Examkin

Question

Difficulty: MediumOSPFv2 Neighbor Adjacencies and Router ID

A network engineer is configuring OSPFv2 between two directly connected routers over a GigabitEthernet link. Although physical link connectivity is established, OSPF neighbor discovery fails and no adjacency is formed. Which two interface-level parameters must match on both routers' interconnecting interfaces for an OSPFv2 neighbor relationship to establish? (Select two.)

  1. OSPF Area IDAnswer
  2. B
    OSPF Process ID
  3. OSPF Hello and Dead timer intervalsAnswer
  4. D
    OSPF Router Priority

Answer

The OSPF Area ID and the OSPF Hello and Dead timer intervals must match on both interconnecting interfaces.
For two routers to establish an OSPFv2 neighbor adjacency, specific fields exchanged in Hello packets must match. These include the OSPF Area ID, Hello and Dead timer intervals, subnet mask, and authentication parameters. If either the Area ID or the Hello/Dead timers differ, Hello packets are discarded and the routers remain in a DOWN or INIT state.

Step-by-Step Solution

1
Analyze OSPF Hello packet fields required for neighbor establishment
Identify parameters carried in Hello packets that must agree between neighboring routers.
Routers drop incoming Hello packets if key fields in the Hello header do not match local interface configurations.
2
Verify matching requirements
Confirm that Area ID, Hello timer, Dead timer, Subnet Mask, and Authentication fields must match.
These mandatory matching fields ensure routers belong to the same logical area and communicate on compatible schedules.
3
Evaluate local vs global OSPF parameters
Process ID and Router Priority do not need to match.
Process ID is purely local to the router's IOS memory, and Router Priority determines DR/BDR election roles rather than neighbor eligibility.

Key Concept

OSPFv2 Mandatory Hello Packet Neighbor Matching Parameters
Estimated Time:1m 15s
Rate this question

Topics

OSPFv2 Neighbor Adjacencies and Router ID

More questions from this topic