Newbie VLAN setup question: 2 GS305E linked with a trunk shall do port-based-VLAN

[Thomas-S]

Consider the following (simplified) scenario. Company A and B share two office rooms (R1 and R2) on one floor of a building. A and B have some of their equipment in both rooms: in room 1 there is Switch-CompanyA-R1 that links Company A's equipment in room 1 and Switch-CompanyB-R1 that links Company B's equipment in room 1. Similarly, in room 2 there are Switch-CompanyA-R2 and Switch-CompanyB-R2.

The two rooms are linked with a only single Network cable. I plan to install two GS305E (one in each room) and use VLANs to connect the existing switches so that the LANs from one company are isolated from the LAN of the other company.

In particular:

GS305E_R1 Port 1 connects to GS305E_R2 Port 1 (this is link between the rwo rooms)

GS305E_R1 Port 2 connects to Switch-CompanyA-R1

GS305E_R1 Port 3 connects to Switch-CompanyB-R1

GS305E_R2 Port 2 connects to Switch-CompanyA-R2

GS305E_R2 Port 3 connects to Switch-CompanyB-R2

How should I configure the VLANs and ports so that Switch-CompanyA-R1 is connected to Switch-CompanyA-R2, Switch-CompanyB-R1 is connected to Switch-CompanyB-R2 while ensuring that these two VLANs are isolated?

(The companies generally trust each other and won't mess wih the setup, but they still want to keep their LAN traffic to themselves.)

Thank you for sharing your wisdom 🙂

[schumaku]

With port-based VLAN, there is no way to have two networks on one physical link.

The connection beween the two rooms (and the repsective network access), you need to run an 802.1q VLAN trunk with (at least one, I would suggest both networks [aka. VLANs]), so VLAN 1 [t]agged and VLAN 2 [t]agged. Then, create two plus two access ports for each network, say VLAN 1 [u]ntagged with PVID 0, resp. VLAN 2 [u]ntagged with PVID 2. 

[Retired_Member]

@Thomas-S 

You case is actually simple and you can find many examples on Internet describing similar implementations. However you need to learn same basics of IP networking. Lake it or not, you are getting out of the Plug-and-Play world.

It looks to me that you currently have 4 separate networks, 2 for each company. In each network, you have a unmanaged switch to which workstations and over IP devices are connected. I guess that there is a router in each of those networks that connects those networks to Internet and supplies IP addresses through its DHCP server. Yes, you can connect those switches to a GS305E in each room and connect the GS305E switches together. Just do not try to find that “802.1q VLAN trunk,” suggested by the other poster, to run between the two rooms. A simple CAT5e or CAT6 cable will do it.:)

You, of course, know that configuration changes must be made to make that work. However first learn the IP configuration of you current networks, i.e. IP subnets and addresses of the default gateways, DHCP servers and DNS servers. Then, come up with a design of the 2 networks you need, one for each company. Forget about VLANs initially. You need to pick two different subnets. In each subnet you need just one router with a DHCP server. Actually, you may just pick 2 of the 4 exiting networks you have to start with, one from each company. You do not need to change them as long as they are on two different subnets. You will need to remove routers from the other two networks. Then, you can start configuring your GS305E switches with VLANs. You just need 2 VLANs, one for each subnet. There is also a default VLAN on GS305E switches that should, but it does not have to, be kept separate.

[schumaku]

Hm, probably - this can be read from the description too.

For my part, I see only two networks, and just one network cable for making both networks available in both rooms.

[Thomas-S]

@Retired_Member: Thanks for the feedback. As @schumaku has pointed out correctly, there are only two networks. IP configuration and routing is not the issue here, I'll take care of that. I was just not familiar with the VLAN and trunk issue. After carefully reading and understanding @schumaku first comment, I found a few useful links (there are many...), two of which I'm including here if anyone ever stumbles over this thread with the same question:

https://www.thomas-krenn.com/en/wiki/VLAN_Basics

https://www.youtube.com/watch?v=Wi48h6UFhlo

Thanks for your thoughts here and sorry that I didn't look this up before. I was kinda scared by the tagging stuff and thought "port-based" would be what I wanted.