Refer to the exhibit. A customer network uses OSPFv2 and MP-BGP protocols. A network administrator installs a new Cisco Nexus Switch in the data center but experiences a BGP RIB failure. Which…

Question

Exhibits

Options

• AChange the administrative distance of OSPF to 220
• BConfigure the route as a BGP backdoor
• CUse a filter list for OSPF to filter both routes
• DImplement next-hop-self

• A
  81% (22)
• B
  7% (2)
• C
  7% (2)
• D
  4% (1)

Explanation

Option A is correct because a BGP RIB failure occurs when BGP learns a prefix that another protocol - here OSPFv2 - has already installed with a lower administrative distance (AD). By default, OSPF has an AD of 110, which beats iBGP's 200, so BGP cannot insert its route into the RIB. Raising OSPF's AD to 220 makes BGP the preferred source, resolving the conflict.

Why the distractors are wrong:

• B (BGP backdoor) reverses the logic - it raises eBGP's AD to 200 so an IGP route is preferred over eBGP, which is the opposite of what's needed here.
• C (OSPF filter list) might seem plausible, but filtering "both routes" would remove BGP routes as well, which doesn't resolve the failure - it just removes visibility.
• D (next-hop-self) fixes a next-hop reachability problem in iBGP topologies where the external next-hop isn't advertised inside the AS; it has nothing to do with AD conflicts.

Memory tip: Think "RIB failure = AD war." OSPF (110) naturally beats iBGP (200), so BGP loses and marks the route as a RIB failure. The fix is to demote OSPF past 200 - setting it to 220 lets BGP win the war and install its routes.

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