QTECH QSW-2800 Инструкция по настройке - Manual (Page 211)

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DHCP configuration example
As shown in the above figure, PC1 is DHCP client, obtain the address through DHCP. Switch1
is a layer 2 access device, it enables DHCP Relay and option82 functions, Ethernet1/2 is a
access port, belongs to vlan3, Ethernet1/3 is a trunk port, connects to DHCP Server, DHCP
Server address is 192.168.40.199. Switch1 creates vlan1 and interface vlan1, configure IP
address of interface vlan1 as 192.168.40.50, configure the address of DHCP Relay forwarding
as 192.168.40.199, configure vlan3 as a sub-vlan of vlan1. The configuration is as follows:
switch(config)#vlan 1
switch(config)#vlan 3
switch(config)#interface ethernet 1/2
Switch(Config-If-Ethernet1/2)#switchport access vlan 3
switch(config)#interface ethernet 1/3
Switch(Config-If-Ethernet1/2)#switchport mode trunk
switch(config)#service dhcp
switch(config)#ip forward-protocol udp bootps
switch(config)#ip dhcp relay information option
switch(config)#ip dhcp relay share-vlan 1 sub-vlan 3
switch(config-if-vlan1)#ip address 192.168.40.50 255.255.255.0
switch(config-if-vlan1)#ip helper-address 192.168.40.199
27.5 DHCP Troubleshooting
If the DHCP clients cannot obtain IP addresses and other network parameters, the following
procedures can be followed when DHCP client hardware and cables have been verified ok.
Verify the DHCP server is running, start the related DHCP server if not running.
In such case, DHCP server should be examined for an address pool that is in the same
segment of the switch VLAN, such a pool should be added if not present, and (This does not
indicate switch cannot assign IP address for different segments, see solution 2 for details.)
In DHCP service, pools for dynamic IP allocation and manual binding are conflicting, i.e., if