I've configured switch ports to trunk multiple VLANs many times, but for the first time I now need to configure a router interface for this; can someone give me the standard IOS commands to set VLAN trunking up on a router port and to define the VLANs in IOS on a 2821 router?
Here's a sample of the config on one of my routers. It's a Cisco 2811 with IOS v12.4(3g), close enough i'd say. 2821 has GigabitEthernet interfaces instead of FastEthernet.
no ip address
encapsulation dot1Q 1 native
ip address 172.16.144.1 255.255.255.240
encapsulation dot1Q 2
ip address 172.16.144.17 255.255.255.240
encapsulation dot1Q 3
ip address 172.16.144.33 255.255.255.224
The port on the switch is configured like this:
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk allowed allowed vlan 1,2,3