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The wrong configuration of dhcp forbidden IP lead to unable to go to the Internet

Publication Date:  2012-10-26 Views:  74 Downloads:  0
Issue Description
 
Use FW as enterprise export to go to online, use SW to concatenate internal network. Export using ADSL directly dialing, internal use DHCP automatically to assign IP address and DNS.
192.168.1.0 segment host unable to get IP address, 192.168.2.0 segment can normally go to the Internet.
Alarm Information
none
Handling Process
If want to forbid multiple IP address assignment, so should repeatedly input the command.
DHCP forbidden - IP 192.168.1.1
DHCP forbidden - IP 192.168.2.1
Root Cause
 Check DHCP configurtion:
dhcp enable
dhcp forbidden-ip 192.168.1.1 192.168.2.1

interface configuration
linterface Vlanif1
? ip address 192.168.1.1 255.255.255.0
? dhcp select interface
? dhcp server dns-list 202.106.0.20

After check, find DHCP configuration have problems. dhpc forbidden ip address configuration is wrong.

DHCP forbidden-ip 192.168.1.1 192.168.2.1
Means the all IP address from 192.168.1.1to 192.168.2.1 is forbidden to assign
Suggestions
If want to forbid multiple IP address assignment, so should repeatedly input the command.

END