Configuring the DHCP Server
The following commands allow you to configure the DHCP server included
in the switch. The parameters available to configure include the IP address range, IP
address lease, and multiple DHCP options. Until EXOS 15.1, the DHCP server had a limited set
of known DHCP options it could send out on request, i.e., Default Gateway, DNS, and WINS
server(s). General option support has been added in EXOS 15.2. This allows you to add
support for any option needed, with no EXOS code changes. The three options mentioned above
can also be overwritten to support a larger number of servers, if needed. This feature
allows the switch administrator to add an option based on DHCP option code value, and
support various was of setting the value.
-
Configure the range of IP addresses assigned by the DHCP
server using the command:
configure
vlan vlan_name dhcp-address-range ipaddress1 - ipaddress2
-
Remove the address range information using the
command:
unconfigure
vlan vlan_name dhcp-address-range
-
Set how long the IP address lease assigned by the server
exists using the command:
configure
vlan vlan_name dhcp-lease-timer lease-timer 
Note
The ExtremeXOS DHCP server allows the configuration of a DHCP lease
timer value greater than two seconds only. The timer value range is 3–4294967295. If the
DHCP lease timer is not configured, the ExtremeXOS DHCP server offers an IP address with
the default lease time of 7200 seconds.
-
To set the generic DHCP option code, default gateway,
Domain Name Servers (DNS) addresses, or Windows Internet Naming Service (WINS) server, use
the following command:
configure
{vlan} vlan_name dhcp-options [code option_number [16-bit value1 {value2
{value3 {value4}}} | 32-bit value1 {value2
{value3 {value4}}} | flag [on | off] | hex string_value | ipaddress ipaddress1 {ipaddress2 {ipaddress3 {ipaddress4}}} | string string_value] | default-gateway | dns-server {primary | secondary} | wins-server] ipaddress
-
To remove the generic DHCP option code, default gateway,
DNS server addresses, and WINS server information for a particular VLAN, use the following
command:
unconfigure {vlan} vlan_name dhcp-options {[ default-gateway | dns-server {primary | secondary} | wins-server]}
-
Remove all the DHCP information for a particular VLAN
using the command:
unconfigure
vlan vlan_name dhcp
You can clear the DHCP address allocation table
selected entries, or all entries.
-
Clear entries using the command:
clear vlan
vlan_name dhcp-address-allocation
[[all {offered | assigned | declined |
expired}] | ipaddress]
You would use this command to troubleshoot IP
address allocation on the VLAN.
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