Accton Technology ES4710BD manual Introduction to Dhcp, Dhcp Configuration

ES4710BD 10 Slots L2/L3/L4 Chassis Switch

Chapter 14 DHCP Configuration

14.1Introduction to DHCP

DHCP [RFC2131] is the acronym for Dynamic Host Configuration Protocol. It is a protocol that assigns dynamically IP addresses to request host from the address pool as well as other network configuration parameters such as default gateway, DNS server, default route and host image file position within the network. DHCP is the enhanced version of BootP. It is a mainstream technology that can not only provide boot information for diskless workstations, but can also release the administrators from manual recording IP allocation and reduce user effort and configuration. Another benefit of DHCP is it can partially ease the pressure on IP demands, when the user of an IP leaves the network, their IP can be assigned to another user.

DHCP is a client-server protocol, the DHCP client requests the network address and configuration parameters from the DHCP server; the server provides the network address and configuration parameters for the clients; if a DHCP server and clients are located in different subnets, DHCP relay is required for DHCP packets to be transferred between the them. The implementation of DHCP is shown below:

Fig 14-1 DHCP protocol interaction

Explanation:

1.DHCP client broadcasts DHCPDISCOVER packets in the local subnet.

2.On receiving the DHCPDISCOVER packet, DHCP server sends a DHCPOFFER packet along with IP address and other network parameters to the DHCP client.

3.DHCP client broadcast DHCPREQUEST packet with the information for the DHCP server it selected after selecting from the DHCPOFFER packets.

4.The DHCP server selected by the client sends a DHCPACK packet and the client gets an IP

address and other network configuration parameters.

The above four steps finish a Dynamic host configuration assignment process. However, if the DHCP server and the DHCP client are not in the same network, the server will not receive the DHCP broadcast packets sent by the client, therefore no DHCP packets will be sent to the client by the server. In this case, a DHCP relay is required to forward such DHCP packets so that the DHCP packets exchange can be completed between the DHCP client and server.

ES4710BD can act as both a DHCP server and a DHCP relay. DHCP server supports not only dynamic IP address assignment, but also manual IP address binding (i.e., specify a specific IP address to a specified MAC address or specified device ID over a long period. The differences and relations between dynamic IP address allocation and manual IP address binding are: 1) IP address

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