[QUOTE="slipstream_242"] Hiya all. I`m trying to configure sub interfaces on my router but it doesn't seem to want to know. I think I know what the problem is but would like to know if I am right or not. can sub interfaces only be created on fastethernet ports? I have tried this on a 2503 and a 2610 and get a message saying that ip routing is only allowed when configuring a sub interface as part of vlan configuration. The ICND book I am working from shows the interface as fastethernet but the ones on both of my routers are normal Ethernet and not fastethernet Any help would be appreciated. Gordon [/QUOTE] Some 10mb ethernet interfaces do provide support for 802.1q. I do not think the 2503 supports this. However I do believe that the 2610 with a > 12.2T IP Plus IOS will support this. You will need to change the encapsulation to 802.1q to allow you to create and use sub interfaces.