ARP issue on the firewall

[ashish_verma]

Hello guys,

I was getting network degrade performance complaint for one of the sites and after investigation I observed that seems to be an ARP issue but I am not able to understand why it is happening. Below is the detail-

We are having one checkpoint cluter on site_1, one cluster on site_2 and a fortigate firewall on site 3, all connected in the same subnet 10.1.0.0/24. Site_1 cluster IP is 10.1.0.5. When I am trying to ping from Site_1 IP to Site_3 fortigate firewall and look into the arp table of Forrigate for 10.1.0.5, I saw the arp entry is changing between the mac address of site_1 cluster and site_2 cluster. Site_2 cluster is also getting some ping replies. I checked in the dash board if there is any NAT configured on site_2 for 10.1.0.5 but did not find anything.

Please help with this issue what might be cause of this. Thanks in advance.