Packet Tracer 5.0实验(五) 快速生成树配置
一、实验目标[*]理解生成树协议工作原理；
[*]掌握快速生成树协议RSTP基本配置方法；
二、实验背景
学校为了开展计算机教学和网络办公，建立了一个计算机教室和一个校办公区，这两处的计算机网络通过两台交换机互相连接组成内部校园网，为了提高网络的可靠性，作为网络管理员，你要用2条链路将交换机互连，现要求在交换机上做适当的配置，使网络避免环路。
三、技术原理
生成树协议(spanning-tree)，作用是在交换网络中提供冗余备份链路，并且解决交换网络中的环路问题；生成树协议是利用SPA算法，在存在交换环路的网络中生成一个没有环路的树形网络。运用该算法将交换网络的冗余备份链路从逻辑上断开，当主链路出现故障时，能够自动的切换到备份链路，保证数据的正常转发；生成树协议版本：STP、RSTP(快速生成树)、MSTP(多生成树协议)；生成树协议的特点是收敛时间长，从主要链路出现故障到切换至备份链路需要50秒的时间；快速生成树协议在生成树协议的基础上增加了两种端口角色：替换端口和备份端口，分别做为根端口和指定端口的冗余端口。当根端口或指定端口出现故障时，冗余端口不需要经过50秒的收敛时间，可以直接切换到替换端口或备份端口，从而实现RSTP协议小于1秒的快速收敛。
四、实验步骤
实验拓扑默认情况下STP协议启用的，通过两台交换机之间传送BPDU协议数据单元，选出根交换机、根端口等，以便确定端口的转发状态。上图中标记为橙色的端口处于block堵塞状态。设置RSTP查看交换机 show spanning-tree 状态，了解根交换机和根端口情况；通过更改交换机生成树的优先级spanning-tree vlan * priority 4096 可以变化根交换机的角色；S1:
Switch>en
Switch#conf t
Enter configuration commands, one per line.End with CNTL/Z.
Switch(config)#hostname S1
S1(config)#end
S1#
%SYS-5-CONFIG_I: Configured from console by console
S1#show spanning-tree //查看交换机spanning-tree 状态
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0060.5C36.5620
Cost 19
Port 1(FastEthernet0/1)
Hello Time2 secMax Age 20 secForward Delay 15 sec
Bridge IDPriority 32769(priority 32768 sys-id-ext 1)
Address 0060.7078.8BDE
Hello Time2 secMax Age 20 secForward Delay 15 sec
Aging Time20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/10 Desg FWD 19 128.10 P2p
Fa0/1 Root FWD 19 128.1 P2p
Fa0/2 Altn BLK 19 128.2 P2p
S1#conf t
Enter configuration commands, one per line.End with CNTL/Z.
S1(config)#interface fa0/10
S1(config-if)#switchport access vlan 10 //将fa0/10划分到vlan 10
% Access VLAN does not exist. Creating vlan 10
S1(config-if)#exit
S1(config)#interface range fa0/1 - 2 //设置fa0/1,fa0/2端口状态为trunk模式
S1(config-if-range)#switchport mode trunk
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up
S1(config-if-range)#exit
S1(config)#spanning-tree mode ? //设置spanning-tree 为RSTP模式
pvst Per-Vlan spanning tree mode
rapid-pvstPer-Vlan rapid spanning tree mode
S1(config)#spanning-tree mode rapid-pvst
S1(config)#
S2:
Switch>en
Switch#show spanning-tree
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0060.5C36.5620
This bridge is the root //根交换机
Hello Time2 secMax Age 20 secForward Delay 15 sec
Bridge IDPriority 32769(priority 32768 sys-id-ext 1)
Address 0060.5C36.5620
Hello Time2 secMax Age 20 secForward Delay 15 sec
Aging Time20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 P2p
Fa0/2 Desg FWD 19 128.2 P2p
Fa0/10 Desg FWD 19 128.10 P2p
Switch#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up
Switch#
Switch#conf t
Enter configuration commands, one per line.End with CNTL/Z.
Switch(config)#hostname S2
S2(config)#interface fa0/10
S2(config-if)#switchport access vlan 10
% Access VLAN does not exist. Creating vlan 10
S2(config-if)#exit
S2(config)#interface range fa0/1 - 2
S2(config-if-range)#switchport mode trunk
S2(config-if-range)#exit
S2(config)#spanning-tree mode rapid-pvst
S2(config)#
五、测试
当主链路处于down状态时，能够自动的切换到备份链路，保证数据的正常转发。
在S2上shutdown 掉 fa0/1
Switch#conf t
Enter configuration commands, one per line.End with CNTL/Z.
Switch(config)#int
Switch(config)#interface fa0/1
Switch(config-if)#shu
Switch(config-if)#shutdown //shutdown fa0/1端口
Switch(config-if)#
%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to administratively down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
Switch#show spanning-tree
VLAN0001
Spanning tree enabled protocol rstp
Root ID Priority 32769
Address 0001.63E2.4A7A
This bridge is the root
Hello Time2 secMax Age 20 secForward Delay 15 sec
Bridge IDPriority 32769(priority 32768 sys-id-ext 1)
Address 0001.63E2.4A7A
Hello Time2 secMax Age 20 secForward Delay 15 sec
Aging Time20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 P2p
Fa0/2 Desg FWD 19 128.2 P2p
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 32778
Address 0001.63E2.4A7A
This bridge is the root
Hello Time2 secMax Age 20 secForward Delay 15 sec
Bridge IDPriority 32778(priority 32768 sys-id-ext 10)
Address 0001.63E2.4A7A
Hello Time2 secMax Age 20 secForward Delay 15 sec
Aging Time20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 P2p
Fa0/2 Desg FWD 19 128.2 P2p
Fa0/10 Desg FWD 19 128.10 P2p
Switch#
PC1:
PC>ipconfig
IP Address......................: 192.168.1.2
Subnet Mask.....................: 255.255.255.0
Default Gateway.................: 192.168.1.1
PC>ping -t 192.168.1.3
Pinging 192.168.1.3 with 32 bytes of data:
Reply from 192.168.1.3: bytes=32 time=78ms TTL=128
Reply from 192.168.1.3: bytes=32 time=94ms TTL=128
Reply from 192.168.1.3: bytes=32 time=78ms TTL=128
Reply from 192.168.1.3: bytes=32 time=78ms TTL=128
Reply from 192.168.1.3: bytes=32 time=78ms TTL=128
Reply from 192.168.1.3: bytes=32 time=94ms TTL=128
Reply from 192.168.1.3: bytes=32 time=93ms TTL=128
Reply from 192.168.1.3: bytes=32 time=93ms TTL=128
Reply from 192.168.1.3: bytes=32 time=62ms TTL=128
Reply from 192.168.1.3: bytes=32 time=94ms TTL=128
Reply from 192.168.1.3: bytes=32 time=79ms TTL=128
Reply from 192.168.1.3: bytes=32 time=94ms TTL=128
......
测试效果:
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