What is the ICMPv6 type for Router Solicitation (RS) messages?

Router Solicitation (RS) messages in ICMPv6 are used by hosts to request routers to provide information about the routing prefix and other network parameters. When a host boots up or connects to the network, it sends out Router Solicitation messages to find any routers on the local network segment that can respond with configuration settings.

The type field in ICMPv6 specifies the kind of message being sent. For Router Solicitation messages, the type is assigned a specific value: 133. This value indicates that the message is a request for routers, prompting them to send Router Advertisement (RA) messages in response. Understanding this value is crucial for networking professionals, as it plays a key role in the IPv6 network configuration process, especially in the context of Stateless Address Autoconfiguration (SLAAC) and dynamic address assignment.

Recognizing the significance of type 133 is important when working with ICMPv6, as it establishes the basis for communication between hosts and routers in an IPv6 network.