OSPF Routing Configuration Flashcards
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Read the first 7 OSPF Routing Configuration flashcards as text
An Aruba switch is configured with OSPF authentication on an interface using 'ip ospf authentication message-digest'. What must match between neighbors for the adjacency to form?
Answer: The MD5 key-id and key string must match on both sides
For MD5 OSPF authentication, both the key-id and the key string must match on neighboring routers; a mismatch in either will prevent adjacency formation.
What is the effect of configuring 'ip ospf priority 0' on an Aruba switch interface participating in a broadcast segment?
Answer: The interface becomes ineligible for DR/BDR election
Setting OSPF priority to 0 makes the router ineligible to be elected as DR or BDR on that segment, useful for leaf switches that should never be DRs.
In an Aruba OSPF deployment, which condition causes an OSPF router to transition from EXSTART to EXCHANGE state?
Answer: Successful election of master/slave and agreement on initial sequence number
The EXSTART-to-EXCHANGE transition occurs after master/slave negotiation completes and both routers agree on the initial DBD sequence number.
An Aruba switch is an ABR between Area 0 and Area 1. Area 1 is configured as a totally stubby area. What routes does the ABR advertise into Area 1?
Answer: Only a default route (Type 3 LSA)
In a totally stubby area, the ABR blocks all Type 3, 4, and 5 LSAs and injects only a single default route as a Type 3 LSA, minimizing the LSDB.
When configuring OSPF virtual links on an Aruba switch, what is the transit area used for?
Answer: To logically connect a disconnected area to Area 0 by traversing another area
A virtual link extends the backbone (Area 0) through a transit area to connect a non-backbone area that lacks a physical connection to Area 0.
Which Aruba AOS-CX command displays the OSPF neighbor state and the dead timer countdown for all OSPF neighbors?
Answer: show ip ospf neighbor
The 'show ip ospf neighbor' command lists all OSPF neighbors with their state, dead time, interface, and router-id.
On an Aruba switch, the OSPF SPF algorithm is triggered after a topology change. What is the purpose of SPF throttling?
Answer: To delay successive SPF calculations and prevent CPU overload during instability
SPF throttling introduces configurable delays between SPF runs so that rapid topology changes don't cause continuous CPU-intensive SPF recalculations.