vPC config with a IOS 3850 switched Port-Channel

I have two Cisco Nexus 9Ks and a downstream 3850 access switch. I want to configure a port-channel on the 3850 with two member-trunks which will be dual-homed up to the 9K Nexus pair with a vPC config on the 9K's

Below is the config I would use on each switch to do this, but my question is this, should I do channel-group mode ON or ACTIVE? What is the default if I just say channel-group 1 on the member interface configs?

Example Config

9K-1

interface port-channel 1

Switchport mode trunk

vpc 1

!

interface eth1/1

switchport mode trunk

channel-group 1

​

9K-2

interface port-channel 1

Switchport mode trunk

vpc 1

!

interface eth1/1

switchport mode trunk

channel-group 1

​

3850_Switch

interface port-channel 1

Switchport mode trunk

​

!

interface G1/0/1

switchport mode trunk

channel-group 1 mode on