Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Strange vlan configuration problem. Please assist.

We created a new IC to our building that I installed two 2950_48 that are stacked together. Off from one of the 2950 is a fiber that runs back to a 3548XL switch for our trunk connection. I configured trunk on both ends and set vlan 2 as our native vlan. However when I look at interface vlan 2 on the 2950_48 it is showing Vlan up and line protocol down. Now here comes the strange part- on the 2950_48, I able to configure each port for different vlan that we have in our infrastructure but only one vlan can be carried over the trunk. None of the other vlan seems to be working at all. The traffic of the working vlan has no problem at all with network communication. The other thing is that I can't get to my 2950s switch for management from telnet or SSH only console works. Obviously because my VLAN 2 is down. Please assist. Thanks.

1 ACCEPTED SOLUTION

Accepted Solutions
VIP Purple

Re: Strange vlan configuration problem. Please assist.

Hello,

looking at your configurations, I think you need to add the native VLAN statement to the trunk ports on your 3548:

interface GigabitEthernet0/1

switchport trunk encapsulation dot1q

switchport trunk native vlan 2

switchport trunk pruning vlan none

switchport mode trunk

!

interface GigabitEthernet0/2

switchport trunk encapsulation dot1q

switchport trunk native vlan 2

switchport trunk pruning vlan none

switchport mode trunk

If that does not help, can you post the output of ´show vtp status´ of both switches ? When you look at the output, make sure that the VTP version, domain name (case-sensitive) and password match.

Regards,

GP

7 REPLIES
VIP Purple

Re: Strange vlan configuration problem. Please assist.

Hello,

can you post the configurations of both switches ? I guess there is something wrong with either your VTP, trunk, or management VLAN configuration, or a combination of the above. Looking at your configs might reveal something...

Regards,

GP

New Member

Re: Strange vlan configuration problem. Please assist.

Thanks for the prompt response. I pasted the config for both switches. At the end of the switches is the show int vlan 2 output. I was wrong earlier about the output of vlan2 up and line down. Both vlan2 and line is down. Please look at both config I label in the beginning which one is which.

VIP Purple

Re: Strange vlan configuration problem. Please assist.

Hello,

looking at your configurations, I think you need to add the native VLAN statement to the trunk ports on your 3548:

interface GigabitEthernet0/1

switchport trunk encapsulation dot1q

switchport trunk native vlan 2

switchport trunk pruning vlan none

switchport mode trunk

!

interface GigabitEthernet0/2

switchport trunk encapsulation dot1q

switchport trunk native vlan 2

switchport trunk pruning vlan none

switchport mode trunk

If that does not help, can you post the output of ´show vtp status´ of both switches ? When you look at the output, make sure that the VTP version, domain name (case-sensitive) and password match.

Regards,

GP

Purple

Re: Strange vlan configuration problem. Please assist.

Could post your show vlan command also to make sure you have created the vlans in the vlan database . thanks..

New Member

Re: Strange vlan configuration problem. Please assist.

Thanks GP,

The problem was that the 2950_48 switch connected to 3548 was in server mode and the domain was wrong. Thanks for your help.

Purple

Re: Strange vlan configuration problem. Please assist.

When you look at the 2950 you are looking at the layer 3 SVI if says up/down. Have you looked at your layer 2 vlan assignments to see if those look ok . If you do a show vlan do all your ports look like they are in the correct vlan ? Are they created at all?? What does it look like when do a "show interface trunk" ? You'll have to post the configs for at least the ports that are the trunks and maybe you could post a "show vlan" command from each side also .

New Member

Re: Strange vlan configuration problem. Please assist.

Can you also post a "show interface trunk", if that command is available to you. Thanks.

123
Views
0
Helpful
7
Replies