Dhcp Address Allocation; Allocation Mechanisms; Dynamic Ip Address Allocation Process - 3Com 4510G Configuration Manual

DHCP Address Allocation

Allocation Mechanisms

DHCP supports three mechanisms for IP address allocation.
Manual allocation: The network administrator assigns an IP address to a client like a WWW server,
and DHCP conveys the assigned address to the client.
Automatic allocation: DHCP assigns a permanent IP address to a client.
Dynamic allocation: DHCP assigns an IP address to a client for a limited period of time, which is
called a lease. Most DHCP clients obtain their addresses in this way.

Dynamic IP Address Allocation Process

Figure 5-2 Dynamic IP address allocation process
As shown in Figure
2) The client broadcasts a DHCP-DISCOVER message to locate a DHCP server.
3) A DHCP server offers configuration parameters including an IP address to the client in a
DHCP-OFFER message. The sending mode of the DHCP-OFFER message is determined by the
flag field in the DHCP-DISCOVER message. Refer to
information.
4) If several DHCP servers send offers to the client, the client accepts the first received offer, and
broadcasts it in a DHCP-REQUEST message to formally request the IP address.
5) All DHCP servers receive the DHCP-REQUEST message, but only the server from which the
client accepts the offered IP address responds. The server returns a DHCP-ACK message to the
client, confirming that the IP address has been allocated to the client, or a DHCP-NAK unicast
message, denying the IP address allocation.
5-2, a DHCP client obtains an IP address from a DHCP server via four steps:
DHCP Message Format
5-2
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