Unable to add allowed VLANs to trunk and port not trunking

Question

I am unable to add any VLANS to be allowed on trunk and the port is not trunking.

I've tried:

Switch0#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)#interface FastEthernet 0/1
Switch(config-if)#switchport trunk encapsulation dot1q
Switch(config-if)#switchport mode trunk
Switch(config-if)#switchport trunk allowed vlan add 1,2,3
Switch(config-if)#end

But it still shows:

Switch#show interface FastEthernet 0/1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Fa0/1       on           802.1q         not-trunking  1

Port      Vlans allowed on trunk
Fa0/1       none

Port        Vlans allowed and active in management domain 
Fa0/1       none

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/1       none

Edit:

Switch#show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/2, Fa0/3, Gi0/1
                                            Gi0/2
2    VLAN0002                         active    Fa0/4, Fa0/5, Fa0/6, Fa0/7
                                            Fa0/8, Fa0/9, Fa0/10, Fa0/11
                                            Fa0/12, Fa0/13, Fa0/14, Fa0/15
                                            Fa0/16, Fa0/17, Fa0/18, Fa0/19
                                            Fa0/20, Fa0/21, Fa0/22, Fa0/23
3    VLAN0003                         active    Fa0/24
1002 fddi-default                     act/unsup 
1003 token-ring-default               act/unsup  
1004 fddinet-default                  act/unsup 
1005 trnet-default                    act/unsup 

Please advise.

I'm using a Cisco Catalyst 3550.

Solution

I'm suspicious that the switchport isn't up - what does "show interface fa0/1 switchport" say?

With the exception of DTP (dynamic trunking protocol), trunking is unidrectional, which is to say one side of the trunk doesn't necessarily need to agree with the other side. Not that you'll get proper traffic flows if trunks are mismatched, but a non-trunking status is in my experience relatively rare.

Comments

[Dan]

What's the output of 'show vlan'? In fact, a sanitised 'show run' would be handy.

[Jeff]

Added show vlan brief output.

[cpt_fink]

Could we get the output from sh int status please?

[Jeff]

Would the other side still affect the VLANs not being allowed on trunk?

[Hyppy]

I don't believe that the VLANs are going to show up in the trunk if the trunk's not active.