H3C S7500 Series Ethernet Switches Operation Manual

Operation Manual – DHCP
H3C S7500 Series Ethernet Switches Chapter 1
DHCP Overview
1-5
1.4 DHCP Packet Processing Modes
After the DHCP server is enabled on a device, the device processes the DHCP packet
received from a DHCP client in one of the following three modes depending on your
configuration:
z Global address pool: In response to the DHCP packets received from DHCP
clients, the DHCP server picks IP addresses from its global address pools and
assigns them to the DHCP clients.
z Interface address pool: In response to the DHCP packets received from DHCP
clients, the DHCP server picks IP addresses from the interface address pools
and assigns them to the DHCP clients. If there is no available IP address in the
interface address pools, the DHCP server picks IP addresses from its global
address pool that contains the interface address pool segment and assigns them
to the DHCP clients.
z Trunk: DHCP packets received from DHCP clients are forwarded to an external
DHCP server, which assigns IP addresses to the DHCP clients.
You can specify the mode to process DHCP packets. For the configuration of the first
two modes, see
DHCP Server Configuration. For the configuration of the trunk mode,
see
DHCP Relay Agent Configuration.
One interface only corresponds to one mode. In this case, the new configuration
overwrites the previous one.
1.5 Protocols and Standards
Protocol specifications related to DHCP include:
z RFC2131: Dynamic Host Configuration Protocol
z RFC2132: DHCP Options and BOOTP Vendor Extensions
z RFC1542: Clarifications and Extensions for the Bootstrap Protocol