1: Experimental environment
1.1: Huawei ensp software
1.2: PC, router and switch
PC in initialization state and router and switch in initialization state
2, Experiment requirements, realize the whole network interworking and DHCP relay on R4
3: Experimental process
3.1: equipment configuration
In the ensp, the PC, router and switch are ready and started.

3.2 configuration ideas
Configure R1
1) Configure interface

Int g0/0/0 ; ip add 12.0.0.1 24 ;un sh
Int g0/0/2 ; ip add 14.0.0.1 24 ;un sh

2) Configure single arm routing and relay

dhcp enable    #Commands in system view
int g0/0/1.10 ;
ip add 192.168.10.1;
d t v 10 ;
a b e;
dhcp select relay;    #Configure relay mode
dhcp relay server-ip 14.0.0.2; #Configure relay address
un sh
int g0/0/1.20 ;
ip add 192.168.20.1;
d t v 20 ;a b e;dhcp select relay;
dhcp relay server-ip 14.0.0.2;
un sh

3) Configure static / default routes
ip route-static 0.0.0.0 0.0.0.0 12.0.0.2
Configure R2
1) Configure interface

int g0/0/0
ip add 12.0.0.2 24
un sh
int g0/0/1
ip add 15.0.0.1 24
un sh;q

2) Configure enable relay mode

dhcp enable
dhcp select relay 
dhcp relay server-ip 14.0.0.2 ##Specify relay address

3) Configure static / default route (operator side)

ip route-static 14.0.0.0 24 12.0.0.1
ip route-static 192.168.10.0 24 12.0.0.1
ip route-static 192.168.20.0 24 12.0.0.1

Configure R4 to provide relay service
1) Configure routing interface

Int g0/0/0 
Ip add 14.0.0.2 24
un sh

2) Configure DHCP relay service

dhcp enable
int g0/0/0
ip add 14.0.0.2 24
dhcp select global  #Declare to go to global mode to find the configured DHCP service on the interface
undo sh
//Configure relay pool, one for each network segment
ip pool DHCP15  #Enter DHCP15 and configure the pool of PC5 15 network segment
network 15.0.0.0 mask 24
gateway-list 15.0.0.1
dns-list 8.8.8.8 2.2.2.2
excluded-ip-address 15.0.0.100 15.0.0.254
static-bind ip-address 15.0.0.88 mac-address 5489-98C3-6B6F
ip pool DHCPvlan10 #Enter DHCPvlan10 to configure the 10.0 segment pool
network 192.168.10.0 mask 24
gateway-list 192.168.10.1
dns-list 8.8.8.8 2.2.2.2
ip pool DHCPvlan20 #Enter DHCPvlan20 to configure the 20.0 segment pool
network 192.168.20.0 mask 24
gateway-list 192.168.20.1
dns-list 8.8.8.8 2.2.2.2

3) Configure routing
ip route-static 0.0.0.0 0.0.0.0 14.0.0.1
3.3 configure SW1 switch

[SW1] vlan batch 10 20
[SW1] interface Ethernet0/0/1
[SW1-Ethernet0/0/1]port link-type access
[SW1-Ethernet0/0/1]port default vlan 10
[SW1-Ethernet0/0/1]un sh
[SW1]interface Ethernet0/0/2
[SW1-Ethernet0/0/2]port link-type access
[SW1-Ethernet0/0/2]port default vlan 20
[SW1-Ethernet0/0/2]un sh
[SW1] interface Ethernet0/0/3
[SW1-Ethernet0/0/3]port link-type access
[SW1-Ethernet0/0/3]port default vlan 10
[SW1-Ethernet0/0/3]un sh
[SW1]interface Ethernet0/0/4
[SW1-Ethernet0/0/4]port link-type access
[SW1-Ethernet0/0/4]port default vlan 20
[SW1-Ethernet0/0/4]un sh
[SW1-Ethernet0/0/4]int g0/0/1
[SW1-GigabitEthernet0/0/1]p l t
[SW1-GigabitEthernet0/0/1]p t a v a
[SW1-GigabitEthernet0/0/1]un sh

3.4 configure R1 router
3.4.1 configure single arm routing

[R1]int g0/0/2
[R1-GigabitEthernet0/0/2]ip add 14.0.0.1 24
[R1-GigabitEthernet0/0/2]un sh
[R1-GigabitEthernet0/0/2]int g0/0/0
[R1-GigabitEthernet0/0/0]ip add 12.0.0.1 24
[R1-GigabitEthernet0/0/0]un sh
[R1]dhcp enable
[R1]int GigabitEthernet 0/0/1.10
[R1-GigabitEthernet0/0/1.10]d t v 10
[R1-GigabitEthernet0/0/1.10]ip address 192.168.10.1 24
[R1-GigabitEthernet0/0/1.10]a b e
[R1-GigabitEthernet0/0/1.10]un sh
[R1-GigabitEthernet0/0/1.10]int GigabitEthernet 0/0/1.20
[R1-GigabitEthernet0/0/1.20]d t v 20
[R1-GigabitEthernet0/0/1.20]ip address 192.168.20.1 24
[R1-GigabitEthernet0/0/1.20]a b e
[R1-GigabitEthernet0/0/1.20]un sh

