MP-BGP IPv6 Route Exchange Troubleshooting
Short answer
C Enable IPv6 unicast-routing, configure IPv6 CEF, and define the IPv6 unicast address family with neighbor activation and network advertisement on router R2.
Question
Key Takeaways
The question tests the distinction between global IPv6 routing enablement and BGP-specific address-family activation; the trap is overlooking the need for explicit neighbor activation within the IPv6 context.
This question examines MP-BGP configuration requirements for exchanging IPv6 routes, specifically identifying the necessary address-family and network commands. The correct solution involves enabling the IPv6 unicast address family on router R2.
Common mistake: Many candidates select 'ipv6 cef' (Option D) assuming it enables all IPv6 features, but CEF alone does not activate BGP address families or route exchange capabilities.
Expert Analysis
Why the Answer Is Correct
Router R2 has an established BGP neighbor with R1, but they are only exchanging IPv4 routes. To exchange IPv6 routes using MP-BGP, R2 must be configured to support the IPv6 unicast address family. Option C provides the complete necessary configuration: it enables IPv6 routing globally, ensures CEF is active for IPv6, enters the BGP configuration mode, defines the IPv6 unicast address family, advertises the specific IPv6 prefix via the 'network' command, and activates the neighbor for this address family. Without these steps, BGP will not process or advertise IPv6 routes.
Why the Other Options Are Wrong
Options A and B appear identical in the text provided ('ipv6 unicast-routing'), which suggests a typo in the exam dump or that they represent partial configurations insufficient for BGP operation. Even if distinct, simply enabling 'ipv6 unicast-routing' is a prerequisite but does not configure BGP itself. Option D, 'ipv6 cef', enables Cisco Express Forwarding for IPv6, which is required for efficient packet switching but does not instruct BGP to enter the IPv6 address family or exchange routes. It is a supporting feature, not the primary mechanism for route exchange.
Community Comment Notes
Community consensus strongly supports Option C. One user noted that Option C includes the critical 'address-family ipv6' block with neighbor activation, stating "And of course the other commands in option C are correct." Another comment confirmed this is a repeated question where C is the right answer, highlighting the importance of recognizing standard MP-BGP IPv6 templates.
Exam Strategy
When troubleshooting MP-BGP, always check both the global IPv6 routing status and the specific BGP address-family configuration. Ensure that neighbors are explicitly activated within the relevant address-family context (e.g., 'neighbor x.x.x.x activate' under 'address-family ipv6 unicast').
Frequently Asked Questions
Why is 'ipv6 unicast-routing' alone not enough for BGP?
Does 'ipv6 cef' activate BGP IPv6 routes?
Community Votes
100% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 3 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 3
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alexnadal99 👍 6 Answered CCorrect. It is the only option were this below is included. ipv6 unicast-routing ipv6 cef ______ ______ ______ address-family ipv6 network 2001:DB8:128::2/128 neighbor 2001:DB8:1::1 activate And of course the other commands in option C are correct.
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dapardo 👍 3 Answered CThis question is repeated. Yes right one is C.
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Sammy3637 👍 1 Answered Clooks like a duplicate question
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