实验三STP.docx
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实验三STP
实验三:
STP
一:
实验目标
1组网要求:
此阿勇两台核心交换机组网来提高网络可靠性,为防止二层环路,需要全网运行STP:
将SW1部署为根网桥,SW2部署为备份网桥,并将接入PC的接口配置为portfast端口。
2分析STP选举过程(根网桥、根端口、指定端口、阻塞端口)。
二:
拓扑图
三:
预期结果
对于vlan8和vlan10,SW3的FA0/2口是阻塞的,对于vlan11,SW3的FA0/1口是阻塞的。
四:
调试
SW3上STP配置:
SW1上STP配置:
SW2上STP配置:
五:
测试
SW3上showspanning-treebri:
Vlan8:
Vlan10:
Vlan11:
Pc2pingpc1:
六:
总结与原理分析
Pc1pingpc2数据流分析:
1Pc1封装icmp包,发现未知目的mac地址且目的IP与自己不在同一个网段,则封装一个arp请求,请求的目的IP为网关IP,目的mac为全F;
2在通过fa0/10口时,arp请求被打上了vlan10的标签;
3进入sw3,sw3查询mac地址表,发现没有pc1的mac地址,便更新mac表;
4由于配置了生成树协议,相对于vlan10,sw3的fa0/2口是阻塞的,所以arp请求被交换机从fa0/1口发送到三层交换机sw1;
5Sw1收到arp请求后,发现目的ip是自身的,然后拆vlan10标,更新mac地址表,便封装一个arp应答,封装时打上vlan10的标,从fa0/3口单播出去;
6Sw3收到arp应答,查询mac地址表后,从fa0/10转发出去,在出口拆掉vlan10的标签;
7Pc1收到arp应答,更新自身的arp缓存表,重新封装icmp包,其目的mac是网关,目的IP是pc2的IP地址,将封装好的icmp包,通过fa0/10口送往SW3;
8Icmp包在fa0/10口被打上vlan10的标签;
9Icmp包进入sw3,sw3查询mac地址表,把icmp包从fa0/1口转发出去;
10SW1收到icmp包,拆vlan10标,发现目的IP地址不是自己的,但是网关却是已知的vlan11,且不知道目的mac地址,便封装一个arp请求,并打上vlan11的标签,洪泛出去;
11由于配置了生成树协议,SW3的fa0/1口相对于vlan11是阻塞的,所以arp请求从sw1的fa0/1口发送到sw2的fa0/1口;
12Sw2收到arp请求后,更新自己的mac地址表,从fa0/3口发送出去,到sw3的fa0/2口;
13Arp请求从sw3的fa0/2进入sw3,sw3更新自己的mac地址表,将arp请求从fa0/11口洪泛出去;
14在通过fa0/11口时,arp请求被拆掉了vlan11的标签,进入到pc2;
15Pc2收到arp请求后,更新自己的arp缓存表,打开arp请求,查看后,发出arp应答;
16Arp应答在经过fa0/11口时,被打上了vlan11的标签;
17Sw3收到arp应答后,更新自身的mac地址表,再查询mac地址表,从fa0/2口转发arp应答给SW2;
18Sw2收到arp应答后,更新自身的mac地址表,再查询mac地址表,从fa0/1口转发给sw1;
19Sw1收到arp应答后,拆掉vlan11的标签,更新mac地址表,重新封装icmp包,并打上vlan11的标签,从fa0/1口转发给sw2;
20Sw2收到icmp包后,查询mac地址表,从fa0/3转发icmp包到sw3;
21Sw3收到icmp包后,查询mac地址表,从fa0/11转发icmp包到pc2;
22Icmp包在经过接口fa0/11时,被拆掉vlan11的标签;
23Pc2收到icmp包后,发现目的IP是自己的,目的mac是自己的,打开icmp包,然后封装一个icmp回应包;
24Icmp回应包在链路中一直被转发其路径是:
PC2—SW3—SW2—SW1—SW3—PC1。
七:
配置showrun
SW1:
!
version12.3
servicetimestampsdebugdatetimemsec
servicetimestampslogdatetimemsec
noservicepassword-encryption
!
hostnameSW1
!
boot-start-marker
boot-end-marker
!
!
noaaanew-model
!
resourcepolicy
!
memory-sizeiomem5
ipsubnet-zero
!
!
ipcef
noipdhcpusevrfconnected
!
!
noipdomainlookup
noftp-serverwrite-enable
!
