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.

---

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