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Catalyst 2940 Switch Software Configuration Guide
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Chapter25 Configuring EtherChannels
Configuring EtherChannels
Default EtherChannel Configuration
Table25-2 shows the de fault E t herCh ann el co nfigurati on .
EtherChannel Configuration Guidelines
If improperly configured, some EtherChannel interfaces are automatically disabled to avoid network
loops and other problems. Follow these guidelines to avoid configuration problems:
•Configure an EtherChannel with up to eight Ethernet interfaces of the same type.
Note Do not configure a GigaStack GBIC port as part of an EtherChannel.
•Configure all interfaces in an EtherChannel to o pera t e at th e s ame sp ee ds an d d upl ex m od es.
•Enable all interfaces in an EtherChannel. An interface 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 interfaces 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 secure port as part of an EtherChannel.
•Before enabling 802.1X on the port, you must first remove it from the EtherChannel. If you try to
enable 802.1X on an EtherChannel or on an active port in an EtherChannel, an error message
appears, and 802.1X is not enabled. If you enable 802.1X on a not-yet active port of an
EtherChannel, the port does not join the EtherChannel .
•An EtherChannel supports the same allowed range of VLANs on all the interfaces in a trunking
Layer 2 EtherChannel. When configuring an interface for PAgP, if the allowed range of VLANs is
not the same, the interfaces do not form an EtherChannel even when PAgP is set to the auto or
Table25-2 Default EtherChannel Configuration
Feature Default Setting
Channel groups None assigned.
PAgP mode No default.
PAgP learn method Aggregate-port learning on all interfaces.
PAgP priority 128 on all interfaces. (Changing this value has no effect.)
LACP learn method Aggregate-port learning on all interfaces.
LACP priority 32768 on all interfaces.
Load balancing Load distribution on the switch is based on the
source-MAC address of the incoming packet.