3.4.2 configure DHCP relay service (specify relay routing address)

[R1-GigabitEthernet0/0/1.20]int GigabitEthernet 0/0/1.10
[R1-GigabitEthernet0/0/1.10]dhcp select relay  #Select relay mode
[R1-GigabitEthernet0/0/1.10]dhcp relay server-ip 14.0.0.2
[R1-GigabitEthernet0/0/1.10]un sh
[R1-GigabitEthernet0/0/1.10]int GigabitEthernet 0/0/1.20
[R1-GigabitEthernet0/0/1.20]dhcp select relay
[R1-GigabitEthernet0/0/1.20]dhcp relay server-ip 14.0.0.2
[R1-GigabitEthernet0/0/1.20]un sh

3.4.3 configure static route
[R1]ip route-static 0.0.0.0 0.0.0.0 12.0.0.2
3.5 configure R2 router
3.5.1 configuration interface

[R2]int g0/0/0
[R2-GigabitEthernet0/0/0]ip add 12.0.0.2 24
[R2-GigabitEthernet0/0/0]un sh
[R2-GigabitEthernet0/0/0]int g0/0/1
[R2-GigabitEthernet0/0/1]ip add 15.0.0.1 24
[R2-GigabitEthernet0/0/1]un sh

3.5.2 configure relay service

[R2]dhcp enable
[R2-GigabitEthernet0/0/1]dhcp select relay
[R2-GigabitEthernet0/0/1]dhcp relay server-ip 14.0.0.2
[R2-GigabitEthernet0/0/1]undo sh
[R2-GigabitEthernet0/0/1]q

3.5.3 configure route

[R2]ip route-static 14.0.0.0 24 12.0.0.1
[R2]ip route-static 192.168.10.0 24 12.0.0.1
[R2]ip route-static 192.168.20.0 24 12.0.0.1

3.6 configure R4 router
3.6.1 configure routing interface

Int g0/0/0 
Ip add 14.0.0.2 24
un sh

3.6.2 configure DHCP relay service

[R4]dhcp enable #System mode claims DHCP enabled
[R4]int g0/0/0
[R4-GigabitEthernet0/0/0]ip add 14.0.0.2 24
[R4-GigabitEthernet0/0/0]dhcp select global  #Declare to go to global mode to find configured DHCP on the interface

3.6.3 configured DHCP service

[R4-GigabitEthernet0/0/0]undo sh
[R4-GigabitEthernet0/0/0]q
[R4]ip pool DHCP15
[R4-ip-pool-DHCP15]network 15.0.0.0 mask 24
[R4-ip-pool-DHCP15]gateway-list 15.0.0.1
[R4-ip-pool-DHCP15]dns-list 8.8.8.8 2.2.2.2
[R4-ip-pool-DHCP15]excluded-ip-address 15.0.0.100 15.0.0.254
[R4-ip-pool-DHCP15]static-bind ip-address 15.0.0.88 mac-address 5489-98C3-6B6F    #Here, mac address is configured with mac of PC5, and 15.0.0.88 address is configured
[R4-ip-pool-DHCP15]dis this
ip pool DHCP15
 gateway-list 15.0.0.1
 network 15.0.0.0 mask 255.255.255.0
 static-bind ip-address 15.0.0.88 mac-address 5489-98c3-6b6f
 excluded-ip-address 15.0.0.100 15.0.0.254
 dns-list 8.8.8.8 2.2.2.2
[R4-ip-pool-DHCP15]q
[R4]ip pool DHCPvlan10
[R4-ip-pool-DHCPvlan10]network 192.168.10.0 mask 24
[R4-ip-pool-DHCPvlan10]gateway-list 192.168.10.1
[R4-ip-pool-DHCPvlan10]dns-list 8.8.8.8 2.2.2.2
[R4-ip-pool-DHCPvlan10]ip pool DHCPvlan20
[R4-ip-pool-DHCPvlan20]network 192.168.20.0 mask 24
[R4-ip-pool-DHCPvlan20]gateway-list 192.168.20.1
[R4-ip-pool-DHCPvlan20]dns-list 8.8.8.8 2.2.2.2
[R4-ip-pool-DHCPvlan20]q
[R4]ip route-static 0.0.0.0 0.0.0.0 14.0.0.1

3.7 check whether the requirements are met

PC5 has obtained the IP of the specified configuration