STP(生成树协议讲解)课件

HUAWEI TECHNOLOGIES CO., LTD.,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,英文标题,:32-35pt,颜色,: R153 G0 B0,内部使用字体,:,FrutigerNext LT Medium,外部使用字体,: Arial,中文标题,:30-32pt,颜色,: R153 G0 B0,字体,:,黑体,英文正文,:20-22pt,子目录,(2-5,级,) :18pt,颜色,:,黑色,内部使用字体,:,FrutigerNext LT Regular,外部使用字体,: Arial,中文正文,:18-20pt,子目录,(2-5,级,):18pt,颜色,:,黑色,字体,:,细黑体,配色参考方案：,建议同一页面内不超过四种颜色，以下是,13,组配色方案，同一页面内只选择一组使用。（仅供参考）,客户或者合作伙伴的标志放在右上角,.,Page,58,华为保密信息，未经授权禁止扩散,单击此处编辑母版标题样式,英文标题,:32-35pt,颜色,: R153 G0 B0,内部使用字体,:,FrutigerNext LT Medium,外部使用字体,: Arial,中文标题,:30-32pt,颜色,: R153 G0 B0,字体,:,黑体,英文正文,:20-22pt,子目录,(2-5,级,) :18pt,颜色,:,黑色,内部使用字体,:,FrutigerNext LT Regular,外部使用字体,: Arial,中文正文,:18-20pt,子目录,(2-5,级,):18pt,颜色,:,黑色,字体,:,细黑体,配色参考方案：,建议同一页面内不超过四种颜色，以下是,13,组配色方案，同一页面内只选择一组使用。（仅供参考）,客户或者合作伙伴的标志放在右上角,.,HUAWEI TECHNOLOGIES CO., LTD.,STP,局域网中通常会存在冗余链路。需要一种方法阻塞冗余链路，消除路径环路，并且在必要时将冗余链路自动切换为转发状态，恢复网络的连通性。,生成树协议就可以实现这样的功能。生成树协议包括,STP,、,RSTP,、,MSTP,等。,本章对,STP,的工作原理进行详细介绍。,引入,了解,STP,消除环路的思想,掌握,STP,的基本概念,掌握,STP,计算过程,掌握,STP,的端口状态,掌握,STP,拓扑改变处理过程,了解,STP,的不足,课程目标,学习完本课程，您应该能够：,STP,介绍,STP,基本概念,STP,计算过程,STP,端口状态,STP,拓扑改变处理过程,STP,协议的不足,目录,Page,4,交换机转发流程回顾,E0/2,E0/3,E0/5,E0/6,00-0D-56-BF-88-10,00-0D-56-BF-88-20,PCA,SWA,SWB,PCB,1,2,3,Page,5,环路引起的问题之一 广播风暴,PCA,SWA,SWB,广播,1,2,3,4,4,Page,6,交换机学习MAC地址表回顾,E0/2,E0/3,E0/5,E0/6,00-0D-56-BF-88-10,00-0D-56-BF-88-20,PCA,SWA,SWB,PCB,1,2,3,Page,7,E0/3,E0/4,E0/5,E0/6,PCA,SWA,SWB,00-0D-56-BF-88-10,E0/2,00-0D-56-BF-88-10,E0/2,00-0D-56-BF-88-10,E0/4,错误目的端口,环路引起的问题之二 MAC地址表不稳定,什么是STP？,STP是二层网络中用于消除环路的协议,通过阻断冗余链路来消除桥接网络中可能存在的路径回环,当前活动路径发生故障时，激活冗余备份链路，恢复网络连通性,ROOT,Physical,Segment A,Physical,Segment B,Physical,Segment C,Physical,Segment D,Physical,Segment E,STP消除环路的思想,将网络拓扑修剪为树形,选择树根节点,确定最短路径,阻塞冗余链路,ROOT,Physical,Segment A,Physical,Segment B,Physical,Segment C,Physical,Segment D,Physical,Segment E,STP,介绍,STP,基本概念,STP,计算过程,STP,端口状态,STP,拓扑改变处理过程,STP,协议的不足,目录,桥和端口的角色,桥的角色：,根桥,指定桥,端口角色：,根端口,指定端口,Alternate端口,根桥,根端口,根端口,指定端口,指定端口,指定端口,Alternate,端口,指定桥,SWA,SWB,SWC,SWA,指定桥,SWB,桥ID,桥ID用于在STP中唯一的标识一个桥，桥ID由两部分组成，长度为8,个字节,桥优先级：高,16位,(065535,默认32768),优先级（16bit） = 4Bit 桥优先级 + 12Bit 扩展系统ID,MAC地址：低48位,桥优先级,桥,MAC,地址,2,字节,6,字节,桥,ID,路径开销（Path Cost）,路径开销用于衡量桥与桥之间路径的优劣,STP中每条链路都具有开销值,路径开销等于路径上全部链路开销之和,SWB,SWC,SWA,1Gig,1Gig,Cost,20,Cost,200,100M,链路开销标准,配置BPDU,网桥通过交互配置BPDU获取STP计算所需要的参数,配置BPDU基于二层组播方式发送，目的地址为01-80-C2-00-00-00,配置BPDU由根桥周期发出，发送周期为Hello Time。