Configure DHCP Servers and DHCP Relay Agents

For small networks, you can configure and enable a DHCP server on a device to provide network settings dynamically to clients. After you configure one hive member as a DHCP server, the other hive members process the DHCPDISCOVERY and DHCPREQUEST messages that they receive from clients as usual, forwarding them to their neighbors through which they connect to the network. The only requirement about which device to use as the DHCP server is that it must be a portal.

When all hive members are in the same subnet and all devices in that subnet are on a single VLAN, you only need to configure the device that you want to be the DHCP server with a pool of IP addresses from which it can draw when responding to DHCP client requests.

When some hive members are in a different subnet from that of the DHCP server, you must also configure those devices to forward DHCP traffic to the IP address of the DHCP server. In this case, the other devices act as DHCP relay agents. You can configure both DHCP servers and relay agents here.

The DHCP Server and Relay Objects table displays the following information:

Name: The name of the object.
Interface: The management interface. For example, mgt0.
IP Address/Netmask: The IP address and netmask that defines the subnet.
Used By: The number of network policies to which this DHCP server and relay object applies. Hover over the number in this column to see a list.

Use this task to add a new DHCP Server and Relay object.

Go to Configure > Common Objects > Basic > DHCP Server and Relay.
Select an existing object, and then select , or select .
Type a Name for this object.
Optional: Type a Description for this object.

Although optional, descriptions can be helpful when you are troubleshooting your network.
Select the management interface on which the DHCP Server or Relay agent is set.
Select the type of service.
If you select DHCP Server, configure the following steps:
1. Set the DHCP server as authoritative (enabled by default): Select the check box to set the DHCP server as authoritative.
  If this DHCP server is the only one on your network, it knows what the valid IP numbers on the network are. If a client tries to register with an invalid IP address (for example, if a client device sill has an active lease with another network), an authoritative DHCP server denies access to that client.
2. Use ARP to check for IP address conflicts (enabled by default): By default, this DHCP server uses ARP to check for IP address conflicts on the network before assigning an IP address to a DHCP client.
  Clear the check box to disable this feature.
3. Enable NAT support: Select this check box to automatically generate ARP responses for the default gateway specified in the DHCP server options.
4. Configure the IP Pool: Define the IP address pool from which the DHCP server draws IPv4 or IPv6 addresses when making assignments.
  To add a new IP pool, select the plus sign, enter the start and end IP addresses, and then select Add.
5. Configure DHCP Server Options: Define custom DHCP options to provide additional network settings to connected clients.
  You can use IPv4 or IPv6 addresses. Configure the following settings:
  - Default Gateway: Enter the IP address of the default gateway or the subnet to which the addresses in the IP pool belong.
  - DNS Server1 IP: Enter the IP address of the primary DNS server for clients to contact when resolving domain names to IP addresses (DHCP option 6).
  - DNS Server2 IP: Enter the IP address of a secondary DNS server for clients to contact if the primary DNS server is unresponsive (DHCP option 6).
  - DNS Server3 IP: Enter the IP address of a third DNS server for clients to contact if neither the primary nor secondary DNS servers respond (DHCP option 6).
  - POP3 Server IP: Enter the IP address of the POP3 server for clients to use (DHCP option 70).
  - SMTP Server IP: Enter the IP address of the SMTP server for clients to use (DHCP option 69).
  - WINS Server1 IP: Enter the IP address of the primary WINS server for NetBIOS name-to-address resolution (DHCP option 44).
  - WINS Server2 IP: Enter the IP address of the secondary WINS server for NetBIOS name-to-address resolution (DHCP option 44).
  - Lease Time: Enter the length of time (60-86400000 seconds) for the DHCP lease; by default, DHCP leases last for 86,400 seconds, or 24 hours (DHCP option 51).
  - Netmask: Enter the netmask defining the subnet to which the addresses in the IP pool belong.
  - Domain Name: Enter the domain name to assign to DHCP clients. This is the default domain name for DNS name resolution (DHCP option 15).
  - MTU: Set the path MTU aging timeout in seconds for clients to use; the minimum value is 68 seconds, and the maximum is 8192 seconds (DHCP option 24).
  - NTP Server1 IP: Enter the IP address of the primary NTP (Network Time Protocol) server with which DHCP clients can synchronize their clocks (DHCP option 42).
  - NTP Server2 IP: Enter the IP address of the secondary NTP server with which DHCP clients can synchronize their clocks (DHCP option 42).
  - Log Server IP: Enter the IP address of the logging server for DHCP clients (DHCP option 7).
6. Configure Custom Options: Define custom DHCP options to provide additional network settings to connected clients.
  You can use IPv4 or IPv6 addresses. To add a new custom DHCP option select the plus sign and complete the fields:
  - Number: Enter a custom option number from 2 to 5, 8 to 14, 16 to 25, 27 to 41, 43, 45 to 50, 52 to 57, 60 to 68, 71 to 224, 227, 228, or from 232 to 254.
    Note
    The following numbers are reserved: 226, ExtremeCloud IQ domain name; 225, ExtremeCloud IQ IP address; 229, PPSK server IP address; 230, RADIUS server authentication IP address; 231, RADIUS server accounting IP address. The following DHCP option numbers are reserved for other information: 3, 6, 7, 15, 26, 42, 44, 51, 58, 59, 69, and 70.
  - Type: Select the type of data that the option will provide:
    - Integer: 0-2, 247, 483, 547
    - IP Address: Four octets of an IP address or eight groups of two octets each for an IPv6 address.
    - String: 1-255 characters
    - Hex: 1-254 hexadecimal digits
If you select DHCP relay agent, designate a Primary DHP Server and a Secondary DHCP Server (optional).
Select Save.