> # PortChannel Protocols

> In earlier Cisco SAN-OS releases, PortChannels required additional administrative tasks to support synchronization. The Cisco NX-OS software provides robust error detection and synchronization capabilities. You can manually configure channel groups or they can be automatically created. In both cases, the channel groups have the same capability and configurational parameters. Any change in configuration applied to the associated PortChannel interface is propagated to all members of the channel group.

> A protocol to exchange PortChannel configurations is available in all Cisco MDS switches. This addition simplifies PortChannel management with incompatible ISLs. An additional autocreation mode enables ISLs with compatible parameters to automatically form channel groups without manual intervention.

> The PortChannel protocol is enabled by default.

> The PortChannel protocol expands the PortChannel functional model in Cisco MDS switches. It uses the exchange peer parameters (EPP) services to communicate across peer ports in an ISL. Each switch uses the information received from the peer ports along with its local configuration and operational values to decide if it should be part of a PortChannel. The protocol ensures that a set of ports are eligible to be part of the same PortChannel. They are only eligible to be part of the same PortChannel if all the ports have a compatible partner.

> The PortChannel protocol uses two subprotocols:

> - Bringup protocol—Automatically detects misconfigurations so you can correct them. This protocol synchronizes the PortChannel at both ends so that all frames for a given flow (as identified by the source FC ID, destination FC ID and OX_ID) are carried over the same physical link in both directions. This helps make applications such as write acceleration, work for PortChannels over FCIP links.
> - Autocreation protocol—Automatically aggregates compatible ports into a PortChannel.

> This section describes how to configure the PortChannel protocol and includes the following sections:

> - Channel Group Creation
> - Autocreation
> - Manually Configured Channel Groups

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