,配置BPDU老化时间为Max Age。,SWA,SWB,配置,BPDU,Root,SWC,配置,BPDU,配置BPDU格式,DMA:目的MAC地址,SMA:源MAC地址,L/T:帧长,LLC Header:配置消息固定的链路头,Payload: BPDU数据,Payload,L/T,SMA,DMA,LLC Header,Root ID,Root Path Cost,Bridge ID,Port ID,Parameters,Byte,Protocol ID,2,Protocol Version ID,BPDU Type,Flags,Message Age,1,1,1,8,4,8,2,2,Max Age,Hello Time,Forward Delay,2,2,2,STP,优先级向量,STP,介绍,STP,基本概念,STP,计算过程,STP,端口状态,STP,拓扑改变处理过程,STP,协议的不足,目录,计算步骤,任务一：选举根桥,任务二：确定端口角色,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,1 Gig,Path Cost =,20,1 Gig,Path Cost =,20,100M,Path cost =,200,100M,Path cost =,200,SWC,BID=32768.MACC,2 Gig,聚合,Path cost =,18,计算方法,配置BPDU,处理,网桥将各个端口收到的配置,BPDU和自己的配置BPDU做比较，得出优先级最高的配置BPDU,网桥用优先级最高的配置BPDU更新本身的配置BPDU ，用于选举根桥和确定端口角色,网桥从指定端口发送新的配置BPDU,配置BPDU比较原则,优先级向量最小者最优,首先比较,Root Bridge ID,其次比较Root Path Cost,再次比较Designate Bridge ID,再其次比较Designate Port ID,最后比较Bridge Port ID,根桥选举过程,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,SWC,BID=32768.MACC,我是根桥,我是根桥,我是根桥,我是根桥,寻找最小桥ID,Root ID =8192.MACB,根桥选举过程（续）,Root ID =8192.MACB,Root ID =0.MACA,Root ID =0.MACA,Root ID =32768.MACC,Root ID =8192.MACB,Root ID =32768.MACC,Root ID =32768.MACC,Root ID =4096.MACD,Root ID =4096.MACD,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWD,BID=4096.MACD,根桥选举过程（续）,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,SWC,BID=32768.MACC,我是根桥,我是根桥,SWA,是根桥,SWA,是根桥,根桥选举过程（续）,Root ID =0.MACA,Root ID =0.MACA,Root ID =0.MACA,Root ID =0.MACA,Root ID =0.MACA,Root ID =0.MACA,Root ID =4096.MACD,Root ID =4096.MACD,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWD,BID=4096.MACD,根桥选举结果,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,SWC,BID=32768.MACC,我是根桥,SWA,是根桥,SWA,是根桥,SWA,是根桥,确定端口角色的标准,根端口：网桥上到根桥最近的端口,指定端口：端口的配置BPDU在其所属链路上是最优的,Alternate端口：端口的配置BPDU在其所属链路上不是最优的，且端口不是根端口,端口角色确定过程,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,1 Gig,Path Cost =,20,1 Gig,Path Cost =,20,100M,Path cost =,200,100M,Path cost =,200,SWC,BID=32768.MACC,2 Gig,聚合,Path cost =,18,Root ID =32768.MACC,RPC=0,Root ID =8192.MACB,RPC=0,端口角色确定过程（续）,Root ID =8192.MACB,RPC=0,Root ID =8192.MACB,RPC=0,Root ID =0.MACA,RPC=0,Root ID =0.MACA,RPC=0,Root ID =32768.MACC,RPC=0,Root ID =32768.MACC,RPC=0,Root ID =4096.MACD,RPC=0,Root ID =4096.MACD,RPC=0,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWD,BID=4096.MACD,端口角色确定过程（续）,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,SWC,BID=32768.MACC,我是根桥,RPC=0,我是根桥,RPC=0,SWA,是根桥,RPC=18,RPC=200,RPC=18,SWA,是根桥,RPC=200,端口角色确定过程（续）,Root ID =0.MACA,RPC=18,Root ID =0.MACA,RPC=200,Root ID =0.MACA,RPC=200,Root ID =0.MACA,RPC=0,Root ID =0.MACA,RPC=0,Root ID =0.MACA,RPC=18,Root ID =4096.MACD,RPC=0,Root ID =4096.MACD,RPC=0,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWD,BID=4096.MACD,端口角色确定过程（续）,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,SWC,BID=32768.MACC,我是根桥,RPC=0,SWA,是根桥,RPC=18,RPC=38,RPC=18,RPC=218,SWA,是根桥,RPC=38,SWA,是根桥,RPC=218,端口角色确定过程（续）,Root ID =0.MACA,RPC=18,Root ID =0.MACA,RPC=38,Root ID =0.MACA,RPC=0,Root ID =0.MACA,RPC=0,Root ID =0.MACA,RPC=18,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWD,BID=4096.MACD,端口角色确定过程（续）,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,SWC,BID=32768.MACC,我是根桥,RPC=0,SWA,是根桥,RPC=18,RPC=38,RPC=18,RPC=58,SWA,是根桥,RPC=38,SWA,是根桥,RPC=58,端口角色确定结果,Alternate,端口：,端口既非根端口也非指定端口,指定端口：,端口拥有该链路上最优的配置消息,根桥路径开销,=38,根桥,ID =0.MACA,Root Path Cost=,18,根桥,ID =0.MACA,Root Path Cost=,38,根桥,ID =0.MACA,Root Path Cost=,0,根端口：,该端口到根桥的开销最小,38200,根桥路径开销,=200,SWB,BID=8192.MACB,STP计算结果,SWB,BID=8192.MACB,SWA,BID=0.MACA,SWD,BID=4096.MACD,SWC,BID=32768.MACC,指定端口,指定端口,根端口,根端口,根端口,指定端口,指定端口,Alternate,端口,Alternate,端口,根桥,指定端口,等路径开销计算,根桥,SWA,BID=0.MACA,SWA,BID=0.MACA,根桥,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWD,BID=4096.MACD,Path cost =,200,Path cost =,200,Path cost =,200,Path cost =,200,Path cost =,200,Path cost =,200,Path cost =,200,D,D,R,R,D,A,D,D,R,R,R,D,D,A,等路径开销计算（续）,R,Path cost =,200,Path cost =,200,SWA,BID=0.MACA,根桥,SWB,BID=8192.MACB,E0/1,E0/2,D,D,A,R,Path cost =,200,Path cost =,200,SWA,BID=0.MACA,根桥,SWB,BID=8192.MACB,E0/1,D,A,Path cost =,200,E0/2,E0/1,E0/1,E0/2,Physical