Dhcp Snooping Problems; Problems Related To Dhcp - Alaxala AX6700S Troubleshooting Manual

3.26 DHCP snooping problems

3.26.1 Problems related to DHCP

If DHCP cannot assign IP addresses in a DHCP snooping configuration, isolate the cause
of the problem according to the failure analysis method described in the following table.
Table 3-83 Failure analysis method when DHCP cannot assign IP addresses in a DHCP
No. Items to check
1 Execute the
show logging
check whether any hardware failure is
recorded in the operation log.
2 Check whether IP addresses cannot be
newly assigned or only IP addresses already
assigned cannot be updated.
3 Execute the
show ip dhcp snooping
statistics
operation status of DHCP snooping.
Check the connection method between the
4
clients and server.
5 Make sure that there is no problem with the
operation of the DHCP server and DHCP
relay.
snooping configuration
command, and
command to check the
3 Troubleshooting Functional Failures During Operation
Action
If any hardware failure is recorded in the operation log,
replace the device.
For other cases, go to No. 2.
If IP addresses cannot be newly assigned, go to No. 3.
If assigned IP addresses cannot be updated, go to No.
9.
If a port is displayed as an untrusted port at which
DHCP snooping is enabled and the port is the one
connected to the target device (to which an IP address
cannot be assigned), go to No. 4.
If the target device is connected to another port,
DHCP snooping is not enabled for the device.
Check the network configuration and the settings of
the DHCP server, and if there is no problem, go to No.
10.
If the Switch is connected as a Layer 2 switch between
the clients and server, go to No. 8.
If the DHCP server on the Switch is used, go to No. 5.
If the DHCP relay on the Switch is used, go to No. 5.
If there is a DHCP relay between the Switch and
clients, go to No. 6.
If a device that adds Option 82 data is located
between the Switch and clients, go to No. 7.
If multiple conditions described above are met, see
each item in the order above.
See 3.6.2 IP addresses cannot be assigned by the
DHCP functionality and make sure that the DHCP
server and DHC relay can assign IP addresses.
If there is no problem, go to No. 8.
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