Analysis:
We found OLT has enable arp unicast function which only allowed 8 dhcp user dial up in one service port. OLT will discard dhcp packets whose amount are more than 8 dhcp users.
ARP unicast function description:
The function of ARP unicast is shown below and it is not needed to enable normally unless there are lots of ARP packets in the network.
If the ARP broadcast converted to unicast function is enabled on the network side, MA5600T/MA5603T/MA5608T queries user's going online information based on destination IP address and VLAN after receiving an
ARP request.
- After detecting that a user goes online, MA5600T/MA5603T/MA5608T sends the ARP request to this user.
- If no online users are detected, when security arp-unicast unknown-policy is set to discard, the ARP request is broadcast cascading-side and network-side ports excluding the source port in the VLAN.
However, the user side cannot receive ARP requests sent by the network side; when security arp-unicast unknown-policy is set to forward, the ARP request is broadcast to the user-side, cascading-side, and network-side ports excluding the source port in the VLAN.
Solution:
Disable ARP unicast function.
