What is Proxy ARP with examples

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Topology used  to understand the concept



Test-1

Ping to 100.100.100.100 from R1

As R1 has static route for 100.100.100.100 with next-hop  192.168.1.2, so R1 tries to resolve MAC for gateway and forwards to R2



Test-2

Ping to 200.200.200.200 from R1, since next-hop is configured as interface g0/0,  R1 thinks network connected on g0/0, so it tries to resolve mac for IP 200.200.200.200. Since R2 not owning this IP it wont respond to ARP request from R1

Solution:- Enable 'proxy-arp' on R2 interface g0/0 ( use ip proxy-arp to enable)



What will Happen: R2 will respond with its own mac for ARP-Request of 200.200.200.200.so R1 Will forward traffic to R2, since R2 Has route to 200.200.200.200, it forwards further




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