!
spanning-treevlan8priority0
spanning-treevlan10priority0
spanning-treevlan11priority4096
!
!
!
interfaceFastEthernet0/0
!
interfaceFastEthernet0/1
switchportmodetrunk
!
interfaceFastEthernet0/2
!
interfaceFastEthernet0/3
switchportmodetrunk
!
interfaceFastEthernet0/4
!
interfaceFastEthernet0/5
!
interfaceFastEthernet0/6
!
interfaceFastEthernet0/7
!
interfaceFastEthernet0/8
!
interfaceFastEthernet0/9
!
interfaceFastEthernet0/10
!
interfaceFastEthernet0/11
!
interfaceFastEthernet0/12
!
interfaceFastEthernet0/13
!
interfaceFastEthernet0/14
!
interfaceFastEthernet0/15
!
interfaceVlan1
noipaddress
!
interfaceVlan8
ipaddress192.168.8.129255.255.255.128
!
interfaceVlan10
ipaddress192.168.10.1255.255.255.0
!
interfaceVlan11
ipaddress192.168.11.1255.255.255.0
!
iphttpserver
ipclassless
!
!
!
!
!
control-plane
!
!
linecon0
exec-timeout00
loggingsynchronous
lineaux0
linevty04
!
End
SW2:
!
version12.3
servicetimestampsdebugdatetimemsec
servicetimestampslogdatetimemsec
noservicepassword-encryption
!
hostnameSW2
!
boot-start-marker
boot-end-marker
!
!
noaaanew-model
!
resourcepolicy
!
memory-sizeiomem5
ipsubnet-zero
!
!
ipcef
noipdhcpusevrfconnected
!
!
noipdomainlookup
noftp-serverwrite-enable
!
!
spanning-treevlan8priority4096
spanning-treevlan10priority4096
spanning-treevlan11priority0
!
!
!
interfaceFastEthernet0/0
!
interfaceFastEthernet0/1
switchportmodetrunk
!
interfaceFastEthernet0/2
!
interfaceFastEthernet0/3
switchportmodetrunk
!
interfaceFastEthernet0/4
!
interfaceFastEthernet0/5
!
interfaceFastEthernet0/6
!
interfaceFastEthernet0/7
!
interfaceFastEthernet0/8
!
interfaceFastEthernet0/9
!
interfaceFastEthernet0/10
!
interfaceFastEthernet0/11
!
interfaceFastEthernet0/12
!
interfaceFastEthernet0/13
!
interfaceFastEthernet0/14
!
interfaceFastEthernet0/15
!
interfaceVlan1
noipaddress
!
interfaceVlan8
ipaddress192.168.8.130255.255.255.128
!
ipdefault-gateway192.168.8.129
iphttpserver
ipclassless
!
!
!
!
!
control-plane
!
!
linecon0
exec-timeout00
loggingsynchronous
lineaux0
linevty04
!
End
SW3:
!
version12.3
servicetimestampsdebugdatetimemsec
servicetimestampslogdatetimemsec
noservicepassword-encryption
!
hostnameSW3
!
boot-start-marker
boot-end-marker
!
!
noaaanew-model
!
resourcepolicy
!
memory-sizeiomem5
ipsubnet-zero
!
!
ipcef
noipdhcpusevrfconnected
!
!
noipdomainlookup
noftp-serverwrite-enable
!
!
!
!
interfaceFastEthernet0/0
!
interfaceFastEthernet0/1
switchportmodetrunk
!
interfaceFastEthernet0/2
switchportmodetrunk
!
interfaceFastEthernet0/3
!
interfaceFastEthernet0/4
!
interfaceFastEthernet0/5
!
interfaceFastEthernet0/6
!
interfaceFastEthernet0/7
!
interfaceFastEthernet0/8
!
interfaceFastEthernet0/9
!
interfaceFastEthernet0/10
switchportaccessvlan10
spanning-treeportfast
!
interfaceFastEthernet0/11
switchportaccessvlan11
spanning-treeportfast
!
interfaceFastEthernet0/12
!
interfaceFastEthernet0/13
!
interfaceFastEthernet0/14
!
interfaceFastEthernet0/15
!
interfaceVlan1
noipaddress
!
interfaceVlan8
ipaddress192.168.8.132255.255.255.128
!
ipdefault-gateway192.168.8.129
iphttpserver
ipclassless
!
!
!
!
!
control-plane
!
!
linecon0
exec-timeout00
loggingsynchronous
lineaux0
linevty04
!
end