Trunk wont allow vlans

[SandervdA]

Hello,

I'm trying to create a trunk on a Cicso C2960X switch on port 1/0/48. in the 'sh int status' it says that port 1/0/48 is a trunk. but when i type 'sh int gi1/0/48 trunk it shows that there are not vlan allowed on the trunk:

 To add a vlan to the trunk I type:

-conf

-int gi1//0/48

-switchport mode trunk

-switchport trunk allowed vlan 1, 117, 126

-end

-wr

configuration switches and netwerking is all fairly new to me, and i dont know why its not working.

[balaji.bandi]

Do you have VLAN created 117 and 126

can you post show vlan

[SandervdA]

Hello,

Yes the vlans are created and the vlans are also working.

We have more Cisco switches at the factory, but they where configured by some one who left the company, and atm there is no one internally I can ask for help. 1 of them also has a working trunk on a gi-port.

[Jon Marshall]

Check - 

1) the port is up 

2) the port on the other end of the link is up and is configured as trunk as well

Jon

[balaji.bandi]

Post below information :

show interface gi1//0/48

show interface gi1//0/48 capabilities.

Or do below steps and let us know. ( make sure you remove the cable and below steps and conenct back)

conf t
!
default int gi1//0/48
!
int gi1//0/48
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk allowed vlan 1, 117, 126
no shut
!

[SandervdA]

Hello,

her are screenshot of the info you asked.

when i trie to type the code you provided i got an error on the word 'encapsulation' 

Kr,

Sander

[balaji.bandi]

The port already dot1.q, so the command not required (switchport trunk encapsulation dot1q)

can you post

show version

show run

show spann summary

[rasmus.elmholt]

It is strange that the status is other on the trunk.

Could you try and do a show int status err-disabled and show int status?

[SandervdA]

Hello.

Thank you for the reply's. On Monday I'll try the different solutions and'll supply screenshot, at home I can't connect to the switch. Also, the trunk I create connects to an old 3Com switch, on a port that is also a trunk (alto on the 3Com I needed to assign tagged and untagged vlans).

[balaji.bandi]

keep us post what is the outcome, more interested to see what was the fix for you. still has an issue, do not forget to give your input information to understand better of the issue here.

[rasmus.elmholt]

And try to do a switchport nonegatiate just to make sure DTP is disabled on the Cisco switch if it is connected to a 3-party switch.

[MHM Cisco World]

trunk status is show OTHER not trunk 
this trunk is connect to second  SW ? are second SW have same encapsulation ? are both use DTP for trunk?
I think the problem not in this SW it is in second SW.

[SandervdA]

Hello,

The switch in question is connected with fiber to our backbone switch. so it's backbone -> switch Cisco -> 3com that is the set-up i need.

but, it shouldn't matter right, how the 2nd switch is configed, the allowed vlan should show on the switch.

Kr,

Sander

[paul driver]

Hello
FYI it doesn't matter if the other end of the trunk isn't configured. As long as the switchport interface that is to be a trunk is enabled as a trunk and also is active it should show the correct vlans allowed to cross the trunk, those that are allowed and active on the switch, But it wont show vlans in a stp forwarding state if they are are being pruned.

In your case its possibly a bug in software of switch, Can you post the feature-set version and sdm template of the switch
sh version
sh sdm prefer

[SandervdA]

Hello Paul,

her are 2 screenshot of the sh version & sh sdm prefer.

Kr,

Sander