实验48: STP、PVST
1. 实验目的
通过本实验，读者可以掌握如下技能：
（1） 理解STP 的工作原理
（2） 掌握STP 树的控制
（3） 利用PVST 进行负载平衡
2. 实验拓扑
拓扑图
3. 实验步骤
我们要在网络中配置2 个VLAN，不同VLAN 的STP 具有不同的根桥，实现负载平衡。
sw1(config)#int f0/0
sw1(config-if)#switch trunk enca d
*Mar 1 00:07:22.347: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/2 on VLAN1. Port consistency restored.
sw1(config-if)#switch trunk enca dot1q
sw1(config-if)#switch mode trunk//以上是配置TRUNK
sw1(config-if)#exit
sw1(config)#int f0/2
sw1(config-if)#switch trunk enca dot1q
sw1(config-if)#switch mode trunk
sw1(config-if)#
*Mar 1 00:07:55.527: %DTP-5-TRUNKPORTON: Port Fa0/2 has become dot1q trunk
sw1(config-if)#exit
sw1(config)#exit
sw1#val
*Mar 1 00:08:07.995: %SYS-5-CONFIG_I: Configured from console by console
sw1#vlan dat
sw1(vlan)#vtp domain cisco//配置VTP域名CISCO
Changing VTP domain name from NULL to cisco
sw1(vlan)#vlan 2 name ke //创建VLAN2
VLAN 2 added:
Name: ke
sw1(vlan)#exit
APPLY completed.
Exiting....
sw1#sh vtp sta//查看VTP的状态，同时也在SW2/3查看，在SW1 上配置VTP 的域名，并创建VLAN 2。由于默认时SW2 和SW3 的VTP 域名为空，它们将自动学习到S1 的VTP 域名，同时S2、S3 也将自动学习到VLAN 2，请确认是否成功。
VTP Version : 2
Configuration Revision : 1
Maximum VLANs supported locally : 256
Number of existing VLANs : 6
VTP Operating Mode : Server
VTP Domain Name : cisco
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x2A 0xC4 0x64 0xED 0x91 0xFB 0x56 0x88
Configuration last modified by 0.0.0 .0 at 3-1-02 00:08:47
Local updater ID is 0.0.0 .0 (no valid interface found)
sw1#sh vlan-switch//在GNS3上要用show vlan-switch来查看VLAN信息，而真实的设备要用SHOW VLAN VLAN-ID
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/1, Fa0/3, Fa0/4, Fa0/5
Fa0/6, Fa0/7, Fa0/8, Fa0/9
Fa0/10, Fa0/11, Fa0/12, Fa0/13
Fa0/14, Fa0/15
2 ke active
1002 fddi-default active
1003 token-ring-default active
1004 fddinet-default active
1005 trnet-default active
VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1 enet 100001 1500 - - - - - 1002 1003
2 enet 100002 1500 - - - - - 0 0
1002 fddi 101002 1500 - - - - - 1 1003
1003 tr 101003 1500 1005 0 - - srb 1 1002
1004 fdnet 101004 1500 - - 1 ibm - 0 0
1005 trnet 101005 1500 - - 1 ibm - 0 0
sw1#sh spanning-tree检查初始的STP 树
VLAN1 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address cc00.13f0.0000
默认的优先级为32768
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree//SW1是根网桥
Topology change flag not set, detected flag not set
Number of topology changes 3 last change occurred 00:07:36 ago
from FastEthernet0/2
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300
VLAN2 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address cc00.13f0.0001
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree
Topology change flag not set, detected flag not set
Number of topology changes 1 last change occurred 00:05:36 ago
from FastEthernet0/0
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 1, topology change 0, notification 0, aging 300
//以上是VLAN 2 的STP 树情况，VLAN 2 的STP 树和VLAN 1 的类似。默认时，Cisco 交换机
会为每个VLAN 都生成一个单独的STP 树，称为PVST(Per VLAN Spanning Tree)。
sw1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
sw1(config)#spanning-tree vlan 2 priority 10000 改变VLAN2的优先级，让VLAN2中SW1成为根网桥 。
sw1(config)#do sh spann
VLAN1 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address cc00.13f0.0000
Configured hello time 2, max age 20, forward delay 15
Current root has priority 10000, address cc01.13f0.0000
Root port is 1 (FastEthernet0/0), cost of root path is 19
Topology change flag not set, detected flag not set
Number of topology changes 3 last change occurred 00:19:36 ago
from FastEthernet0/2
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300
可以看到VLAN1 中SW1已经不是根网桥了。
VLAN2 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 10000, address cc00.13f0.0001
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree VLAN2中SW1成为根网桥 。
Topology change flag not set, detected flag not set
--More—
sw2(config)#int f0/0
sw2(config-if)#switch trunk enca dot1q
sw2(config-if)#switch mode trunk
sw2(config-if)#e
*Mar 1 00:04:19.151: %DTP-5-TRUNKPORTON: Port Fa0/0 has become dot1q trunk
sw2(config-if)#exit
sw2(config)#int f0/1
sw2(config-if)#switch trunk enca dot1q
sw2(config-if)#switch mode trunk
sw2(config-if)#
*Mar 1 00:04:35.239: %DTP-5-TRUNKPORTON: Port Fa0/1 has become dot1q trunk
