Guidelines for EtherChannels

You cannot use Firepower 1010 switch ports or VLAN interfaces in EtherChannels.

You can configure up to 48 EtherChannels, depending on how many interfaces are available on your model.

When you add the first member interface, it sets the required hardware properties of all member interfaces.

• The media type of member interfaces can be either RJ-45 or SFP; SFPs of different types (copper and fiber) can be mixed. You cannot mix RJ-45 and SFP interfaces.

• All interfaces must be set to the same speed and duplex.

• The first interface sets the speed capacity, which cannot be changed later.

  • For SFP Detect interfaces—You can include interfaces with different speed capacities as long as they have a common speed. When you set the speed to SFP Detect (the default), the speed will be dynamically set to the highest common speed. If you later change the member interfaces so that the common speed is now higher, the EtherChannel speed will also be higher automatically.

    You can set a specific speed, but only speeds that are available on the first member interface. For example, if your first interface is 1/10GB, then the available speeds for the EtherChannel will be 1GB, 10GB, and SFP Detect. If you later remove the 1/10GB interfaces and replace them with 1/10/25GB interfaces, you cannot manually set the speed to 25GB. In this case, you can use SFP Detect to use the 25GB speed.

  • For non-SFP Detect interfaces—All additional interfaces must have the same speed capacity. For example, if your first interface speed capacity is 10MB/100MB/1GB, you must add other 10MB/100MB/1GB interfaces. You can set the EtherChannel (and its member interfaces) to any of those speeds. You cannot later add 1/10GB interfaces to the EtherChannel, even if you remove the lower capacity interfaces. You also cannot mix interface capacities (for example 1GB and 10GB interfaces) by setting the speed to be lower on the larger-capacity interface.

The device to which you connect the EtherChannel must also support 802.3ad EtherChannels.

The device does not support LACPDUs that are VLAN-tagged. If you enable native VLAN tagging on the neighboring switch using the Cisco IOS vlan dot1Q tag native command, then the device will drop the tagged LACPDUs. Be sure to disable native VLAN tagging on the neighboring switch. In multiple context mode, these messages are not included in a packet capture, so that you cannot diagnose the issue easily.

The LACP rate depends on the model. When you set the rate (normal or fast), the device requests that rate from the connecting switch. In return, the device will send at the rate requested by the connecting switch. We recommend that you set the same rate on both sides.

• Firepower 9300—The LACP rate is set to fast by default in FXOS, but you can configure it as normal (also known as slow).

• Secure Firewall 3100—The LACP rate is set to normal (slow) by default, but you can configure it as fast on the device.

• All other models—The LACP rate set to normal (also known as slow), and it is not configurable, which means the device will always request a slow rate from the connecting switch. We recommend setting the rate on the switch to slow, so both sides send LACP messages at the same rate.

In Cisco IOS software versions earlier than 15.1(1)S2, did not support connecting an EtherChannel to a switch stack. With default switch settings, if the EtherChannel is connected cross stack, and if the primary switch is powered down, then the EtherChannel connected to the remaining switch will not come up. To improve compatibility, set the stack-mac persistent timer command to a large enough value to account for reload time; for example, 8 minutes or 0 for indefinite. Or, you can upgrade to more a more stable switch software version, such as 15.1(1)S2.

All the configuration refers to the logical EtherChannel interface instead of the member physical interfaces.