Control-plane multicast in IPv6 — which multicast group does RIPng (RIP for IPv6) use for its updates?

Introduction / Context:
Routing protocols in IPv6 rely on specific link-local multicast groups to confine control-plane exchanges to directly attached peers. Recognizing the multicast group for a given protocol allows quick validation with packet captures and simplifies troubleshooting adjacency problems.

Given Data / Assumptions:

• We are examining RIP next generation (RIPng) for IPv6.
• We focus on the destination multicast address used for periodic updates and triggered updates.

Concept / Approach:
RIPng uses the link-local multicast address FF02::9 to send routing updates to all RIP-enabled routers on the local link. Other common control groups are FF02::A for EIGRPv6 and FF02::5/FF02::6 for OSPFv3. Using link-local scope prevents unnecessary propagation beyond the local network segment.

Step-by-Step Solution:
Identify the protocol: RIPng.Recall the IPv6 multicast mapping: RIPng → FF02::9.Choose FF02::9 as the correct answer.

Verification / Alternative check:
Sniff traffic on an interface with RIPng enabled and you will observe UDP port 521 packets destined to FF02::9.

Why Other Options Are Wrong:

• A: FF02::A is for EIGRPv6.
• C/D: FF02::5 and FF02::6 are OSPFv3 control groups.
• E: FF02::1 (all-nodes) is not used for routing protocol updates.

Common Pitfalls:
Confusing RIPng with OSPFv3 multicast groups and forgetting that IPv6 uses different addresses than IPv4 multicast control groups.

Final Answer:
FF02::9