Stateless auto-configuration uses the following ICMPv6 messages for its activities:
Before we discuss the principle of SLAAC, it is necessary to explain a Router Advertisement message.
The fundamental block of SLAAC is a Router Advertisement message. RA message is used for sending all necessary configuration parameters to nodes. Routers send out RA messages periodically, or in response to RS message.
Description of individual fields of RA message:
The significance of possible combination of M and O flags is shown in the following table.
M flag |
O flag |
Significance |
1 |
- |
DHCPv6 assigns all parameters |
0 |
1 |
Combination of SLAAC (IPv6 address, prefix, routing) and DHCPv6 (other configuration parameters) |
0 |
0 |
DHCPv6 is not available |
Prf |
Significance |
01 |
High |
00 |
Medium (default) |
11 |
Low |
10 |
Reserved (must not be sent) |
Description of individual fields of Prefix Information option: