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Networking

6.2 UDP Client Server

1. Simple UDP Client-Server

Here’s a simple UDP client-server example for use in Cisco Packet Tracer using the IoT scripting environment (such as a generic PC or IoT device).

1.2 ✅ Server Code (UDP Server)

from udp import *
from time import *


def onUDPReceive(ip, port, data):
  print("received from "
    + ip + ":" + str(port) + ":" + data)


def main():
  socket = UDPSocket()
  socket.onReceive(onUDPReceive)
  print(socket.begin(1235))


  count = 0
  while True:
    count += 1
    socket.send("192.168.1.1", 1235, "hello " + str(count))
    sleep(5)


if __name__ == "__main__":
  main()

1.2 ✅ Client Code (UDP Client)

from udp import *
from time import *


def onUDPReceive(ip, port, data):
  print("received from "
    + ip + ":" + str(port) + ":" + data)


def main():
  socket = UDPSocket()
  socket.onReceive(onUDPReceive)
  print(socket.begin(1235))


  count = 0
  while True:
    count += 1
    socket.send("192.168.1.2", 1235, "hello " + str(count))
    sleep(5)


if __name__ == "__main__":
  main()

1.3 🛠 Notes:

  • These scripts should be placed on appropriate IoT/PC devices.
  • Make sure the IP addresses match your network setup.
  • Use UDPSocket, not TCP.
  • Unlike TCP, no connection setup is needed — the client can start sending immediately.