网络工程 - STP - 端口路径成本不会更新 - 吾爱随笔录

这些是 STP 的默认路径成本：

10 Mbps --> 100

100 Mbps --> 19

1 Gbps --> 4

我有这个拓扑：

所有接口都设置为 100Mb/s，因此每个路径成本等于 19。我将连接到 S4 (fa0/1) 的 S1 上的接口的速度强制为 10 Mbps。但是，路径成本仍设置为 19 (100 Mbps) 而不是 100 (10 Mbps)。

我错过了什么吗？

[编辑]

Current configuration : 1142 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname S1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
!
!
ip cef
no ip domain lookup
!
!
!         
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
ip tcp synwait-time 5
! 
!
!
!
!
interface FastEthernet0/0
!
interface FastEthernet0/1
 speed 10
!
interface FastEthernet0/2
 speed 100
!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!         
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface Vlan1
 no ip address
!
no ip http server
no ip http secure-server
!
!
!
no cdp log mismatch duplex
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line aux 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
line vty 0 4
 login
!
!
end

 VLAN1 is executing the ieee compatible Spanning Tree protocol
  Bridge Identifier has priority 32768, address cc05.2858.0000
  Configured hello time 2, max age 20, forward delay 15
  We are the root of the spanning tree
  Topology change flag set, detected flag set
  Number of topology changes 36 last change occurred 00:01:17 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 14, 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 cc05.2858.0000
   Designated bridge has priority 32768, address cc05.2858.0000
   Designated port id is 128.1, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 4555, received 0

 Port 2 (FastEthernet0/1) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.2.
   Designated root has priority 32768, address cc05.2858.0000
   Designated bridge has priority 32768, address cc05.2858.0000
   Designated port id is 128.2, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 4744, received 755

 Port 3 (FastEthernet0/2) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 32768, address cc05.2858.0000
   Designated bridge has priority 32768, address cc05.2858.0000
   Designated port id is 128.3, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 4634, received 335