> # Autocreation

> The autocreation protocol has the following functionality:

> - A port is not allowed to be configured as part of a PortChannel when the autocreation feature is enabled. These two configurations are mutually exclusive.
> - Autocreation must be enabled in both the local and peer ports to negotiate a PortChannel.
> - Aggregation occurs in one of two ways:
> - A port is aggregated into a compatible autocreated PortChannel.
> - A port is aggregated with another compatible port to form a new PortChannel.
> - Newly created PortChannels are allocated from the maximum possible PortChannel (128 for Generation 1 or a combination of Generation 1 and Generation 2 switches, or 256 for Generation 2 switches) in a decreasing order based on availability. If all 128 (or 256) numbers are used up, aggregation is not allowed.
> - You cannot change the membership or delete an autocreated PortChannel.
> - When you disable autocreation, all member ports are removed from the autocreated PortChannel.
> - Once the last member is removed from an autocreated PortChannel, the channel is automatically deleted and the number is released for reuse.
> - An autocreated PortChannel is not persistent through a reboot. An autocreated PortChannel can be manually configured to appear the same as a persistent PortChannel. Once the PortChannel is made persistent, the autocreation feature is disabled in all member ports.
> - You can enable or disable the autocreation feature on a per-port basis or for all ports in the switch. When this configuration is enabled, the channel group mode is assumed to be active. The default for this task is disabled.
> - If autocreation of channel groups is enabled for an interface, you must first disable autocreation before downgrading to earlier software versions or before configuring the interface in a manually configured channel group.

> Tip When enabling autocreation in any switch in the Cisco MDS 9000 Family, we recommend that you retain at least one interconnected port between the switches without any autocreation configuration. If all ports between two switches are configured with the autocreation feature at the same time, you may face a possible traffic disruption between these two switches as the ports are automatically disabled and reenabled when ports are added to an autocreated PortChannel.

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