300-440 Question 50
Single answerA network engineer is configuring a BGP session between two routers to exchange both IPv4 and IPv6 routes. The engineer wants to use a single BGP session to handle both address families. Which configuration step is necessary to achieve this functionality?
- A
Enable BGP Multiprotocol Extensions (MP-BGP) and configure address-family IPv4 unicast and IPv6 unicast under the BGP process.
- B
Configure separate BGP sessions for IPv4 and IPv6 address families on the same peer.
- C
Enable BGP Multiprotocol Extensions (MP-BGP) and configure address-family IPv4 multicast and IPv6 unicast under the BGP process.
- D
Use dual-stack routing without enabling any specific BGP extensions.
Show answer and explanation
Correct answer: A
Explanation
To exchange both IPv4 and IPv6 routes over a single BGP session, BGP Multiprotocol Extensions (MP-BGP) must be enabled. This extension allows multiple address families (e.g., IPv4 unicast and IPv6 unicast) to be configured under the same BGP process. This eliminates the need for separate BGP sessions for different address families, simplifying configuration and reducing overhead.
- A. Correct.
Correct. Enabling BGP Multiprotocol Extensions (MP-BGP) allows the exchange of multiple address families (e.g., IPv4 and IPv6) over a single BGP session. Configuring 'address-family IPv4 unicast' and 'address-family IPv6 unicast' under the BGP process ensures that both IPv4 and IPv6 routes can be exchanged.
- B. Incorrect.
Incorrect. Configuring separate BGP sessions for IPv4 and IPv6 is unnecessary when MP-BGP is used. MP-BGP supports multiple address families over a single session.
- C. Incorrect.
Incorrect. While MP-BGP must be enabled, configuring 'address-family IPv4 multicast' is not relevant for unicast routing. The question specifically focuses on IPv4 and IPv6 unicast routing.
- D. Incorrect.
Incorrect. Dual-stack routing enables devices to support both IPv4 and IPv6 protocols, but it does not facilitate the exchange of routes over a single BGP session. MP-BGP is required for this functionality.