| 8.2 |  | TCP/IP Suite Control Messages |
| 8.2.6 |  | Router discovery message |

| When a host on the network boots, and the host has not been manually configured with a default gateway, it can learn of available routers through the process of router discovery. This process begins with the host sending a router solicitation message to all routers, using the multicast address 224.0.0.2 as the destination address. Figure shows the ICMP router discovery message. The router discovery message may also be broadcast to include routers that may not be configured for multicasting. If a router discovery message is sent to a router that does not support the discovery process, the solicitation will go unanswered. When a router that supports the discovery process receives the router discovery message , a router advertisement is sent in return. The router advertisement frame format is shown in Figure and an explanation of each field is shown in Figure .
| Web Links ICMP Router Discovery Messages http://www.cis.ohio-state.edu/cgi-bin/ rfc/rfc1256.html