计算机网络中GBN协议的C#代码实现

GBN协议的C是指窗口大小，即发送方可以发送的未确认分组的最大数量。GBN协议中，C的值决定了发送方可以发送的分组数量，同时也影响了网络的吞吐量和延迟。如果C的值过小，网络的吞吐量会受到限制，而如果C的值过大，网络可能会发生拥塞，导致延迟增加和分组丢失。因此，在实际应用中，需要根据网络的情况和应用的需求来选择合适的C的值。

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计算机网络中GBN协议算法具体代码

以下是GBN协议的Python代码实现：

发送端代码：

from socket import *
import time

serverName = 'localhost'
serverPort = 12000

# 创建客户端套接字
clientSocket = socket(AF_INET, SOCK_DGRAM)

# 设置超时时间
clientSocket.settimeout(1)

# 发送窗口大小
N = 4

# 初始化变量
base = 0
nextseqnum = 0
pkt = []

# 读取文件
f = open('file.txt', 'r')
data = f.read()

# 分割数据
for i in range(0, len(data), 500):
    pkt.append(data[i:i+500])

while True:
    # 发送窗口未满
    if nextseqnum < base + N:
        # 发送数据包
        message = pkt[nextseqnum]
        clientSocket.sendto(message.encode(), (serverName, serverPort))
        
        # 输出发送信息
        print('Sent packet', nextseqnum)
        
        # 第一个数据包发送时开始计时
        if nextseqnum == base:
            start_time = time.time()
        
        # 增加序列号
        nextseqnum += 1
        
        # 发送完最后一个数据包，退出循环
        if nextseqnum == len(pkt):
            break
        
    try:
        # 接收ACK
        ack, serverAddress = clientSocket.recvfrom(2048)
        
        # 解析ACK序号
        acknum = int(ack.decode())
        
        # 输出接收信息
        print('Received ACK', acknum)
        
        # 确认ACK是否在窗口内
        if acknum >= base and acknum < nextseqnum:
            # 滑动窗口
            base = acknum + 1
            
            # 判断是否收到最后一个ACK
            if base == len(pkt):
                break
            
    except timeout:
        # 超时重传
        print('Timeout, sequence number =', base)
        nextseqnum = base
        
        # 重新发送窗口内的数据包
        for i in range(base, base+N):
            message = pkt[i]
            clientSocket.sendto(message.encode(), (serverName, serverPort))
            print('Resent packet', i)
            
        # 重置计时器
        start_time = time.time()
        
# 输出传输时间
end_time = time.time()
print('Transmission time:', end_time - start_time, 'seconds')

# 关闭套接字
clientSocket.close()

接收端代码：

from socket import *

serverPort = 12000

# 创建服务器套接字
serverSocket = socket(AF_INET, SOCK_DGRAM)

# 绑定服务器端口
serverSocket.bind(('', serverPort))

# 接收窗口大小
N = 4

# 初始化变量
expectedseqnum = 0

while True:
    # 接收数据包
    message, clientAddress = serverSocket.recvfrom(2048)
    
    # 解析数据包序号
    seqnum = int(message.decode())
    
    # 输出接收信息
    print('Received packet', seqnum)
    
    # 判断是否是期望的数据包
    if seqnum == expectedseqnum:
        # 发送ACK
        ack = str(seqnum)
        serverSocket.sendto(ack.encode(), clientAddress)
        
        # 输出发送信息
        print('Sent ACK', seqnum)
        
        # 增加期望序号
        expectedseqnum += 1
        
    # 判断是否是重复的数据包
    elif seqnum < expectedseqnum:
        # 发送ACK
        ack = str(seqnum)
        serverSocket.sendto(ack.encode(), clientAddress)
        
        # 输出发送信息
        print('Sent ACK', seqnum)
        
    # 判断是否是超出窗口范围的数据包
    else:
        # 不发送ACK，等待发送端重传
        print('Discarded packet', seqnum)

计算机网络中GBN协议算法具体的C-Sharp代码

以下是GBN协议的C#代码实现：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;

namespace GBNProtocol
{
    class GBNClient
    {
        private const int TIMEOUT = 5000;
        private const int WINDOW_SIZE = 4;
        private const int BUFFER_SIZE = 256;
        private const int SERVER_PORT = 8888;
        private const string SERVER_IP = "127.0.0.1";

        private static int lastAck = 0;
        private static int lastSent = 0;
        private static int lastReceived = -1;

        static void Main(string[] args)
        {
            byte[][] message = new byte[WINDOW_SIZE][];
            bool[] acks = new bool[WINDOW_SIZE];
            IPEndPoint serverEndpoint = new IPEndPoint(IPAddress.Parse(SERVER_IP), SERVER_PORT);
            Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            Console.Write("Enter message to send: ");
            string input = Console.ReadLine();
            byte[] data = Encoding.ASCII.GetBytes(input);

            while (lastAck < data.Length)
            {
                for (int i = lastSent; i <= Math.Min(lastSent + WINDOW_SIZE - 1, data.Length - 1); i++)
                {
                    message[i % WINDOW_SIZE] = new byte[BUFFER_SIZE];
                    data.CopyTo(message[i % WINDOW_SIZE], 0);
                    clientSocket.SendTo(message[i % WINDOW_SIZE], serverEndpoint);
                    lastSent++;
                }

                clientSocket.ReceiveTimeout = TIMEOUT;
                byte[] buffer = new byte[BUFFER_SIZE];

                try
                {
                    EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
                    int bytesReceived = clientSocket.ReceiveFrom(buffer, ref remoteEndPoint);

                    if (bytesReceived > 0)
                    {
                        string ackString = Encoding.ASCII.GetString(buffer, 0, bytesReceived);
                        int ack = Int32.Parse(ackString);

                        if (ack > lastAck && ack <= lastSent)
                        {
                            for (int i = lastAck + 1; i <= ack; i++)
                            {
                                acks[(i - 1) % WINDOW_SIZE] = true;
                            }

                            lastAck = ack;
                        }
                    }
                }
                catch (SocketException e)
                {
                    Console.WriteLine("Timeout. Resending packets...");
                    continue;
                }

                if (acks[lastReceived % WINDOW_SIZE])
                {
                    lastReceived++;
                }

                Array.Clear(message[lastReceived % WINDOW_SIZE], 0, BUFFER_SIZE);
                acks[lastReceived % WINDOW_SIZE] = false;
            }

            clientSocket.Close();
            Console.WriteLine("All packets sent and acknowledged.");
            Console.ReadKey();
        }
    }
}