VLANS with 2651 router

[Sean McCoy]

I have a 2651 LAN router. Is it possible to create VLAN's on that router? I have some L2 switches on my local segment that support VLANS. Any ideas or NO GO? Thanks.

[Jon Marshall]

Hi Sean

Just to clarify. Are you talking about running a router on a stick configuration where the 2651 will have subinterfaces using 802.1q encapsulation ?

If so then yes it should do it. You will need IP PLUS IOS feature set as a minimum.

HTH

Jon

[Sean McCoy]

Jon-

That is pretty much what I want to do. These additional VLANS will be for testing purposes. I probably cannot obtain the IP PLUS IOS feature set due to the fact that the router is out of warranty/contract. The other option I have would be to configure the available FE0/1 interface in the additional subnet and set the VLAN id on the switch port to reflect that, correct?

[Jon Marshall]

Sean

Yes you can allocate an IP address to the fe0/1 interface out of a vlan and then assign the port that the fe0/1 interface connects to into the same vlan.

Note that IP PLUS is minimum, so you may have a better IOS on the router already. Worth checking. Easiest way is just to try and configure an subinterface

int fa0/1.10

encapsulation dot1q 10

ip address x.x.x.x x.x.x.x

Jon

[Sean McCoy]

Jon-

Thanks for the quick response. My other question is how do I now configure FE0/1 to tell it the DHCP server lives on the other interface/subnet?

Sean

[Jon Marshall]

Sean

You need to use the "ip helper-address x.x.x.x" command. So lets say your DHCP server is 192.168.5.10

int fe0/1

ip helper-address 192.168.5.10

This will take a broadcast request for an IP address from any client on the vlan that fe0/1 connects to and forward it on in a unicast packet to the DHCP server.

Jon

[Sean McCoy]

Jon-

Thanks! Works like a charm. I owe you one.

Sean

[Sean McCoy]

Jon-

One last question. I have network printers on the FE0/0 subnet. Anyone on the new FE0/1 subnet cannot print to them. Do I need to make additional changes to FE0/1 to allow this? Thanks.

Sean