思科网络技术学院教程(第二章 高层协议)

1、Copyright ?1998, Cisco Systems, Inc.,ICRC_revision_11.3,高层协议,第二章,应用层与会话层,Copyright ?1998, Cisco Systems, Inc.,ICRC_revision_11.3,应用层,选择网络应用支持用户的事务应用,?Graphics ?Visual Images PICT TIFF JPEG GIF,表示层,为应用层提供代码格式的转换,?Text ?Data ASCII EBCDIC Encrypted,?Sound ?Video MIDI MPEG QuickTime,login:,网络文件系统 (NFS)

2、结构化查询语言 (SQL) 远程过程调用 (RPC) X 窗口系统 互连网浏览器 DNA 会话控制协议 (SCP),会话层,Service Request,Service Reply,支持在不同主机上对等应用程序之间的对话,传输层,Copyright ?1998, Cisco Systems, Inc.,ICRC_revision_11.3,传输层概览,将会话层数据分割成较小的分组 建立端到端的连接 将分组从一端主机发送到另一端主机 保证数据可靠传输,面向连接的会话,同步,同步,确认,连接协商,数据传输,(发送分组),Sender,Receiver,连接建立,流量控制,流量控制,Buffer

3、Full,Transmit,Not Ready,Stop,Sender,Receiver,流量控制,Buffer Full Process Segments Buffer OK,Transmit,Not Ready,Stop,Sender,Receiver,流量控制,Buffer Full Process Segments Buffer OK,Transmit,Not Ready,Stop,Ready,Go,Sender,Receiver,流量控制,Buffer Full Process Segments Buffer OK,Transmit,Not Ready,Stop,Ready,Go,R

4、esume Transmission,Sender,Receiver,窗口技术,窗口技术,窗口技术,窗口技术,窗口技术,窗口技术,窗口技术,Window size = 1,Send 1,Receive 1,Ack 2,Send 2,Receive 2,Ack 3,Send 1,Send 2,Receive 1,Receive 2,Window size = 3,Send 3,Receive 3,Ack 4,Send 4,Sender,Receiver,Sender,Receiver,正向确认,Sender,Receiver,1,2,3,4,5,6,正向确认,Sender,Receiver,Se

5、nd 2,Send 1,Send 3,1,2,3,4,5,6,1,2,3,正向确认,Sender,Receiver,Send 2,Send 1,Send 3,Ack 4,Send 4,1,2,3,4,5,6,1,2,3,正向确认,Sender,Receiver,Send 2,Send 1,Send 3,Ack 4,Send 5,Send 4,Send 6,1,2,3,4,5,6,1,2,3,4,6,正向确认,Sender,Receiver,Send 2,Send 1,Send 3,Ack 4,Send 5,Send 4,Send 6,Ack 5,1,2,3,4,5,6,1,2,3,4,6,正向确认,Sender,Receiver,Send 2,Send 1,Send 3,Ack 4,Send 5,Send 4,Send 6,Ack 5,Send 5,1,2,3,4,5,6,1,2,3,4,5,6,正向确认,Sender,Receiver,Send 2,Send 1,Send 3,Ack 4,Send 5,Send 4,Send 6,Ack 5,Send 5,Ack 7,1,2,3,4,5,6,1,2,3,4,5,6,正向确认,Sender,Receiver,Send 2,Send 1,Send 3,Ack 4