H3C Technologies H3C SecPath F5020 - Manual (Page 11)

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An interface can act as a client or a server during IP address negotiation:
• Client—Obtains an IP address from the server. Use the client mode when the device accesses the
Internet through an ISP.
• Server—Assigns an IP address to the client. Before you configure the IP address of the server, you
must perform one of the following tasks:
{
Configure a local address pool and associate the pool with the ISP domain.
{
Specify an IP address or an address pool for the client on the interface.
When IP address negotiation is enabled on a client, the server selects an IP address for the client in the
following sequence:
1. If the AAA server assigns an IP address to the client or has a specified address pool, the server
assigns that IP address or an IP address from the specified address pool to the client. The IP
address or address pool is configured on the AAA server instead of the PPP server. For information
about AAA, see Security Configuration Guide.
2. If an address pool is associated with the ISP domain used during client authentication, the server
assigns an IP address from the associated address pool to the client.
3. If an IP address or address pool is specified for the client on the interface of the server, the server
assigns that IP address or an IP address from that address pool to the client.
DNS server address negotiation
IPCP negotiation can determine the DNS server IP address.
When the device is connected to a host, configure the device as the server to assign the DNS server IP
address to the host.
When the device is connected to an ISP access server, configure the device as the client to obtain the
DNS server IP address from the ISP access server.
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.