Troubleshooting Tip: DHCP lease missing when legacy devices use BOOTP

[mle2802]

Description	This article describes how to troubleshoot a missing DHCP lease entry from the DHCP monitor dashboard.
Scope	FortiGate.
Solution	On FortiGate, a DHCP reservation is configured and the IP is leased out but there is no entry in DHCP monitor. Checking the DHCP lease list using the command 'execute dhcp lease-list' will show no DHCP lease record for the host. However, an ARP entry can be seen binding to the device MAC address. Use the command 'get sys arp | grep <device MAC address>': FortiGate-30G # get system arp | grep 3c:d9:2b:0e:5d:49 Address Age(min) Hardware Addr Interface 192.168.139.214 0 3c:d9:2b:0e:5d:49 lan Run DHCP debugging using the following command and see that the client is using BOOTP protocol instead of DHCP: FortiGate60F # diagnose debug reset FortiGate60F # diagnose debug application dhcps -1 FortiGate60F # diagnose debug enable FortiGate60F # [note]BOOTREQUEST from 3c:d9:2b:0e:5d:49 via internal [debug]found a per server host (server_id=1, ip=192.168.139.214) [note]BOOTREPLY for 192.168.139.214 to 4 (3c:d9:2b:0e:5d:49) via internal [debug]sending using lpf_dhcpd_send_packet [debug]locate_network prhtype(1) pihtype(1) [debug]found a fixed lease by hardware address Since the IP is assigned using BOOTP, FortiGate will not add the entry as DHCP lease. To fix this, configure the client to use DHCP instead of BOOTP for IP assignment.