Can I route between 3 VLANs with 2 ethernet ports?

[ckaiser]

Hi.I'm working with an inherited environment and know enough about routing and switching to be really dangerous. :-) I'm a Windows admin who is learning routing and switching OTJ... so bear with me.

I need some help with a design...

I have a 4006 core switch connected to a 3640 router. The router does our internal WAN routing; the switch does our main office LAN routing.

There are two ethernet ports on the router and two on the switch.

Currently, VLAN 2 is connected to one of the ports and VLAN 99 is on the other. One VLAN is for voice, the other is for data.

I would like to be able to create a third main office VLAN and use it for data in order to isolate my servers from my local workstations.

So if my current data vlan is 172.24.1.0 and my voice VLAN is 172.24.2.0, I'd like to be able to make a third VLAN, 172.24.3.0 and assign all the workstation ports on the switch to that VLAN and route that traffic. Since I only have 2 ethernet ports on the switch and router, I assume I need to do some virtualization to manage that. We do have L3 routing on the switch, but don't have a supervisor3 module.

I think I can do it with subinterfaces and trunking?

I haven't been able to find a reference that walks me through it yet, though. Nothing seems to show me that I can create another VLAN, assign an IP address to it, and route that traffic. I found references to doing this with the supervisor3, but not without it.

I can clean up and post configs if that helps...

Can anyone help?

Thanks!

Charlie

[thisisshanky]

Do you have a L3 engine in the 4006 ? You wont need external routing, if you are having a L3 engine in your 4006. You can simply create the vlan interface in the L3 engine and configure an IP address for it. You will also need to first create the same Vlan in the switch database. If there are multiple switches, and VTP is running, you will need to create the vlan in the VTP server.

[ckaiser]

Yes; there is an L3 engine in there. None of the documentation I've found tells me how to create the VLAN configs properly given this setup, though. If there's a good configuation guide available, I'd love to find it.

Thanks!

[s.uslay]

The other option is to use dot1q trunking in 3640 on the same interface..(there are different versions of coding depending on IOS version but basically as below)

i.e

interface FastEthernet0/0

no shut

interface FastEthernet0/0.1

description old data vlan 2

encapsulation dot1Q 2

ip address 172.24.1.X 255.255.255.0

interface FastEthernet0/0.2

description new data vlan 3 ?

encapsulation dot1Q 3

ip address 172.24.3.x 255.255.255.0

interface FastEthernet0/1

description old voice VLAN 99

ip address 172.24.2.0 255.255.255.0

you also need to enable trunking on 4006 port attached to 3640 fast0/0 .

These documents are useful if you prefer this way;

(It is for 3550 but will still work for 4006)

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a008015f17a.shtml

SU