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How does ARP work on WAN port and on IP alias


I have 10  public ip addresses  and I have only 1 WAN port . So I have created aliases on the WAN port of the  firewall . Then  I have forwarded the ports of all the public ips to internal machines . The questions I have 

1. Will the alias broadcast mac address ?

2.Will the WAN interface broadcast mac address ?

3. How will the upstream device will know which IP has which mac ?

4. What is the use of proxy arp in this scenario ?

5. Does gratuitous arp play any role here .?


Here is the setup

ISP link Fibre Connection >ISP device >Switch >Firewall >LAN computers 


Please let me know the arp flow over the wan and the working of IP alias . 




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