Which IPv6 multicast address is designated for all routers?

The correct address designated for all routers in IPv6 is indeed FF02::2. This is a link-local multicast address that is utilized specifically for routing protocols to communicate with all IPv6 routers in a local segment. When a packet is sent to this address, it is delivered to all routers within the same network link, making it essential for operations that require coordination or communication among multiple routers, such as routing updates.

The address FF02::1 is a multicast address for all nodes on a local link, meaning it reaches all IPv6-enabled devices, not just routers. FF00::1 is not a valid multicast address; multicast addresses start with the prefix FF00::/8. FF01::2 refers to a multicast address for all routers on the same node-local scope, which is more restricted compared to link-local.

This distinction illustrates the importance of multicast addresses in managing and facilitating efficient communication between devices in a network. In particular, the usage of FF02::2 supports the functionality of various routing protocols which rely on reaching all routers to share necessary routing information.