Setup vlan but still get communication between them. Netgear

[dany2010]

Hi,

 

Just started setting up some VLAN's on the network.

 

First time doing this. The LEA setup a couple but computers on one VLAN can still talk to the other.

 

All ports are untagged from the default group 1 VLAN which is what I think is causing the crossover. However removing the T or U from VLAN 1 stops all communications to the port.

 

Am I right in thinking if all ports are untagged in VLAN 1 this would be joining the two VLANS together?

[SYNACK]

Am I right in thinking if all ports are untagged in VLAN 1 this would be joining the two VLANS together?

 

Yes, all untagged in vlan one means they are all native in the same vlan, to have separate ones you need to isolate them out and have ports native to the other vlan.

 

If you want to communicate between vlans each vlan needs to be on its own subnet and you need a layer3 router inbetween the vlans, if your core switch is layer3 it should manage this but otherwise you would need an external router. In order for these vlans to get to the internet the internet router must also have routes back to the internal vlans using the layer3 switch as their gateway otherwise the traffic will not make it back.

[cpjitservices]

What sort of switches are you running ? it may be that the vlans can talk to each other because the switch is doing it's Inter-VLAN routing (if its a layer 3). You may need to add policies so that traffic can't travel between VLANs.

[dany2010]

The LEA has in school a Cisco 3550 switch. This splits the admin and curriculum and acts as a gateway allowing only machines on a IP range.

 

If I do tracert it uses the gateway for to their admin server as this doesn't connect to the Netgear. If I tracert a printer that's picked up DHCP on the admin VLAN from the Curriculum VLAN goes straight there through the Netgear and not the Cisco..

 

Its a Netgear GS748T v5.

 

 

I've just found out through playing that the switch isn't tagging frames.

 

I've removed two test ports from the default VLAN leaving them tagged in just the curriculum VLAN, and communication between them stopped. Set the PVID to the vlan, still nothing.

Set the port to untagged in the VLAN curriculum membership and they can talk.

Edited August 12, 2014 by dany2010