Allied Telesis x900-48 series - Manual (Page 33)

Page 33 | AlliedWare™ OS How To Note: DHCP snooping on AT-9900-style switches
Troubleshooting > The DHCP ACK is dropped by the switch
Another possibility for dropping an ACK is when there is already an entry for the port in the
DHCP snooping database.
In the example above, a client on port 2 has attempted a DHCP request but the server’s
ACK was dropped by the switch because there is already an entry on port 2. The entry on
port 2 is static. Even though the server offered the same IP to the same MAC (as appears in the
DHCP snooping database) the static entry causes the DHCP process to not be completed.
DHCPSN_Process: [0b44ca0c] Type: REQUEST
DHCPSN_Process: [0b44ca0c] On DHCP Snooping non-trusted port
DHCPSN_Process: [0b44ca0c] DHCP Snoop forwarding pkt at L2 for VLAN 1 InPort 2
DHCPSN_Process: [0b44ca0c] L2 Dest MAC is broadcast
DHCPSN_Process: [0b44ca0c] Type: REQUEST, L2 forward to trusted ports
DHCPSN_Process: [0b44ca0c] Forward ports (except 2)
DHCPSN_Process: [0b44ca0c] Tagged:None
DHCPSN_Process: [0b44ca0c] Untagged:48
DHCPSN_Process: [0b44d22c] DHCP Snooping pkt for VLAN 1 from port 48
DHCPSN_Process: [0b44d22c] Type: REPLY
DHCPSN_Process: [0b44d22c] On DHCP Snooping trusted port
DHCPSN_Process: [0b44d22c] Lookup result for CHAddr 00-00-00-00-00-02: Port 2
DHCPSN_Process: [0b44d22c] DHCP Snoop forwarding pkt at L2 for VLAN 1 InPort 48
DHCPSN_Process: [0b44d22c] L2 Dest MAC is unicast
DHCPSN_Process: [0b44d22c] Using chaddr lookup result for dest port(s)
DHCPSN_Process: [0b44d22c] L2 forward packet directly to port 2
DHCPSN_Process: [0b44d22c] Forward ports (except 48)
DHCPSN_Process: [0b44d22c] Tagged:None
DHCPSN_Process: [0b44d22c] Untagged:2
DHCPSN_Process: [0b44da4c] DHCP Snooping pkt for VLAN 1 from port 2
DHCPSN_Process: [0b44da4c] Type: REQUEST
DHCPSN_Process: [0b44da4c] On DHCP Snooping non-trusted port
DHCPSN_Process: [0b44da4c] DHCP Snoop forwarding pkt at L2 for VLAN 1 InPort 2
DHCPSN_Process: [0b44da4c] L2 Dest MAC is broadcast
DHCPSN_Process: [0b44da4c] Type: REQUEST, L2 forward to trusted ports
DHCPSN_Process: [0b44da4c] Forward ports (except 2)
DHCPSN_Process: [0b44da4c] Tagged:None
DHCPSN_Process: [0b44da4c] Untagged:48
DHCPSN_Process: [0b44e26c] DHCP Snooping pkt for VLAN 1 from port 48
DHCPSN_Process: [0b44e26c] Type: REPLY
DHCPSN_Process: [0b44e26c] On DHCP Snooping trusted port
DHCPSN_Process: [0b44e26c] Lookup result for CHAddr 00-00-00-00-00-02: Port 2
DHCPSN_Process: [0b44e26c] DHCP ACK Found...
DHCPSN_Process: [0b44e26c] Error adding entry to DB
DHCPSN_Process: [0b44e26c] Discard packet, DHCP ACK not forwarded