DHCP-SERVER-POLICY

This chapter summarizes Dynamic Host Control Protocol (DHCP) server policy commands in the CLI command structure.

DHCP automatically assigns network IP addresses to requesting clients to enable them access to network resources. DHCP tracks IP address assignments, their lease times and their availability. Each subnet can be configured with its own address pool. Whenever a DHCP client requests an IP address, the DHCP server assigns an IP address from that subnet‘s address pool. When the controller's (wireless controller, service platform, or access point) onboard DHCP server allocates an address to a DHCP client, the client is assigned a lease, which expires after a pre-determined interval. Before a lease expires, wireless clients (with assigned leases) are expected to renew them to continue using the addresses. Once the lease expires, the client is no longer permitted to use the leased IP address. The controller's DHCP server policy ensures all IP addresses are unique, and no IP address is assigned to a second client while the first client's assignment is valid (its lease has not expired). IP address management is conducted by a controller‘s DHCP server and not by an administrator.

The controller‘s internal DHCP server groups wireless clients based on defined user-class option values. Clients with a defined set of user class values are segregated by class. A DHCP server can associate multiple classes to each pool. Each class in a pool is assigned an exclusive range of IP addresses. DHCP clients are compared against classes. If the client matches one of the classes assigned to the pool, it receives an IP address from the range assigned to the class. If the client doesn't match any of the classes in the pool, it receives an IP address from a default pool range (if defined). Multiple IP addresses for a single VLAN allow the configuration of multiple IP addresses, each belonging to different subnet. Class configuration allows a DHCP client to obtain an address from the first pool to which the class is assigned.

Use the (config) instance to configure DHCP/DHCPv6 server policy parameters. To navigate to the config DHCP server policy instance, use the following commands:

<DEVICE>(config)#dhcp-server-policy <POLICY-NAME>

nx9500-6C8809(config)#dhcp-server-policy test
nx9500-6C8809(config-dhcp-server-policy-test)#?
DHCP policy Mode commands:
  bootp        BOOTP specific configuration
  dhcp-class   Configure DHCP class (for address allocation using DHCP
               user-class options)
  dhcp-pool    Configure DHCP server address pool
  dhcp-server  Activating dhcp server based on criteria
  no           Negate a command or set its defaults
  option       Define DHCP server option
  ping         Specify ping parameters used by DHCP Server

  clrscr       Clears the display screen
  commit       Commit all changes made in this session
  do           Run commands from Exec mode
  end          End current mode and change to EXEC mode
  exit         End current mode and down to previous mode
  help         Description of the interactive help system
  revert       Revert changes
  service      Service Commands
  show         Show running system information
  write        Write running configuration to memory or terminal

nx9500-6C8809(config-dhcp-policy-test)#

This chapter is organized into the following subsections:

• dhcp-server-policy commands.
• dhcpv6-server-policy commands.