GBN(Go-Back-N)协议的python本机模拟实现-计算机网络

import random
 
def go_back_n_receiver(window_size):
    """
    实现GBN接收方的模拟
    :param window_size: 接收窗口大小
    :return: 输出丢失的分组序号和重传的分组序号
    """
    expected_sequence = 0  # 期望的下一个序号
    received_packets = []  # 已接收的分组序号列表
    lost_packets = []  # 丢失的分组序号列表
    retransmitted_packets = []  # 重传的分组序号列表
 
    while True:
        sequence = random.randint(0, window_size - 1)  # 模拟收到的分组序号
        if sequence not in received_packets:  # 如果分组未重复
            received_packets.append(sequence)  # 加入接收列表
            received_packets.sort()  # 排序以便于处理
 
            # 如果序号正确，输出信息
            if sequence == expected_sequence:
                print(f"Received packet: {sequence}")
                expected_sequence = (expected_sequence + 1) % (window_size + 1)
            else:
                # 如果序号不正确且不在接收窗口内，则为丢失分组
                if sequence not in range(expected_sequence, expected_sequence + window_size):
                    lost_packets.append(sequence)
                    print(f"Lost packet: {sequence}")
                # 如果是重复分组，则为重传分组
                else:
                    retransmitted_packets.append(sequence)
                    print(f"Retransmitted packet: {sequence}")
 
    return lost_packets, retransmitted_packets
 
# 使用示例
lost_packets, retransmitted_packets = go_back_n_receiver(window_size=5)
print(f"Lost packets: {lost_packets}")
print(f"Retransmitted packets: {retransmitted_packets}")

这段代码模拟了GBN协议中接收方的行为。它随机生成分组序号，并将其与期望的序号进行比较。如果序号正确，输出接收信息；如果序号不正确且不在接收窗口内，则记为丢失分组；如果是重复分组，则记为重传分组。最后返回丢失的分组序号和重传的分组序号。