problem with multiple alias on WAN

Question

We have the following issue. 
 We're migrating from cisco asa to XG. The two firewall are installed side-by-side and we're moving published services on at time by removing the public ip address from the Cisco ASA and adding them as Alias on the WAN interface of the XG . 
 We ran into the following issue . 
 We started adding one alias to XG and all worked fine, after we created the rules on XG for publishing the server behind the ALIAS . 
 Then we added a new ALIAS to WAN interface but found that id didn't work. 
 After some research we found the on the cisco asa there was an ARP entry ( dynamic ) only for the primary WAN interface IP and the first Alias we created . 
 It looks like additional aliases didn't set the ARP . 
 Adding a static ARP on the CIsco asa for the additional ALIASES solved the issue , but it looks to me it should not be needed 
 thanks

Aditya Patel · Accepted Answer

HI Sixteen 
 As per your issue you loose internet connection after 2-3 days , seems consistent unless you reboot the appliance would need to conduct simple test 
 Test 1. 
 First, check the arp table for WAN interface if the Gateway address is associated with a Mac Address . If it is complete then it is possible the ARP entry on the Router is deleted. If it shows "In-complete" you may add a Static Arp Entry for the same and the MAC address would be your WAN gateway's MAC address. 
 To diagnose this issue could you run a command in console/SSH 
 console >system diagnostics utilities arp ping interface PortB (Gateway address) 
 If you got the reply , you may check again if the internet connection is restored or not . 
 If the connection is restored then it is possible that the ISP gateway may have rebooted automatically and the ARP table on the router is wiped clean. Now at this stage the XG appliance already have an ARP entry and would not send again . 
 You would need to follow two steps if necessary to maintain the ARP on the ISP gateway . 
 Connect a Common Layer 2 switch in between the WAN interface and ISP connection . If that does not work , Arp bind the MAC address with XG WAN address on the Gateway Router. 
 Hope this would resolve your issue.