Assume all router-IDs are properly configured, and global IPv6 addresses are used to establish eBGP sessions. Which of the following configurations is required on router A so that router B can…

Question

Options

• Agroup "IPv6_iBGP" family ipv6 next-hop-self peer-as 65540 neighbor 2001:DB8:2::2 exit exit
• Bgroup "IPv6_iBGP" next-hop-self type internal peer-as 65540 neighbor 2001:DB8:2::2 exit exit
• Cgroup "IPv6_iBGP" family ipv6 peer-as 65540 neighbor 2001:DB8:2::2 exit exit
• Dgroup "IPv6_iBGP" family ipv6 type internal neighbor 2001:DB8:2::2 exit exit

• A
  75% (30)
• B
  15% (6)
• C
  5% (2)
• D
  5% (2)

Explanation

Option A is correct because it includes the two essential elements for this scenario: family ipv6 (enabling the exchange of IPv6 prefixes over the BGP session) and next-hop-self (instructing Router A to advertise itself as the next-hop to Router D, rather than passing through the eBGP-learned next-hop from Router B, which Router D likely cannot reach). Without both of these, Router D will either not receive the IPv6 routes at all, or receive them with an unreachable next-hop.

• Option B is wrong because it omits family ipv6 - without this, the iBGP session will not carry IPv6 address family prefixes, so no IPv6 routes are exchanged.
• Option C is wrong because it omits next-hop-self - Router A learns routes from Router B via eBGP with Router B's address as the next-hop, and since Router D has no path to that external next-hop, traffic cannot actually flow.
• Option D is wrong for the same next-hop-self reason as C, and also omits peer-as, making the peer relationship ambiguous or invalid depending on the platform.

Memory tip: Think "IPv6 iBGP needs two F's" - Family (to speak IPv6) and Forward yourself (next-hop-self), so your iBGP peer doesn't get stuck chasing an unreachable external next-hop.

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