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Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  TCP/IP Network Configuration and Management Protocols (BOOTP, DHCP, SNMP and RMON)
           9  Host Configuration and TCP/IP Host Configuration Protocols (BOOTP and DHCP)
                9  TCP/IP Dynamic Host Configuration Protocol (DHCP)

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DHCP Parameter Configuration Process For Clients With Non-DHCP Addresses
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DHCP Message Generation, Addressing, Transport and Retransmission
Next Topic/Section

DHCP Messaging, Message Types and Formats

The topics on DHCP configuration and operation demonstrated how DHCP works by showing the processes by which various leasing and information-exchange activities are accomplished. All of these procedures rely heavily on the exchange of information between client and server, which are carried in DHCP messages. Like all protocols, DHCP uses a special message format, and a set of rules that govern how messages are created, addressed and transported.

In this section I provide the details of how DHCP creates and sends messages, and show the formats used for DHCP messages and options. I begin with a description of how DHCP creates, addresses and transports messages, and how it deals with message retransmission. I then outline the DHCP general message format, showing how it is similar to the BOOTP message format upon which it is based, and also where it differs. I describe DHCP options, the format used for them, and the special option “overloading” feature used for efficiency. I conclude the section with a complete list of DHCP options.

Related Information: DHCP is most closely related to BOOTP in the area of messaging, so you'll find lots of references to BOOTP in this section. Note especially that DHCP options are based closely on BOOTP vendor extensions, and many of the specific DHCP option types are the same as BOOTP vendor information fields. To avoid duplication, the summary table in this section lists the options/extensions for both protocols, indicating which ones are used by both BOOTP and DHCP, and which are used only by DHCP.


Quick navigation to subsections and regular topics in this section



Previous Topic/Section
DHCP Parameter Configuration Process For Clients With Non-DHCP Addresses
Previous Page
Pages in Current Topic/Section
1
Next Page
DHCP Message Generation, Addressing, Transport and Retransmission
Next Topic/Section

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