Configuring Etherchannels - Cisco Catalyst 4500 Series Configuration Manual

Chapter 24 Configuring EtherChannel and Link State Tracking

Configuring EtherChannels

These subsections describe how EtherChannels are configured:
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EtherChannel Configuration Overview
You can configure EtherChannels manually or use the Port Aggregation Control Protocol (PAgP) or the
Link Aggregation Control Protocol (LACP) (Cisco IOS Release 12.2(25)EWA and later), to form
EtherChannels. The EtherChannel protocols allow ports with similar characteristics to form an
EtherChannel through dynamic negotiation with connected network devices. PAgP is a
Cisco-proprietary protocol and LACP is defined in IEEE 802.3ad.
PAgP and LACP do not interoperate. Ports configured to use PAgP cannot form EtherChannels with
ports configured to use LACP and vice versa.
Table 24-1
Table 24-1
Mode
on
auto
desirable
passive
active
Manual EtherChannel Configuration
Manually configured EtherChannel ports do not exchange EtherChannel protocol packets. A manually
configured EtherChannel forms only when you configure all ports compatibly in the EtherChannel.
PAgP EtherChannel Configuration
PAgP supports the automatic creation of EtherChannels by exchanging PAgP packets between LAN
ports. PAgP packets are exchanged only between ports in auto and desirable modes.
OL-25340-01
EtherChannel Configuration Overview, page 24-3
Manual EtherChannel Configuration, page 24-3
PAgP EtherChannel Configuration, page 24-3
IEEE 802.3ad LACP EtherChannel Configuration, page 24-4
lists the user-configurable EtherChannel modes.
EtherChannel Modes
Description
Mode that forces the LAN port to channel unconditionally. In the on mode, a usable
EtherChannel exists only when a LAN port group in the on mode is connected to another
LAN port group in the on mode. Because ports configured in the on mode do not negotiate,
there is no negotiation traffic between the ports.
PAgP mode that places a LAN port into a passive negotiating state in which the port
responds to PAgP packets it receives but does not initiate PAgP negotiation.
PAgP mode that places a LAN port into an active negotiating state in which the port
initiates negotiations with other LAN ports by sending PAgP packets.
LACP mode that places a port into a passive negotiating state in which the port responds
to LACP packets it receives but does not initiate LACP negotiation.
LACP mode that places a port into an active negotiating state in which the port initiates
negotiations with other ports by sending LACP packets.
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
About EtherChannel
24-3