%AUTOSTATE-6-SHUT_DOWN: Putting interface Port-channel1.102 into Autostate mode

[admin_2]

there is a catalyst 4003 with ws-4232-l3 route module ,it connects to the facility of Redback through 4 fast ethernet links, not port channel

someday,they didn't work well ,the four links were down ,but the other ports also worked well ,we did nothing,and information said Putting interface Port-channel1.102 into Autostate mode

31w5d: %AUTOSTATE-6-SHUT_DOWN: Putting interface Port-channel1.104 into Autostate mode

31w5d: %AUTOSTATE-6-SHUT_DOWN: Putting interface Port-channel1.105 into Autostate mode

31w5d: %AUTOSTATE-6-SHUT_DOWN: Putting interface Port-channel1.106 into Autostate mode

31w5d: %AUTOSTATE-6-BRING_UP: Taking interface Port-channel1.106 out of Autostate mode

after 8 minutes ,the port worked well automatically. i want to know the meaning of the information above ,what's the reason result in

[#2]

When the last external port on a VLAN goes down, all Layer 3 interfaces/subinterfaces on that VLAN shut down (are autostated) unless sc0 is on the VLAN or another router is in the chassis with an interface/subinterface in the VLAN. When a Layer 3 interface goes down, this message is reported to the console for each Layer 3 interface