Second IP Address Makes the Problem

There is a network issue happened in my company.

One server is relocated and the administrator wanted to keep the old ip address which is 10.200.200.5. So I created a vlan 200 and assinged IP address 10.200.200.0/24. The Vlan interface ip is 10.200.200.1.

After the configuration, we server can ping all other vlans except 10.0.99.5. I have checked the ACL on all devices and found no ban. I pinged from the switch and found that: 10.0.99.5--10.200.200.1 is OK, 10.200.200.5--10.0.99.1 NOT OK.

So the problem is on the server. After login to the server, I found that the is a secondary ip address on the server's NIC. The secondary ip address is 10.0.99.9/24. After removing the secondary ip address, the communication is GOOD.

The issue is when the server sends packet to 10.0.99.0/24, the MAC address is not pointing to ther gateway. And there is no Proxy ARP on the default gateway. So the server cannot get the MAC address of any ip address of 10.0.99.0/24. This makes the problem.

In conclusion, the problem is related to ARP. The server cannot get the mac of ip.