Assign VLAN to multiple ports in SonicWALL TZ300

I can see two orders of problems with this setup:

1. You need to setup trunks between the switches or nothing that is not in the default vlan will actually be delivered. Any link between two switches needs to be setup as a 802.1q trunk.
2. Port 12 and Port 22 are in a different broadcast domain. All the "l3 interfaces" on the switches are (as you said) in vlan0, while Port 12 and 22 on SW3 are in vlan2. If you need different VLANs to be able to talk to each other, you need InterVLAN routing.

The theory behind point 1 is that VLAN traffic can only pass through a trunk. These stops "client" devices (such as your PC2) from seeing traffic that doesn't belong to them.

You seem familar at least in principles with the concept of "broadcast domain". You should also know that the only device that can traverse multiple broadcast domain is a Layer3 or higher device. It seems to me that these switches are managed L2 devices. You need a router and a good bit of vlan theory :) Later tonight i'll post a quick sketch with all the bits needed to get this working.

Your second question: "Can a port be added to multiple vlans?" No it can't. In port-based vlans, such as the ones you're using, it's a moot point. THere are different flavors of VLANs. If you need more than one vlan to go through that port, again, you need a trunk and a capable device on the other end that can handle them. But i doubt that is your requirement.

You should stick to port-based vlans since they're the most common form, the easiest to setup and the one most people use.

Why do you need more than one vlan on a client port? what kind of device do you have on that port? The only common use case is a virtualization Hypervisor. In that case, you need a trunk on that port.

Also: Unrelated but i felt i needed to point it out. Your topology is very prone to failure. If top or bottom switches should die, a big chunk of your network would collapse. Consider a different topology and some spanning-tree.

I got it working.

First of all, it was a hardware problem

I had a cheap-o Linksys switch plugged into the LAN (X0) port of the Sonicwall. The 3Com 4500G switch and my laptop were connected to cheap-o switch. That way the switch and my laptop could both be connected to the LAN (X0) port on the Sonicwall.

Turns out the 3Com switch was plugged into a bad port on the cheap-o switch, making the software settings impossible to properly test. I switched the 3Com to another port on the cheap-o switch.

Then I just had to set up the routes

On the Sonicwall, I configured two routes, so that any traffic destined for VLAN 1 or VLAN 11 IP addresses is routed through VLAN 4094.

Then, on the 3Com switch, I set up a static route to the Sonicwall IP, effectively telling the switch to send traffic to the Sonicwall if it didn't know where else to send it.

With this combination in place, traffic began to flow correctly up, down, and across the network.

Note: Instead of setting up the static route on the switch, I could have enabled RIP on the Sonicwall and broadcast the Sonicwall IP to the 3Com switch as a default route. It would end up in the same place on the switches routing table, supposedly doing the same thing. I might enable RIP and disable the current static route eventually, but it's working for now so I'm going to leave it alone for a while.