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交换和 VLAN Switching and VLAN. 深圳职业技术学院计算机系网络专业. 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 ) 5. VLAN 操作( VLAN Operations ) 6. 配置和验证静态 VLAN
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交换和VLANSwitching and VLAN 深圳职业技术学院计算机系网络专业
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) 5. VLAN操作(VLAN Operations) • 6.配置和验证静态VLAN • (Configuring and Verifying Static VLANs)
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)
交换机学习主机地址 (Switche Learn Host Address) MAC address table A B 0260.8c01.1111 0260.8c01.3333 E0 E1 E2 E3 C D 0260.8c01.2222 0260.8c01.4444 • 初始MAC地址表是空的 • Initial MAC address table is empty
交换机学习主机地址 (Switche Learn Host Address) MAC address table E0: 0260.8c01.1111 A B 0260.8c01.1111 0260.8c01.3333 E0 E1 C D E2 E3 0260.8c01.2222 0260.8c01.4444 • A向C发送帧(Station A sends a frame to Station 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
交换机学习主机地址 (Switche Learn Host Address) MAC address table E0: 0260.8c01.1111 E3: 0260.8c01.4444 A B 0260.8c01.1111 0260.8c01.3333 E0 E1 E2 E3 C D 0260.8c01.2222 0260.8c01.4444 • 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接口的所有接口泛洪 • The frame from station D to station C is flooded out to all ports except port E3 (unknown unicasts are flooded)
交换机过滤帧( Switches Filter Frames) MAC address table E0: 0260.8c01.1111 E2: 0260.8c01.2222 E1: 0260.8c01.3333 A B E3: 0260.8c01.4444 0260.8c01.1111 0260.8c01.3333 E0 E1 X X D C E2 E3 0260.8c01.2222 0260.8c01.4444 • 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
存储转发特征(Store-and-forwardFeature) • 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 because the entire frame must be received before the switching process begins.
直通特征(Cut-throughFeature) • 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 destination 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.
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 offers 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.
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 collision 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
配置SVI地址(Configuring SVI Address) • Switch(config)#interface vlan 1 • Switch(config-if)#ip address 10.1.1.1 255.255.255.0 • Switch(config-if)#no shutdown
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)#switchport 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
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.)
密码破解(Password Recovery) • 8. 进入特权模式(switch>enable) • 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)
VLAN预览(VLAN Overview) • 分段Segmentation • 灵活 • Flexibility • 安全 • Security 3rd floor 2nd floor 1st floor SALES HR ENG 1 VLAN =1广播域=1逻辑子网 A VLAN = A broadcast domain = Logical network (subnet)
Switch A Red VLAN Black VLAN Green VLAN VLAN操作(VLAN Operations) • 每一个逻辑的VLAN就像一个独立的物理网桥 • Each logical VLAN is like a separate physical bridge
Switch A Red VLAN Black VLAN Green VLAN VLAN操作(VLAN Operations) Switch B Red VLAN Black VLAN Green VLAN • 同一个VLAN可以跨越多个交换机 • VLANs can span across multiple switches
Switch A Red VLAN Black VLAN Green VLAN VLAN操作(VLAN Operations) Switch B Trunk Fast Ethernet Red VLAN Black VLAN Green VLAN • TRUNK链路携带多个VLAN的数据 • Trunks carries traffic for multiple VLANs • Trunks利用特定的封装来识别不同的VLAN • Trunks use special encapsulation to distinguish between different VLANs
VLAN成员模式(VLAN Membership Modes) 静态VLAN (Static VLAN) 动态VLAN(Dynamic VLAN) Trunk Port e0/4 Port e0/9 VLAN5 VLAN10 VMPS 1111.1111.1111 = vlan 10 MAC = 1111.1111.1111
配置静态VLAN (Configuring Static VLANs) • 1.创建VLAN (create the VLAN) • Switch#vlan databaseSwitch(vlan)#vlan vlan_numberSwitch(vlan)#exit • 2.将接口指定到VLAN中 • assign the VLAN to one or more interfaces : • Switch(config)#interface fastethernet 0/9Switch(config-if)#switchport access vlan vlan_number
配置静态VLAN实例(Configuring Static VLANs Example) • Switch(config)#int f0/2 • Switch(config-if)#switchport mode access • Switch(config-if)#switchport access vlan 2 • Switch(config-if)#int f0/3 • Switch(config-if)#switchport mode access • Switch(config-if)#switchport access vlan 3 • Switch(config-if)#end • Switch#vlan database • Switch(vlan)#vlan 2 name v2 • VLAN 2 added: • Name: v2 • Switch(vlan)#vlan 3 name v3 • VLAN 3 added: • Name: v3 • Switch(vlan)#vlan 4 name v4 • VLAN 4 modified: • Name: v4 • Switch(vlan)#no vlan 4 • Deleting VLAN 4... • Switch(vlan)#exit • APPLY completed. • Exiting....
验证静态VLAN配置(Verifying Static VLANs Configuration) • Switch#sh vlan brie • VLAN Name Status Ports • ---- -------------------------------- --------- ------------------------------- • 1 default active Fa0/1, Fa0/4, Fa0/5, Fa0/6 • Fa0/7, Fa0/8, Fa0/9, Fa0/10 • Fa0/11, Fa0/12 • 2 v2 active Fa0/2 • 3 v3 active Fa0/3 • 1002 fddi-default active • 1003 token-ring-default active • 1004 fddinet-default active • 1005 trnet-default active • Switch#
思考题(Questions) • 1. 交换机三种主要的功能是什么? • 2. 交换机怎样学习主机地址? • 3. 什么是存储转发? • 4. 什么是快速转发? • 5. 什么是无碎片方式转发? • 6. 简述交换机密码破解的步骤? • 7. 什么是VLAN?