Route public IP addresses across switches in internal network

[ecallenil]

Here's the situation:

I have an incoming internet connectoin handing off public IP addresses.  This device is on the opposite side of the building and I need to get the connection back to my main server room to connect to the firewall.

I have managed switches on each end (where the connection comes in, and in the server room).  Both are model GS724T.  These switches route my internal private network traffic.  For the uplilnk, I have a fiber trunk (2 fiber ports).

What is the best way to route the public traffic through the same switches as the private traffic so I can get the public traffic back to the server room?  I'm thinking I need to do VLAN but the fiber trunk ports need to be tagged and work for both the public and private networks.

[broadband radio]----[GS724T]-----------{fiber trunk}-----------------[GS724T]------------[firewall]

Any help is appreicated.

[fordem · Accepted solution]

Yes - trunks can handle traffic from multiple VLANs, that is why it's called a trunk you'll need to make it a member of all the VLANs you want it to pass traffic for, and configure it to pass the VLAN tags.

[fordem]

Let's start by being very careful as to the words we choose - router route & switches switch, unless those switches are layer 3 switches, and as far as I know, the GS724s are layer 2.

As you have suggested, you can create a VLAN and pass the internet traffic across that - it will only take one switch port at each end

[ecallenil]

Thanks, fordem, and you are correct.  I used terms that are not correct.  Instead of "route" I meant something more along the lines of the switches "send" or "pass" traffic.  My question is if it is wise, or even possible, to use the already established trunk to pass this traffic?  It woud not be desirable from a labor standpoint to run more cable between the switches.  Would the trunk be able to pass traffic both on internal and external networks at the same time?

[fordem]

A VLAN is a virtual LAN - think of it this way ...

You have two switches, each with four computers in their own little LAN, each group of four computers can talk to one another, but the computers on one LAN cannot see the computers on the other LAN - these are physically separate LANs.

Now let's take a single switch that supports VLANs and create two VLANs, each with four ports, and connect the computers to them - this configuration will work exactly like the one above, each group of four computers will be able to talk to one another, but the computers on one LAN cannot see the computers on the other LAN - these are virtually separate LANs.

Yes - you can do exactly what you're suggesting because the internal VLAN will never see the external VLAN.

[ecallenil]

Thanks for your reply and sorry for any confusion.  I understand what you are saying in that VLANS are separate LANS.  What I would like ot know is if the trunk between the two switches can handle 2 VLANS?  In other words, I would set  up VLAN1 and VLAN2 on each switch, the fiber trunk connects both switches, and I woudl be able to pass traffic from VLAN1 on switch A to VLAN 1 on switch B.

[switch A]-------------------------{fiber trunk}------------------------------[switch B]

VLAN1 VLAN2                                                                            VLAN1 VLAN2

[fordem · Accepted solution]

Yes - trunks can handle traffic from multiple VLANs, that is why it's called a trunk you'll need to make it a member of all the VLANs you want it to pass traffic for, and configure it to pass the VLAN tags.

[ecallenil]

Great!  Thanks for your help!