Segment,收到低优先级配置BPDU时的处理,根桥,根桥,BPDU,BPDU,BPDU,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,SWD,BID=4096.MACD,BPDU,低优先级配置,BPDU,Hello Timer,BPDU,STP,介绍,STP,基本概念,STP,计算过程,STP,端口状态,STP,拓扑改变处理过程,STP,协议的不足,目录,临时环路问题,当拓扑结构发生变化，新的配置BPDU,要经过一定的时延才能传播到整个网络，在所有网桥收到这个变化的消息之前可能会存在临时环路,根桥,SWA,BID=0.MACA,SWB,BID=8192.MACB,SW C,BID=4096.MACC,D,R,D,R,根桥,SWA,BID=0.MACA,SW B,BID=8192.MACB,SWC,BID=4096.MACC,D,R,D,D,R,D,新链路,通过中间状态避免临时环路,STP为端口定义了五种状态：,Disabled、Blocking、Listening、Learning、Forwarding,各端口状态对配置BPDU收发、MAC地址学习以及数据收发的处理有所不同,Forward Delay延时,从中间状态Listening经过一个延时进入另一个中间状态Learning,从Learning状态再经过一个延时进入Forwarding状态,延时长度为Forward Delay,STP端口状态机,Disabled,Listening,Blocking,Forwarding,Learning,1,）端口,enabled,2,）端口,disabled,3,）端口被选为根端口或指定端口,4,）端口被选为,Alternate,端口（阻塞）,5,）,Forward Delay,延时,（,1,）,（,2,）,（,2,）,（,2,）,（,2,）,（,1,）,（,2,）,（,4,）,（,4,）,（,5,）,（,4,）,（,5,）,（,3,）,STP端口状态示例,SWB,SWA,SWD,SWC,Forwarding,Forwarding,Forwarding,Forwarding,Forwarding,Forwarding,Forwarding,Blocking,Blocking,根桥,Forwarding,STP,介绍,STP,基本概念,STP,计算过程,STP,端口状态,STP,拓扑改变处理过程,STP,协议的不足,目录,E1/0/1,拓扑发生变化,HostA,HostB,ROOT,SWC,SWA,SWB,SWD,SWE,链路中断,E1/0/1,E1/0/2,E1/0/1,E1/0/2,E1/0/2,E1/0/3,E1/0/2,E1/0/1,E1/0/2,E1/0/1,从中断到恢复需要等待MAC地址老化，将近5分钟的时间！,STP,阻塞,STP拓扑改变处理过程,拓扑改变消息,TCN,拓扑改变应答消息,TCA,拓扑改变置位的,BPDU,HostA,HostB,ROOT,链路中断,E1/0/1,E1/0/2,E1/0/1,E1/0/2,E1/0/1,E1/0/2,E1/0/3,E1/0/2,E1/0/1,E1/0/2,E1/0/1,拓扑改变时网桥使用较小的MAC地址生存期,从中断到恢复最长需要等待50秒的时间！,1,2,3,4,4,5,5,5,STP,阻塞,SWC,SWA,SWB,SWD,SWE,TCN BPDU,Payload,L/T,SMA,DMA,LLC Header,网桥发送TCN BPDU,的条件为,有端口转变为,Forwarding状态，且该网桥至少包含一个指定端口,有端口从Forwarding状态或Learning状态转变为Blocking状态,Parameters,Byte,Protocol ID,2,Protocol Version ID,BPDU Type,1,1,TCA以及TC置位的配置BPDU,Payload,L/T,SMA,DMA,LLC Header,6,5,4,3,2,1,0,Topology Change,Topology Change Acknowledgment,7,标志位置位,第,7位置位表示该消息为TCA,第0位置位表示该消息为TC置位BPDU,1到6位保留,标志位,Root ID,Root Path Cost,Bridge ID,Port ID,Parameters,Byte,Protocol ID,2,Protocol Version ID,BPDU Type,Flags,Message Age,1,1,1,8,4,8,2,2,Max Age,Hello Time,Forward Delay,2,2,2,拓扑改变,收敛时延分析,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,D,D,R,R,D,A,根桥故障,BPDU,等待,Max Age