London(config)# interface #fa0/1
London(config-if)# switchport trunk encapsulation dot1q
London(config-if)# switchport mode trunk
%LINEPROTO-5-UPDOWN:Line protocol on Interface FastEthernet0/1, changed state to down
%LINEPROTO-5-UPDOWN:Line protocol on Interface FastEthernet0/1, changed state to up
London(config-if)#end
NewYork# show dtp interface fa0/1
DTP information for FastEthernet0/1
TOS/TAS/TNS: ACCESS/AUTO/ACCESS
TOT/TAT/TNT: NATIVE/ISL/NATIVE
Communication between London and New York is down. Which command set must be applied to resolve this issue?