Allied Telesis x900-48 series - Manual (Page 30)

Page 30 | AlliedWare™ OS How To Note: DHCP snooping on AT-9900-style switches
Troubleshooting > The DHCP ACK is dropped by the switch
The DHCP snooping database will indicate that the DHCP process has not been completed
but that the IP has been seen:
This can be caused when the ACK packet is dropped by the QoS process. It has failed to
match a policy for that port and as a result the traffic is dropped.
Manager > sh dhcpsnooping database
DHCP Snooping Binding Database
-----------------------------------------------------------------------------
Database Version ..... 1
Full Leases/Max Leases ... 0/151
Check Interval ........... 60 seconds
Database Listeners ....... CLASSIFR
Current valid entries
MAC Address IP Address Expires(s) VLAN Port ID Source
-----------------------------------------------------------------------------
None...
-----------------------------------------------------------------------------
Entries with client lease but no listeners
MAC Address IP Address Expires(s) VLAN Port ID Source
-----------------------------------------------------------------------------
None...
-----------------------------------------------------------------------------
Entries with no client lease and no listeners
MAC Address IP Address Expires(s) VLAN Port ID Source
-----------------------------------------------------------------------------
00-06-5b-31-14-af 172.16.1.100 3174 1 1 2 Dynamic
-----------------------------------------------------------------------------
Manager > show conf dyn=classifier
# CLASSIFR configuration
create classifier=1 macsaddr=dhcpsnooping prot="ip" ipsaddr=dhcps
create classifier=99 prot="ip"
Manager > show conf dynamic=qos
# QOS configuration
create qos policy=1
create qos trafficclassifier=1
create qos flow=1 action=FORWARD
create qos flow=99 action=DISCARD
add qos policy=1 trafficclassifier=1
add qos trafficclassifier=1 flow=1
add qos trafficclassifier=1 flow=99
add qos flow=1 classifier=1
add qos flow=99 classifier=99