ssage Protocol v6 Type: 133 (Router solicitation) Code: 0 checksum: 0x18e0 [correct] ICMPV6 option (Source link-layer address) Type: Source link-layer address (1) Length: 8 Link-layer address: b8:27:eb:f1:8d:0d Figure 3.30 Example: soliciting for routers on the link. In a more typical Ethernet case there would not be an unsolicited Router Advertisement readily available, but a host would have to send a Router Solicitation to hasten reception of the Router Advertisement and hence to speed up address autoconfiguration procedures. On some other types of links, such as point-to-point, a router may send unsolicited Router Advertisement with full information immediately after the link layer has been established. In the trace shown in Figure 3.30 we can see the source IPv6 address of the Router Solicitation packet to be the link-local IPv6 address stack starting to do DAD at trace step 6. We can note from the timestamps that a second has passed, which is the default time to wait for a Neighbor Advertisement to arrive. As there was no conflict detected, the link-local address was moved to 'preferred' state and hence became available for full use. The Router Solicitation also includes the Source Link-Layer Address option with the host's link-layer address, hence enabling message receivers to update their Neighbor Cache entries. Joining Solicited-node Multicast Group Again Another thing to perform after the DAD has provided a preferred address is to resend the 'Multicast Listener Report Message v2' for joining the Solicited-node multicast address group, but now from the configured link-local IPv6 address, as shown in Figure 3.31, and required by RFC 3810 Section 5.2.13. Another reason for retransmission is to ensure that all MLD routers on the link get the report, as stated in RFC 3810 Section 6.1 [45]. Reception of the Next Router Advertisement In packet 12, the next unsolicited Router Advertisement is received. The new Router Advertisement is exactly the same as before and hence not expanded herein; it does not cause any