PPP for IPv6
On IPv6 networks, PPP negotiates only the IPv6 interface identifier instead of the IPv6 address and IPv6 DNS server address during IPv6CP negotiation.
IPv6 address assignment
PPP cannot negotiate the IPv6 address.
The client can get an IPv6 global unicast address through the following methods:
Method 1—The client obtains an IPv6 prefix in an RA message. The client then generates an IPv6 global unicast address by combining the IPv6 prefix and the negotiated IPv6 interface identifier. The IPv6 prefix in the RA message is determined in the following sequence:
IPv6 prefix authorized by AAA.
RA prefix configured on the interface.
Prefix of the IPv6 global unicast address configured on the interface.
For information about the ND protocol, see Layer 3—IP Services Configuration Guide.
Method 2—The client requests an IPv6 global unicast address through DHCPv6. The server assigns an IPv6 address to the client from the address pool authorized by AAA. If no AAA-authorized address pool exists, DHCPv6 uses the address pool that matches the server's IPv6 address to assign an IPv6 address to the client. For information about DHCPv6, see Layer 3—IP Services Configuration Guide.
Method 3—The client requests prefixes through DHCPv6 and assigns them to downstream hosts. The hosts then uses the prefixes to generate global IPv6 addresses. This method uses the same principle of selecting address pools as method 2.
The device can assign a host an IPv6 address in either of the following ways:
When the host connects to the device directly or through a bridge device, the device can use method 1 or method 2.
When the host accesses the device through a router, the device can use method 3 to assign an IPv6 prefix to the router. The router assigns the prefix to the host to generate an IPv6 global unicast address.
IPv6 DNS server address assignment
On IPv6 networks, two methods are available for the IPv6 DNS address assignment:
AAA authorizes the IPv6 DNS address and assigns this address to the host through RA messages.
The DHCPv6 client requests an IPv6 DNS address from the DHCPv6 server.