0/24 subnet and configured for OSPFv2 single-area routing in Area 0. R1 and R2 have their OSPF interface priorities set to 100 and 50, respectively. R3 and R4 both have their OSPF interface priorities configured as 0. All routers are booted simultaneously and reach steady-state OSPF convergence. What is the expected OSPF neighbor state between R3 and R4 when executing the `show ip ospf neighbor` command on R3?
- 2WAY/DROTHER, because routers configured with a priority of 0 only build full adjacencies with the DR and BDR on broadcast multi-access networks.Cevap
- BFULL/DROTHER, because all OSPF routers on the same broadcast multi-access segment automatically establish full neighbor relationships with every router.
- CINIT/DROTHER, because setting an interface priority to 0 prevents a router from processing incoming OSPF Hello packets from other non-DR routers.
- DEXSTART/DROTHER, because routers with an interface priority of 0 are barred from negotiating Master/Slave parameters during database description exchange.
Cevap
The expected OSPF neighbor state between R3 and R4 is 2WAY/DROTHER because DROTHER routers on a broadcast multi-access network form full adjacencies only with the DR and BDR, remaining in the 2-WAY state with each other.
On a broadcast multi-access network (such as Ethernet), OSPF reduces protocol overhead by electing a Designated Router (DR) and Backup Designated Router (BDR). Routers configured with an interface priority of 0 (DROTHERs) build FULL neighbor adjacencies only with the DR and BDR. Between two DROTHER routers (in this scenario, R3 and R4), bidirectional communication is established via Hello packets, so their neighbor relationship settles permanently in the 2-WAY state (displayed as 2WAY/DROTHER). This is normal operating behavior.
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OSPF Neighbor States and DR/BDR Adjacency Requirements on Multi-Access Networks
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