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Trunking with 4003 & 3500XL

I am unable to get trunking working betweeen the Gbic's on the 4003 & 3500. The 4003 can see the modules but the 3500XL's do not go active even though everything is set up for dot1q encapsulation. The whole assembley has recently been powered down & moved to a new location. Prior to this every thing was ok.

Community Member

Re: Trunking with 4003 & 3500XL

You may want to check trunking mode on those ports. They default to auto and if both ends are set to auto, they'll never bring the trunk up. If that's the case, I'd suggest you set one end to desirable.

set trunk module/port desirable vlan_range dot1q

Community Member

Re: Trunking with 4003 & 3500XL

Since this work previously, I may be something simple like have fiber jumper transmint and receive cables plugged in backwards. The cable may have also been damaged.


Re: Trunking with 4003 & 3500XL

I have found it is best to set the 4000 side to on for dot1q trunking and 3500 to switchport trunk mode with encapsulation of dot1q.

You have to watch though as to what you have set the native vlan to be as it will not pass packets for it if you don't .

Here is part of setting I have used.

duplex full

switchport trunk encapsulation dot1q

switchport trunk native vlan 169

switchport mode trunk

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