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1、 2006, Shenzhen Polytechnic, All rights reserved.1交换和VLAN Switching and VLAN深圳职业技术学院计算机系网络专业 2006, By Shenzhen Polytechnic. All rights reserved.2教学目标（ Objectives ）1. 交换机学习主机地址 （Switche Learn Host Address）2. 两种交换方法（Two Switching Methods） 3. 配置端口安全（Configuring Port Security） 4.密码破解（Password Recovery）
2、5. VLAN操作（VLAN Operations） 6.配置和验证静态VLAN(Configuring and Verifying Static VLANs) 2006, By Shenzhen Polytechnic. All rights reserved.3 地址学习（Address learning） 决定转发或过滤（Forward/filter decision） 避免环路（Loop avoidance）交换机三种功能 （Three Switch Functions ） 2006, By Shenzhen Polytechnic. All rights reserved.4交换机学
3、习主机地址 （Switche Learn Host Address） 初始MAC地址表是空的 Initial MAC address table is emptyMAC address table0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0E1E2E3ABCD 2006, By Shenzhen Polytechnic. All rights reserved.5交换机学习主机地址 （Switche Learn Host Address） A向C发送帧（Station A sends a frame to Station
4、C） 交换机将A的MAC地址和其对应的接口E0放入MAC地址表 Switch caches station A MAC address to port E0 by learning the source address of data frames 该帧向除了E0接口的所有接口泛洪 The frame from station A to station C is flooded out to all ports except port E0 MAC address table0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0:
5、0260.8c01.1111E0E1E2E3DCBA 2006, By Shenzhen Polytechnic. All rights reserved.6交换机学习主机地址 （Switche Learn Host Address） D向C发送帧(Station D sends a frame to station C) 交换机将D的MAC地址和其对应的接口E3放入MAC地址表 Switch caches station D MAC address to port E3 by learning the source Address of data frames 该帧向除了E3接口的所有接口泛
6、洪 The frame from station D to station C is flooded out to all ports except port E3 (unknown unicasts are flooded)MAC address table0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0: 0260.8c01.1111 E3: 0260.8c01.4444E0E1E2E3DCAB 2006, By Shenzhen Polytechnic. All rights reserved.7交换机过滤帧（ Swit
7、ches Filter Frames） A向C发送帧 Station A sends a frame to station C 目的地址已知，帧不被泛洪 Destination is known, frame is not flooded E0: 0260.8c01.1111 E2: 0260.8c01.2222 E1: 0260.8c01.3333 E3: 0260.8c01.44440260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0E1E2E3X XDCABMAC address table 2006, By Shenzhe
8、n Polytechnic. All rights reserved.8两种交换方法（Two Switching Methods） 2006, By Shenzhen Polytechnic. All rights reserved.9存储转发特征（Store-and-forward Feature）1. 在转发之前整个帧被接收 The entire frame is received before any forwarding takes place. 2.由于交换开始之前要接收完整帧，较大的数据 帧延迟较大Latency is greater with larger frames beca
9、use the entire frame must be received before the switching process begins. 2006, By Shenzhen Polytechnic. All rights reserved.10直通特征（Cut-through Feature）1.在接收完整帧之前，帧就被转发。The frame is forwarded through the switch before the entire frame is received. 2.最快的是只要读到目的地址就转发。At a minimum the frame destinatio
10、n address must be read before the frame can be forwarded.3.这种模式降低了延迟，但是不进行检错This mode decreases the latency of the transmission, but also reduces error detection. 2006, By Shenzhen Polytechnic. All rights reserved.11直通分类（Cut-through Class）一、快速转发（Fast-forward ）1.快速转发提供了最低的延迟Fast-forward switching off
11、ers the lowest level of latency.2.只要读到目的地址，就立刻转发Fast-forward switching immediately forwards a packet after reading the destination address. 2006, By Shenzhen Polytechnic. All rights reserved.12直通分类（Cut-through Class）二、Fragment-free （无碎片方式）1.无碎片方式在转发之前过滤掉碰撞碎片 Fragment-free switching filters out colli
12、sion fragments before forwarding begins. 2.无碎片方式在转发之前要读到帧的前64字节Fragment-free switching waits until the packet is determined not to be a collision fragment(64bytes) before forwarding 2006, By Shenzhen Polytechnic. All rights reserved.13配置SVI地址（Configuring SVI Address）Switch(config)#interface vlan 1Sw
13、itch(config-if)#ip address 10.1.1.1 255.255.255.0Switch(config-if)#no shutdown 2006, By Shenzhen Polytechnic. All rights reserved.14配置端口安全（Configuring Port Security）Switch(config)#int f0/1 Switch(config-if)#switchport mode access Switch(config-if)#switchport port-security Switch(config-if)#switchpor
14、t port-security mac-address 0060.6700.dd5b Switch(config-if)#switchport port-security violation restrict Switch#sh port-security Secure Port MaxSecureAddr CurrentAddr SecurityViolation Security Action(Count) (Count) (Count) -Fa0/1 132 1 0 Restrict 2006, By Shenzhen Polytechnic. All rights reserved.1
15、5密码破解（Password Recovery）1. 拔掉电源（Unplug the power cable） 2.按下mode按钮（hold down the mode button） 3.输入flash_init （type flash_init） 4.执行dir flash: （type dir flash:） 5.重命名配置文件 （rename flash:config.text flash:config.old） 6.启动（Boot） 7.在进入setup模式提示下输入N （enter N at the prompt to start the setup program.） 2006, By Shenzhen Polytechnic. All rights reserved.16密码破解（Password Recovery）8. 进入特权模式（switchenable）9. 重命名配置文件（rename flash:config.old flash:config.text）10. 将配置文件拷贝到RAM中运行（copy flash:config.text system:running- config）11.修改密码 （enable password cisco）12.存盘（write）13.重启（reload
