Router on a stick – Adding VLANs to a cisco router

Telnet to your cisco router, enable then go into config t. Passwords may be required depending on how it has been configured…

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config t

Ensure that ip routing has been enabled…

ip routing

To create the VLAN adapter you’ll need to run the following commands to create a “router on a stick”…   Note: the .2 after the interface name creates a virtual adapter on the interface.

interface FastEthernet1/1.2
description “VM Host Network”
encapsulation dot1Q 2
ip address 172.25.2.1 255.255.255.0

The following is another example of a VLAN (110) on a router. This one has the ip helper-address (DHCP server) specified for this range.

interface FastEthernet1/1.110
description “Ak IDN”
encapsulation dot1Q 110
ip address 172.25.20.1 255.255.255.0
ip helper-address 172.25.20.15

That is the router side of things setup. Remember to save your changes via…

copy run start

Now you’ll need to add the VLAN to your switches. If you have VTP in your environment its as simple as adding the extra vlan onto your “server” vtp switch. Telnet (or null cable) to your “server” switch and go into “enable” mode, then go into the vlan database and add the required vlans as per above…

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vlan database

vlan 2 name “VM Host Network”

vlan 110 name “Ak IDN”

VTP will propagate the vlans out to your client switches. Done.