Timer,链路中断,SWA,BID=0.MACA,SWB,BID=8192.MACB,SWC,BID=32768.MACC,D,D,R,R,D,A,SWC,根端口,DOWN,BPDU,BPDU,BPDU,拓扑改变,收敛时延分析（续）,ROOT,SWC,SWA,SWB,SWD,SWE,E1/0/1,E1/0/1,E1/0/2,E1/0/1,E1/0/3,E1/0/2,E1/0/1,E1/0/2,E1/0/1,E1/0/2,新增链路,或故障恢复链路,新阻塞链路,STP,介绍,STP,基本概念,STP,计算过程,STP,端口状态,STP,拓扑改变处理过程,STP,协议的不足,目录,收敛时间长,Power Up,Blocking,Listening,Learning,Forwarding,Disabled,Forward Delay Timer,Forward Delay Timer,缺省情况下一个端口从Blocking状态过渡到Forwarding状态至少需要30秒钟（两倍的Forward Delay）。对于一个拓扑不稳定网络，会导致网络的长时间中断,拓扑变化收敛机制不灵活,ROOT,SWC,SWA,SWB,SWD,SWE,E1/0/1,E1/0/2,E1/0/1,E1/0/2,E1/0/1,E1/0/2,E1/0/3,E1/0/2,E1/0/1,E1/0/2,E1/0/1,STP,阻塞,主机频繁上下线时，网络会产生大量TCN,Page,54,LANE,SWA,LANA,LANB,LANC,SWB,SWC,LAND,Root,LANC,的指定端口,E0/10,E0/20,E0/10,E0/20,E0/10,E0/20,STP基本配置物理拓扑,Page,55,STP基本配置配置命令,LANE,SWA,LANA,LANB,LANC,SWB,SWC,LAND,Root,LANC,的指定端口,E0/10,E0/20,E0/10,E0/20,E0/10,E0/20,Quidwaysysname SWA,SWAstp enable,SWAstp mode stp,SWAstp priority 4096,Quidwaysysname SWB,SWBstp enable,SWBstp mode stp,SWBstp priority 8192,Quidwaysysname SWC,SWCstp enable,SWCstp mode stp,E0/24,Page,56,SWCdisplay stp,-CIST Global InfoMode STP-,CIST Bridge :,32768.00e0-fc41-43b9,Bridge Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20,CIST Root/ERPC :,4096.00e0-fc41-4259,/ 20000,CIST RegRoot/IRPC :,32768.00e0-fc41-43b9,/ 0,CIST RootPortId :128.10,BPDU-Protection :Disabled,TC or TCN received :117,TC count per hello :1,STP Converge Mode :Normal,Share region-configuration :Enabled,Time since last TC :0 days 0h:0m:0s,STP基本配置验证STP全局状态,Page,57,SWCdisplay stp interface Ethernet 0/20,-CISTPort20(Ethernet0/20),Forwarding,-,Port Protocol :Enabled,Port Role :,Root Port,Port Priority :128,Port Cost(Dot1T ) :Config=auto / Active=200000000,Designated Bridge/Port :,4096.00e0-fc41-4259,/ 128.20,Port Edged :Config=default / Active=disabled,Point-to-point :Config=auto / Active=false,Transit Limit :147 packets/hello-time,Protection Type :None,Port STP Mode :STP,Port Protocol Type :Config=auto / Active=dot1s,BPDU Encapsulation :Config=stp / Active=stp,PortTimes :Hello 2s MaxAge 20s FwDly 15s RemHop 20,TC or TCN send :0,TC or TCN received :0,BPDU Sent :0,TCN: 0, Config: 0, RST: 0, MST: 0,BPDU Received :0,TCN: 0, Config: 0, RST: 0, MST: 0,STP基本配置验证STP端口信息,STP,消除环路的基本思想,STP,协议中的基本概念,STP,计算过程,STP,中端口的状态,STP,拓扑改变处理过程,STP,协议的不足,本章总结,