Enabling RIPng on Cisco IOS — identify the correct interface command To enable RIP next generation (RIPng) on an interface after you have already created the RIPng process (for example, Router1(config)# ipv6 router rip CURIOS), which single interface command must you use?

Introduction / Context:
RIP next generation (RIPng) is the IPv6 version of RIP. On Cisco IOS, RIPng follows a two-part configuration: create the RIPng process in global configuration and then enable that process on each participating interface. This is different from IPv4 RIP, which typically uses network statements under the routing process to match and activate interfaces automatically.

Given Data / Assumptions:

• The RIPng process name (for example, CURIOS) already exists via ipv6 router rip CURIOS in global configuration mode.
• You now need the exact interface command to join the interface to the RIPng process.
• Standard Cisco IOS commands are assumed.

Concept / Approach:
For RIPng, enabling the protocol on an interface requires the form ipv6 rip enable under the interface. This attaches the interface to the named RIPng process and begins sending and receiving RIPng updates to the link-local multicast address FF02::9 on UDP port 521. No network statements are used for RIPng on IOS classic.

Step-by-Step Solution:
Create RIPng process: ipv6 router rip CURIOS (already done in the premise).On the desired interface, issue: ipv6 rip CURIOS enable.Verify with show ipv6 rip and show ipv6 protocols to ensure the interface is active in the process.

Verification / Alternative check:
Packet capture on the interface will show RIPng updates to FF02::9 once the interface command is present.

Why Other Options Are Wrong:

• B: ipv6 router rip belongs to global configuration, not interface configuration.
• C/D: These commands enable OSPFv3 and EIGRPv6 respectively, not RIPng.
• E: ripng enable is not valid IOS syntax; IOS uses the ipv6 rip enable form.

Common Pitfalls:
Forgetting that RIPng is enabled per interface and using IPv4-style network statements, which will not work. Also, placing ipv6 router rip under an interface is a mode error.

Final Answer:
Router1(config-if)# ipv6 rip CURIOS enable