VLANs accross 3com switches

Posted on 2009-12-26
Medium Priority
Last Modified: 2012-05-08
I have a 3com Unified switch and a 4500.  On the Unified switch I had configured a VLAN 2 on ports 21-24.  The remaining 20 ports were on the default VLAN 1 and port 1 was plugged into port 1 of my 4500 switch allowing the 47 ports from the 4500 to work with the remaining 19 ports on the Unified.  None of the VLAN 1 ports were tagged.

I need to create a VLAN 3 and have ports on both switches to be part of it so I configured VLAN 3 on both switches.  I then configured ports 10-15 on both switches to be part of VLAN 3 untagged.  I then plugged ports 10 together.  The traffic on each switch is isolated from the other vlans and can communication with each other on the same switch, but not across the two switches.  VLAN 1 is still fine.  

What else needs to be done to get VLAN 3 speak with devices on both switches.
Question by:JordanNolan
  • 2

Expert Comment

ID: 26126123
Did you set up a trunk port on both switches and connect them together.
LVL 21

Accepted Solution

Rick_O_Shay earned 375 total points
ID: 26127614
You should have only one tagged link or one tagged multilink trunk between the switches or spanning tree will block one of them.

You want to tag the link on both switches with all of the VLANs you want to go between switches so in your case VLAN1 and VLAN 3. Keep in mind some switches won't allow tagging on ports in the default VLAN. All of the user/device ports should be in the respective VLANs but as untagged ports.

If you need to get from VLAN to VLAN an internal or external routed interface will be required.

Author Comment

ID: 26129493
I attempted to set the ports on each switch that are connecting the two to a trunk, but on the 3com Unified it switched the vlan to the default of 1.  I will give it another try
LVL 21

Expert Comment

ID: 26137979
I am not sure if you are saying that you tried to put all the device ports into a trunk which you wouldn't.
Just the link between the switches needs to be tagged and have all the VLANs configured on it.

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