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Update Chap05 - Network Protocols.html #68

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2 changes: 1 addition & 1 deletion A Beginner's Guide to the ESP8266 - article/Full HTML/Chap05 - Network Protocols.html
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Expand Up @@ -151,7 +151,7 @@ <h4><i>MAC addresses and ARP <span style="font-weight: normal;">(optional)</span
<i>It is actually impossible to send packets directly to another machine using only the IP address. To send a packet to a specific device on the LAN (Wi-Fi or Ethernet), you have to know its MAC-address. The MAC address is a unique number that is unique for every network device, and it never changes, it's hardwired in the network chip. This means that every ESP8266, every network card, every smartphone ... ever made, has a different MAC address. </i>
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<i>So before the ESP can send a packet to your smartphone for example, it has to know its MAC address. It doesn't know this yet, the ESP only knows the IP address of the smartphone, say 192.168.1.6. To do this, the ESP sends a broadcast message (i.e. a message addressed to all devices on the LAN) saying "I'm looking for the MAC address of the device with the IP address 192.168.1.6". The ESP also includes its own IP and MAC address with the message. When the smartphone receives this broadcast message, it recognizes its own IP address, and responds to the ESP by sending its own MAC address. Now the ESP and the phone both know each other's IP and MAC addresses, and they can communicate using IP addresses. This method is called the Addres Resolution Protocol, or ARP.</i>
<i>So before the ESP can send a packet to your smartphone for example, it has to know its MAC address. It doesn't know this yet, the ESP only knows the IP address of the smartphone, say 192.168.1.6. To do this, the ESP sends a broadcast message (i.e. a message addressed to all devices on the LAN) saying "I'm looking for the MAC address of the device with the IP address 192.168.1.6". The ESP also includes its own IP and MAC address with the message. When the smartphone receives this broadcast message, it recognizes its own IP address, and responds to the ESP by sending its own MAC address. Now the ESP and the phone both know each other's IP and MAC addresses, and they can communicate using IP addresses. This method is called the Address Resolution Protocol, or ARP.</i>
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