如何在局域网上连接两个Cisco催化剂2950？

Question

我试图连接(2)思科催化剂2950's通过各自的FastEthernet 0/1端口，但出于某种原因，他们没有通信。我这样做是为了物理上扩展我的网络并添加更多的网络端口。

在SwitchA (10.10.10.1)上，我有：

!
interface Porth-Channel1
 description UPLINK
 switchport mode trunk
 switchport nonegotiate
 flowcontrol send off
end
!
interface FastEthernet0/1
 description ETHERNET-UPLINK
 switchport mode trunk
 channel-group 1 mode active
end

在SwitchB (10.10.10.2)上，我有：

!
interface Porth-Channel1
 description UPLINK
 switchport mode trunk
 switchport nonegotiate
 flowcontrol send off
end
!
interface FastEthernet0/1
 description ETHERNET-UPLINK
 switchport mode trunk
 channel-group 1 mode active
end

我在8端口2960 ( SwitchC )上设置了相同的配置，如果我将SwitchC的FastEthernet 0/1插入SwitchB或SwitchA，它就能工作。但是如果我把FastEthernet 0/1的SwitchB插入到SwitchA上，它就不能工作了。

我是不是遗漏了什么？我如何获得它，以便我可以连接2个思科2950交换机在一起？

更新1

在SwitchA上：

#show int port-channel 1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Po1         on           802.1q         trunking      1

Port      Vlans allowed on trunk
Po1         1-4094

Port        Vlans allowed and active in management domain
Po1         1-2,5,30,112,115,120

Port        Vlans in spanning tree forwarding state and not pruned
Po1         1-2,5,30,112,115,120

在SwitchB上：

#show int port-channel 1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Po1         on           802.1q         trunking      1

Port      Vlans allowed on trunk
Po1         none

Port        Vlans allowed and active in management domain
Po1         none

Port        Vlans in spanning tree forwarding state and not pruned
Po1         none

对于SwitchB，我尝试添加所有允许的vlans，但是它没有改变任何事情：

#config t
#int port-channel 1
#switchport trunk allowed vlan all

我也试过：

#switchport trunk allowed vlan 1-4094

但允许的vlan并没有改变到我说的。我该怎么解决这个问题？

更新2

我在两个交换机上运行了一个show int po1 switchport：

SwitchA

#show int po1 switchport
Name: Po1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: Off
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Protected: false

Appliance trust: none

SwitchB

#show int po1 switchport
Name: Po1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: down
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: Off
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Protected: false

Appliance trust: none

仍然不知道为什么show int po1 trunk会显示Vlans allowed on trunk: none

Answer 1

你为什么第一次使用港口通道？我不认为有任何与端口通道相关的接口.

尝试在Fa0/1上添加vlans。

Switch(config-if)# switchport trunk allowed vlan add 1

还有，你打开自动MDIX了吗？如果没有，请确保在界面上使用交叉电缆或启用自动MDIX：

Switch(config-if)# mdix auto