Cisco Systems DSC9148D8G48PK9 Prerequisites for PortChannels, Manually Configured Channel Groups

Chapter 6 Configuring PortChannels

Prerequisites for PortChannels

•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.

Manually Configured Channel Groups

A user-configured channel group cannot be converted to an autocreated channel group. However, you can convert an autocreated channel group to a manual channel group. Once performed, this task is irreversible. The channel group number does not change, but the member ports operate according to the properties of the manually configured channel group, and the autocreation of channel group is implicitly disabled for all member ports.

Tip If you enable persistence, be sure to enable it at both ends of the PortChannel.

Prerequisites for PortChannels

Before configuring a PortChannel, consider the following guidelines:

•Configure the PortChannel across switching modules to implement redundancy on switching module reboots or upgrades.

•Ensure that one PortChannel is not connected to different sets of switches. PortChannels require point-to-point connections between the same set of switches.

	Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
6-12	OL-29284-01, Release 6.x