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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter36 Configuring EtherChannels and Link-State Tracking
Configuring EtherChannels
EtherChannel Configuration Guidelines
If improperly configured, some EtherChannel ports are automatically disabled to avoid network loops
and other problems. Follow these guidelines to avoid configuration problems:
Do not try to configure more than 48 EtherChannels on the switch stack.
Configure a PAgP EtherChannel with up to eight Ethernet ports of the same type.
Configure a LACP EtherChannel with up to16 Ethernet ports of the same type. Up to eight ports can
be active, and up to eight ports can be in standby mode.
Configure a cross-stack EtherChannel with up to two 10-Gigabit Ethernet module ports.
Configure all ports in an EtherChannel to operate at the same speeds and duplex modes.
Enable all ports in an EtherChannel. A port in an EtherChannel that is disabled by using the
shutdown interface configuration command is treated as a link failure, and its traffic is transferred
to one of the remaining ports in the EtherChannel.
When a group is first created, all ports follow the parameters set for the first port to be added to the
group. If you change the configuration of one of these parameters, you must also make the changes
to all ports in the group:
Allowed-VLAN list
Spanning-tree path cost for each VLAN
Spanning-tree port priority for each VLAN
Spanning-tree Port Fast setting
Do not configure a port to be a member of more than one EtherChannel group.
Do not configure an EtherChannel in both the PAgP and LACP modes. EtherChannel groups running
PAgP and LACP can coexist on the same switch or on different switches in the stack. Individual
EtherChannel groups can run either PAgP or LACP, but they cannot interoperate.
Do not configure a Switched Port Analyzer (SPAN) destination port as part of an EtherChannel.
Do not configure a secure port as part of an EtherChannel or the reverse.
Do not configure a private-VLAN port as part of an EtherChannel.
Do not configure a port that is an active or a not-yet-active member of an EtherChannel as an
IEEE 802.1x port. If you try to enable IEEE 802.1x on an EtherChannel port, an error message
appears, and IEEE 802.1x is not enabled.
If EtherChannels are configured on switch interfaces, remove the EtherChannel configuration from
the interfaces before globally enabling IEEE 802.1x on a switch by using the dot1x
system-auth-control global configuration command.
Do not enable link-state tracking on individual interfaces that will be part of a downstream
Etherchannel interface.