Passing VLANs between switches 1

[shipoffools]

I have a catalyst 3524 in one building that is configured with two separate VLANS 1 and 2. All other switches on campus are set to use VLAN1. I want to be able to set some of the other ports in other buildings to use VLAN2, but it doesnt seem that the information is passing from the switch with the 2 VLANs. Obviously I am not a Cisco wiz. I just try and keep things together. Any help would be appreciated.

 

[ADB100]

You need to set up a VLAN trunk between switches, configurations can vary depending on what types of switches you have. How are the switches connected? and how many are there? Are there any Layer-3 devices in the network? A Bit more information is needed before I can answer your question

Andy

 

[shipoffools]

All of the switches are layer2. We have 9 of them all 3548 except for the one building with the 3524. The buildings are all connected with fiber. What else do you need?

 

[ADB100]

Right. I assume you have 1000BaseSX or 1000BaseLX GBICs linking all the 3500XLs together - daisy-chain fashion?

If thats the case you need to make the Gigabit Ethernet interfaces VLAN Trunks. Configuration would be:

interface GigabitEthernet 0/1
switchport mode trunk
switchport trunk encapsulation dot1q
!

Once you have Trunks connecting your switches you need to make sure the VLANs you are using exist on all switches. Cisco has a proprietary protocol for propogating VLAN information amongst Cisco Catalyst switches (not my recommended way of configuring them but an option). To create VLANs and automatically update all switches with the information you need to create a VTP Domain. From the switch command line (NOT conf t, just the standard enable prompt) type 'vlan database<cr>'. You then need to specify a VTP domain name 'vtp domain xxxx' (whatever you want). Then create the vlans by typing 'vlan x' where 'x' is the VLAN number (from 1 to 1005). Type 'exit' to allow any VTP changes you made to take effect. If all the other switches have never had VTP configured they should automatically inherit the VTP Domain name and accept the VTP Database of VLANs. If they have had VTP configured then you would need to set the VTP domain name manually on each switch as above.
You can check the vlan database by typing 'show vlan', this should list the VLANs configured and the ports that are assigned to each VLAN. You can check whether a port is a trunk by typing 'show interface gigabitethernet 0/1 switchport'

That should get you going, BUT I would seriously consider getting someone in to sort this out professionally. Nine 3548's equates to 432 switchports and I wouldn't recommend this many devices on a 'daisy-chained' layer-2 network.

Andy

 

[shipoffools]

Thanks Ill give that a shot. We are actually a small campus and have the switches deployed across multiple buildings.

 

[ADB100]

Still, with 400+ ports in the same VLAN its a big broadcast domain - even though the switches are located in different buildings they network is still the same - an issue in one building could potentially disrupt the whole network.

Andy