> # Interface Addition to a PortChannel

> You can add a physical interface (or a range of interfaces) to an existing PortChannel. The compatible parameters on the configuration are mapped to the PortChannel. Adding an interface to a PortChannel increases the channel size and bandwidth of the PortChannel.

> A port can be configured as a member of a static PortChannel only if the following configurations are the same in the port and the PortChannel:

> - Speed
> - Mode
> - Rate mode
> - Port VSAN
> - Trunking mode
> - Allowed VSAN list or VF-ID list

> After the members are added, regardless of the mode (ACTIVE and ON) used, the ports at either end are gracefully brought down, indicating that no frames are lost when the interface is going down (see the "Generation 1 PortChannel Limitations" topic and "Graceful Shutdown" topic).

> ## Compatibility Check

> A compatibility check ensures that the same parameter settings are used in all physical ports in the channel. Otherwise, they cannot become part of a PortChannel. The compatibility check is performed before a port is added to the PortChannel.

> The check ensures that the following parameters and settings match at both ends of a PortChannel:

> - Capability parameters (type of interface, Gigabit Ethernet at both ends, or Fibre Channel at both ends).
> - Administrative compatibility parameters (speed, mode, rate mode, port VSAN, allowed VSAN list, and port security).

> Note Ports in shared rate mode cannot form a PortChannel or a trunking PortChannel.

> - Operational parameters (remote switch WWN and trunking mode).

> A port addition procedure fails if the capability and administrative parameters in the remote switch are incompatible with the capability and administrative parameters in the local switch. If the compatibility check is successful, the interfaces are operational and the corresponding compatibility parameter settings apply to these interfaces.

> ## Suspended and Isolated States

> If the operational parameters are incompatible, the compatibility check fails and the interface is placed in a suspended or isolated state based on the configured mode:

> - An interface enters the suspended state if the interface is configured in the ON mode.
> - An interface enters the isolated state if the interface is configured in the ACTIVE mode.

> Copyright 2010-2013, Cisco Systems, Inc. All rights reserved.