最新15 交换基础与VLN(共26张PPT课件).pptx
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1、 2006, Shenzhen Polytechnic, All rights reserved.1交换交换(jiohun)和和VLANSwitching and VLAN九江职业九江职业(zhy)技术学院信息工程系网络专业技术学院信息工程系网络专业第一页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.2教学教学(jio xu)(jio xu)目标(目标( Objectives )1. 交换机学习主机地址交换机学习主机地址 (Switche Learn Host Address)2. 两种交换方法两种交换方法(fngf)(T
2、wo Switching Methods) 3. 配置端口安全(配置端口安全(Configuring Port Security) 4.密码破解(密码破解(Password Recovery) 5. VLAN操作(操作(VLAN Operations) 6.配置和验证静态配置和验证静态VLAN (Configuring and Verifying Static VLANs)第二页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.3 地址学习(地址学习(Address learning) 决定转发或过滤(决定转发或过滤(Forw
3、ard/filter decision) 避免避免(bmin)环路(环路(Loop avoidance)交换机三种交换机三种(sn zhn)功能功能(Three Switch Functions ) 第三页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.4交换机学习交换机学习(xux)主机地址主机地址 (Switche Learn Host Address) 初始初始(ch sh)MAC地址表是空的地址表是空的 Initial MAC address table is emptyMAC address table0260.8
4、c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0E1E2E3ABCD第四页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.5交换机学习交换机学习(xux)主机地址主机地址 (Switche Learn Host Address) A向向C发送帧(发送帧(Station A sends a frame to Station C) 交换机将交换机将A的的MAC地址和其对应的接口地址和其对应的接口(ji ku)E0放入放入MAC地址表地址表Switch caches stat
5、ion A MAC address to port E0 by learning the source address of data frames 该帧向除了该帧向除了E0接口的所有接口泛洪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: 0260.8c01.1111E0E1E2E3DCBA第五页,共二十六页。
6、2006, By Shenzhen Polytechnic. All rights reserved.6交换机学习主机交换机学习主机(zhj)地址地址 (Switche Learn Host Address)D向向C发送帧发送帧(Station D sends a frame to station C)交换机将交换机将D的的MAC地址地址(dzh)和其对应的接口和其对应的接口E3放入放入MAC地址表地址表 Switch caches station D MAC address to port E3 by learning the source Address of data frames该帧向
7、除了该帧向除了E3接口的所有接口泛洪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)MAC address table0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0: 0260.8c01.1111E3: 0260.8c01.4444E0E1E2E3DCAB第六页,共二十六页。 2006, By Shenzhen Polytechnic.
8、 All rights reserved.7交换机过滤交换机过滤(gul)帧(帧( Switches Filter Frames) A向向C发送帧发送帧 Station A sends a frame to station C 目的目的(md)地址已知,帧不被泛洪地址已知,帧不被泛洪 Destination is known, frame is not flooded E0: 0260.8c01.1111E2: 0260.8c01.2222E1: 0260.8c01.3333E3: 0260.8c01.44440260.8c01.11110260.8c01.22220260.8c01.3333
9、0260.8c01.4444E0E1E2E3XXDCABMAC address table第七页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.8两种交换两种交换(jiohun)方法(方法(Two Switching Methods)第八页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.9存储转发特征存储转发特征(tzhng)(Store-and-forward Feature)1. 在转发之前整个帧被接收在转发之前整个帧被接收 The entire fr
10、ame is received before any forwarding takes place. 2.由于交换开始之前要接收完整帧,较大的数据由于交换开始之前要接收完整帧,较大的数据(shj)帧延迟较大帧延迟较大 Latency is greater with larger frames because the entire frame must be received before the switching process begins. 第九页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.10直通特征直通特征(t
11、zhng)(Cut-through Feature)1.在接收完整帧之前,帧就被转发。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最快的是只要读到目的地址(dzh)就转发。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,但是不进行检错这种模式降低了延迟,但是不进行
12、检错 This mode decreases the latency of the transmission, but also reduces error detection. 第十页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.11直通分类直通分类(fn li)(Cut-through Class)一、快速转发(一、快速转发(Fast-forward )1.快速转发提供了最低的延迟快速转发提供了最低的延迟 Fast-forward switching offers the lowest level of latency
13、. 2.只要只要(zhyo)读到目的地址,就立刻转发读到目的地址,就立刻转发Fast-forward switching immediately forwards a packet after reading the destination address. 第十一页,共二十六页。 2006, By Shenzhen Polytechnic. All rights reserved.12直通分类直通分类(fn li)(Cut-through Class)二、二、Fragment-free (无碎片方式)(无碎片方式)1.无碎片方式在转发之前过滤无碎片方式在转发之前过滤(gul)掉碰撞碎片掉碰撞
14、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无碎片方式在转发之前要读到帧的前64字节字节Fragment-free switching waits until the packet is determined not to be a collision fragment(64bytes) before forwarding第十二页,共二十六页。 2006, By Shenzhen Polytechnic. All rights rese
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