Open Stack

We have openstack mikata running and its trunk with cisco 2960 switch
and following configuration i have on switch side


!
interface GigabitEthernet1/0/1
 description compute-1
 switchport trunk allowed vlan 10,20
 switchport mode trunk
 spanning-tree guard root
end


why cisco trunk interface putting it into err-disabled mode? everytime
we have to reset interface to fix it. am i missing any configuration
here?