sw2(config-if)#do sh vlan-switch
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/2, Fa0/3, Fa0/4, Fa0/5
Fa0/6, Fa0/7, Fa0/8, Fa0/9
Fa0/10, Fa0/11, Fa0/12, Fa0/13
Fa0/14, Fa0/15
2 ke active
1002 fddi-default active
1003 token-ring-default active
1004 fddinet-default active
1005 trnet-default active
VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1 enet 100001 1500 - - - - - 1002 1003
2 enet 100002 1500 - - - - - 0 0
1002 fddi 101002 1500 - 0 - - - 1 1003
1003 tr 101003 1500 1005 0 - - srb 1 1002
1004 fdnet 101004 1500 - - 1 ibm - 0 0
1005 trnet 101005 1500 - - 1 ibm - 0 0
sw2(config-if)#do sh vtp sta
VTP Version : 2
Configuration Revision : 1
Maximum VLANs supported locally : 256
Number of existing VLANs : 6
VTP Operating Mode : Server
VTP Domain Name : cisco//已经更新了VLAN信息了。
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x2A 0xC4 0x64 0xED 0x91 0xFB 0x56 0x88
Configuration last modified by 0.0.0 .0 at 3-1-02 00:08:47
Local updater ID is 0.0.0 .0 (no valid interface found)
sw2(config-if)#do sh spanning
VLAN1 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address cc01.13f0.0000
Configured hello time 2, max age 20, forward delay 15
Current root has priority 32768, address cc00.13f0.0000
Root port is 1 (FastEthernet0/0), cost of root path is 19
Topology change flag not set, detected flag not set
Number of topology changes 7 last change occurred 00:10:30 ago
from FastEthernet0/1
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300
Port 1 (FastEthernet0/0) of VLAN1 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.1.
Designated root has priority 32768, address cc00.13f0.0000
Designated bridge has priority 32768, address cc00.13f0.0000
Designated port id is 128.1, designated path cost 0
Timers: message age 2, forward delay 0, hold 0
Number of transitions to forwarding state: 1
BPDU: sent 4, received 342
VLAN2 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address cc01.13f0.0001
Configured hello time 2, max age 20, forward delay 15
Current root has priority 32768, address cc00.13f0.0001
Root port is 1 (FastEthernet0/0), cost of root path is 19
Topology change flag not set, detected flag not set
Number of topology changes 1 last change occurred 00:06:25 ago
from FastEthernet0/0
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300
sw2(config-if)#exit
sw2(config)#spanning-tree vlan 1 priority 10000 改变VLAN1的优先级，让SW2在VLAN1中成为根网桥 。
sw2(config)#do sh span
VLAN1 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 10000, address cc01.13f0.0000
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree//SW2已经变为了根网桥。
Topology change flag not set, detected flag not set
Number of topology changes 8 last change occurred 00:02:56 ago
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 1, topology change 0, notification 0, aging 300
w3(config)#int f0/1
sw3(config-if)#switch trunk enca dot1q
sw3(config-if)#switch mode trunk
sw3(config-if)#
*Mar 1 00:06:44.879: %DTP-5-TRUNKPORTON: Port Fa0/1 has become dot1q trunk
sw3(config-if)#exit
sw3(config)#int f0/2
sw3(config-if)#switch trunk enca dot1q
sw3(config-if)#switch mode trunk
sw3(config-if)#
*Mar 1 00:07:05.223: %DTP-5-TRUNKPORTON: Port Fa0/2 has become dot1q trunk
sw3(config-if)#do sh vlan-switch
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/0, Fa0/3, Fa0/4, Fa0/5
Fa0/6, Fa0/7, Fa0/8, Fa0/9
Fa0/10, Fa0/11, Fa0/12, Fa0/13
Fa0/14, Fa0/15
2 ke active
1002 fddi-default active
1003 token-ring-default active
1004 fddinet-default active
1005 trnet-default active
VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1 enet 100001 1500 - - - - - 1002 1003
2 enet 100002 1500 - - - - - 0 0
1002 fddi 101002 1500 - 0 - - - 1 1003
1003 tr 101003 1500 1005 0 - - srb 1 1002
1004 fdnet 101004 1500 - - 1 ibm - 0 0
1005 trnet 101005 1500 - - 1 ibm - 0 0
sw3(config-if)#do sh vtp sta
VTP Version : 2
Configuration Revision : 1
Maximum VLANs supported locally : 256
Number of existing VLANs : 6
VTP Operating Mode : Server
VTP Domain Name : cisco
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x2A 0xC4 0x64 0xED 0x91 0xFB 0x56 0x88
Configuration last modified by 0.0.0 .0 at 3-1-02 00:08:47
Local updater ID is 0.0.0 .0 (no valid interface found)
