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Zorluk: OrtaOSPFv2 Network Types and DR/BDR Selection

Match each OSPFv2 network type or interface configuration on a Cisco router to its corresponding DR/BDR election behavior and default Hello/Dead timer settings.

  • Broadcast Multi-AccessElects DR/BDR; default Hello/Dead timers are 10s / 40s
  • Point-to-PointSuppresses DR/BDR election; default Hello/Dead timers are 10s / 40s
  • Interface Priority 0Excludes interface from DR/BDR election; remains permanently in DROTHER state
  • Non-Broadcast Multi-Access (NBMA)Elects DR/BDR; default Hello/Dead timers are 30s / 120s

Cevap

Broadcast Multi-Access matches with 'Elects DR/BDR; default Hello/Dead timers are 10s / 40s'; Point-to-Point matches with 'Suppresses DR/BDR election; default Hello/Dead timers are 10s / 40s'; Interface Priority 0 matches with 'Excludes interface from DR/BDR election; remains permanently in DROTHER state'; Non-Broadcast Multi-Access (NBMA) matches with 'Elects DR/BDR; default Hello/Dead timers are 30s / 120s'.
Each OSPFv2 network type defines specific election rules and default timer values. Broadcast multi-access networks elect a DR and BDR with 10s Hello and 40s Dead timers. Point-to-Point networks suppress DR/BDR elections while maintaining 10s/40s timers. Interface priority 0 explicitly prevents participation in DR/BDR elections, locking the interface into DROTHER state. NBMA networks elect a DR and BDR with extended 30s/120s timer intervals.

Adım Adım Çözüm

1
Determine DR/BDR election requirement for multi-access vs. point-to-point topologies
Broadcast and NBMA networks require DR/BDR elections; Point-to-Point networks bypass DR/BDR elections entirely.
DR/BDR elections prevent the N(N−1)/2N(N-1)/2 full mesh adjacency scaling issue on shared multi-access media.
2
Verify default Hello and Dead timers for each network type
Broadcast and Point-to-Point default to 10s Hello / 40s Dead. NBMA defaults to 30s Hello / 120s Dead.
Non-broadcast topologies use longer timers to accommodate potential WAN delays and manual neighbor definitions.
3
Evaluate explicit priority configuration overrides
An OSPF interface priority set to 0 overrides all Router ID tie-breakers and forces the interface to remain a DROTHER.
Priority 0 is designed specifically to prevent low-capacity or hub-and-spoke spoke routers from becoming DR/BDR.

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OSPFv2 Network Types and DR/BDR Selection Rules
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OSPFv2 Network Types and DR/BDR Selection

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