DHCP problems with relay. Please help

DHCP problems with relay. For more information, see Linux general technology-Linux technology and application. The VM is used as a DHCP experiment with relay. Three LINUX instances are installed with DHCP: 221.2.141.2/24. The Gateway is the relay eth0IP relay. There are three virtual NICs eth0: 221.2.141.1/24 eht1: 221.2.142.1/24 eht2: 221.2.143.1/24 client
DHCP settings: dhcpd. conf: ddns-update-style none;
Default-lease-time 21600;
Max-lease-time 43200;
Subnet 221.2.141.0 netmask 255.255.255.0 {
Range 221.2.141.100 221.2.141.200;
Option subnet mask limit 255.0;
Option routers 221.2.141.1;
}
Subnet 221.2.142.0 netmask 255.255.255.0 {
Range 221.2.142.100 221.2.142.200;
Option subnet mask limit 255.0;
Option routers 221.2.142.1;
}
Subnet 221.2.143.0 netmask 255.255.255.0 {
Range 221.2.143.100 221.2.143.200;
Option subnet mask limit 255.0;
Option routers 221.2.143.1;
}
Service dhcpd start
Relay: net. ipv4.ip _ forward = 1
Interfaces = "eth1 eth2"
Dhcpservers = "221.2.141.2"
Service dhcrelay start

Is there any problem? Why does the client fail to accept DHCP allocation?