In this assignment, you need our given UDP socket class to implement RDT protocol.
Then implement an Echo Server and Client.
I. Requirement
i. Your protocol needs to ensure the reliability of data transfer. Packet loss and payload corruption might happen.
i. To deal with packet loss, using ack and retransmission according to GBN the textbook.
ii. To deal with payload corruption, you need to design a checksum of your payload.
ii. Payload Example
Your payload might be like this:
| SYN | FIN | ACK | SEQ | SEQ ACK | LEN | CHEKCSUM | Payload| | 1 bit|1 bit| 1 bit| 4 byte| 4 byte | 4 byte | 2 byte | LEN |
i. Checksum Calculation Example
def calc_checksum(payload): sum = 0
for byte in payload: sum += byte
sum = -(sum % 256) return (sum & 0xFF)
CS305 Computer Network Lab Tutorial
II. API reference: rdt code example:
from udp import UDPsocket # import provided class class socket(UDPsocket):
def __init__():
super(socket, self).__init__()
def recvfrom():
• your code here pass
def sendto():
• your code here pass
server code example:
from rdt import socket
server = socket()
server.bind((SERVER_ADDR, SERVER_PORT))
while True:
dara, addr = server.recvfrom()
server.sendto(data, addr)
client code example:
from rdt import socket
client = socket()
client.send(DATA, (SERVER_ADDR, SERVER_PORT))
data = client.recvfrom()
assert data = DATA
client.close()
