If you're doing this within Cisco Learning Labs environment, something to keep in mind is that the "switches" are to the best of my knowledge actually based on a Router platform/image. So, as a side effect, you have to turn switching on for the port to accept switch-like commands.
On a Catalyst switch, you would not need to enter this command.
it's a lab switch and it gives "experimental" in the show hardware command so I'm thinking its L2. However I configured vlan1 with an IP address so I'm good there. I think where I got sideways was forgetting that I have to enter in the switchport command first before then using the sub-interface commands if that makes sense.
btw... thanks for the reply.
thanks, Travis. that answers a follow up thought I had since on the reload it comes back with "router" as the default prompt. your comment now shines a bit more light on the subject. and I didn't remember having to enter switchport more than once before previously (other labs) so I thought I was losing my mind. thanks, again.
ONE IP on Vlan interface per Layer 2 is ALL you get; but no IPs under interface;
On Layer 3, you have IPs per Vlans (multiple Vans if u wish) and same thing for interfaces; every one interface can have IP just u have to do no switchport;
if u using cisco learning labs, u are using IOU; not a real gear but close; there are L2 and L3 IOUs;
In certain IOS Software on Unix images supporting Layer-2 features, the default port behavior is to not be be in switchport mode. Where that's the case, the lab exercise content will specifically state to configure the interface to be a layer-2 switchport via the switchport sub-interface command. The default hostname in those images may also be "router" as you have noted. Both of those peculiarities have been changed in recent IOS Software on Unix images for Layer-2 so that the default hostname is "switch" and the ethernet ports are enabled and in switchport mode by default.
Technical Support Engineer
hey bro, i'll copy paste from this reference: http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008015bfd6.shtml#topic1
In switches that support both L3 interfaces and L2 switchport, the message Command rejected: [interface] not a switching port displays when you try to enter a command related to layer 2 on a port that is configured as a layer 3 interface.
In order to convert the interface from layer 3 mode to layer 2 mode, issue the interface configuration command switchport. After you issue this command, configure the port for any layer 2 properties.
mind that L3 interface stated above refers to routed interface (not SVI).
So, there's one more question.. is this means in every switches that support both L3 and L2 inteface, let say 4500 or 6500, i'll have to issue "switchport" on port to make it L2? not quite. switches are hardwares and what controls command is Operating System. there are IOS and CatOs. if you running IOS on 6500 then you'll have to issue "switchport", but on CatOS there's no need doing that.
hope it helps.