我试图通过每个FastEthernet 0/1端口连接（2）Cisco Catalyst 2950，但由于某些原因，它们没有通信。 我这样做是为了物理扩展我的networking并添加更多的networking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configuration了相同的configuration，如果将SwitchC的FastEthernet 0/1插到SwitchB或SwitchA上，就可以正常工作。 但是如果我把SwitchB的FastEthernet 0/1插到SwitchA上，就不起作用了。
我错过了什么吗？ 我如何得到它，所以我可以连接2台Cisco 2950交换机？
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vlan，但是它不会改变任何东西：
#config t #int port-channel 1 #switchport trunk allowed vlan all
我也试过：
#switchport trunk allowed vlan 1-4094
但是允许的VLAN不会改变我所说的。 我该如何解决？
我在两个交换机上运行了show int po1 switchport ：
#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
#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
仍然没有线索为什么show int po1 trunk显示show int po1 trunk Vlans allowed on trunk: none
你为什么首先使用Port-channel？ 我没有看到有任何与该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
另外，你有自动MDIX打开？ 如果没有，请确保使用交叉电缆或在接口上启用自动MDIX：
Switch(config-if)# mdix auto