第 6 讲 数据链路层（ 2 ）
If you can't read please download the document
DESCRIPTION
第 6 讲 数据链路层（ 2 ）. 知识回顾. 数据链路层的功能 帧定界 差错检测 循环冗余检码. CRC 工作原理. 举例 CRC. 本讲内容及教学目标. 掌握 PPP 协议在数据链路层的工作原理 了解面向比特的链路层协议 HDLC 的帧 理解停止等待协议 理想化的数据传输 具有最简单流量控制的数据链路层协议 实用的停止等待协议 理解滑动窗口协议，实现流量控制 了解传输层类似的流量控制功能. 数据链路层协议分类. 点到点线路 广播线路 局域网使用 Internet 中主要的数据链路层协议 SLIP （ Serial Line IP ） - PowerPoint PPT PresentationTRANSCRIPT
-
6 2
-
CRC
-
CRC
-
PPP HDLC
-
InternetSLIP Serial Line IP ;PPP Point-to-Point Protocol -SLIPPPPISPInternet
-
PPP PPP (Point-to-Point Protocol) PPP PPP;PPPISP
-
ISP PPP
IP ISPPPP
-
PPP
-
Maximum Transmission UnitMTU IPMTU1500IP1500IP64KBIPIP
-
PPP
-
PPP 1992 PPP 1993 1994 PPP [RFC 1661] PPP IP LCP (Link Control Protocol) NCP (Network Control Protocol)
-
PPP () F = 0x7E 0x 7E 01111110 A 0xFF C 0x03PPP PPP
-
PPP PPP 2 0x0021 PPP IP 0xC021, PPP 0x8021 IP 121112 1500 PPP 7EFF03FACFCSF7E
-
PPP PPP PPP 0x7E 2 (0x7D, 0x5E) 0x7D , 2 (0x7D, 0x5D) ASCII 0x20 0x7D PPP SONET/SDH PPP
-
0 1 0 0 1 1 1 1 1 0 1 0 0 0 1 0 1 00 1 0 0 1 1 1 1 1 1 0 0 0 1 0 1 00 1 0 0 1 1 1 1 1 0 1 0 0 0 1 0 1 0 F 8 5 1 0 5 1 0 F 0 0
-
PPP PPP PPP IP FCS
-
PPP ISP PC LCP PPP PPP NCP PC IP PC NCP IP LCP
-
LCP LCP LCP NCP LCP NCP LCP LCP
-
HDLC HDLC1974IBM SDLC (Synchronous Data Link Control) ISO SDLC HDLC (High-level Data Link Control)ISO 3309CCITT HDLC LAP (Link Access Procedure)HDLC LAP LAPBB(Balanced) LAPB ()
-
HDLC F (Flag) 6 1 0 8 bit 888168 Info F F A C FCSFCS
-
HDLC01111110511010
-
HDLC F 6 1 5 1 0 F 5 1 0
-
A BAP2AP1
-
cont. 1 2 2
-
A B
-
()
-
cont.
-
ABDATADATADATADATA B B B BABDATA BDATA B
-
ABACKACK(a)
-
A(timeout timer) tout B A
-
1 B B B A ACK B A ACK
-
0 1
-
N(S) 0 1
-
ARQ ARQ ARQ
- nlml
-
(slide)--1n0~2n-1sending windowreceiving window
-
WWWll+WWj
-
ll+WiW
-
30~73012345670123456701234567012345670123456701234567012345670123456701234567012345670123456701234567
-
-10~11010101010101010101010101
-
piggybacking
-
go-back-n11112n-1(n)
-
selective repeat112n-11/2
-
PPPPPP
-
P105,3-09,3-11,3-13,3-14,3-19ARQARQ