Arp vs Proxy Arp Same thing ? Or Different.

erickafabianaerickafabiana Member Posts: 22 ■□□□□□□□□□
in CCNA & CCENT
Hello guys I found this post on a website and im determining if their is a difference between Arp and Proxy Arp ?

"All frames must be delivered to a node on the local network segment. If the destination IPv4 host is on the local network, the frame will use the MAC address of this device as the destination MAC address. If the destination IPv4 host is not on the local network, the source node needs to deliver the frame to the router interface that is the gateway or next hop used to reach that destination. The source node will use the MAC address of the gateway as the destination address for frames containing an IPv4 packet addressed to hosts on other networks. The gateway address of the router interface is stored in the IPv4 configuration of the hosts. When a host creates a packet for a destination, it compares the destination IP address and its own IP address to determine if the two IP addresses are located on the same Layer 3 network. If the receiving host is not on the same network, the source uses the ARP process to determine a MAC address for the router interface serving as the gateway."

There are circumstances under which a host might send an ARP request seeking to map an IPv4 address outside of the range of the local network. In these cases, the device sends ARP requests for IPv4 addresses not on the local network instead of requesting the MAC address associated with the IPv4 address of the gateway. I notice that routers will use this particular circumstance but never "End Devices like PC's, I always see the end device PC Target IP Default Gateway if the Destination IP is not Local. But I always see routers, Target IP Destination IP Regardless of Local or Remote.
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    ARP is answering for your own IP with your MAC. Proxy ARP is answering for another IP with your own MAC.
    An expert is a man who has made all the mistakes which can be made.
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  • rob42rob42 Member Posts: 423
    A 'Proxy APR' is is when a Host or a Router responds to a ARP Request that arrives from one of its connected networks, for a host that is on another of its connected networks.

    E.g. a Host on Network 172.122.1.0 want to send a Packet to 192.168.1.100, but doesn't have the MAC Address. The ARP Req arrives at the Default Gateway and the Router has the 192.168.1.0 Network connected to another port (or knows the next hop to get to the 192.168.1.0 Network), so it forwards that ARP Req and gets a response from 192.168.1.100. The Router than forwards the reply back to the Host on its 172.122.1.0 Network. The Router has acted as a 'Proxy' for 192.168.1.100
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  • erickafabianaerickafabiana Member Posts: 22 ■□□□□□□□□□
    networker050184 wrote: »
    ARP is answering for your own IP with your MAC. Proxy ARP is answering for another IP with your own MAC.

    Thankyou !
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  • erickafabianaerickafabiana Member Posts: 22 ■□□□□□□□□□
    rob42 wrote: »
    A 'Proxy APR' is is when a Host or a Router responds to a ARP Request that arrives from one of its connected networks, for a host that is on another of its connected networks.

    E.g. a Host on Network 172.122.1.0 want to send a Packet to 192.168.1.100, but doesn't have the MAC Address. The ARP Req arrives at the Default Gateway and the Router has the 192.168.1.0 Network connected to another port (or knows the next hop to get to the 192.168.1.0 Network), so it forwards that ARP Req and gets a response from 192.168.1.100. The Router than forwards the reply back to the Host on its 172.122.1.0 Network. The Router has acted as a 'Proxy' for 192.168.1.100

    yes thankyou I now fully understand ARP :D
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