> # PortChannel Limitations

> PortChannels have the following restrictions:

> - The maximum number of PortChannels allowed is 256 if all switching modules are Generation 2 or Generation 3, or both.
> - The maximum number of PortChannels allowed is 128 whenever there is a Generation 1 switching module in use with a Generation 2 or Generation 3 switching module.
> - Ports need to be configured in dedicated rate mode on the Generation 2 and Generation 3 switching module interfaces to be used in the PortChannel.

> Note The number of PortChannels allowed does not depend on the type of supervisor module. However, Generation 3 modules require the Supervisor 2 module on the MDS 9506 and 9509 switches.

> The Generation1, Generation 2, and Generation 3 modules have the following restrictions for PortChannel configuration:

> - Generation 1 switching module interfaces do not support auto speed with a maximum of 2 Gbps.
> - Generation 1 and Generation 2 module interfaces do not support auto speed with maximum of 4 Gbps.
> - Generation 2 and Generation 3 switching module interfaces cannot be forcefully added to a PortChannel if sufficient resources are not available.

> When configuring PortChannels on switches with Generation 1, Generation 2, and Generation 3 switching modules, follow one of these procedures:

> - Configure the PortChannel, and then configure the Generation 2 and Generation 3 interfaces to auto with a maximum of 2 Gbps.
> - Configure the Generation 1 switching modules followed by the Generation 2 switching modules, and then the Generation 3 switching modules, and then configure the PortChannel.

> When configuring PortChannels on switches with only Generation 2 and Generation 3 switching modules, follow one of these procedures:

> - Configure the PortChannel, and then configure the Generation 3 interfaces to auto with a maximum of 4 Gbps.
> - Configure the Generation 2 switching modules, followed by the Generation 3 switching modules, and then configure the PortChannel.

> Table 13-11 describes the results of adding a member to a PortChannel for various configurations.

> Table 13-11 PortChannel Configuration and Addition Results
> PortChannel Members | Configured Speed | New Member Type | Addition Type | Result
> --- | --- | --- | --- | ---
> PortChannel | New Member
> No members | Any | Any | Generation 1 or Generation 2 or Generation 3 or Generation 4 | Force | Pass
> Auto | Auto | Generation 1 or Generation 2 or Generation 3 or Generation 4 | Normal or force | Pass
> Auto | Auto max 2000 | Generation 2 or Generation 3 or Generation 4 | Normal | Fail
> Force | Pass or fail1
> Auto | Auto max 4000 | Generation 3 or Generation 4 |  |
> Auto max 2000 | Auto | Generation 2 or Generation 3 or Generation 4 | Normal | Fail
> Force | Pass
> Auto max 2000 | Auto max 4000 | Generation 3 or or Generation 4 |  |
> Auto max 4000 | Auto | Generation 2 or Generation 3 or or Generation 4 |  |
> Auto max 4000 | Auto max 2000 | Generation 2 or Generation 3 or or Generation 4 |  |
> Generation 1 interfaces | Auto | Auto | Generation 2 or Generation 3 | Normal | Fail
> Force | Pass
> Auto max 2000 | Auto | Generation 1 | Normal or force | Pass
> Auto max 2000 | Auto | Generation 2 or Generation 3 | Normal | Fail
> Force | Pass or fail1
> Auto max 4000 | Auto | Generation 1 or Generation 2 |  |
> Auto max 4000 | Auto | Generation 3 |  |
> Generation 2 interfaces | Auto | Auto | Generation 1 | Normal or force | Fail
> Auto max 2000 | Auto | Generation 1 | Normal or force | Pass
> Auto max 2000 | Auto | Generation 2 or Generation 3 | Normal | Fail
> Force | Pass
> Auto | Auto max 2000 | Generation 2 or Generation 3 | Normal | Fail
> Force | Pass
> Generation 3 interfaces | Auto | Auto | Generation 1 | Normal or force | Fail
> Auto max 2000 | Auto | Generation 1 | Normal or force | Pass
> Auto max 2000 | Auto | Generation 2 | Normal | Fail
> Force | Pass
> Auto | Auto max 2000 | Generation 2 | Normal | Fail
> Force | Pass
> Auto max 2000 | Auto | Generation 3 | Normal | Fail
> Force | Pass
> Auto | Auto max 2000 | Generation 3 | Normal | Fail
> Force | Pass
> Generation 4 interfaces | Auto | Auto | Generation 1 | Normal or force | Fail
> Auto max 2000 | Auto | Generation 1 | Normal or force | Pass
> Auto max 2000 | Auto | Generation 2 | Normal | Fail
> Force | Pass
> Auto | Auto max 2000 | Generation 2 | Normal | Fail
> Force | Pass
> Auto max 2000 | Auto | Generation 3 or Generation 4 | Normal | Fail
> Force | Pass
> Auto | Auto max 2000 | Generation 3 or Generation 4 | Normal | Fail
> Force | Pass

> 1If resources are not available.

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