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New Member

valn mismatch issue

i have a 6500 with gigabit module. Each of the gigabit ports are configured as diffrent vlans..Easc of this ports are connected to a 3550. all the ports on 3550, along with the gbic ports are configured as switchports and no trunks.

vlan is working well, but am having a vlan mismatch on my console on all the gigabit ports.

1. do i need to change all the vlan id on the 3550 to match the vlan id of the gigabit port it is connected to.

2. or can i ignore this vlan mismatch messages since my network is working fine?

3. what is the best practice on this scenario. Its just so annoying when you are at the console.

thanks a lot

9 REPLIES
New Member

Re: valn mismatch issue

Maybe you can post the log message?

Joe

New Member

Re: valn mismatch issue

You COULD just leave it as it is, and your trunks will continue to pass traffic just fine. However, it would be favorable to set the configuration on your trunks to have identical native vlans. Doing this will solve your problem. Good luck.

- Matt

New Member

Re: valn mismatch issue

they are not configured as trunks as mentioned.

New Member

Re: valn mismatch issue

I apologize, as I misread your post. Would you mind providing an output of the config for a port on the 6500 & a port on the 3550. Along with an output of the error messages you are receiving? Thanks.

- Matt

New Member

Re: valn mismatch issue

its evening in here..so i could only tell you how are they configured..(exact configuratiuon and error messages to follow)

the gigabit are configured as desirable

the 3550 are configured as switchports

thx

New Member

Re: valn mismatch issue

New Member

Re: valn mismatch issue

I guess i there is a need to trunk only if you have some common network on switches...the far end L3 switch is just for my outside connectivity (the default gateway in fact)

Re: valn mismatch issue

Hi,

there is a best practice to have the same VLAN IDs on access ports interconnecting switches in your network (unless there is a SERIOUS reason why not to do it).

If you leave different VLANs on both line sides, you are INTERCONNECTING different VLANs, in fact, creating one common "superVLAN".

Example: VLAN2 on switch2 connect to VLAN3 on switch3 - the result is one big VLAN with common STP and different IDs on particular switches. You can get into troubles in the future when involving VTP or trunks, e.g., or even when forgetting about this "interconnecting" fact.

That's why Cisco considers this configuration non-recommended and you are receiving syslog error messages.

You can ignore these messages (there are some tricks how to stop them).

But best solution is to change VLAN ID if you can.

Regards,

Milan

New Member

Re: valn mismatch issue

thx a lot milan...that clears my doubts.

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