4 dhcp troubleshooting, Dhcp, Roubleshooting – PLANET WGSW-50040 User Manual

Page 143

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18-5

Switch(dhcp-A-config)#dns-server 10.16.1.202

Switch(dhcp-A-config)#netbios-name-server 10.16.1.209

Switch(dhcp-A-config)#netbios-node-type H-node

Switch(dhcp-A-config)#exit

Switch(config)#ip dhcp excluded-address 10.16.1.200 10.16.1.201

Switch(config)#ip dhcp pool B

Switch(dhcp-B-config)#network 10.16.2.0 24

Switch(dhcp-B-config)#lease 1

Switch(dhcp-B-config)#default-route 10.16.2.200 10.16.2.201

Switch(dhcp-B-config)#dns-server 10.16.2.202

Switch(dhcp-B-config)#option 72 ip 10.16.2.209

Switch(dhcp-config)#exit

Switch(config)#ip dhcp excluded-address 10.16.2.200 10.16.2.201

Switch(config)#ip dhcp pool A1

Switch(dhcp-A1-config)#host 10.16.1.210

Switch(dhcp-A1-config)#hardware-address 00-03-22-23-dc-ab

Switch(dhcp-A1-config)#exit

Usage Guide: When a DHCP/BOOTP client is connected to a VLAN1 port of the switch, the client can only

get its address from 10.16.1.0/24 instead of 10.16.2.0/24. This is because the broadcast packet from the

client will be requesting the IP address in the same segment of the VLAN interface after VLAN interface

forwarding, and the VLAN interface IP address is 10.16.1.2/24, therefore the IP address assigned to the client

will belong to 10.16.1.0/24.

If the DHCP/BOOTP client wants to have an address in 10.16.2.0/24, the gateway forwarding broadcast

packets of the client must belong to 10.16.2.0/24. The connectivity between the client gateway and the switch

must be ensured for the client to get an IP address from the 10.16.2.0/24 address pool.

18.4 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 command

network-address” and “host” are run for a pool, only one of them will take effect; furthermore, in

manual binding, only one IP-MAC binding can be configured in one pool. If multiple bindings are

required, multiple manual pools can be created and IP-MAC bindings set for each pool. New

configuration in the same pool overwrites the previous configuration.

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