12
Dynamic Host Configuration Protocol
(DHCP)
DHCP is an application layer protocol that dynamically assigns IP addresses and other configuration
parameters to network end-stations (hosts) based on configuration policies determined by network
administrators.
DHCP relieves network administrators of manually configuring hosts, which can be a tedious and error-
prone process when hosts often join, leave, and change locations on the network and it reclaims IP
addresses that are no longer in use to prevent address exhaustion.
DHCP is based on a client-server model. A host discovers the DHCP server and requests an IP address,
and the server either leases or permanently assigns one. There are three types of devices that are involved
in DHCP negotiation:
DHCP Server
This is a network device offering configuration parameters to the client.
DHCP Client
This is a network device requesting configuration parameters from the server.
Relay Agent
This is an intermediary network device that passes DHCP messages between the
client and server when the server is not on the same subnet as the host.
DHCP Packet Format and Options
DHCP uses the user datagram protocol (UDP) as its transport protocol.
The server listens on port 67 and transmits to port 68; the client listens on port 68 and transmits to port
67. The configuration parameters are carried as options in the DHCP packet in Type, Length, Value (TLV)
format; many options are specified in RFC 2132. To limit the number of parameters that servers must
provide, hosts specify the parameters that they require, and the server sends only those parameters.
Some common options are shown in the following illustration.
Figure 27. DHCP packet Format
The following table lists common DHCP options.
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Dynamic Host Configuration Protocol (DHCP)
Summary of Contents for Z9000
Page 1: ...Dell Configuration Guide for the Z9000 System 9 7 0 0 ...
Page 80: ...grub reboot 80 Management ...
Page 128: ... 0 Te 1 1 Te 1 2 rx Flow N A N A 128 Access Control Lists ACLs ...
Page 491: ...Figure 70 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 491 ...
Page 496: ...Figure 73 MSDP Default Peer Scenario 1 496 Multicast Source Discovery Protocol MSDP ...
Page 497: ...Figure 74 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 497 ...
Page 498: ...Figure 75 MSDP Default Peer Scenario 3 498 Multicast Source Discovery Protocol MSDP ...
Page 760: ...Figure 100 Single and Double Tag TPID Match 760 Service Provider Bridging ...
Page 761: ...Figure 101 Single and Double Tag First byte TPID Match Service Provider Bridging 761 ...