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New Member

2 catalyst 3750G interVLAN ios 12.1


I got a step by step guide on how to interVlan this 2 switches but I am running into a problem.

when I create the VLAN ID 1058 (set by isp) it does not show up in my show vlan. therefore I cannot assign ports to it. if I create a VLAN ID 300, it shows up and I am able to continue my installation. Does this switch support extended vlan ID or am I missing something extra.


  • Other Network Infrastructure Subjects

Re: 2 catalyst 3750G interVLAN ios 12.1


Extended Vlans are supported on 3750. You have disable VTP on the switch or to set it up to trasparent mode before setting up the extended range vlans on it.

conf t

vtp mode transparent.



-amit singh

New Member

Re: 2 catalyst 3750G interVLAN ios 12.1


it worked, the ports belong to vlan 1058, now following this new link it tells me to set one interface to "switchport mode trunk" to make the to switches connect, but the switch is giving me the following message that cannot change a interface that belongs to switchport auto to switchport mode trunk.

I will keep readig and hopefully figure it out,

any ideas?

thanks agian

Re: 2 catalyst 3750G interVLAN ios 12.1

Could you please post the full error... Aahh I see...

Actually you need to set up the encapsulation first on the port and then set it up for trunking.

conf t

int x/y

switchport trunk encapsulation dot1q

switchport mode trunk.


-amit singh