Dhcp Configuration; Dhcp Overview - Zte ZXR10 5900 Series User Manual

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C h a p t e r

DHCP Configuration

Table of Contents
DHCP Overview .................................................................83
Configuring DHCP ..............................................................84
DHCP Configuration Example...............................................99
DHCP Maintenance and Diagnosis ...................................... 103

DHCP Overview

Dynamic Host Configuration Protocol (DHCP) enables a host on the
network to obtain an IP address ensuring its normal communica-
tion and relevant configuration information from a DHCP server.
DHCP adopts UDP as the transmission protocol. Host sends a mes-
sage to Port 67 of the DHCP server and the DHCP server returns
the message to Port 68 of the host. The DHCP works in the fol-
lowing steps:
1. Host sends a broadcast packet DHCPDiscover including the re-
quest of IP address and other configuration parameters.
2. DHCP server returns a unicast packet DHCPOffer including the
valid IP address and configuration.
3. Host selects the server which returns DHCPOffer arriving at
first and sends a unicast DHCPRequest to the server, indicating
to accept relevant configuration.
4. Selected DHCP server returns a unicast packet DHCPAck for
confirmation.
By now the host can use the IP address and relevant configuration
obtained from the DHCP server for communication.
DHCP supports three mechanisms for IP address allocation:
1. Automatic allocation-DHCP assigns a permanent IP address
to a client.
2. Dynamic allocation-DHCP assigns an IP address to a client for
a limited period of time (or until the client explicitly relinquishes
the address).
3. Manual allocation-the network administrator assigns an IP ad-
dress to a client and DHCP is used simply to convey the as-
signed address to the client.
Usually Dynamic allocation method is adopted. The valid time seg-
ment of using the address is called lease period. Once the lease
period expires, the host must request the server for continuous
lease. The host cannot continue to lease until it accepts the re-
quest, otherwise it must give up unconditionally.
Confidential and Proprietary Information of ZTE CORPORATION 83