I just created a new VLAN 51 on my 6224 core switch.
I've assigned it an IP Address, configured routing, assigned it to multiple trunks, and I've assigned an access port to it as well. This is the 8th VLAN i'm setting up, haven't had any issues with the others.
Here is what I see when I do show ip interface vlan 51
PHX_Core_Switch#show ip interface vlan 51
Routing Interface Status....................... Down
Primary IP Address............................. 10.200.51.1/255.255.255.0
Routing Mode................................... Enable
Administrative Mode............................ Enable
Forward Net Directed Broadcasts................ Disable
Proxy ARP...................................... Enable
Local Proxy ARP................................ Disable
Active State................................... Inactive
MAC Address.................................... 5C26.0AF9.9E8C
Encapsulation Type............................. Ethernet
IP MTU......................................... 1500
Bandwidth...................................... 10000 kbps
Destination Unreachables....................... Enabled
ICMP Redirects................................. Enabled
Why is this interface down?! Help?! I'm going nuts over here!