滑动窗口实验报告

滑动窗口实验报告（含源码）一、 实验目的1. 实现一个数据链路层协议的数据传送部分。2. 更好地理解数据链路层协议中的“滑动窗口”技术的基本工作原理。3. 掌握计算机网络协议的基本实现技术。二、 实验要求在一个数据链路层的模拟实现环境中，用C语言实现下两个数据链路层协议。1. 1比特滑动窗口协议2. 回退N帧滑动窗口协议三、 实验内容充分理解滑动窗口协议，根据滑动窗口协议，模拟滑动窗口协议中发送端的功能，对系统发送的帧进行缓存并加入窗口等待确认，并在超时或者错误时对部分帧进行重传。编写停等及退回N滑动窗口协议函数，响应系统的发送请求、接收帧消息以及超时消息，并根据滑动窗口协议进行相应处理。四、 源代码及注释#include sysinclude.h#include using namespace std;extern void SendFRAMEPacket(unsigned char* pData, unsigned int len);/1比特滑动窗口#define WINDOW_SIZE_STOP_WAIT 1/回退N帧协议#define WINDOW_SIZE_BACK_N_FRAME 4/缓存区大小#define BUFFER_SIZE 50typedef enum DATA,ACK,NAK Frame_kind;/帧头typedef struct Frame_headFrame_kind kind;unsigned int seq;unsigned int ack;unsigned char data100;/帧typedef struct FrameFrame_head head;unsigned int size;/缓存区Frame bufferBUFFER_SIZE;/当前希望确认的帧，最近缓存的帧，下一次要发送的帧unsigned int expect_frame = 0, last_buffered_frame = 0, next_frame = 0;/* 停等协议测试函数*/int stud_slide_window_stop_and_wait(char *pBuffer, int bufferSize, UINT8 messageType) Frame_head* p = (Frame_head*)pBuffer;/unsigned int frameNum = ntohl(*(unsigned int*)pBuffer);switch (messageType)/网络层要发送一帧数据时case MSG_TYPE_SEND : /缓存当前要发送的帧bufferlast_buffered_frame % BUFFER_SIZE.head = *p;bufferlast_buffered_frame % BUFFER_SIZE.size = bufferSize;/更新下次缓存的位置+ last_buffered_frame;/如果当前有空闲的窗口可以用if (last_buffered_frame - expect_frame ack);/试探 for (int i = expect_frame; i = exp_ack)/期望帧+1+ expect_frame;/如果有缓存帧没发出if (next_frame last_buffered_frame)/发出一个缓存帧SendFRAMEPacket(unsigned char*)(&buffernext_frame % BUFFER_SIZE), buffernext_frame % BUFFER_SIZE.size);/窗口上界+1+ next_frame;/否则，无法继续发送帧，退出。等待下次再更新期望确认帧else break;return 0;/超时 case MSG_TYPE_TIMEOUT : /超时重发，把当前窗口内未确认的帧重发一遍for (int i = expect_frame; i ntohl(bufferi % BUFFER_SIZE.head.seq) continue;SendFRAMEPacket(unsigned char*)(&bufferi % BUFFER_SIZE), bufferi % BUFFER_SIZE.size);return 0; default : break;return -1;/* 回退n帧测试函数*/int stud_slide_window_back_n_frame(char *pBuffer, int bufferSize, UINT8 messageType) Frame_head* p = (Frame_head*)pBuffer;unsigned int timeoutNum = *(unsigned int*)pBuffer;switch (messageType)/网络层要发送一帧数据时case MSG_TYPE_SEND : bufferlast_buffered_frame % BUFFER_SIZE.head = *p;bufferlast_buffered_frame % BUFFER_SIZE.size = bufferSize;+ last_buffered_frame;/窗口数未达上限，则发送当前缓存帧，更新窗口上界if (last_buffered_frame - expect_frame ack); cout receive ack : ack endl; for (int i = expect_frame; i next_frame; + i)unsigned int exp_ack = ntohl(bufferi % BUFFER_SIZE.head.seq);cout exp_ack : exp_ack = exp_ack)+ expect_frame;if (next_frame last_buffered_frame)SendFRAMEPacket(unsigned char*)(&buffernext_frame % BUFFER_SIZE), buffernext_frame % BUFFER_SIZE.size);+ next_frame;else break;return 0;/超时 case MSG_TYPE_TIMEOUT : cout time out : timeoutNum endl;/超时重发for (int i = expect_frame; i frameNum) continue;cout frameNum endl;SendFRAMEPacket(unsigned char*)(&bufferi % BUFFER_SIZE), bufferi % BUFFER_SIZE.size);return 0; default : break;return -1;/* 选择性重传测试函数*/int stud_slide_window_choice_frame_