Troubleshooting guide

3. Troubleshooting Functional Failures During Operation
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(f) Checking the filters and QoS configuration information
Only certain packets might have been discarded by filtering, or packets might have been discarded
by bandwidth monitoring, drop control, or the QoS control shaper.
On the Switch and the relay device between the DNS server and the DHCP server, make sure that
the setting conditions for filters and QoS control in the configuration are correct, and that
bandwidth monitoring, drop control, or the shaper is used appropriately in the system
configuration. For details about the procedure, see 3.25.1 Checking the filters and QoS
configuration information.
In addition, if DHCP snooping is used, packets might have been discarded by a terminal filter.
Check whether the setting conditions for DHCP snooping in the configuration are correct. For
details about the procedure, see 3.27 DHCP snooping problems.
(g) Checking the Layer 2 network
If you do not find any incorrect settings or a failure in the steps (a) to (f), there might be a problem
with the Layer 2 network. Check the Layer 2 network according to 3.6 Layer 2 network
communication failures.