Users Guide
Dynamic Host Conguration Protocol (DHCP)
The Aggregator is auto-congured to operate as a dynamic host conguration protocol (DHCP) client. The DHCP server, DHCP relay
agent, and secure DHCP features are not supported. The DHCP is an application layer protocol that dynamically assigns IP addresses and
other conguration parameters to network end-stations (hosts) based on conguration policies determined by network administrators.
DHCP relieves network administrators of manually conguring 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 oering conguration parameters to the client.
DHCP Client This is a network device requesting conguration 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.
NOTE: The DHCP server and relay agent features are not supported on an Aggregator.
Supported Modes
Stacking, PMUX, Standalone, VLT
Topics:
• Assigning an IP Address using DHCP
• Debugging DHCP Client Operation
• DHCP Client
• How DHCP Client is Implemented
• DHCP Client on a Management Interface
• DHCP Client on a VLAN
• DHCP Packet Format and Options
• Option 82
• Releasing and Renewing DHCP-based IP Addresses
• Viewing DHCP Statistics and Lease Information
Assigning an IP Address using DHCP
The following section describes DHCP and the client in a network.
When a client joins a network:
1 The client initially broadcasts a DHCPDISCOVER message on the subnet to discover available DHCP servers. This message includes
the parameters that the client requires and might include suggested values for those parameters.
2 Servers unicast or broadcast a DHCPOFFER message in response to the DHCPDISCOVER that oers to the client values for the
requested parameters. Multiple servers might respond to a single DHCPDISCOVER; the client might wait a period of time and then
act on the most preferred oer.
3 The client broadcasts a DHCPREQUEST message in response to the oer, requesting the oered values.
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