在部分设备支持STP协议的网络中实施STP( 五 )


Topology Changes: 5
Bridge Identifier: 7000 00051a5e92f8
Designated Root: 6000 00051a612eb8
maxAge: 20 bridgeMaxAge: 20
helloTime: 2 bridgeHelloTime: 2
forwardDelay: 15 bridgeFwdDelay: 15
holdTime: 1 rootCost: 12
rootPort: 24 priority: 0x7000
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Select menu option (bridge/port): summ //查看主交换机STP端口状态
Select bridge port (1-24,all) [all]: all
Port stpState fwdTransitions stpCost
--------------------------------------------------------------------
1 Disabled 0 19
2 Disabled 0 19
3 Disabled 0 19
4 Disabled 0 19
5 Disabled 0 19
6 Disabled 0 19
7 Disabled 0 19
8 Disabled 0 19
9 Disabled 0 19
10 Disabled 0 19
11 Disabled 0 19
12 Disabled 0 19
13 Disabled 0 19
14 Disabled 0 19
15 Disabled 0 19
16 Disabled 0 19
17 Disabled 0 19
18 Disabled 0 19
19 Disabled 0 19
20 Forwarding 1 18
21 Forwarding 1 18
Enterfor more or "q" to quit--:
22 Forwarding 1 18
23 Forwarding 1 18
24 Forwarding 2 18
-----------------------------------primary3300 (1)----------------------
Select menu option (bridge): dis //查看主交换机STP状态
stpState: enabled agingTime: 1800
Time since topology change: 0 hrs 1 mins 42 seconds
Topology Changes: 6
Bridge Identifier: 6000 00051a612eb8
Designated Root: 6000 00051a612eb8
maxAge: 20 bridgeMaxAge: 20
helloTime: 2 bridgeHelloTime: 2
forwardDelay: 15 bridgeFwdDelay: 15
holdTime: 1 rootCost: 0
rootPort: No Port priority: 0x6000
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3.将直接连接终端的端口设为stpfaststart状态(相当于CISCO的portfast)
Menu options: --------------3Com SuperStack 3 Switch 3300---------------
address - Administer bridge addresses
detail - Display detail information
stpCost - Set the Spanning Tree path cost
stpFastStart - Enable/Disable Fast Start per port
summary - Display summary information
vltMode - Enable/Disable VLT tagging on a port
Type "q" to return to the previous menu or ? for help.
-----------------------------------primary3300 (1)----------------------
Select menu option (bridge/port): stpfa//选择stpfaststart菜单
Select bridge port (1-24) [1]: 1 //选择端口1
Enter new value (disabled,enabled) [disabled]: enable
再继续把主交换机和备份主交换机的所有直接连接终端工作站的端口都设为stpfaststart状态 。
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至此,设置完成 。将主交换机电源拨掉,ping 服务器备份网卡,大约经过43秒恢复连通,相比起来收敛时间较长 。(我的经验是全CISCO网络启用标准STP协议(相对于RSTP而言)和uplinkfast功能需时4-5秒,全3com网络的resilient links功能几乎是瞬时)不过这也是很好解释的,forward time 15秒加上maximum-aging time 20秒都需要35秒时间 。将主交换机电源重新插上,大致需要相同时间恢复 。反复试了两次,没有出现产生环路的情况 。
要害在于理论上stp协议是一种分布式算法,它要求网络中交换机的全部支持 。在二级交换机不支持STP的情况,它扮演的角色是什么?

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